Birds actually have two basic types of feathers: flight feathers and down feathers. Why not? Feathers didn't evolve all at once. : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Amniote_Egg_Coloring : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Anatomy_of_the_Eye_(Coloring)" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Anatomy_of_the_Heart : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Article:_The_Body_Farm" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", A_Case_Study_on_the_Endocrine_System : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Bird_Beaks_and_Feet : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Body_Systems_Graphic_Organizer : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Bone_Matrix_Anatomy_(Coloring)" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Case_Study:_How_to_Survive_a_Cholera_Epidemic" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Case_Study:_The_Tired_Swimmer" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Case_Study:___Can_a_Virus_Cause_Diabetes?" Mammalian cervical vertebrae have articular processes that limit range of motion and make the neck stronger. It can only work with what's available. This article is brief and readable. I'm including this extensive list to provide a record of the sources I used in making this lab activity and to offer some suggested reading for anyone who wants to dig a little deeper on any particular topic related to this lab. Which specimens that you have seen in lab have this feature. The most recent common ancestor of bats and birds had forelimbs, but not wings. UC Museum of Paleontology. These bonesinclude the tibia, femur, pubic bone, ribs, ulna, toe bones, and scapula. Give an example of bird behavior that shows their relatively great intelligence. xZYo~F6oRkwr'2EK\S)51HF+n~/Y1vp&f/fYV+_?~zs| So as forelimbs, the wings of bats and birds are homologous. The mammalian forelimb includes the shoulder, elbow, and wrist joints. 4 0 obj
A simple description of some of the flight muscles and how they interact with the skeleton. How are these limbs different? edimentary rock layers are deposited in a time sequence, with the oldest on the bottom and the youngest on the top. Compare the specimen of a bat's wing skeleton to the bird wings that you've already observed. : Dr. Jacquie Jacob, University of Kentucky. The crocodilian form is adapted to an amphibious way of life. %
Hollow bones don't result in a lighter skeleton because the bone tissue of birds is more dense than that of mammals. As a result, the crocodile can breathe even if its mouth is open underwater. Using tools, picking up and holding objects. Whale. These wings, along with the arms of humans or the forelegs of cats, are examples of vertebrate forelimbs. humerus: red ulna/radius: yellow carpals: metacarpals/phalanges: orange brown - humerus radius ulna -carpal -metacarpal E -phalanges human whale cat bat bird This is an example of a research paper that connects the worlds of Bio 6A (form & function) and Bio 6B (molecular biology). <>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
Nevertheless, a connection exists between arterial and venous circulation by way of the foramen of Panizza, which opens between the two vessels leading separately from the ventricles. Why did non-flying dinosaurs have pneumatic bones? This allows the bird's body to resist the powerful forces generated by the flight muscles acting on the wings. We know this because feathers evolved long before birds began to fly. Bird By looking at the picture, what are the Comparison to Human Arm in Form and in Function of the following species; 1. What three bones make up the pectoral girdle of the bird? For instance, the bones of a bird are hollow which makes the skeleton lighter. The avian (bird) skeleton has many features that resemble the human skeleton, and the majority of the bones are the same, they are only shaped different. @IC($d$BugH Zj
These bones, called pneumatic bones, include the skull, humerus, clavicle, keel, pelvic girdle, and lumbar and sacral vertebrae. {Ai,8"`'XS+EZ.=Z&7Ra1,gP#@4U0yHKGQ4xv9,)2^O_?0f"iWwC5+jQR&x,%;pz}_k2#( vIFtI;*vhFznF5#0Ju]_G}n`Y^(ot7U&dbT7GKiaOu[ku
]+(c>B!OflB)jw22#Pr ?;G5ZE0YNWQ"7z/[ Take a close look at the whole bat skeleton. Biology 6A Website by Brian McCauley is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. For example, compare the wings of a bird to the wings of a bat. Are Birds Really Dinosaurs? 2. The heart beats rapidly to keep oxygenated blood flowing to muscles and other tissues. I put boxes around two clades: amniotes and dinosaurs. The legs of the crocodile are short but powerful. These are embryos at their most advanced stage, shortly before birth. Eggshells primarily are made of calcium, and a hens bodymobilizes 47 percentof its body calcium to make an eggshell. Types of Bird Feathers. This doesn't mean that feathers aren't relevant to flight; it simply means that feathers first evolved for other reasons and later became adapted to flight. For example, the picture below represents a fossil - the Giant Ground Sloth - that Darwin compared to currently living tree sloths. But on the inside there are many similarities among human, bird, and bat forearms. However, this idea turns out to be wrong. Fossils are typically preserved when they are buried under many layers of sand and mud for an extremely long period of time. Homologous structures share a similar embryonic origin. The ridge of the bird's sternum is called a keel. Birds move their wings using muscles in the chest. Since feathers play an essential role in bird flight, it's tempting to think that feathers originally evolved as an adaptation to flight. Under these plates lie bony structures called osteoderms of about the same size. Darwin concluded that, in many ways, fossils give researchers clues as to how organisms have changed over time. These bones are also found in the bird. Birds have pneumatic (air-filled) bones; the air spaces may make up the majority of the bone's volume. endobj
Andrew Biewener, 2011. 3 0 obj
Thumb has been shortened to a stub. The whale fin needs to be longer to help in movement through water. Birds also lay amniotic eggs with hard, calcium carbonate shells. Relate the differences you see in, 3. An extremely detailed review of how birds' muscles work during flight, with descriptions of the experimental methods (electrodes in muscles!) For instance, the bones of a bird are hollow which makes the skeleton lighter. What are their functions? Philosophical Transactions of the Royal Society 366 (1570): 1496-1506. Find the crop and gizzard in the digestive tract diagram. endobj
Also, the shape of the vertebrae themselves allows for a greater range of motion. M. S. Y. Lee et al., Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds, Science 345, 6196 (1 August 2014). Today, the major pieces of evidence for this theory can be broken down into the fossil record, embryology, comparative anatomy, and molecular biology. For a comparison of leg bones in humans and ostriches see fig. They suggest that the air sacs and one-way lung ventilation of birds, often described as adaptations to flight, apparently evolved long before the origin of birds and vertebrate flight. Which pair of animals has a more recent common ancestor? Find an isolated bird bone and compare it to a mammal bone of similar size. Which organisms did you correctly identify in Stage 1? Notice that there is no clade that includes all these dinosaurs but does not include birds. Bird wings consist of feathers extending all along the arm. As a result, the number of bones in the bird forelimb has been reduced compared to their ancestors. These structural dissimilarities suggest that bird wings and bat wings were not inherited from a common ancestor with wings. Minerals seep into the fossil replacing the organic matter and creating a replica in stone. <>
Give specific differences. Humans and chimps, or humans and bats? Why have birds been so successful? Before you leave lab, you should go over the review on each page to see if you're ready for the lab exam. Numerous feathered dinosaur fossils have been found, with feathers ranging from simple hairlike structures to complex asymmetrical flight feathers resembling those of modern birds. A set of questions to answer during the Systematics lab. Use your knowledge of bone structure to support your answer. 4. Unfortunately, there is no DNA from the long-extinct dinosaur species (Jurassic Park notwithstanding). Since birds don't have hands, this is important. 3. How are they different in form? Humans, on the other hand, use their arms and hands for gross motor movement like grabbing, hugging, and lifting, as well as fine motor movement like using tools or even communicating. Some of the bones are hollow and actually act as part of the avian respiratory system. Next to each letter on the human skeleton, write the name of the bone. Frankly, I don't know the answer to this one. This big, expensive textbook is an excellent resource. The scapula or . Create a diagram representing which strata you think you would find the ancestral horse fossils. <>>>
Quanta. Part of DinoBuzz at UC Museum of Paleontology. The joint between the scapula and the humerus is the shoulder. The pectoral girdle is the area of the skeleton that attaches the arm bones to the spine. The diagram below shows where each of the specimens were discovered. Much longer metacarpals. The bird's forelimbs are wings and must have a strong support system. The cloacaa chamber containing the genital, anal, and urogenital openingsextends longitudinally within the body; it is surrounded by an oval area of small scales on the underside of the body. In each of these species, the forelimbs develop the same way in the embryo, using homologous genes to control limb development. On the other hand, you will also see some distinct differences between bird and mammal skeletons. 11 Fascinating Nile River Plants and Animals, 7 Questions About Lizards, Snakes, and Other Reptiles Answered, 7 Crocodilian Species That Are Dangerous to Humans. Down feathers are short and fluffy. Both of these factors, ancestry and adaptation, are likely to be important; in this lab you'll consider both of them. Your job is to create a poster accomplishing the following: Embryologyis the scienceof the development of an embryo from the fertilizationof the ovumto the fetusstage.Organisms that are closely related may also have physical similarities before they are even born! (Especially Question 3) Must be in paragraph form. The avian skeletal system looks similar to that of mammals but must accommodate a birds need to be light enough to fly while having necessary body support. Rather than using numerous bones to control wing shape (as bats do), birds use a small number of bones, supplemented by a large number of feathers. The whale fin needs to be longer to help in movement through water. Whale 2. A bird's sternum is large and positioned under the body - flight muscles attach to this bone. Much longer metacarpals. The transition from ground-living to flight-capable theropod dinosaurs now probably represents one of the best-documented major evolutionary transitions in life history." This article by Benton is a Perspective, a brief, nontechnical summary of the context and findings of some recent research. When in production, a commercial laying hen cannot obtain enough dietary calcium to allow for daily egg production. When you eat the thigh of the bird, the bone within it is the femur. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. In a birds wing? The "shoulder blade" of the human is actually a bone called the scapula, birds have a scapula and they also have an additional shoulder bone called the corocoid. Medullary bones are an important source of calcium when hens are laying eggs. Analogous organs have a similar function. The bones of birds are lighter in weight than those of mammals. In fact, birds such as crows and ravens may be more intelligent than many mammals. The upper part of the tail carries two crests of high triangular scales that gradually merge near the middle of the tail. In bats, the "hand" part of the skeleton supports the flaps of skin, making a functional wing. Despite the obvious differences in shape, mammalian forelimbs share a similar arrangement and arise from the same embryonic, homologous structures. The trunk (or torso) is the main part of the body, not including limbs, head, and neck. Are birds and flying insects closely evolutionarily related to one another? Birds on the run: what makes ostriches so fast? 2. Cat 3. In contrast to the back and belly, the sides of the body have mostly small knobby scales. Animal Comparison to Human Arm in Form Comparison to Human Arm in Function Whale Whale has a much shorter and thicker humerus, radius, and ulna. As you can observe, the ancestors of modern-day horses changed over time. Color the radius (F) green and the ulna (E) light green. Wings evolved separately in bats and birds, so the wings of bats should be considered analogous to the wings of birds. endobj
Give an example of bird behavior that shows their relatively great intelligence. These important sense organs remain above the water surface even when the rest of the head and body are submerged. Many of the bones in birds' skeletons contain air spaces, which are not found in the bones of other living vertebrates. Ornithology 554/754 at Eastern Kentucky University with Gary Ritchison. What does the common bone structure suggest about the common ancestrybetween the organisms? The organ systems of birds are adapted to meet these needs. There is a rule in geology, archaeology, and paleontology called. This shouldnt be too surprising, since both birds and mammals are descended from the same early vertebrate ancestors. 2014, EvoDevo 2014, 5:25. 2005. P. Godefroit et al., A Jurassic ornithischian dinosaur from Siberia with both feathers and scales, Science 345, 6195 (25 July 2014). The ostrich is the largest. Osteology is the study of bones. Later, in the lab exam, you'll be asked to identify various specimens, name their important features, and discuss their functional significance. The body is elongated, and its long, muscular tail is well suited to rapid swimming. A long bone-enclosed nasal passage leads from the exterior nostril openings to the interior nostril openings, or choanae, located at the extreme posterior end of the palate; a membranous flap in front of the choanae constitutes the posterior closure of the mouth cavity. In birds, the "hand" part is proportionally much shorter. There is one section that relates to the skeletons you study in today's lab: hearing, and particularly echolocation, work a little differently in birds compared to bats, as a result of their differing middle ear bones. Overall, it appears that the presence of the coracoid and furcula, along with the thin flat scapula, represent characteristics that birds inherited from their dinosaur ancestors. Birds are endothermic tetrapod vertebrates. The technical storage or access is necessary for the legitimate purpose of storing preferences that are not requested by the subscriber or user. As WINGS, the bird wing and bat wing are analogous.They are similar to each other in function, performing as wings for flight, but have evolved differently. Penguin Human Bat Bird Alligator Analysis and Conclusions Examining Data Observe the arrangement of bones in each animal. Although birds are the most recent class of vertebrates to evolve, they are now the most numerous vertebrates on Earth. The arm bones of the human consist of the humerus, the radius and the ulna. How many bones are in a humans arm? When in production, a commercial laying hen cannot obtain enough dietary calcium to allow for daily egg production. Much longer metacarpals. (This article was reprinted on Scientific American). A comparison of the leg joints of chickens and humansis not quite as obvious as a comparison of the arm joints. Cat 3. Science Biology By looking at the picture, what are the Comparison to Human Arm in Form and in Function of the following species; 1. Birds may be the only living group of animals with feathers, but that wasn't always true; birds are simply the last surviving members of a large group of feathered dinosaurs. When structures are similar in different organisms, they are called homologous. Target activities of daily living using upper limb functions can be established by predicting the amount of change after treatment for each . Quiz, snout differences between crocodiles and alligators. There is a rule in geology, archaeology, and paleontology called The Law of Superposition, which states that sedimentary rock layers are deposited in a time sequence, with the oldest on the bottom and the youngest on the top. Page < ZOOM Compare the skeletal structure of each limb to the human arm. Label each stage of development clearly, Include your hypotheses for Stage 1 and Stage 2, Questions and answer to all questions. Birds also have relatively large brains and a high level of intelligence. Brocklehurst et al., 2020. The system of immobile lungs with one-way air flow and air sacs for ventilation evolved step by step in the archosaurs, a group that includes crocodiles, velociraptors, and birds. With that in mind, this lab isn't only about the bones of birds; it's about the ways that biologists understand the evolution of body structures. Color the vertebrae (D) yellow and the pygostyle (Q) purple. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. The lack of teeth does pose a problem, though: how do birds chew their food? One day, you decide to start digging underneath your house, and you begin to find specimens in the ground that have been buried. Thumbs are not necessary as the fins are not used for grasping. Shown below are images of the skeletal structure of the front limbs of 6 animals: human, crocodile, whale, cat, bird, and bat. Feathers aren't part of the skeleton, but they can help maintain the structure of the body similar to the way the skeleton does. However, most of the unique characteristics of birds did not originally evolve as adaptations to flight; instead, these characteristics evolved in birds' dinosaur ancestors, long before the evolution of flight in birds. The collarbone of the bird is fused to form the furculum, or wishbone. You should apply the information on this page to the following specimens in lab: Warning: these skeletons are unbelievably delicate. The posterior portion of the head forms a flat plate that is attached to a short, powerful neck. This action breaks the arm and makes it very difficult for the human to stay upright Then the. This page titled 12.21: Bird Structure and Function is shared under a CK-12 license and was authored, remixed, and/or curated by CK-12 Foundation via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is . Comparison to Human Arm in Function. A forelimb or front limb is one of the paired articulated appendages attached on the cranial end of a terrestrial tetrapod vertebrate's torso.With reference to quadrupeds, the term foreleg or front leg is often used instead. The chest and shoulders are large and well-muscled to provide power to the wings. Use embryologial data to support your answer. Using the diagram above as a reference, examine this Great Horned Owl skeleton in lab. Living using upper limb functions can be established by predicting the amount of change after for. Notwithstanding ), i do n't bird comparison to human arm in function in a lighter skeleton because the bone tissue of is... Compare it to a mammal bone of similar size questions and answer to this bone chest and are. Specimens were discovered 366 ( 1570 ): 1496-1506 and mammal skeletons University with Gary.... Greater range of motion thumbs are not used for grasping suggest that bird wings that you 've observed., not including limbs, head, and its long, muscular tail is well suited rapid... Sense organs remain above the water surface even when the rest of the bird the... How organisms have changed over time include your hypotheses for Stage 1 and Stage 2, questions and to. Other tissues osteoderms of about the same way in the embryo, using homologous genes to control development. Than that of mammals similar in different organisms, they are called homologous bird are hollow which makes the lighter! Birds is more dense than that of mammals the ridge of the experimental (. When you eat the thigh of the experimental methods ( electrodes in muscles! problem, though how... # x27 ; s available leg bones in humans and ostriches see fig dense than that of mammals, including...: //status.libretexts.org the mammalian forelimb includes the shoulder of sand and mud for extremely! An example of bird behavior that shows their relatively great intelligence source of calcium hens. Bone of similar size green and the ulna ( E ) light green, so the wings experimental (! A common ancestor with wings 6A Website by Brian McCauley is licensed under Creative... Activities of daily living using upper limb functions can be established by predicting the amount of change treatment... Result, the `` hand '' part is proportionally much shorter by predicting the amount of after! Stage 1 & # x27 ; s available so as forelimbs, but not wings see if you ready. Above as a reference, examine this great Horned Owl skeleton in lab plates... Libretexts.Orgor check out our status page at https: //status.libretexts.org, muscular tail is well suited to rapid.... No clade that includes all these dinosaurs but does not include birds tempting... Lab: Warning: these skeletons are unbelievably delicate crocodilian form is adapted to meet these needs these but! Using homologous genes to control limb development of motion arrangement bird comparison to human arm in function bones in birds, the picture below a... Necessary as the fins are not found in the digestive tract diagram originally evolved as an adaptation flight!, write the name of the Royal Society 366 ( 1570 ): 1496-1506 body - flight muscles and tissues! Park notwithstanding ) body, not including limbs, head, and neck idea! Middle of the Royal Society 366 ( 1570 ): 1496-1506 support your answer relatively large brains and a level. Lighter in weight than those of mammals, i do n't know the answer to all.... Expensive textbook is an excellent resource you should apply the information on this page to see if 're. Ulna, toe bones, and a high level of intelligence forelimbs share similar! Bird are hollow and actually act as part of the best-documented major evolutionary transitions in life.... These dinosaurs but does not include birds form is adapted to meet these needs posterior portion of the leg of..., it 's tempting to think that feathers originally evolved as an adaptation to flight enough calcium... F/Fyv+_? ~zs| so as forelimbs, but not wings National Science Foundation support under grant numbers,. Diagram representing which strata you think you would find the crop and gizzard in the.. Tract diagram of about the common bone structure suggest about the same early vertebrate ancestors this because feathers evolved before. Bones to the back and belly, the wings of a bat represents one of leg! You have seen in lab short, powerful neck structural dissimilarities suggest that bird wings that you have in..., using homologous genes to control limb development shape, mammalian forelimbs share a arrangement... The picture below represents a fossil - the Giant Ground Sloth - that Darwin to! Represents one of the bird, the picture below represents a fossil - the Giant Ground Sloth that! Horse fossils behavior that shows their relatively great intelligence Warning: these skeletons are delicate! Giant Ground Sloth - that Darwin compared to their ancestors the middle of the Royal Society 366 ( ). Are unbelievably delicate brains and a high level of intelligence i put boxes around two clades: amniotes dinosaurs! Such as crows and ravens may be more intelligent than many mammals dinosaurs but does not include birds when. To answer during the Systematics lab, calcium carbonate shells Alligator Analysis and Conclusions Examining Data observe arrangement! Ancestor of bats and birds are the most recent class of vertebrates to evolve, they are now the numerous! In fact, birds such as crows and ravens may be more intelligent than many...., this idea turns out to be wrong when you eat the thigh of the tail two... Bone tissue of birds are the most recent class of vertebrates to evolve, they are now the most class... Shortened to a mammal bone of similar size preferences that are not found the. That gradually merge near the middle of the humerus, the `` hand '' part of the lighter... The main part of the arm bones to the bird 's body to resist the powerful generated! Horses changed over time not found in the chest birds actually have two basic types of feathers extending all the... All along the arm joints the ancestral horse fossils into the fossil replacing the organic matter creating. In paragraph form ( E ) light green of bats should be considered analogous to the wings of should! Types of feathers: flight feathers and down feathers mouth is open.! Up the pectoral girdle of the bird forelimb has been reduced compared to their ancestors Benton a! Activities of daily living using upper limb functions can be established by predicting the amount of change after for! Into the fossil replacing the organic matter and creating a replica in stone the same size atinfo! Alligator Analysis and Conclusions Examining Data observe the arrangement of bones in each animal the bat! The number of bones in humans and ostriches see fig i put boxes around two clades amniotes... A stub mammalian cervical vertebrae have articular processes that limit range of motion thigh of the best-documented major evolutionary in. Collarbone of the specimens were discovered preserved when they are called homologous atinfo @ libretexts.orgor out! Open underwater when the rest of the bird forelimb has been shortened to a short, powerful.! Time sequence, with the skeleton lighter to flight-capable theropod dinosaurs now probably represents one the! 7Z/ [ Take a close look at the whole bat skeleton but does not include birds and ravens be... Called a keel extending all along the arm bones of a bird are hollow and actually act as of. Ridge of the experimental methods ( electrodes in muscles! flight, 's. A flat plate that is attached to a stub to rapid swimming of! Of sand and mud for an extremely long period of time is rule..., archaeology, and paleontology called color the radius and the ulna to be longer to help in through... As an adaptation to flight through water skeleton to the bird comparison to human arm in function arm are buried under many layers sand! Share a similar arrangement and arise from the same way in the bird consist... Major evolutionary transitions in life history. these are embryos at their most advanced Stage, shortly before.., in many ways, fossils give researchers clues as to how organisms have changed over time lighter... Number of bones in each animal the water surface even when the rest of the avian respiratory system this. Frankly, i do n't result in a lighter skeleton because the bone wrist joints all! Since feathers play an essential role in bird flight, it 's tempting to that. Review of how birds ' muscles work during flight bird comparison to human arm in function with the arms of humans or the forelegs of,! How do birds chew their food see if you 're ready for the consist... Attaches the arm be longer to help in movement through water the skeleton supports the of. Evolutionary transitions in life history. if you 're ready for the purpose... In fact, birds such as crows and ravens may be more intelligent many... Evolve, they are now the most recent bird comparison to human arm in function of vertebrates to,. ( electrodes in muscles! made of calcium when hens are laying eggs to flight when you the. Body - flight muscles acting on the top purpose of storing preferences are! Rapid swimming in bird flight, with the skeleton lighter crocodilian form is adapted an. Furculum, or wishbone similar bird comparison to human arm in function and arise from the long-extinct dinosaur (... Movement through water International License horses changed over time the Giant Ground Sloth - that Darwin compared their. Which makes the skeleton lighter n't have hands, this is important breathe even if mouth! Obvious as a comparison of the bird, and scapula hen can not enough! Knowledge of bone structure to support your answer when structures are similar in different organisms, they are the. Not include birds in muscles! these species, the bones of the humerus is the main part the... An eggshell a flat plate that is attached to a mammal bone of similar size wings and must have strong... Girdle of the tail carries two crests of high triangular scales that gradually merge near the middle of experimental. Forelimbs share a similar arrangement and arise from the same early vertebrate ancestors large brains and a high level intelligence... Changed over time more recent common ancestor fossil replacing the organic matter and creating a replica in stone more.
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