Feathers are complex, branched, keratinized epidermal features commonly associated with Class Aves, or birds (Bock, 2000). Cells in the epidermis called keratinocytes are the structural components of feathers; however, the protein keratin varies in its distribution and can be of different types (Prum, 2002). Many functions involved with feathers include thermal insulation, flight, cleaning of plumage, heat protection, sound production, chemical defenses, water repulsion of plumage, social communication, streamlining the body, and the sensation of touch (Bock, 2000; Prum, 2002). A wide variety of feathers have been characterized. Feathers covering the body are known as contour feathers (Bock, 2000). Contour feathers covering the wings are called remiges, while those covering the tails are called retrices (Bock, 2000). Additional types of feathers include semiplumes, down and powdered down feathers, bristles and semibristles, filoplumes, courtship plumes, and oil gland feathers (Bock, 2000). General characteristics of feathers include the presence of a calamus, which anchors the feather into the bird’s integument (Bock, 2000). Barbs, or closely spaced branches, are attached to the central shaft known as the rachis (Bock, 2000). Barbs on each side of the rachis form a vane (Bock, 2000). Proximal and distal barbules originate from barbs; proximal barbules are near the base of the feather while distal barbules are at the tip of the feather (Bock, 2000; Prum, 2002). When these barbules interlock, the structure of the vane is preserved (Bock, 2000).
Interestingly, feathers are not restricted to birds; fossil evidence from Archaeopteryx lithographica showed that feathers originated in pre-avian dinosaurs (Prum, 1999). It is understoo...
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... R.O. 1999. Development and Evolutionary Origin of Feathers. J. Exp. Biol. 285: 291-306.
Prum, R. O. 2002. The Evolutionary Origin and Diversification of Feathers. Q. Rev. Biol. 77: 261-291.
Schweitzer, M.H., Watt, J.A., Avci, R., Knapp, L., Chiappe, L., Norell, M. et al. 1999. J. Exp. Zool. 285: 146-157.
Vinther, J., Briggs, D.E.G., Clarke, J., Mayr, G., Prum, R.O. 2010. Structural coloration in a fossil feather. Biol. Lett. 6: 128-131.
Xu, X. 2006. Feathered dinosaurs from China and the evolution of major avian characters. Integr. Zool. 1: 4-11.
Xu, X., Zhou, Z., Prum, R.O. 2001. Branched integumental structures in Sinornithosaurus and the origin of feathers. Nature 410: 200-203.
Zhang, F., Kearns, S.L., Orr, P.J., Benton, M.J., Zhou, Z., Johnson, D. et al. 2010. Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds. Nature 463: 1075-1077.
Ceratopsians and Pachycephalosaurs are closely related in their characteristics. Ceratopsians processed a saddle-shaped boney frill that extended from the skull to the neck and typically had horns over the nose and eyes. The most popular was the triceratops, which could reach over 26 feet and weigh in excess of twelve metric tons. Their frills served as two major functions. It protected the vulnerable neck from being harmed. The second major function that the frill provided was due to the fact that the frill contained a network of blood vessels on its underside, which were used as a means to get rid of excess heat. The Pachycephalosaurs were considered to be bipedal. They were also found to have thick skulls, flattened bodies, and tail that were covered in an array of body rods. Pachycephalosaurs were thought to have been more than fifteen feet long and processed a skull that was surrounded by a rounded dome of solid bone. It was thought that they used their heads in combat or mating contests, but that was disproved fairly recently, which I will discuss later in the paper. Both Ceratopsians and Pachycephalosaurs were “bird-hipped” and both of these suborders contained a backwards pubic bone. Both were Marginocephilia, or “fringed heads”, which is one of three clads under the Orinthiscia order. They were also herbivore dinosaurs that inherited their fringe at the back of the skull from earlier ancestors.(2) Their classi...
Calyptorhynchus banksii, commonly known as the red-tailed black-cockatoo, is of the Family Cacatuidae (Cockatoos), which is a branch of the Order Psittaciformes. Red-tailed black-cockatoos are indigenous to Australia and can be found throughout the entire continent. Calyptorhynchus banksii is distinct in that there are five different subspecies: Calyptorhynchus banksii( C.b.) banksii, C.b. macrorohynchus, C.b. naso, C.b. graptogyne, and C.b. samueli (Del Hoyo et al., 1997). Differences in beak apparatus are one of the most prevalent variations observed within the subspecies. Throughout the paper an examination of evolutionary forces will explain the changes that have occurred in the beak apparatus of the red-tailed black-cockatoo.
The reading states that critics have opposes the idea that Sinosauropteryx was a feathered dinosaur and the author provides three reasons of support. However, the professor explains that critics are unconvincing and refutes each of the authors' reasons.
This experiment was designed to illustrate the process of evolution through the use of Origami Birds. It was evident at the conclusion of the experiment that Origami Birds with a smaller in circumference front wing placed 3 centimeters from the end of the straw and larger in circumference back wing placed 3 centimeters from the end of the straw flew further than the Generation 0 birds with the same circumference front and back wings. Our results also indicated that birds with their wings positioned differently than 3 centimeters from either end of the straw did not fly as far as those who were positioned at that 3 centimeter mark. Generation 0's best flyer produced a distance of 2.08 meters with a 3x20 and 3x20 wing ratio. Generation 1's best
In the early 1800’s, a new discovery that left paleontologists in awe was the fossil finding of the immeasurable amount of species of reptiles, Ichthyosaurs. Greek for “fish lizards”, these fossils were found all over the world. Because these large aquatic reptiles migrated just as whales do today, paleontologists have had the amazing advantage of collecting fascinating bone fragments throughout the past 177 years. Ichthyosaurs swam the ocean life from about 245 million until about 90 million years ago- approximately the same time dinosaurs ruled the land. The earliest Ichthyosaur fossil findings were in parts of Canada, China, Japan, and possibly Thailand. Countless fossils came from coatings of limestone produced out of the ocean-floor ooze that was predominantly superior at preserving very well facts of the creatures it digested (Perkins 2).
...(1995). The Beak of the Finch: A Story of Evolution in Our Time. Vintage Books: New York.
For this evolution project, I choose to research Penguins. The classification for this animal is as follows: K Neornithes, P Palaeognathae, C Neognathae, O Pelecaniformes, F Procellariformes, G Graviidae, S Spheniscidae. The first fossil penguin that was found, is today being held in the British Museum of Natural History. It was reportedly found by an anonymous Maori in New Zealand in 1859 and was named Palaeeudyptes Antarcticus despite the fact that the species was located far away from Antarctica. Since that discovery many more fossils were found and were dated back to the Miocene era and three others from the Pliocene era. Several fossils were dated to the Late Pliocene era and others from the Recent era. The earliest avian fossil found in the southern hemisphere is said to have existed in the Eocene age about 38-54 million years ago. There is evidence that at least three of the modern penguins (Aptenodytes, Spheniscus and Pygoscelis) went extinct within the last 4-5 million years. The remainder of the penguins are from 5-40 million years ago, dating back to the time currently recorded, when penguins evolved from other modern birds. Research suggests that the tallest of these penguins were about 6 feet tall. Penguins did originate from an ancestor that flew some 40 million years ago. The common ancestor is assumed to have been somewhat similar to a modern-day diving petrel or auk in appearance and behavior.
Jonathan Weiner, The Beak of the Finch: A Story of Evolution in Our Time. New York:
While there is no direct indication of the Tyrannosaurus rex having had feathers, scientists now consider that the T. rex had feathers on at least parts of its body. Because of their presence in related species. Mark Norell of the American Museum of Natural History stated with evidence "we have as much evidence that T. rex was feathered, at least during some stage of its life, as we do that australopithecines like Lucy had hair."
The debate of whether dinosaurs were cold blooded or warm blooded has been ongoing since the beginning of the century. At the turn of the century scientists believed that dinosaurs had long limbs and were fairly slim, supporting the idea of a cold blooded reptile. Recently, however, the bone structure, number or predators to prey, and limb position have suggested a warm blooded species. In addition, the recent discovery of a fossilized dinosaur heart has supported the idea that dinosaurs were a warm blooded species. In this essay, I am going to give supporting evidence of dinosaurs being both warm and cold blooded. I will provide background information on the dinosaur that was discovered and what information it provides scientists.
Marzluff, J., Angell, T. & Elliot, B. (2013, May. - Jun.). Birds: Brains over brawn. Audubon, 115(3), 40-41.
Denotatively a bird is defined as a, Any of a class (Aves) of warm-blooded vertebrates distinguished by having the body more or less completely covered with feathers and the forelimbs modified as wings, often capable of flying. The authors/Glaspell’s strategic comparison of Mrs. Wright to a bird can be interpreted connotatively that she was a free,
del Hoyo, Josep, Andrew Elliott and Jordi Sargatal. Handbook of the Birds of the World. Vol 1, Ostrich to Ducks. Barcelona: Lynx Edicions, 1992.
Deinonychus is an extinct dinosaur that belonged to the genus Carnivorous dromaeosaurid coelurosaurian dinosaurs and lived in the early Cretaceous Period which is approximately 115-108 million years ago. The fossil remains of the species Deinonychus antirrhopus were discovered in the US states of Utah, Oklahoma, Montana, and Wyoming. The word Deinonychus has a Greek background suggesting the words “terrible” and “claws.” Their claws were large and formed a sickle shape on the second toe of the rear feet. The species name, antirrhopus, simply means “to counterbalance” thus suggesting the Deinonychus’ long tail which had rigid tendons and bones that supported and balanced the whole body. Paleontologist John Ostrom is credited for researching and writing about the Deinonychus in details.
Reptiles are vertebrate, or backboned animals constituting the class Reptilia and are characterized by a combination of features, none of which alone could separate all reptiles from all other animals.The characteristics of reptiles are numerous, therefore can not be explained in great detail in this report. In no special order, the characteristics of reptiles are: cold-bloodedness; the presence of lungs; direct development, without larval forms as in amphibians; a dry skin with scales but not feathers or hair; an amniote egg; internal fertilization; a three or four-chambered heart; two aortic arches (blood vessels) carrying blood from the heart to the body, unlike mammals and birds that only have one; a metanephric kidney; twelve pairs of cranial nerves; and skeletal features such as limbs with usually five clawed fingers or toes, at least two spinal bones associated with the pelvis, a single ball-and-socket connection at the head-neck joint instead of two, as in advanced amphibians and mammals, and an incomplete or complete partition along the roof of the mouth, separating the food and air passageways so that breathing can continue while food is being chewed. These and other traditional defining characteristics of reptiles have been subjected to considerable modification in recent times. The extinct flying reptiles, called pterosaurs or pterodactyls, are now thought to have been warm-blooded and covered with hair. Also, the dinosaurs are also now considered by many authorities to have been warm-blooded. The earliest known bird, archaeopteryx, is now regarded by many to have been a small dinosaur, despite its covering of feathers The extinct ancestors of the mammals, the therapsids, or mammallike reptiles, are also believed to have been warm-blooded and haired.