Ok Week 2 Assignment
1. Please go back to the week one assignment.... Question 3: Question 3 asked you to discuss one significant passage or phrase. Please go to any two of your classmates assignments and read their quotes from question #3 week one. Then click reply and add a 2-3 sentence comment or critique on their chosen passage. I shared a link with you on how to post... sorry of the poor audio quality!
2. Read chapters 4 and 5 "teeth" and "Getting Ahead"...
Part 1. What are 3 significant evolutionary facts about teeth? Think of things like who, what, why, where and how. Please list these "facts" or "significant events" that Shubin discusses. Please give the
page number and a "short part of the sentence or quote" that it comes from.
Part 2. What are some of the reasons why almost all animals have heads? Give 3 examples that Shubin states from chapter 5. Please include the page number and a brief part of the quote or
sentence. Also name 2 animals that don't have a head.... feel free to put a link to the picture of the animal in the blog if you think it will help.
Part One: 1. As animals evolved, the pattern of teeth changed. Teeth now fit into one another, from the top row to the bottom row, neatly. The book says, "These patterns of wear are so fine that different species of early mammals can be distinguished by their patterns of tooth wear and occlusion" (72).
ReplyDelete2. As animals evolved, so did the kinds of teeth in their mouths. Teeth became specialized to do certain jobs. Some were grinders, while other ripped meat. The book says, "The mouth developed a kind of division of labor" (73).
3. The process by which teeth are made is similar to the process by which other parts of the body are made. The book says, "Teeth, breasts, feathers, and hair all develop from the interactions between layers of skin" (79). The process involves two layers of skin coming together, folding, and secreting proteins.
Part Two: Animals have heads to protect the precious equipment that is housed inside the head. There is a brain, some tissues, and other organs. The book says, "Another part of our skull lies underneath the brain, forming a platform that holds it up" (82). The head is also the home to numerous nerves. The nerves allow information to travel from your nose to your brain, where it can be processed. The book says, "The cranial nerve that goes to our nasal structures, the olfactory, has one job: to take information from our nasal tissues to our brain" (84). Though the body is somewhat segmented, the head helps connect it all, ad what occurs in the brain can affect the entire body. The book says, "This was a revolutionary idea because it linked heads and bodies as two versions of the same fundamental plan" (89). Two animals that have no head are starfish and bivalves(types of molusks).
I like the quote Elizabeth choose that stated how the head connects the body because the brain controls everything. It is fascinating to think that even though our head is only a small part of our body it controls every other body part.
DeleteElizabeth's quote about the head and the body being two different "versions of the same plan" is thought-provoking in the sense that even though it is technically all one body, the part that controls the entirety of it is almost a separate piece.
DeleteElizabeth pointed out how teeth evolved with the animals to do certain tasks needed for their diet. Animals with only incisors would not be able to eat a substance such as a carrot because they would not be able to mash it, only cut it. Their teeth have to evolve so that their certain diets can work.
DeleteMelissa Sybertz Your Inner Fish assignment #2
ReplyDelete2. Evolutionary facts about teeth:
- A rodent-sized mammal was found with a specific teeth set up from 150 million years ago. They had incisors in the front were specialized to cut food, then farther back the canines to puncture it, and finally,in the way back,molars to mash it. These mice-like rodents have a similar mouth and tooth set up as us. Just try to imagine how you would go about eating a carrot without your molars. Shubin writes,”These little mammals, which resemble mice, have a fundamental piece of our history inside of them.” (p. 73).
- An organism called Tritheledonts(creatures 10 million years ago) have a certain way of chewing. The individual cusps do not interlock in a precise way like us. Instead, the entire inner surface of the upper tooth shears against the outer surface of the lower tooth, like scissors. Shubin writes,”When we go back in time, to rocks about 10 million years older in Nova Scotia, we find tritheledonts with an incipient version of this way of chewing.” (p.72).
-The only reason that we, as humans, can maintain our vast diet is because of our ancestors. They had mouths full of different types of teeth that had different jobs that enable us to eat almost anything. Shubin writes, “Our diverse diet, ranging from fruit to meat to Twinkie, is possible only because out distant mammalian ancestors developed a mouth with different types of teeth that can occlude precisely”(p. 74).
2. part 2- reasons why almost all animals have heads:
The head of an animal is where all the nerves, and muscles work to send signals to certain parts of the body in order to give vital information, like chewing, swallowing, and breathing. Shubin writes,”The muscles and cranial nerves we use to swallow and talk...”(p 92) Animals need heads to protect the brain from being damaged. When the brain is damaged, vital actions can be slowed down causing the animal to be more likely killed or eaten. Shubin writes,”Inside the skull are a number of compartments and spaces that house different organs. Obviously, the brain occupies the largest of these. ”(p. 83) The head of an animal is where all things connect. All things lead back to the brain and nerves and muscles in our head. “The trigeminal branches do two major things: they control muscles...”(p. 84).
Two animals that don't have a head are sea urchins and coral.
I think Melissa's quote about how humans have vast diets because our mouths are full of different types of teeth is interesting. I find this interesting because its hard to think of what our diets would consist of if we had only one type of teeth. Our diets as humans would be completely changed.
DeleteI think Mable's idea that the difference between the rodent sized mammal's teeth and our current teeth today is an important aspect of history was a nice connection. I think that it led in nicely to her next point.
DeleteMikayla Kingman
ReplyDeleteJuly 25, 2013
Part 1: “For years, paleontologists have argued about why hard skeleton s, those containing hydroxyapatite, arose in the first place. For those who believed that skeletons began with jaws, backbones, or body armor, conodonts provide an “inconvenient tooth,” if you will. The first hard hydroxyapatite-containing body parts were teeth. Hard bones arose not to protect animals, but to eat them.”(76)
“By about 150 million years ago, in rocks from around the world, we find small rodent-size mammals with a new kind of tooth row, one that paved the way for our own existence. What made these creatures kinds of teeth set in it.”(73)
“We had the earliest teeth in the fossil record for over 150 years before we realized what they were. The reason comes down to how fossils are preserved. The hard bits, for example teeth, tend to get preserved easily.”(76)
Part 2: “Attached to the bones and organs in the head are the muscles we use to bite, to talk, and to move our eyes and whole head.”(83) This states that the head is very useful for the body where some of the most important muscles in the body are occupied in the head.
“The plate-like bones of our skulls form over our gill arches, and the muscles, nerves, and arteries, which all had a very simple segmental pattern early on are rewired to make our adult heads.”(89) The simple form of our bodies are formed around the main parts and functions in our bodies. The pattern that follows for adult life is very important to form our bodies correctly, the plate like bones in the head are useful to our bodies to protect our functions in our heads.
“Vessels and nerves make curious loops and turns as they travel through the skull.”(82) Importantly I believe that most animals have heads because important functions travel through and connect with the brain and head.
Two animals that don’t have heads are star fish and worms.
I agree with you when you mention how important the head is for everyday activities. Some people may be unaware that the muscles used for essential everyday activities such as eating are attached to the head. Without the head, humans would not be able to do these activities. So even though the head is only one body part, it is an important one since it effects the whole body.
DeleteI think Mikayla explained the conodont's uses and history well and had a good quote with it. Mikayla also had good reasons for why almost all animals have heads. She explained nicely the uses and functions that make so many animals require heads.
Delete2.) Part 1:
ReplyDelete1. Fossils of creatures in which were found to be half reptile and half mammal showed the earliest signs of tooth-to-tooth occlusion. The fossils were found in 10 million year old rocks in places such as Nova Scotia and seemed to have a similar way of chewing as humans do. "This was a reptile with tooth-to-tooth occlusion. My fossil was part mammal, part reptile." (70)
2. Small rodent fossils found in rocks about 150 million years old displayed an even closer similarity to human teeth. Their complex sets of teeth were the same as our own. They had all-purpose teeth and a similar way of chewing. "What made these creatures special was the complexity of their mouths: the jaw had different kinds of teeth in it." (73)
3. What was originally discovered to be a 250 million year old organism called a Conodont was later found to be the earliest record of teeth. This was not known until much later. They were discovered later to be the teeth of an ancient jawless fish. "We had the earliest teeth in the fossil record for over 150 years before we realized what they were." (76)
Part 2:
Animals have heads for many different reasons. One of these reasons is to protect the important organs that lie in the inside of our heads, most importantly, our brains. Shubin writes, "Inside the skull are a number of compartments and spaces that house different organs. Obviously, the brain occupies the largest of these" (83). The head also contains two very important cranial nerves known as the trigeminal and the facial. Both nerves "carry information about both sensation and action" (84). Lastly, the head connects and also continues the body's segmental configuration. This configuration is why all of our body parts are distinct from one another. The author states, "Heads may not look it, but they also contain a very deep segmental pattern"(89).
Two animals that do not have a head are worms and sponges.
I never thought about how sponges don't have heads. I always just assumed sponges were more like plants but now i realize that they are living things.
DeleteShannon points out that fossils that are found from a very long time ago can still be related to humans. Even though there is a lot of time that passes between them a connection can still be made. Also, Shannon shows that the head follows the same pattern as the rest of the body because it is segmented.
DeleteAP Biology
ReplyDelete2. Part 1: Facts/Significant Events
1. Teeth, in their early days were only used for biting other organisms and breaking those organisms down through, grinding, piercing, and puncturing. However later versions of teeth are being utilized as protection as time has passed and animals developed different needs and ways to effectively use them.
1. Quote: “Teeth originally arose to bite creatures; later, a version of teeth was used in a new way to protect them”(78).
2. Researchers discovered that conodonts were actually teeth not animals, vegetables, or minerals. The realization that conodonts were teeth came when paleontologists found lamprey-like fossils that started to come out of rocks in South America and the western United States. Researchers started seeing whole assemblages of conodonts in their mouths. It then became clear that conodonts were actually teeth, inside ancient jawless fish. This changed the oldest discovered teeth to conodonts. Scientists thought they had discovered the oldest teeth 150 years ago, until they made the conodonts discovery.
2. Quote: “Conodonts were the teeth of an ancient jawless fish. We had the earliest teeth in the fossil record for over 150 years before we realized what they were” (76).
3. Tritheledonts were discovered in fossil form 1984 when Neil Shubin and his expedition team went to Nova Scotia. Bill a member of his research team uncovered the fossil in a rock they brought back from the expedition. This was a huge discovery because tritheledonts are very rare part mammal, part reptile organisms. In the fossil which was a jaw, Neil noticed he was looking at a tooth to tooth occlusion of an organism that was alive during the time when fish/reptiles were moving from water to land and displayed mammal-like features as well. The tooth to tooth occlusion of this tritheledont uncovered what the teeth of organisms from this high profile time period looked like, bumpy and ridged with cusps that had little patches of wear.
3. Quote: “Looking at the teeth under the microscope gave me the biggest surprise: the cusps had little patches of wear. This was a reptile with tooth-to-tooth occlusion. My fossil was part mammal, part reptile” (70).
2. Part 2:
Almost all animals have heads for many reasons. Heads are essential for receiving and sending out orders throughout an organism's body, in order for the body to function. One reason why animals have heads is because the plates that form the skull in heads is a form of support and protection for the otherwise defenseless and very valuable organ/muscle that the skull encompasses, the brain. Shubin writes, “Another part of our skull lies underneath the brain, forming a platform that holds it up”(82). There are many more reasons to why almost all animals have heads, another reason why almost all animals have heads is because the heads of animals carry nerves. For example, one of the four major nerves in the cranium or head is the cranial nerve. The cranial nerve has one job, the nerve runs from the nasal tissues in a nose up into the brain carrying information such as smell so our brain can activate transmitters to distinguish the actual smell of an object. Shubin writes, “The cranial nerve that goes to our nasal structures, the olfactory, has one job: to take information from our nasal tissues to our brain”(84). Lastly, heads are connected to the body, helping to receive and send nerve transmissions throughout, making the whole body a cohesive unit that feels a sensation, sends a signal to the brain, then relays energy back to the place where there was a sensation to perform a task. This is how we function as animals, and humans and without a head we would be nothing as aerobic organisms. Shubin writes, “This was a revolutionary idea because it linked heads and bodies as two versions of the same fundamental plan”(89). Lastly, two animals that do not happen to have a head ar worms and sponges, which were organisms stated to be headless in the book.
I agree with all of Chris' reasons as to why almost all animals have heads. He gave great quotes that really support his reasons. His answer pointed out to me that without the nerves that are in the head, the whole body would not be able to function properly.
DeleteSpecifically refering the the function/reason for the head, I think Chris did a very thorough job in explaining the the prompt and providing straightforward evidence and relating quotes.
DeleteAlicen Clifford
ReplyDeleteJust by looking at the teeth of animals from millions of years ago or modern day, you can tell what type of animal they are/were (herbivore, carnivore, etc). Shubin says, “We can learn a lot about an animal by looking at its teeth. The bumps, pits, and ridges on teeth reflect the diet. Carnivores, such as cats, have blade-like molars to cut meat, while plant eaters have a mouth full of flatter teeth that can macerate leaves and nuts” (60).
Organisms’ teeth evolved differently depending on their diet to make it easier to chew their food. Shubin writes, “Incisors in the front become specialized to cut food, canines further back to puncture it, and molars in the extreme back to shear and mash it” (73).
In order to survive, fish would have to adapt to other fish evolving. Shubin explains, “First, big fish ate little fish; then an arms race began. Little fish developed armor, big fish obtained bigger jaws to crack the armor, and so on” (76).
Almost all animals have heads because they contain the many nerves that send information to our brains, controls muscles, and have many other jobs. Shubin explains one of the nerves, “The trigeminal’s branches do two major things: they control muscles, and they carry sensory information from much of our face back to our brain. The muscles controlled by the trigeminal nerve include those we use to chew as well as tiny muscles deep inside the ear” (84). Some nerves have only one job, and it is to take information obtained by our senses to our brain. Shubin states, “The simplest cranial nerves have only one function, and they attach to one muscle or organ. The cranial nerve that goes to out nasal structures, the olfactory, has one job: to take information from our nasal tissues to our brain” (84). Every head when developing contains the four arches that form many structures that result in structures that are needed in some organisms to survive (such as the hyoid, which helps organisms to swallow). Shubin says, “Every head on every animal from a shark to a human shares those four arches in development” (90).
Two animals that don’t have a head are worms and sponges.
I like how you included the contrast between the type of teeth in carnivores and plant eaters. It is amazing how the type of animal can be determined just by looking at its teeth, no matter how old it is.
DeleteYou make a good point in being specific on how an animals teeth play a big role in humans today finding out how ancient creatures lived. One of the most important parts of fossil history (in my opinion) is using those fossils to paint a picture of the world millions of years ago.
DeleteI like how you talked about the different characteristics of the teeth of different kinds of animals. its amazing how teeth can adapt to fit the animals diet and lifestyle over time. i also liked how you talked about how teeth of animals are very important in identifying fossils.
DeleteAndrea Damon
ReplyDeleteJuly 26, 2013
Part One:
In this chapter we learn that the beginnings of chewing began 190 million years prior. The creatures, mammals, which existed then, had upper and lower teeth that co-existed the same way our teeth fit together today. This is evolutionary in the way that it started a new way of eating and set a new pattern of teeth. “Each tooth had a characteristic pattern of wear at the face where upper and lower teeth fit together. I was seeing some of the first evidence of our pattern of precise chewing, only in a tiny mammal 190 million years ago” (Shubin 67).
From page 73 to 74, Shubin writes, “Our diverse diet, ranging from fruit to meat to Twinkie, is possible only because our distant mammalian ancestors developed a mouth with different kinds of teeth that can occlude precisely.” Evolution has given humans the opportunity to have a wide range in diet due to the different teeth we have. Incisors to cut food, canines to puncture, and molars to shear or mash. This allows humans to survive on any diet and is a significant change in teeth from when they first started to appear to now.
Teeth are significant because of their hardness. This hardness is due to the molecule hydroxyapatite, which does not bend or compress. “Hard bones arose not to protect animals, but to eat them. With this, the fish-eat-fish world really began in earnest”(Shubin 76). Because fish were likely to be eaten by other fish, they began to form protective traits. Competition was high and changed the fish’s diet along with the need for defense.
Part Two:
The head is the most important body part we have. Animals that do have heads use it for the same reason as we do. “Inside the skull are a number of compartments and spaces that house different organs”(Shubin 83). The head has vital organs within that make us function the way we do, in particular the brain. A head is very complex because of its three dimensions. This quote also emphasizes the complexity of the brain, “The reason a slap to the face hurts so much, beyond the emotional pain, is because the trigeminal carries sensory information from the skin of our face back to our brain”(Shubin 84). We feel anything inflected anywhere on our bodies because of our brain and the sensitivity of the nerves. The brain does not do it alone, obviously. The brain has to send messages to someone, and that is our body. “This was a revolutionary idea because it linked heads and bodies as two different versions of the same fundamental plan”(Shubin 89). They co-exist together to complete all the functions of the body, the reason we live. Two animals that do not have heads would be a worm and a starfish.
You wrote, "Two animals that do not have heads would be a worm and a starfish". I always assumed that worms did have heads, even though the head part was not distinguishably different from the rest of the body. I suppose it begs the question of what exactly can be considered a head. Does a head need to be clear and obvious like it is for humans?
DeleteI think it is interesting to think about the fact that if we did not have different types of teeth, we could not eat all types of food. The ways that our mouths have evolved greatly influences our diets.
DeleteI agree with and share the same fascination with Elizabeth in regards to worms not having heads. Your writing sparked interest for me because I have seen many worms and not once have I ever thought that worms don't have heads. It does go to show that we, as humans can take things for granted and just assume instead of really uncovering the truth about science. I always thought the head of a worm was included in it popsicle-shaped body, but come to find out from Andrea's writing that it isnt is just remarkable and makes me curious in regards to what is assumed in the world of science when people don't actually know the truth
DeletePart 1.
ReplyDeleteTeeth begun to have specialized jobs to help the animal chew and eat food. The fact that the teeth were developing to the animals’ diets is significant. Also, it was helpful to the creatures. The ‘division of labor’ helped as well. “What made these creatures special was the complexity of their mouths: the jaw had different kinds of teeth in it.”(73)
2. Humans used to think that we had the earliest examples of teeth but we did not. These fish were soft-bodied but could has hard teeth that allowed them to eat other fish. ”Conodonts were the teeth of an ancient jawless fish.” (76)
3. “Hard bones arose not to protect animals, but to eat them.”(76). The first example of hard bones were teeth. Though many scientists originally thought that hard bones came about as a type of amour it was now proven that it was a development to allow the fish-eat-fish life to begin. Now organisms like fish could hunt each other.
Part 2.
1.”They control muscles, and they carry sensory information from much of our face back to our brain.”(84) This quote relates to the very important functions that our head is able to preform. Almost all animals have heads because it is vital to our survive to be able to carry out those functions.
2. Our heads are important because they contain the nerves that allow us to hear and see, as well as reaching other parts of our body and allowing us our senses. ”Some of the nerves that go to our eyes and ears are also simple in this way: the optic nerve is involved with vision, the acoustic nerve works in hearing.”(84)
3.Heads are important due to the way that they hold our brain and help us carry out functions necessary to life. In the book Shubin discusses that the head was made and the pattern that is used. ”To Goethe, this revealed the essential pattern within: the head is made up of vertebrae that fused and grew a vault to hold our brains and sense organs.”(88-89). Shubin goes on to say that it was part of a fundamental plan.
Name 2 animals that don't have a head:
1.Sponges
2.Worms
You wrote about how certain teeth have different jobs- that teeth are specialized. I find it extremely interesting that humans have all sorts of teeth that are shaped differently. It reflects the fact that our diet is diverse. We, unlike some animals, are not exclusively omnivores or herbivores. We need different teeth to help us consume each type of food that we eat. The placement of the teeth in the mouth are also important, as biting teeth wouldn't do much good if they were located where your molars are.
DeleteThis comment has been removed by the author.
DeleteCaitlyn's writing, as well as the writing of everyone else greatly supports how evolved teeth have become throughout history. Her writing also portrays that the evolutionary path for teeth is so specific and detail oriented because she talks about the diets of animals and how they can vary based on what they eat, and how teeth coincide with an animals diet just makes the evolution of teeth that much more marvelous.
DeletePart 1:
ReplyDeleteTeeth did not start out the way they are found in humans today. They began around 500 to 250 million years ago in an ancient fish." The conclusion became abundantly clear: Conodonts were teeth. And not just any teeth. Conodonts were the teeth of an ancient jawless fish."(Shubin 76) This is the fist knowledge that we have of teeth existence and it is believed that these teeth adapted so that the fish could eat other fish. We also know a great deal about teeth because they are so well preserved over time." Teeth are the hardest parts of our bodies, because the enamel includes a high proportion of the mineral hydroxyapatite-higher even then is found in bone. Thanks to their hardness, teeth are often the best-preserved animal part we find in the fossil record for many time periods." (Shubin 61) The structure of a tooth needs to be hard because the animal is using the teeth to break down other creatures into smaller parts so that it can consume them. If the teeth were softer than the creature it was biting, then the would fail to do their job and would probably break. The structure of teeth also tell a lot about an animal's diets and eating habits. For example if an animal has sharp teeth it probably eats meat and if it has dull grinding teeth it probably eats plants." We can learn a lot about an animal by looking at its teeth. The bumps, pits, and ridges on teeth often reflect the diet." (Shubin 60) It is because of the great preservation of teeth and the knowledge they possess that we know so much about ancient animal's diets and to an extent, how they lived.
Part 2:
The brain is the most important part of the body. It controls everything that happens in the body. The quote " Inside the skull are a number of compartments and spaces that house different organs." (Shubin 83) only hints at the complexity of the brain and all the jobs it preforms. " The reason a slap to the face hurts so much, beyond the emotional pain, is because the trigeminal carries sensory information from the skin of our face back to our brain." (Shubin 84) This quote shows how the brain registers pain through a nerve. The brain is connected to the entire body in different ways as well. The brain has nerves that connect to the eyes, ears, nose, and all throughout the rest of the limbs and body. It is through this connection that we are able to walk and talk and preform everyday functions. During the first few weeks of life the brain develops through four arches that are first found in the throat area. Everything that is created in each arch is regulated by a nerve and one nerve only connects to structures developed in one of the arches." When we identify the cells in each arch according to where they end up in the adult, things start to make a lot of sense." (Shubin 87) Just as the quote state, once we identify the cells and then find out which nerves go to these specific cells then the brain seems to make more sense. The reason that most animals have heads is because the brain acts like a control center by using nerves to connect itself to the rest of the body. Two animals that do not have heads are worms and sponges.
I like how Matt worded his first answer making the information flow as one paragraph. He chose valuable quotes that pin pointed the information he was portraying in his own words within his explanation.
DeleteI like Matt's second quote in the second paragraph because it helps to explain nerves. He shows us that the brain doesnt just have nerves i one spot, but through the entire body, which allows us to do everything that we do.
DeleteJennie Reichenbach
ReplyDeleteWeek 2 Assignment
#2, Part 1.
Fact 1: A scientist is able to tell what an animal eats by looking at the structure of it’s teeth. For example, carnivores have sharp molars used to cut meat. Shubin writes, “The bumps, pits, and ridges on teeth often reflect the diet.” (60)
Fact 2: Teeth are the hardest part of our bodies. This is why they are preserved the best when an animal fossil is found. Shubin writes, “Teeth are the hardest parts of our bodies, because the enamel includes a high proportion of the mineral hydroxyapatite--higher even than is found in bones.” (61)
Fact 3: Reptiles have extremely different jaws and tooth structures than us. Shubin writes, “Reptiles also lack the precise occlusion--the fit between upper and lower teeth-- that humans and other mammals have. Also, whereas we mammals replace our teeth only once, reptiles typically receive visits from the tooth fairy for their entire lives, replacing their teeth continually as they wear and break down.” (62)
Part 2: Almost all animals have heads for many reasons.
Reason 1: The head contains the cranial nerves which basically tell the other parts of the head what to do. Shubin writes, “Attached to the bones and organs in the head are the muscles we use to bite, to talk, and to move our eyes and whole head. Twelve nerves supply these muscles, each exiting the brain to travel to a different region inside our head. These are the dreaded cranial nerves.” (83)
Reason 2: Heads are used to do important things, like hear and chew which are used for survival. Shubin writes, “The muscles controlled by the trigeminal nerve include those we use to chew as well as tiny muscles deep inside the ear.” (84)
Reason 3: The skull protects the delicate organs and nerves inside of the head. The most important part it protects is the brain. Shubin writes, “Inside the skull are a number of compartments and spaces that house different organs. Obviously, the brain occupies the largest of these.” (83)
Two animals that don’t have a head are worms and sponges.
I think what Jennie said about how scientists are able to tell what an animal eats is interesting. Through animals teeth you can find out a lot interesting things. It's interesting how one little tooth can show the diet of an animal.
DeleteI liked Jennie's comparison of reptile teeth to human teeth. Its really fascinating how something like teeth can seem standard, but when looking into it further you can see stark contrasts from reptile teeth to mammal teeth. Teeth are truely customized.
DeletePart 2:
ReplyDelete“That molecule, known as hydroxyapatite, impregnates the molecular and cellular infrastructure of both teeth and bones, making them resistant to bending, compression, and other stresses. Teeth are extra hard because of their outer layer, enamel, is far richer in hydroxyapatite than any other structure in the body including the bone.” (pg74)
“The first hard hydroxyapatite-containing body parts were teeth. Hard bones arose not to protect animals but to eat them. With this, the fish –eat-fish world really begin earnest. First, big fish ate little fish; then arms race began. Little fish developed amour, big fish obtained bigger jaws to crack the amour, and so on. Teeth and bones really changed the competitive landscape.” (pg76)
“Teeth develop by an interaction of two layers of tissues in our developing skin. Basically, two layers approach each other cells divide, and the layers change share and make proteins. The outer layer spits out the molecular precursors of enamel, the inner layer the dentine and pulp of the inside of the tooth. Over time, the structure of the tooth is laid down, then tweaked to make the patterns of cusps and troughs that distinguished each species.” (pg 78)
Part 3:
The majority of animals have heads and the following explain some of the reasons why they have heads.
1.In the head, there are many bones and organs, the brain being the largest organ in a human skull. Muscles that are used to carry out everyday activities such as eating, talking, or moving the head itself are attached to the head. As stated by Shubin, “attached to the bones and organs in the head are the muscles we use to bite, talk, and to move our eyes and whole head.” (pg83)
2.The four different arches form and give animals heads. As explained by Shubin, “ the first arch tissues from the upper and lower jaws, two tiny ear bones (the malleus and incus) ad all the vessels and muscles that supply them. The second arch forms the third small ear bone (the stapes), a tiny throat bone and most of the muscles that control facial expressions. The third arch forms bones, muscles and nerves deeper in the throat; we use to swallow. Finally, the forth arch forms the deepest parts of our throat, including parts of our larynx and the muscles and vessels that surround it and help it function” (pg87)
3.Genes that are “turned on” three weeks into develop instruct cells to make different parts of the head. The structure of each part of the head depends on the genetic address. In Shubin’s words, “genes instruct cells to make the different portions of our head. Think of each region of our heads gaining a genetic address that makes it distinctive. Modify this genetic address and we can modify the kinds of structures that develop there.” (pg93)
I forgot to add that sponges and worms do not have heads.
DeleteI like that you added the genetic reasoning behind an animal having a head and also the four arches that form. I believe that these are also essential reasons as to why organisms have heads...it is written in their genes that the head is a major part of the body. Due to the fact that the genes create a creature that has millions of years of history and has adapted to its environment, it makes sense that one of the reasons an organism has a head would be because it is an essential piece of the body.
Delete2.
ReplyDeletePart 1
One significant evolutionary fact about teeth is that the tritheledont is one of the first mammals that started to develop specialized teeth. Each tooth was made a little differently so it could be used for different aspects of eating. The author states, “..is possible only because our distant mammalian ancestors developed a mouth with different kinds of teeth that can occlude precisely.” (74). Another evolutionary fact about teeth is that conodonts were ancient teeth that had been found in early fossil records, but it took the scientists 150 years to figure out what they were. Conodonts bodies were all soft tissue so they were not preserved; only their teeth were. Scientists discovered teeth before they even knew it. At first, they though conodonts were their own animal or mineral. However, soon they found out they were teeth. The author states, “Conodonts were the teeth of an ancient jawless fish.” (76). Also, another evolutionary fact about teeth is that teeth are a good view onto what the particular organism ate. It can tell a scientist what type of animal it is. It can tell a scientist the organism’s diet. Teeth are preserved very well because of their enamel and they give scientist a good look at the organism. Also, they can show a scientist a range of time periods. It can show the evolution of feeding habits. This could lead a scientist to infer a specific adaption an animal made to make themself stronger. The author states, “…since teeth are such a great clue to an animal’s diet, the fossil record can give us a good window on how different ways of feeding came about.” (61).
Part 2
Almost all animals have heads because it provides a center for all the nerves. Each nerve is located in the head and then is attached to a muscle or organ. The nerve goes from the brain to the muscle or organ. The brain sends the muscles or organs messages that tell it what to do and when to do it. The head provides a place for all of the nerves to connect to the brain. Cranial nerves are nerves in the brain that control the face. The author states, “The simplest cranial nerves have only one function, and they attach to one muscle or organ.” (84). Another reason almost all animals have heads is because they have developed from a common ancestor. All heads on animals develop in the same pattern, but in different specific ways. All of the organisms have adapted different ways and changed the way that their head develops. This adaption is part of evolution. It explains how all species evolved from a common ancestor, but now all look different. The head is just one of the many things that all organisms develop in the same general pattern. The author states, “Every head in every animal from a shark to a human shares those four arches in development.” (90). Also, almost all animals have heads because it protects their brain. Without their brain they would not be able to perform daily functions. The brain controls the entire body and tells everything else what to do. If the brain was not well protected it could easily become injured and an organism would not be able to survive without it. The head protects the brain so that organisms can carry out a normal life. The author states, “The plates cover our brain. Pat the top of your head, and you are feeling them. These large plates fit together like jigsaw-puzzle pieces and form much of our cranium.” (82). Two animals that do not have a head are worms and bivalves.
I like how you talked about how the teeth of the tritheledont were all a little different in order to carry out a specific chewing technique. It's interesting that an organism from that long ago was so advanced in eating techniques.
DeleteI like how you mentioned that the tritheledont was one of the first fish to develop specialized teeth. The fish eat fish world really changed once smaller fish started to develop protection form bigger fish. But then the bigger fish got bigger teeth and jaws to compensate for that evolutionary change. Its amazing how teeth and bones could drastically change the competitive nature of our world.
DeleteWho would have thought the “normal” teeth that occupy every human’s mouth was so different 500 million years ago? "The conclusion became abundantly clear: Conodonts were teeth. And not just any teeth. Conodonts were the teeth of an ancient jawless fish."(Shubin 76)
ReplyDeleteThanks to the great preservation of these jawless fish teeth, it became the first discovery of teeth existence. This structure is among the hardest part of our bodies, hence why they are found in great condition when a fossil is discovered. “Teeth are the hardest parts of our bodies, because the enamel includes a high proportion of the mineral hydroxyapatite--higher even than is found in bones.” (Shubin 61)
Teeth adapted over time so that fish could indulge on other fish. “The first hard hydroxyapatite-containing body parts were teeth. Hard bones arose not to protect animals but to eat them. With this, the fish –eat-fish world really begin earnest. First, big fish ate little fish; then arms race began. Little fish developed amour, big fish obtained bigger jaws to crack the amour, and so on. Teeth and bones really changed the competitive landscape.” (Shubin 76)
Part 2
The head is the most important body part one can have. First off, it contains the nerves that allow us to hear, see, use our senses, and send out vital information. "Inside the skull are a number of compartments and spaces that house different organs. Obviously, the brain occupies the largest of these" (Shubin 83). The head contains the cranial nerves which informs the other organs inside the head what to do. “Attached to the bones and organs in the head are the muscles we use to bite, to talk, and to move our eyes and whole head. Twelve nerves supply these muscles, each exiting the brain to travel to a different region inside our head. These are the dreaded cranial nerves.” (Shubin 83). If our heads were not connected to our bodies, we would not be able to work correctly and efficiently. “This was a revolutionary idea because it linked heads and bodies as two versions of the same fundamental plan”( Shubin 89).
Starfish and sponges do not have heads.
I think it's amazing how teeth became more evolved over time to eat. It is weird to think that animals have different teeth used for different jobs when eating.
DeletePart One:
ReplyDelete• Teeth evolved with the animal to cope with their diet. Animals have very different mouths depending on their diet. Every tooth has a unique property so that the animal’s diet can exist such as ridges and bumps. “Carnivores, such as cats, have blade-like molars to cut meat, while plant eaters have a mouth full of flatter teeth that can macerate leaves and nuts.” (Shubin 60)
• The pattern of teeth in small rodent- sized mammals 150 million years old are the same as ours mouth pattern. Instead of a mouth full of all the same kind of teeth, these small rodent-sized mammals developed a mouth full of various kinds of teeth. “Incisors in the front became specialized to cut food, canines further back to puncture it, and molars in the extreme back to shear and mash it.” (Shubin 73)
• Teeth have a crystal molecule inside of them known as hydroxyapatite which makes teeth resistant of bending, compression, and other forms of stresses. It’s basically why teeth are the strongest bones in our body. “The enamel of teeth is richer in hydroxyapatite than any other structure in the body.” (Shubin 74)
Part Two:
1.) The head is essential because it stores the vital organs we need to function. “Inside the skull are a number of compartments and spaces that house different organs.” (Shubin 83) The compartments and spaces house the brain, eyes, parts of our ears, and nasal structures.
2.) The head also contains the muscles we need to do the things we do in everyday life such as biting, talking, moving our eyes and head. All these muscles are supplied by the twelve nerves which we call the cranial nerves. “Twelve nerves supply these muscles, each exiting the brain to travel to a different region inside our head.” (Shubin 83)
3.) Inside the head are many different nerves such as the trigeminal and facial nerve which carry information on sensations and actions. They send signals to our brain on how we feel things. “The reason a slap to the face hurts so much, beyond emotional pain, is because the trigeminal carries sensory information from the skin of our face back to our brain.” (Shubin 84)
4.) Two animals that do not have a head are worms and sponges.
I like how you mention the differences in teeth animals have depending on their diet. People often forget how vital teeth are to their diets. If humans only had flatter teeth, we would not be able to eat meat or anything that requires the teeth to break down before swallowing.
DeletePart 1:
ReplyDelete1. Teeth are extremely hard because they have to be able to break down all the different types of food that we eat everyday. Teeth contain a crystal molecule called hydroxyapatite which makes them resistant to bending, compression, and other types of stresses. The author states, “Teeth are extra hard because their outer layer, enamel, is far richer in hydroxyapatite than any other structure in the body, including bone” (74).
2. Early mammals had very specific ways that they bit into things. These different patterns showed up on the cusps of the teeth of each type of mammal. The author writes, “These patterns of wear are so fine that different species of early mammals can be distinguished by their patterns of tooth wear and occlusion” (72).
3. Small rodent-size mammals from about 150 million years ago developed a new kind of tooth similar to the teeth we have today. These rodents had different types of teeth in the mouth that each had different jobs, such as incisors in the front for cutting food, canines to puncture the food, and molars in the way back to smash the food. Shubin states, “What made these creatures special was the complexity of their mouths: the jaw had different kinds of teeth set in it. The mouth developed a kind of division of labor” (73).
Part 2:
The head is an extremely important part of the body, which is why almost all animals have one. The skull holds many of our important organs, the largest and most important being the brain. Shubin states, “Inside the skull are a number of compartments and spaces that house different organs. Obviously, the brain occupies the largest of these. Other spaces contain our eyes, parts of our ears, and our nasal structures” (83). All of the muscles used to perform everyday and basic tasks are also connected to the organs located in the head. Another reason why almost all animals have a head is because it contains the cranial nerves, which send information and attach to specific body parts. The author writes, “The simplest cranial nerves have only one function, and they attach to one muscle or organ. The cranial nerve that goes to our nasal structures, the olfactory, has one job: to take information from our nasal tissues to our brain. Some of the nerves that go to our eyes and ears are also simple in this way” (84). Finally, the head contains arches that act as a map for the cranial nerves, muscles, arteries, and glands inside. Shubin writes, “As we’ve seen, much of the secret of heads lies in the arches, the swellings that gave us the road map for the complicated cranial nerves and key structures inside the head” (90).
Two animals that do not have heads are sponges and worms.
I think that Rachel's first quote about teeth is significant. I think that it is strange to think that teeth are harder than bones because of their enamel.
DeleteI think Rachel's first fact is significant because it is the reason why our teeth are the strongest bones in the body. It is important to know that because of hydroxyapatite our teeth withstand compression and other stresses whereas our other bones can't withstand some stresses.
DeletePart One:
ReplyDeleteAs humans our mouths are used for many things like talking and eating. If all of our teeth were the same size and shape than it would be harder to chew which is why we have all different kinds of teeth with their own purpose. All teeth are essential for eating because they all do their very own special and different jobs. “Human mouths reveal that we are all-purpose eaters, for we have several kinds of teeth. Our front teeth, the incisors, are flat blades specialized for cutting. The rearmost teeth, the molars, are flatter, with a distinctive pattern that can macerate plant or animal tissue. The premolars, in between, are intermediate in function between incisors and molars”(61).
Its crazy how scientists can look at a fossil of the jaw and the teeth inside and know what it is. They can differ a reptile jaw from a human jaw just by looking at the fossil. “Under Bill’s microscope was a tiny jaw, not more than half an inch long. In it were a few minute teeth. The jaw’s owner was clearly a reptile, because the teeth had only a single root at the base, whereas mammal teeth have many”(70).
Teeth are actually extremely interesting but the way they develop. There are two layers of tissue that approach each other and divide than change shape and make proteins. It’s fascinating how the structure of the tooth changes. “Teeth develop by an interaction of two layers of tissue in our developing skin. Basically, two layers of tissue approach each other, cells divide, and the layers change shape to make proteins. The outer layer splits out the molecular precursors of enamel, the inner layer the dentine and pulp of the inside of the tooth. Over time, the structure of the tooth is laid down, then tweaked to make the patterns of cusps and troughs that distinguish each species”(78).
Part Two:
It is important for almost all animals to have heads because it hold the essential organs It contains the spaces for our eyes nose and ears which is special because it allows us to see hear and smell. It also contains many other needed parts, the brain. “Inside the skull are a number of compartments and spaces that house different organs. Obviously, the brain occupies the largest of these. Other spaces contain our eyes, parts of our ears, and our nasal structures”(83).
Having a head is also essential for housing the nerves and muscles. Muscles are attached to the bones and organs in the head. Twelve nerves supply theses muscles that are needed in the head for the animal to be able to talk move their eyes and more. “Attached to the bones and organs in the head are the muscles we use to bite, to talk and to move our eyes and whole head. Twelve nerves supply theses muscles, each existing the brain to travel to a different region inside our head”(83).
It’s important to know that our heads have a specific pattern upon them. The curves in our heads define bones, muscles, arteries and nerves. Each thing defines our head into the shape it is. So someone may have a larger forehead than another person due to the structure of the bones, nerves, arteries and muscles. “Heads may not look it, but they also contain a very deep segmental pattern. Our arches define segments of bones, muscles, arteries, and nerves”(89). Two animals that do not have heads are worms and sponges.
Yes, I also agree about how important our heads are and I never realized all the different things they are in control of. It would be very difficult to survive without heads because they play such a big role. It would be so difficult to live and not be able to talk or eat!
DeleteI liked how you mentioned how complex the structure of our head is, relative to how people perceive it to be. It is made up of many essential things that control our body. The head stores the nerves and muscles that allow an animal to talk and move.
DeletePart one
ReplyDeleteThe earliest mammals had certain patterns of biting that we still have today. Fossils shows that the upper teeth and lower teeth come down together with scrapes and cusps that fit together. Animals have different patterns, so this helps to identify the animal. However, reptiles do not have these same patterns. Shubin writes, “Early mammals, such as those Farish’s team uncovered in Arizona, had very precise patterns of biting. Scarps on the cusps of an upper tooth fit against mirror images of the scrapes on the lower tooth. These patterns of wear are so fine that different species of early animals can be distinguished by their patterns of tooth wear and occlusion” (72).
When Tritheledonts were studied, scientist found that their cusps do not interlock in the same way that mammals do, but the entire inner surface of the upper tooth shears against the lower tooth. This species is a reptile with mammal like teeth, and after scientist encounter this species they start to see new species with new teeth patterns, which led to the teeth we have now. Shubin writes, “By about 150 million years ago, in rocks from around the world, we find small rodent sized animals with a new kind of tooth row, one that paved the way for our own existence. What made these creatures special was the complexity of their mouths: the jaw had different kinds of teeth set in it” (73).
Conodonts were discovered in the 1830s, and 150 years later scientist discovered there were teeth in the fossils. These creatures are the first ones with bony heads. The inside of the skull has the same tissue structure of our teeth. Shubin writes, “The whole shield is made up of thousands of small teeth fused together. Teeth originally aroused to bite creatures; later, a version of teeth was used in a new way to protect them” (78). Teeth evolved over time to help protect creatures.
Part two
Animals have heads for multiple reasons. The head protects and contains many organs that are necessary for our survival. ”Inside the skull are a number of compartments and spaces used that house different organs” (83). Without heads holding the organs inside, humans would not be able to eat, communicate, or do many things that we can do today. “Attached to our bones and organs in the head are the muscles we use to bite, to talk, and to move our eyes and our whole head” (83). Heads also have cranial nerves that attach to one muscle or organ, but four have very complex functions, including the trigeminal and facial nerve. “Much like a cable that can carry television, a single branch of trigeminal or facial nerve can carry information about both sensation and action” (84). The head serves many purposes in our lives.
Starfish and worms do not have heads.
I find the fact about how the inside of the skull contains the same tissue structure as our teeth very interesting. i would have never thought that two unlike body parts would be so similar.
DeleteI also like the fact about how the skull has the same tissue structure as our teeth. i think this shows how amazing our body is. as i think about it more, i realize that it only makes sense for these two parts of the body to have similar tissue structure because they both need to be very strong.
DeletePart 1: 1.) Reptiles’ teeth only have one root at the base, as opposed to the many found in mammals. Reptiles’ teeth are minute in size and although that doesn’t change the tension, the single root is clearly significant in reptiles only. “The jaw’s owner was clearly a reptile, because the teeth had only a single root at the base, whereas mammal teeth have many” (70).
ReplyDelete2.) Tooth wear and occlusion were, and are, very distinguishable to a certain species of animal. Scientists could easily describe the animal that is present based on the decay and wear-pattern on the teeth. Scrapes on the cusps of an upper tooth, chewing wear, and occlusion of the sharpness of teeth all play roles in shaping the defined image of a species’ tooth. “Farish’s Arizona mammals have a different pattern of cusps and chewing than those of the same age from South America, Europe, or China” (72).
3.) Teeth can also define the way an animal is developed from the start, and the teeth can affect the process of organ-making within the body. Although no two teeth are the same, they usually all follow a similar pattern, much like the pattern of the “one bone, two bones, lotsa blobs,” pattern in many different mammals. The tissue and inner and outer layers of cells produce the molecules necessary for organ development among creatures. “Teeth not only herald a whole new way of living, they reveal the origin of a whole new way of making organs” (78).
Part 2: Pretty much, the brain is the epicenter of everything going on in the body at all times. The brain is found within the skull, which is found in the cranium, which is also called the head. Basically, your brain and tons of nerves are located in your head, so it’s kind of apparent why most animals have heads. The bones and organs in your head are attached to the muscles that control your mouth, eyes, and pretty much your entire cranium. Also, inside your head, there are sensors, and, you should’ve guessed it, more nerves, that react and control the signals that are sent and received throughout your body. If you step on a thumbtack, that nerve in your foot is going from your foot to your head, and sensing and applying the reaction you always get whenever it happens. Facial muscles are also controlled by nerves and muscles in your face (part of your head), and we use these to smile, frown, flare our nostrils, raise our eyebrows, lower our eyebrows, etc. I would quote this all, but that would take me a while, so pretty much the information discussed on pages 83 - 85 is where this will be located. Two animals that are without heads are worms and coral. I am not sure if coral is a mammal, so to be safe, I’ll also mention seastars.
I like the way that Cam explains the brain and everything inside the head and how it works. The head is a very important part in an organism because it is pretty much the command center for the entire body.
DeleteI think Cam's description of the brain and its functions were very clear and to the point. He kept on task and made his response very understandable yet entertaining. I liked how he emphasized the major functions of the brain that sometimes may be overlooked in an everyday setting because we as humans don't realize how crucial its presence truly is.
DeletePart 1
ReplyDelete1. As animals evolved the kind,pattern, and arrangement of teeth have changed but the job of teeth have always had the same concept throughout the years.
Shubin writes, "The job of teeth is to make bigger creatures into smaller pieces. When attached to a moving jaw, teeth slice, dice, and macerate. Mouths are only so big, and teeth enable creatures to eat things that are bigger than their mouths." (60)
2. Just by looking at an animals teeth scientist are able to tell us what an animal eats.
Shubin writes, "The bumps, pits, and ridges on teeth often reflect the diet. Carnivores, such as cats, have blade-like molars to cut meat, while plant eaters have a mouth full of flatter teeth that can macerate leaves and nuts." (60)
3. Teeth allow scientist to identify the type of animal in a fossil because of the teeth hardness and how animal teeth preserve overtime. The teeth allow scientist to discover more about teeth and about an animals life style.
Shubin writes, "Thanks to their hardness, teeth are often the best-preserved animal part we find in the fossil record for many time periods. This is lucky; since teeth are such a great clue to an animals diet, the fossil record can give us a good window on how different ways of defog came about." (61)
Part 2.
1. The reason why most animals have heads is because heads protect the brain that contains nerves that help end and receive signals from the body.
Shubin writes, " Attached to the bones and organ in the head are the muscles we use to bite, to talk, and to move our eyes and whole head. Twelve nerves supply these muscles, each exiting the brain to travel to a different region inside our head. These are the dreaded cranial nerves." (83)
2. Another reason is because of the arches we have in our heads and in animals. These arches allow animals to eat, swallow, and support gills in fishes.
Shubin writes, "As for the third and fourth arches, we find that many of the structures we use to talk and swallow are, in sharks, parts of tissues that support the gills. The muscles and cranial nerves we use to swallow and talk moves the gills in sharks and fish." (92)
3. Also most animals have genes like humans, that turn on 3 weeks after development. These genes help form heads, body parts bones ect...
Shubin writes, "These genes instruct cells to make the different portions of our heads. Think of each region of our head as gaining a genetic address that makes it distinctive. Modify this genetic address and we can modify the kinds of structures that develop there." (93)
i think Brittnee's reasons for why animals have to have heads are good ones. She didn't use insignifcant reasons and she made sure to explain them so anyone and everyone could understand.
DeletePart 1: three evolutionary facts:
ReplyDelete- Teeth are not talked about very often during science classes, even though they are a very important part to the human body. Shubin writes, “Yet the little tooth contains so much of our connection to the rest of life that it is virtually impossible to understand our bodies without knowing teeth.” (60). Without teeth we would not be able to bite or chew our food. We would only be able to eat things that fit in our mouths and could be swallowed without chewing. Teeth are very complex and are different between animals and humans depending on what they eat.
-Animals and humans do not have the same types of teeth. Over time animals teeth change according to their diets. Here the author writes, “Carnivores such as cats, have blade-like molars to cut meat, while plant eaters have a mouth full of flatter teeth that can macerate leaves and nuts.”(60) It would not be good if an animal that eats meat had flat and dull teeth because they would not be able to kill and eat their prey.
- All the teeth in the human mouth are used for different things. Here Shubin explains all the teeth in the human mouth, “Our front teeth, the incisors, are flat blades specialized for cutting. The rearmost teeth, the molars, are flatter, with a distinctive pattern that can macerate plant or animal tissues. The premolars in between, are intermediate in function between incisors and molars.”(61). Humans need to have teeth that work for whatever they eat. While some animals only eat meat or plants, humans eat both so we need to have teeth that can chew both.
Part 2: Almost all animals have heads to protect the nerves and muscles that control the body. One of the most important nerve in the head is the cranial nerve, which tells other parts of the head what to do. So without this nerve in our head we would not be able to do things like talk, move our heads, or most the things we do today. Shubin writes, “Thousands of nerve branches, muscles, and bones sit within this small box.”(82). The “small box” they are referring to is the head. The head helps protect the nerves, muscles, and bones from being damaged. All of the nerves, muscles, and bones have important jobs within the body. “Attached to the bones and organs in the head are muscles we use to bite, to talk, and to move our eyes and whole head.”(83). Without a head there would be no place to store the nerves and muscles that make you move your head and talk. “As its name implies, it is the main nerve that controls the muscles of facial expression.”(85). Nerves in the brain control things all over the body. If the nerves were to get damaged then severe things could happen to the body. Two animals that do not have heads are sponges and starfish.
Isn't it weird how starfish are able to live without heads? Great detail and explanation about why it is very important for animals to have them.
DeleteI really like how Jenna points out that animals' teeth have adapted over time to their diet. It shows the evolution of teeth and how they have become more complex over the years. Also, Jenna points out how the head is a center for all the nerves. She points out that the head protects some of the most important things in our body.
DeleteI think its important that Jenna pointed out how without teeth we would only be able to eat things that fit in our mouths and that wouldn't need to be chewed because if this were true our diets would be very different. Food that wouldn't need to be chewed would be a lot harder to find.
Delete2. Part 1: One significant fact about the evolution of teeth that Shubin discusses is that the reason humans can have such a varied diet today is because our mouths evolved to have many different types of teeth, such as molars and canines. All types of teeth are designed to chew a different type of food. On page 73 is says, “The mouth developed a kind of division of labor.” Another fact about the evolution of teeth that Shubin discusses is that teeth are the hardest part of a body because of the enamel, which contains high amounts of the mineral hydroxyapatite. “Teeth are the hardest parts of our bodies, because the enamel includes a high proportion of the mineral hydroxyapatite-higher even than bones,” as it says on page 61. The author also states that through evolution, reptiles have maintained different mouths from mammals in that their top and bottom teeth do not match up. Shubin writes on page 61, “Reptiles also lack the precise occlusion-the fit between upper and lower teeth-that humans and other mammals have.’’
ReplyDeletePart 2: Three reasons why most animals have heads that Shubin states are that heads contain the bones necessary for the ability to hear, swallow, and chew. As he states on page 83, “... these bones start development looking like rods, which ultimately break up and change shape to help us chew, swallow, and hear.”
Two animals without heads are clams and worms.
I think your reasoning for Part Two is interesting. You basically stated that the reason we have heads is to survive the way we do. Before, I thought about it the other way around, that our heads allow us to these actions, not that these actions were the reason our head came about.
DeleteWeek #2
ReplyDeletePart 1.
The type of animal can be recognized by just examining its teeth and jaw. “The reptile Bill had found was a tritheledont, a creature known from South Africa as well as now from Nova Scotia.” (70) The men in the book were able to tell this fossil was part reptile by the structure of the jaw. Also, they were fathomed by the structure of the teeth, making it appear as a mammal too. Their fossil was part mammal, part reptile.
Different parts of the jaw consist of different teeth, each usually has a purpose. As mammals develop over time, their teeth become more advanced to help themselves while chewing foods. “The mouth developed a kind of division of labor. Incisors in the front became specialized to cut food, canines further back to puncture it, and molars in the extreme back to shear or mash it.” (73)
As our ancestors developed, their teeth became more precise. Different teeth were used for different jobs. This is how us as humans can maintain the diet we do today. “Our diverse diet, ranging from fruit to meat to Twinkie, is possible only because our distant mammalian ancestors developed a mouth with different kinds of teeth that can occlude precisely.” (74)
Part 2.
“The trigeminal’s branches do two major things: they control muscles, and they carry sensory information from much of our face back to our brain.” (84) When Shubin writes this it makes it noticeable that our head does not only just carry our brain but works our whole entire body.
“Our skulls are made up of three fundamental parts: think plates, blocks, and rods. The plates cover our brains.”(82) This quote is significant because it is important to know there is something covering our precious brain.
“Attached to bones and organs in the head are the muscles we use to bite, to talk, and to move our eyes and whole head.” (83) Shubin states these facts about what is connected to the head to make it clear that our head connects to everything throughout our body.
Two animals that don’t have heads are worms and starfish.
Great quotes used for your important facts about teeth. Who would have thought an animal could be revealed with a scientist examining only the jaw!
DeleteI love how Dayna mentions the fact that the head does not just house the brain, but the whole body. It's the truth. Our brains are control center for our entire body.
DeletePart 1: Three significant evolutionary facts about teeth:
ReplyDeleteThe first important thing about teeth is that we are able to chew things into smaller pieces and break things down, so that we can swallow and eat food. “The job of teeth is to make bigger creatures into smaller pieces.”(60) Teeth are significant because since they are the hardest part in the body they are hard to disintegrate so it is easy to find teeth as fossils. “Teeth are the hardest part of our bodies, because the enamel includes a high proportion of the mineral hydroxyapatite higher even than is found in bones. Thanks to the hardness, teeth are often the best-preserved animal part we find in the fossil record for many time periods.”(61) Since there are many different animals there are many different ways in which their teeth should be so, over time teeth have evolved depending on what an animal may eat, if they eat meat or if they eat plants and fruit to make it easier and more convenient. "Our diverse diet, ranging from fruit to meat to Twinkie, is possible only because our distant mammalian ancestors developed a mouth with different kinds of teeth that can occlude precisely."
Part 2: Three reasons animals have head:
The skull is a very important part of the body, it's needed to protect what is inside because without it the brain and nervous inside could become damaged and it would be very hard for an animal to survive. "We literally have to saw through the cheek, forehead, and cranium to see the vessels and organs"(82).One really important reason animals have heads is that they hold and store important things, like the brain without the brain they would not be able to function well at all. "Inside the skull are a number of compartments and spaces that house different organs"(83).With the brain animals like humans have the ability to control other parts of their head that is very necessary that they use on a daily basis like eating. "Attached to the bones and organs in the head are the muscles we use to bite, to talk, and to move our eyes and whole head"(83).
Worms and Sponges don’t have heads.
Yes it is important for animals to have heads, without heads it would make it very hard to survive. The head does house the brain and organs along with muscles and nerves.
DeleteI like how Jessy says that teeth are the hardest part of the body and do not disintegrate. Teeth are the most common and best preserved fossil found, therefore they are very helpful to scientists.
DeleteJessy points out that the head isn't just a place to house organs but it protects them. It acts as armor and without it our brain, nerves and muscles would be at a greater risk of being damaged.
DeleteKara Marx
ReplyDeleteAP Bio
Part 1
1. As organisms evolved everything related to teeth has changed but the job of teeth has stayed the same throughout the years. Our teeth are for cutting up food for us so we can get the necessary nutrients to live. Shubin writes, "The job of teeth is to make bigger creatures into smaller pieces. When attached to a moving jaw, teeth slice, dice, and macerate. Mouths are only so big, and teeth enable creatures to eat things that are bigger than their mouths." (60)
2. The hardness of teeth and how they preserve over time helps scientists identify what animal they belonged to and what they ate. Depending on the size and shape of the teeth, scientists can tell what that animal ate and often how they lived.
Shubin writes, "Thanks to their hardness, teeth are often the best-preserved animal part we find in the fossil record for many time periods. This is lucky; since teeth are such a great clue to an animals diet, the fossil record can give us a good window on how different ways of defog came about." (61)
3. As animals evolved and their sources of food changed, so did their teeth. Some teeth were specialized to be grinders, while others for ripping meat. Shubin writes, "The mouth developed a kind of division of labor" (73).
Part 2.
1. Most animals have heads is because a head is designed to protect the brain that contains nerves that help receive signals from the body.
Shubin writes, " Attached to the bones and organ in the head are the muscles we use to bite, to talk, and to move our eyes and whole head. Twelve nerves supply these muscles, each exiting the brain to travel to a different region inside our head. These are the dreaded cranial nerves." (83)
2. We alos have heads because of the arches we have. These arches allow animals to eat, swallow, and support gills in fish. Shubin writes, "As for the third and fourth arches, we find that many of the structures we use to talk and swallow are, in sharks, parts of tissues that support the gills. The muscles and cranial nerves we use to swallow and talk moves the gills in sharks and fish." (92)
3. Also most animals have genes that "turn on" 3 weeks after development. These genes help form body parts, such as heads. Shubin writes, "These genes instruct cells to make the different portions of our heads. Think of each region of our head as gaining a genetic address that makes it distinctive. Modify this genetic address and we can modify the kinds of structures that develop there." (93)
I find it interesting how the shape of teeth alone can help scientists identify the animal in which the teeth came from. Its also interesting how the teeth are shaped in special ways to accommodate the animals diet.
DeleteI think it's interesting that teeth have evolved based on the changes in the diet of the animal and the resources around it.
DeleteI think Kara picked great quotes that supported her three evolutionary facts about teeth. I also find it interesting how scientist can look at the shape and size of a tooth and know the animals type of diet.
DeleteYour third point about why animals have heads is very significant, because without those genes, we truly wouldn't have heads and this quote was overlooked by most of us (including myself)
DeletePart 1:
ReplyDelete1. The pattern of teeth is very fine and unique so that one each tooth fits comfortably in the mouth of an animal. “Open and close your mouth: your teeth always come together in the same position, with upper and lower teeth fitting together precisely… (70)”
2. As animals evolved so did various parts of their bodies. One part of animals that evolved was their teeth. When I say that their teeth evolved, I mean that the types of teeth changed and the “jobs” of those teeth changed as well. “Our front teeth, the incisors, are flat blades specialized for cutting… (70)”
3. The hardness of just a single tooth makes them crucially important. “Hard bones arose not to protect animals, but to eat them. With this, the fish-eat-fish world really began in earnest… (76)”
Part 2:
The head of an animal acts and works like a “control center” to the rest of the body. Animals have heads to protect the “control center’ or the brain. I’m referring to the brain as a control center because the brain sends signals throughout the body. These signals that are sent throughout body carry information of the essential things we do in our everyday lives. Things like breathing eating (chewing and swallowing). “The trigeminal’s branches do two major things: they control muscles…(84)” The head is the most important part of any species’ body. If any part of the head is damaged, the body will not be allowed to perform its normal functions the way it’s supposed to. “Inside the skull are a number of compartments and spaces that house different organs…(83)” Two animals that don’t have heads are worms and sponges.
Answer 1: •Teeth can reveal the diet if the animal. "The bumps, pits and ridges on teeth often reflect the diet."
ReplyDelete•Teeth are the hardest parts of our bodies. "The enamel includes a high proportion of the mineral hydroxyapatite"
•Can show a paleontologist if it is a mammal or a reptile. "Also, whereas we mammals replace our teeth only once, reptiles typically receive visits from the tooth fairy for their entire lives, replacing their teeth continuously as they wear and break down."
Answer 2: Heads contain all of our sensory organs, and protect them. They compactly store the brain and all the sensory organs so that they can function efficiently together.
Two animals without heads: Sea Cucumber and Oysters
Part 2:
ReplyDelete1. Mammals over 150 million years ago developed different kinds of teeth to carry out a specific chewing action. They had incisors to cut food, canines to puncture food, and molars to mash food. Neil Shubin wrote, “What mad these creatures special was the complexity of their mouths: the jaw had different kinds of teeth set in it. The mouth developed a kind of division of labor.”(73)
2. The earliest teeth in fossil records were Conodonts, which were the teeth of a jawless fish 250-500 million years old. Neil Shubin wrote, “The conclusion became abundantly clear: conodonts were teeth. And not just any teeth. Conodonts were the teeth of an ancient jawless fish.” (76)
3. Teeth are created by an interaction between two layers of tissue, the same way as hair and feathers are created. Neil Shubin wrote, “It turns out that exactly the same process underlies the development of all the structures that develop within skin: scales, hair, feathers, sweat glands, even mammary glands.” (78)
Part 3:
1. Heads house and protect the brain (which is necessary for all body functions) and other organs including eyes, ears and nose. Neil Shubin wrote, “Inside the skull are a number of compartments and spaces that house different organs.” (83)
2. Heads also contain all of the nerves that connect to the brain and send signals to different parts of the body. Neil Shubin wrote, “Vessels and nerves make curious loops and turns as they travel through the skull. Thousands of nerve branches, muscles, and bones sit within this small box.” (82)
3. Finally our head is the location of the muscles that control our mouth, eyes, and allow us to move our head. Neil Shubin wrote, “Attached to the bones and organs in the head are the muscles we use to bite, to talk, and to move our eyes and whole head.” (83)
Two creature without heads are worms and starfish.
I think that Jen's second quote about why almost all animals have heads is significant. It's hard to imagine so many important branches, muscles, and bones in a somewhat small space for a human, but it's even harder to imagine that the same structures fit into smaller organisms' heads.
DeleteI think that the use of Jen's three quotes to answer the question in why most animals have heads is spot on. she contrasted three different uses of the head that make our complex system work. It protects the organs, controls the functions of our bodies, and allow us to do a variety of things with our mouth, jaw, teeth, ect.
Delete2). Part #1
ReplyDelete"This was a reptile with tooth-to-tooth occlusion. My fossil was part mammal, part reptile." (70). When the team found these fossils, it was a breathtaking discovery because they now had a reptile like creature, who were not supposed to have tooth to tooth occlusion, which is a characteristic of a mammal. this discovery was important in telling scientists more history about where mammals and especially humans came from.
"The mouth developed a kind of division of labor" (73). When teeth were evolving in mammals and reptiles and any other type of animal, they were becoming specialized for certain jobs pertaining the certain diet or environment. different teeth were evolving for grinding up fibrous plants, and shredding meat.
"Hard bones arose not to protect animals, but to eat them.”(76). For a long time scientists thought that the first hard bones were used for armor. They were wrong. The first hard bones were actually teeth used to eat other animals who were developing armor almost in a sort of animal kingdom arms race.
Part #2
Most animals have heads to protect and house the most important parts of the animal such as the brain, eyes, etc. "Another part of our skull lies underneath the brain, forming a platform that holds it up." (82). The bones of the skull that make up the head work together to protects and house and support anything that the animal has inside of its head. Another reason animals have heads is because the brain needs to be protected. If something happens to the brain it will affect your entire body. The brain controls the different sections of your body to work as one unit. "This was a revolutionary idea because it linked heads and bodies as two versions of the same fundamental plan" (89) LAstly the brain has archways that act as a map for arteries, nerves, and glands inside of the brain inside of the head. “As we’ve seen, much of the secret of heads lies in the arches, the swellings that gave us the road map for the complicated cranial nerves and key structures inside the head” (90). Two animals that do not have heads on their bodies are worms and sponges.
Part 1
ReplyDeleteOne fact about the evolution of teeth is in the difference between the teeth of mammals and reptiles. Reptiles' teeth are replaced multiple times throughout the course of their life due to the wear and tear try go through. But humans' teeth are replaced once in our lifetime because the foods we eat cause less abrasion in the teeth. Shubin writes, "Also, whereas we mammals replace our teeth only once, reptiles typically receive visits from the tooth fairy for their entire lives, replacing their teeth continually as they wear and break down."
Another fact is that there was a type of rodent found with a new kind of tooth row. The animal possessed different kinds of teeth, each used for a different job, allowing the animal to eat a variety of foods. Shubin writes," the mouth developed a kind of division of labor. The incisors in the front became specialized to cut food, canines further back to puncture it, and molars in the extreme back to shear or mash it."
A third fact about teeth is that they have evolved to suit the food that the animal eats. For example sharp teeth like blades are used for cutting meat. Shubin writes, “We can learn a lot about an animal by looking at its teeth. The bumps, pits, and ridges on teeth often reflect the diet."
Part 2
Many animals have heads because it is a place that is used or housing different nerves, muscles and bones that are important for the daily functions of an animal. The nerves allow signals to be sent to the brain from a certain part of the body. Shubin writes,” Vessels and nerves make curious loops an turns as they travel through the skull. Thousands of nerve branches, muscles, and bones sit within this small box." The skull also protects important organs such as the brain, which is the most important part in the body. Shubin writes, “Inside the skull are a number of compartments and spaces the house different organs. Obviously, the rain occupies the largest of these. Other spaces contain our eyes, parts of our ears, and our nasal structures." Also the head allows us to perform important activities like chewing and hearing. Without these actions we couldn't survive. Shubin writes, "The muscles controlled by the trigeminal nerve include those we use to chew and tiny muscles deep inside the ear." Two animals that do not have heads are starfish and worms.
I find it interesting how reptiles go through many pairs of teeth but our teeth are only replaced once. I never really realized how even though teeth are made up of the same material they are still different depending on the organism.
DeleteI find it fascinating that certain types of animals have evolved to replace their own teeth. Their bodies know what they have to do to survive, so they have adapted.
DeletePart 1:
ReplyDeleteOne of three significant evolutionary facts about teeth are that they were originially formed for the purpose of eating other fish, but later formed for a different purpose. "Teeth originally arose to bite creatures; later, a version of teeth was used in a way to protect them." -78
Another fact is that eventually, after the process of the forming of the teeth, each tooth becomes a different shape which sets different animals apart. "Over time, the structure of the tooth is laid down, then tweaked to make the patterns of cusps and troughs that distinguish each species." -78
A third fact is that when the process of the formation of teeth surfaced, other parts of the body such as hair and glands began to take on the same pattern of the interaction of two layers of tissue in our skin. "Once the process that makes teeth came into being, it was modified to make the diverse kinds of organs that lie within the skin."-79
Part 2:
One of three reasons why almost all animals have heads is because an abundance of important organs and tissues that control the body and parts of the body are being protected by the skull. "Thousand of nerve branches, muscles, and bones sit within this small box. At first glance, the whole array is a bewildering mess."-82
Another fact is that in the skull, multiple places are made to hold important organs such as the brain, eyes, ears, and nasal structure. "Inside the skull are a number of compartments and spaces that house different organs."-83
A third reason why most animals have heads is that 3 parts of the skull, have different jobs in the formation of the head. Plates protect the brain, blocks have many arteries and nerves throughout them and hold the brain up, rods make up the jaw, some bones in the ears, and bones in the throat. "Our skulls are made up of three fundamental parts: think plates, blocks, and rods."-82-83
Two animals that do not have heads are worms and insects.
I find it interesting how teeth are different depending on the animal and their diet. It is amazing how scientists can identify animals with just their teeth.
DeleteI think Rachael's first quote is significant because it describes how teeth evolved as the need for teeth changed over time. I also like that it her third fact of part one, Rachael connected teeth to other parts of the body.
Delete1. Three significant evolutionary facts about teeth:
ReplyDelete1.The first teeth are found in early jawless fishes, and emerged before other hard structures like skeletons, which proves that teeth were the first hard tissues, not backbones or armor as many scientists originally thought. ‘“Hard bones arose not to protect animals, but to eat them” (76).
2. Skeletons essentially originated as masses of teeth fused together to form a hard, shiny plate. “Cut the bone of the skull open, embed it in plastic, pop it under the microscope, and you do not find just any old tissue structure; rather, you find virtually the same structure as in our teeth” (78).
3.)The formation of early teeth was the basis upon which all glands, scales, feathers, and hair were formed. “Once the process that makes teeth came into being, it was modified to make the diverse kinds of organs that lie within skin” (79).
2. Why do animals have heads?
The necessity of a head in nearly all organisms becomes blatantly obvious once its many functions are considered. The most significant purpose of the head is to house the brain and crucial parts of the complex web of nerves that emerge from it. This fact is most simply supported by Shubin’s statement that “We literally have to saw through the cheek, forehead, and cranium to see the vessels and organs” (82). The skull and basic structure of the head suggests that it’s contents are of the most vital importance to the sustenance of life. The head also serves as the center of the nervous system, as proven by the fact that most if not all nerves connect either directly or indirectly to the head. “Attached to the bones and organs in the head are the muscles we use to bite, to talk, and to move our eyes and whole head” (83). The head is also significant when considering the evolutionary links between organisms because its structure displays a segmented structure that can be used to link humans to sharks and other similar animals, because during embryonic development, different arches form different parts of the head, and these arches are essentially the same as arches that can be found in shark embryos. “Those insignificant-looking swellings and indentations have captured the imagination of anatomists for 150 years, because they look like the gill slits in the throat regions of fish and sharks” (90).
Two animals without heads are jellyfish and worms.
I strongly agree with Kady that the brain the center of the nervous system. Although the book does not come out and say this, I agree with what she inferred. It is very true that without the head we would not be able to use the muscles we use to bite, talk, and move. Also, I did not think of a jelly fish as an animal who does not have a head. Good idea!
DeleteCody Marx
ReplyDelete2. Part One –
The teeth of reptiles began to evolve with “tooth-to-tooth occlusion” – the way mammals’ mouths are today – about 200 million years ago. Shubin discovered evidence of this while on an expedition that yielded the jaw of a tritheledont. He writes that, “the tritheledonts were the gems, of course, because they showed that some kinds of reptiles already displayed our mammalian kind of chewing” (72).
On page 73, Shubin states that, “the mouth developed a kind of division of labor.” What he means, is that fossils of 150-million-year-old rodents displayed incisors at the front of the mouth and molars toward the back. Each type of tooth was used for different methods of ingestion, and this is an early form of our mouths.
Without teeth, humans would look very different from the way we look today. This is because the production of teeth led to the production of other organs in the human body; the process of making teeth more or less applies to the making of other parts. Shubin sums this up on pages 79 and 80; “The developmental tools that make teeth have been repurposed to make other important skin structures.”
Part Two –
First and foremost, almost all animals have heads to protect their brain, a very fragile and important organ which controls the body. Shubin describes how protected the brain is, writing “the tissues of the head are encapsulated in a bony box. We literally have to saw through the cheek, forehead, and cranium to see the vessels and organs” (82).
The majority of animals have heads to house important muscles and nerves in addition to the brain. Said muscles enable us to do the simple things in life, such as feeding ourselves and communicate with others. Cranial nerves supply those muscles. The author writes, “attached to the bones and organs in the head are the muscles we use to bite, talk, and to move our eyes and whole head” (83).
Heads also connect the entire segmented body as a whole, which is a very important factor when considering how different the organs and body parts can be. Shubin compares the head with the rest of the body on page 89; “The segmental configuration [of the body] is obvious when you look at the levels of the spinal cord that are associated with each part of our body . . . Heads may not look it, but they also contain a very deep segmental pattern.”
Two animals without heads are worms and sponges.
I like how Cody expressed the importance of the brain by explaining all of the connections it contains to the rest of the body. I also like that he pointed out that even though all the organs in the body are different the brain connects to all of them.
DeleteI like that Cody talks about the fragileness of the brain and how protected it is. The brain is one of the most important organs in the body. It is our control center for our bodies. Without it, we would not be able to think or use the other parts of our bodies.
DeleteQuestion 1: animals have small teeth for three reasons page 61 “ Fossil records can give us a window on how different ways of feeding developed.” Over time by looking at different types of fossil we can tell how different animals eating habbits changed over time based on the shapes of their teeth. Page 78 “teeth originally arose to bite creatures, later; a version of teeth was used in a new way to protect them.” Over time the teeth of animals changed in order to be used not only as a form of eating but a form of self-defense. Page 74 “Every fish amphibian bird reptile and mammal on the planet is like us.” The teeth of all animals adapted from one creature based on the different needs of that animals life the shape and structure of their teeth changed based on their needs in everyday life.
ReplyDeleteQuestion 2: There are many discoveries that point to the reasons why animals have small heads. There have been discovered fossils that seem to be half reptile and half mammal which showed very early signs of tooth-to-tooth occlusion. These fossils were found in rocks that were approximately 10 million years old, in places such as Nova Scotia and were interpreted as having the same chewing mechanics as humans and small animals do. “This was a reptile with tooth-to-tooth occlusion. My fossil was part of mammal, part reptile.” (70) The head is essentially the most important part of the body, it is rather important that it is small so it isn’t injured easily.” They control muscles, and they carry sensory information from much of our face back to our brain.”(84) An animal’s skull protects nerves and delicate organs inside the head. The most important part protects the brain. “Inside the skull are a number of compartments and spaces that house different organs. Obviously, the brain occupies the largest of these.” (83)
Two animals that don’t have heads are worms and sponges.
I like how you talked about the fact that we are able to tell by looking at different fossils what kind of things certain animals ate.I never knew that we could figure out what animals eat just by looking at their teeth, because of all the different ways the teeth could be shaped.
DeleteI find it interesting how scientist were able to see an animals fossil and tell just by looking at there teeth what they ate and the type of animal it was. I think Ale sis had great quotes that supported her answers.
DeleteWeek two assignment
ReplyDelete2) Teeth can give detailed information about chewing and the diets of the animals. "Because teeth preserved so well in fossil record, we have very detailed information about how major patterns of chewing- and the ability to use new diets-arose over time"(73). Teeth are the first hard skeletons and they showed us why hard bone was created. "Hard bones arose not protect animals, but to eat them"(76). Teeth also show us how different animals eat different things and the images of wear show up on the teeth. "These patterns of wear are so fine that different species of early mammals can be distinguished by their patterns of tooth wear and occlusion"(72).
3) Almost all animals have heads because it is where the brain and other important organs are that are vital to our survival live. "Inside the skull are a number of compartments and spaces that house different organs" (83). Another reason we need a head is because attached to those bones are the muscles we need to move our jaw to eat or talk. "Attached to the bones and organs inside the head are the muscles we use to bite, to talk, and to move our eyes and whole head"(83). Lastly heads are important because all the nerves that carry information travel to the brain located in the head. without these we wouldn't be able to do simple things like smell, hear, taste and touch. "The facial nerve also controls muscles and relays sensory information" (85).
4)Two animals that don't have heads are amoebas and worms like flathead worms.
Its interesting how teeth can tell a whole story, from chewing to why hard bones were created and how different animals eat different things. Its amazing how teeth preserve so well in fossil record, it helps us understand what creature it came from and what types of food they ate.
DeleteI think Cheryl did a good job answering number three. I like how she said the organs in our head are vital to surviving. Also she points out that with out a head we would not be able to do simple things like smell, hear, taste, or touch.
Delete1. Three significant evolutionary facts about teeth are that humans are all purpose eaters containing incisors, molars, and premolars that can rip apart meat and even eat plants, humans only loose one set of teeth as they age whereas crocodiles can loose many at a time and keep having more grow in, and mammals have occlusion while reptiles don't.
ReplyDelete"Reptile also lack precise occlusion -the fit between upper and lower teeth- that humans and other animals have" this is 27% of the book. I don't have the page number because I have it as an e-book on a kindle app.
2. Almost all animals have heads, because as embryos all animal start out looking very similar. There are four arches that, for at least humans, develop into pieces of the ear, the hyoid ,and jaw bone. Amphioxus, an old fossil, shows us that notochords which are present in any developing embryo, are present and they don't have heads. The same thing occurs with some worms.
I like that you looked at the question somewhat differently that most people did, because your answer followed the same thoughts that were presented in the book and related more closely to the theme of the chapter.
DeleteI like that Libby mentioned a comparison between humans and crocodiles, and mammals and reptiles. I also like that she mentioned the development of the human head and the headless fossil that had notochords.
DeleteAssignment #2
ReplyDeleteQuestion 2
Part 1:
1) Teeth are meant to help animals eat other organisms often larger than themselves. Often teeth are the only mechanism that certain organisms have that aid them in eating. “Mouths are only so big, and teeth enable creatures to eat things that are bigger than their mouths.” (pg.60)
2) “We can learn a lot about an animal by looking at it’s teeth. The bumps, pits, and ridges on teeth often reflect diet.” (pg.60) Animals are not the only organisms that can show their diet pattern though their teeth, human teeth show that we have many different kinds of teeth to support our various diet habbits.
3) “Teeth are extra hard because their outer layer, enamel, is far richer in hydroxyapatite than any other structure in the body, including bone.” (pg. 74) The hydroxyapatite in teeth and bones allow humans and animals to perform everyday functions such as moving, breathing, and eating.
Part 2:
1) “Our skulls are made up of three fundamental parts: think plates, blocks, and rods. The plates cover our brain.” (pg. 82) One of the reasons that most organisms have heads is to protect the brain. There are plates that cover the brain and all of the plates fit together like a puzzle.
2) The skull houses many different and important organs. Eyes, ears, and nasal passages are some of these important organs. “Much of the challenge in understanding head anatomy comes from seeing different spaces and organs in three dimensions.” (pg. 83)
3) There are arches in the skull where the areas that we talk and swallow are in the head. “The muscles and cranial nerves we use to swallow and talk move the gills in sharks and fish.” (pg. 92)
Two animals that do not have heads are frogs and sharks.
It is strange to think that somehow all of the amazing things we have the ability to do all are started in the head. Good thing we have plates protecting our source of where everything starts!
Delete