DINOSAURS



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Dinosaurs are 200 million years old. Dinosaurs are slow, obsolete, and bound for extinction. The first dinosaur was the Megalosaurus. Over 100 feet long and up to 50 feet tall is the biggest a dinosaur can get. The largest dinosaur was the Sauropod. The smallest dinosaur was about the size of a chicken. Sixty-five million years ago the dinosaurs died. Since they went extinct, more than 50% of other life formed on the planet. Paleontologist debate to this day whether predatory dinosaurs actively hunted their prey, or scavenged them. Dinosaurs are another creature that lays eggs in nest. Dinosaurs are a diverse and varied groups of animals. The first dinosaur fossils were recognized in the early nineteenth century. Since then, mounted dinosaurs appear in museums, and they are a big part of life today. Jurassic Park, a dinosaur series, have been featured the best-selling books and features. Dinosaurs that were non-avian suddenly became extinct approximately over 65 million years ago
Wikipedia dinosaur

megalosaurus.jpgMegalosaurus.


external image sauropods-tn.jpgSauropod.

Herbivore/Carnivore.





Herbivore: plant eaters.
Carnivore: meat eaters.kill other animals.
About 65% of dinosaurs were herbivores. The others were known as carnivores. It's never been proven how many species of dinosaurs there have been. The estimation was 250 to over 1300 species.


Warm-Bloodedness!


Some dinosaurs are warm-blooded; endothermic. They have active, heat-producing metabolisms. No matter what the outside conditions are, these metabolisms maintain a internal body temperature that is constant. Only some dinosaurs are endothermic, but not all. Dinosaurs were suggested warm-blooded because of the isotopes in their bones. Warm-blooded animals maintain a constant body temperature. Some dinosaurs are not warm-blooded. They would be classified as cold-blooded. Reptiles are known to be cold-blooded. Since dinosaurs are classified as reptiles, they are known to be cold-blooded too.

Definitions!



Endothermy; the ability to generate heat internally rather than via behaviors such as basking or muscular activities.
Homeothermy; maintaining a constant body temperature.
Tachymetabolsim; maintaining a high metabolite rate, particularly when at rest. Requires a fairly high and stable body temperature, since biochemical processes run about half as fast if an animals temperature drops by 10 degrees celcius. Most enzymes have an optimum operating temperature and their efficiency drops rapidly outside the preferred range.


endothermy.jpg


Hair and Fur!




The first clear evidence of hair or fur is in fossils of Castorocauda from 164 million years ago in the mid Jurrasic. The maxillae is the upper jaws, and the premaxillae are the small bones located in front of the maxillae as channels. They supplied blood vessels and nerves from vebrissae, which are whiskers. They suggested this is the evidence of fur. Foramina don't show that an animal had vebrissae. For example; the modern lizard Tupinambis has foramina, which is almost identical to those found in the non-mammalian cynodont Thrinaxodon. Feathers are often associated with birds. Because of that, feathered dinosaurs are often touted as the transitional fossils birds and dinosaurs.

vibrissae.jpg


Did you know?




- Dinosaurs weren't the first reptiles to rule the earth?
- All species of dinosaurs haven't been discovered yet?
- The dinosaur kingdom was split into two main groups?

The first dinosaurs evolved in the middle to late Triassic period which was about 230 million years ago. Archosaurs and Therapsids were the dominate land reptiles before dinosaurs. Archosaurs are known as "ruling lizards". Therapsids are known as "mammal-like reptiles". For 20 million years or so after the first dinosaurs appeared the most fearsome reptiles. These reptiles were dinosaurs. The only dinosaurs ever found were the ones that left fossils behind. Without fossils, it's hard to find all species that existed. Fossil evidence is abundant for late Jurassic and late Cretaceous (Jurassic- 150 million years ago. Cretaceous- 80-65 million years ago) dinosaurs. Long stretches of geologic time, across very continents, remain unaccounted for. Dividing dinosaurs into herbivores and carnivores makes more sense. In paleontologist' eyes, they believe something differently. Dinosaurs are divided into Saurischian and Ornithischian dinosaurs. Saurschian dinosaurs are lizard-hipped. Ornithisnchian are bird-hipped. Birds also evolved from these dinosaurs.

Facts About Dinosaurs Site

=Dinosaur Teeth.

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The teeth on a dinosaur can tell you many things about that dinosaur. It can tell you things like what type of food they eat, what type of dinosaur it is. Dinosaur teeth are harder than a bone. They are strong. If a dinosaur's tooth us broken or comes out, another one grows back in. They are replaceable. There are many different shapes and sizes of dinosaur teeth. Some are long, and some are short. Dinosaur teeth gives lots of facts about dinosaurs.
Teeth


=Female/Male Dinosaur.

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The female dinosaur is different from a male dinosaur. When Paleontologists discuss between a male and female dinosaur they say female dinosaurs have larger hips than male dinosaurs. This is because of child birth. Female's lay large eggs. The bigger their hips, the easier it gets through the passage. A Tyrannosaurous Rex is a good example. Paleontologists believe this species of dinosaurs are larger than males. This means the female does most of the hunting and is more competetive.
It is hard to find the sex of a dinosaur. Single birds are easy to find. But when looking for a dinosaur's sex you have to be pretty lucky. For a dinosaur you need a handful of fossils. Fossils aren't very easy to find. Sometimes, a gender is hard to find for a dinosaur.

Genders