Course Hero Logo

Figure 1411 herrerasaurus source httpwwwwikidinocomwp

Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. This preview shows page 454 - 456 out of 559 pages.

Figure 14.11 - Herrerasaurus (source: -content/uploads/Herrerasaurus-britannica.jpg)Figure 14.12- Ceratosaurus (source: )Ceratosauran(“horned-reptile”) fossils appear in the late Triassicanother 2 million years after Herrerasaurus. They varied in size fromtwo meters (six feet) long up to five times that. They are the mostcommon therapod fossils found. Some species were delicate, whileothers were robust. Regardless of their size or form, they were allagile predators. They had a three-clawed hand with a single fourthdigit stub. Unique to these dinosaurs was a large head topped withhorned crests; thus the name. In many ways they resembled birds,especially in the bones of their hips, hands, and legs. This late in theTriassic there were plenty of small sauropods for these fleetpredators to eat.By the time that theTetanurae(“stiff tail”) arrived on the scene inthe Middle Jurassic, they had lost their fourth digit of their hands,but their hands were larger with bigger claws on even shorter butmore muscular arms. As their name implies, they had a stouterstiffer tail than their forebears that helped support a thick neck andlarge head with long serrated sickle-like teeth. The stiff tails were avery diverse group that ranged from chicken-size to monstrousproportions.Megalosaurus(“giant-reptile”) was a one-ton Tetanurae, the first discovered dinosaur to be given a properscientific name. They developed the characteristics we associatewith the monster carnivores of movie fame.
Carnosauria and CoelurosauriaCarnosauria (“meat reptile”) and Coelurosauira (“hollow-tailedreptile”) were sister clade offshoots ofthe Tetanurae. Carnosauria eventually gave rise to themighty Allosauroidea (“strange reptile”) that are the predators ofour nightmares. Even the medium-sized ones had heavy bones andbig musculature. One type weighed in excess of 5 tons. Thelarge Allosauroidea were not just heavy, at 12 meters (38 feet) longand almost 5 meters (17 feet) tall, they were giants. What madethem especially ‘strange’ was their unique skeletal structure. Theyhad special shielding belly ribs (gastralia - found today only inreptiles) that only attached to the skin. They had inherited three-fingered hands from their ancestors with the modification of havingsharp 15-centimeter (6-inch) claws. They had huge heads with browhorns behind the eyes, and 1.3 meter (4 foot) long serrated teeth.Fossil Apatosaurus (Brontosaurus) bones have been found withgouges in them that match the marks made by those awful teeth.They lived from the Middle Jurassic to the Middle Cretaceous.Apparently the cooling of the Cretaceous contributed to theirextinction.Figure 14.13 - Carnosauria gastralia 'belly ribs"(source: )

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 559 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Fall
Professor
NoProfessor

Newly uploaded documents

Show More

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture