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Triassic Period—Dinosaur origins and oldest dinosaurs

What is a dinosaur? Bonnie Sachatello-Sawyer, Don and Liza Charlesworth at Short synopsis of dinosaur characteristics and misconceptions.

What is a dinosaur? American Museum of Natural History. Short definition and classroom activity for helping students understand the difference between dinosaurs and other animals.

What is a dinosaur? Mike Taylor. Dinosaur FAQ.  This web page examines the historical and cladistic definition of dinosaurs. More technical than some may need, but lists many of the specific bones/body parts that differentiate dinosaurs from other animals. Also discusses the case for Eoraptor as a basal dinosaur or a pre-dinosaur.

Dinosaur Evolution, University of Bristol, Department of Geology. Sections about the evolution of vertebrates leading to dinosaurs, classification of dinosaurs, evolution of archosaurs, evolution of birds, and the dinosaur evolutionary tree.

Rise of Dinosaurs in Late Triassic. Science News, ScienceDaily. Brief news article summarizing finds in New Mexico that show early dinosaurs and dinosauromorphs (thecodonts, dinosaur ancestors) living side-by-side, which indicates a gradual evolution rather than the sudden extinction of the dinosaur ancestors followed by rapid diversification of dinosaurs.

South American dinosaurs oldest?

Eoraptor. Wikipedia.  Summary of what many scientists think is the world’s oldest dinosaur. Found in Triassic rocks ~225 to 230 million years old.  Small, theropod or theropod-like dinosaur.

Eoraptor. University of Texas, Austin, C-T lab. CT scan of Eoraptor skull and short description of implications of this skull for basal theropod dinosaur lineage.

Ischigualasto Formation, Argentina, University of California, Berkeley. Good summary of this famous South American rock unit from which the oldest known dinosaur fossils, Herrerasaurus and Eoraptor, were found.

Theropoda: Basal Theropods. Palaeos. Technical summary of the earliest carnivorous dinosaurs. Scroll down the page for descriptions of Eoraptor and Herrerasaurus. References and links to further information and images are provided for both genera.

Madagascar dinosaurs oldest?

Discovery of oldest dinosaur bones reported in Science. University of California, Santa Barbera. Press release on discovery of fossil dinosaur bones of what may be oldest dinosaur known. Found in Triassic rocks ~225 to 230 million years old. <not yet named>

Field museum scientists discover what appear to be World’s oldest dinosaur fossils. Field Museum, Chicago, IL. Press release on find of jawbone of a prosauropod that may be the oldest dinosaur known. <not yet named>

European dinosaurs oldest?

Silesaurus.  Wikipedia. Summary of this possible dinosaur or pre-dinosaur (dinosauromorph) found in Triassic rocks ~230 million years old.


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