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Origin and evolution of reptiles
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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.
Proposals have been made to reclassify the pterosaurs, dinosaurs, and certain other groups out of the class Reptilia into one or more classes of their own. The class Reptilia is divided into 6 to 12 subclasses by different authorities. This includes living and extinct species. In addition, a number of these subclasses are completely extinct.
The subclasses contain about 24 orders, but only 4 of these are still represented by living animals.Of the living orders of reptiles, two arose earlier than the age of reptiles, when dinosaurs were dominant. Tuataras, of the order Rhynchocephalia, are found only on New Zealand islands, whereas the equally ancient turtles, order Chelonia, occur nearly worldwide. The order Crocodilia emerged along with the dinosaurs. Snakes and lizards, order Squamata, are today the most numerous reptile species.
W. H. Freeman and Company, New York. 2) http://www.trueauthority.com/dinosaurs/about.htm 3) Dr. Robert Riesz, University of Toronto, “Ceratopsia and Ornithopoda” http://www.erin.utoronto.ca/w
Oxygen breathing lungs are a universal trait of class reptilia. As such, it would have been necessary for the Plesiosauroid - a marine reptile, to return to the ocean surface to inhale air. Oxygen expenditure in reptiles is proportional to strenuosity of locomotion (Frappell, Schultz & Christian, 2002). Therefore the Plesiosauroid must have held physiological traits that enabled the species to avoid oxygen deficit while hunting deep-sea dwelling prey. This essay will outline the hypothesised respiratory, circulatory, pulmonary and sensory attributes of the Plesiosauroid as they relate to diving. These hypotheses will be supported by investigating the physiological adaptations of the Plesiosaur’s biological analogues, and the prospect of similar adaptations in the former will be speculated upon.
Raelians Raelians also love hierarchy. They group themselves into six levels, ranging from novice to Rael himself, who alone occupies the 6th level. Cocolios is a 3rd-level Raelian and a "regional guide." Chabot, a 4th-level Raelian and a "national guide," sets up an interview with Lear, a 5th-level Raelian. Adherence to the movement and to another religion * Adherence to the Raelian religion excludes adherence to another religion.
Paul, Gregory S. (2002). "Looking for the True Bird Ancestor". Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Baltimore: Johns Hopkins University Press. pp. 171–224. ISBN 0-8018-6763-0.
The idea of cloning dinosaurs and other prehistoric life became popularized by the 1992 film Jurassic Park (based on Michael Crichton’s 1990 novel). Though it may have sparked new interest into the field of paleontology, it did so with deceiving inaccuracies. However, the technical fallacies of the actual dinosaurs are somewhat forgivable as it added to the film’s dramatic appeal. Velociraptor, as depicted in the film, was about the size of a grown man. In reality, velociraptor came to about the kneecap. Furthermore, velociraptor would more likely have been covered in feathers rather than the lizard-like skin portrayed in the movie. One scene shows velociraptor fogging the window of a door. This is an endothermic or warm blooded trait as it implies the dromaeosaurid’s body temperature is above the temperature of his environment. There is also no evidence of dilophosaurus bearing a neck frill, and brachiosaurus did not have the ability to chew his food in a circular motion (iguanodon was the first dinosaur to develop this technique by acquiring back molars to allow for equine or bovine-like chewing). Fortunately, tyrannosaurus remained very close to his biological authenticity, with the only paleobiological errors stemming from a lack in computer animation such as rudimentary ball and joint programs. However, the erroneous nature of the deoxyribonucle...
Hutchinson, John R., Garcia, Mariano “Tyrannosaurus was not a fast runner.” Nature 28 Feb 2002: 1018-1021
Dinosaurs were first believed to be cold-blooded because they were thought to be related closely to reptiles which are cold-blooded creatures. Cold-blooded animals don’t actually have “cold” blood, instead they rely on the temperature from their environment to regulate their own body temperature. They do this by taking advantage of external heat by basking in the sun, and by lying in the shade to cool down. A more correct term is “ectothermic” which means “heat from outside.” On the other hand, a warm-blooded animal creates heat internally by chemical reactions inside their body. They are able to regulate their body temperature internally instead of relying on their environment. Author of the article, “Dinosaurs: Warm or Cold Blooded?” Beverly Eschberger explains, “endothermic animals have a continually high requirement for food to fuel the heat generation. Providing they can find food their constantly-optimum body temperature means that they can stay active even when it is very cold” (par 3). Even though it was believed that dinosaurs were closely related to cold-blooded reptiles, most dinosaurs had similar behaviors of a bird which is a warm blooded animal. Believing dinosaurs were warm blooded would help explain the reason why dinosaurs were so dominant and plentiful for such a long period of time. There are many other factors that play a vital role in ...
Nicholson KE, Harmon LJ, Losos JB. Evolution of Anolis Lizard Dewlap Diversity. PLOS ONE. 2007
The American alligator scientific name is Alligator mississippiensis. The Chinese alligator is the only other alligator in the alligator family and its scientific name is alligator sinensis. The American alligator is in the kingdom Animalia because it is an animal. The phylum is chordate because it has vertebrae. The American alligator is in the class reptilia because it is cold blooded, lays shelled eggs, scaly skin and breaths air. Alligators are in the order crocodilian because it is a large animal that appeared during the Cambrian stage. The American alligator is in the family alligator idea because it has larger, broader snouts, and can withstand colder temperatures. The genus is alligator and the species is Mississippiensis (Florida nature,2006).
Dinosaurs are an extinct group of animals that thrived for 165 million years starting 230 million years ago in the Late Triassic period of the Mesozoic Era. Despite being extinct for the past 65 million years and not being able to study them in their true form, scientists have been able to estimate many different behaviors of dinosaurs. This paper will show that the close study and examination of different types of body and trace fossils, along with animal models, can be provided as evidence to estimate different types of behaviors in dinosaurs. The different types of behaviors examined below will fall into the categories of: mating; reproduction and nesting; social lives; locomotion; feeding; and fighting. To begin, a great deal of information gathered from fossils and compared to living animal models have been used to estimate mating behaviors.
They ruled the world before the time of the dinosaurs, from the Cambrian Period to the
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.
There are two kinds of species of alligators. There is the American alligator and the Chinese alligator. Many people have a hard time telling the difference between alligators and crocodiles. Alligators are related in the same family as the crocodile, but these two animals are very different. An alligator’s upper jaw overlaps the lower jaw. Alligators have a broad snout while crocodile have a very narrow snout. Alligators have much less aggressive and energetic than the crocodiles. Alligators live in tropical climates and crocodiles live in somewhat colder climates. Their kingdom is Animalia. Their Phylum is Chordata. They come from the class Reptilia. Their order is Crocodylia. Their family is Alligatoridae. Their genus is Alligator and their species is alligator messissipiensis and they are known as American alligators.
Frogs are needed for everyday life. They are part of pond life. Each animal is important because even in the pond, there is a food chain. Frogs are amphibians, animals that spend half of their lives under water, and remainder on land. The first frog appeared in the early Jurassic period about 200 million years ago.
Frogs are amphibians in the order Anura. The order Anura is broken down into 22 different families of frogs and toads. Although they belong to the same order, frogs and toads are different in a lot of ways. Some of the more distinct differences are their skin and where they live. Frogs usually have smooth moist skin and toads usually have dry watery looking skin. Frogs spend most of their lives in or near water and toads spend more time on land. Amphibian means "double life." Frogs and toads each have two parts to their lives: when they live on water and when they live land. A frog's life starts in the water when it is hatched from an egg as a tadpole. A tadpole looks very different from an adult frog. A tadpole has a tail, no limbs, and breathes through gills. After a while the tadpole goes through metamorphosis. During the change the frog grows limbs, the tail disappears, it uses lungs to breathe, and it doesn't have to live in water anymore. As a tadpole, the frog feeds mostly on vegetation. The tadpoles have a small rasping mouth suited especially for scraping algea from the bottom of ponds. Depending on the species, it can take a few weeks to a year or more for the tadpoles to become fully grown. Not all frogs hatch as tadpoles. Some species of frogs hatch as froglets. Froglets look just like adult frogs but are a lot smaller. Froglets don't go through a metamophosis. Most species that hatch as froglets are found in dry places. Frogs who live in dry places where rains are seasonal have to grow up quickly because a tadpole will die if their temporary pond dries up. Adult frogs can live in water or on land, but it always needs to be near water so its respiratory organs don't dry out.