Triassic Period

Therapsids, cynodonts, and the first mammals

The Evolution of Mammals, Enchanted Learning. Brief summary of the evolution of mammals, with links to information about the oldest mammal fossil from the Triassic.

Lystrosaurus. Wikipedia. Summary of the synapsid Lystrosaurus, the most common land vertebrate of the early Triassic period.

Cynodont. Wikipedia. Summary of the Triassic synapsid cynodonts, mammal-like reptiles that had very mammal-like characteristics.

Archosaurs and thecodonts

Lecture 11--Great Triassic Assemblages, Columbia University, Lamont Doherty Earth Observatory. Maps and description of the Chinle Group (western United States), which is famous for its Triassic fossils. The site includes cladograms of archosaurs, diagrams showing changes in wrist structures among the archosaurs, and discussions of the phytosaurs, aetosaurs, ornithosuchia, and suchia, including Postosuchus, a famous, large carnivorous Triassic archosaur. If you continue to scroll down the page, there are also descriptions of Triassic dinosaurs from the Chinle, including Coelophysis.

Order Thecodontia, Kheper. Discussion of the relationship between the thecodonts (a subdivision of reptiles that has fallen out of favor) and archosaurs, as well as descriptions and images of the main suborders, Proterosuchia, Parasuchia, Rauisuchia, Aetosauria, Dromaoesuchia, and Ornithosuchia. The Ornithosuchia, are the ancestors of dinosaurs.

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.

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.

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.

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.

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.

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

Coelophysis, and early dinosaurs

Coelophysis and Ghost Ranch. New Mexico Museum of Natural History and Science. Excellent site with information about the early theropod dinosaur Coelophysis, and the digs at Ghost Ranch, New Mexico.

Walking with Dinosaurs Chronology, BBC. Information about the animals of the Late Triassic, including the Triassic dinosaurs Coelophysis and Plateosaurus. Based on the "Walking with Dinosaurs" video series.

Triassic Period, Enchanted Learning-Zoom Dinosaurs. Fun, nontechnical summary of the geology, climate, and life of the Triassic Period. Fact sheets, K-3 appropriate printouts, and classroom activities are provided. Also at this site are concise summaries of the Triassic dinosaurs Eoraptor, Coelophysis,and Plateosaurus.

Lecture 11--Great Triassic Assemblages, Columbia University, Lamont Doherty Earth Observatory. Maps and description of the Chinle Group (western United States), which is famous for its Triassic fossils, including the Coelophysis fossils at Ghost Ranch, New Mexico. Scroll down the page to get to Coelophysis text and images.

Prosauropods. SUNY (State University of New York) Orange Online Biology Library. Slightly technical explanation of what prosauropods are, how they lived, when they lived, where they lived, differences among different types of prosauropods and the relationship between prosauropods and their larger cousins, the sauropods.

Paleontologists Overturn Claim that Coelophysis was a Cannibal. American Museum of Natural History. Short news article summarizing research that reexamined the fossil gut contents of Coelophysis and determined that the dinosaur’s last meal was small crocodiles rather than baby Coelophysis.

Coelophysis. Wikipedia. Summary with pictures of this famous early theropod dinosaur from the Triassic of the United States.

Plateosaurus. Wikipedia. Summary with pictures of this famous prosauropod dinosaur from the Triassic of Africa.


Last Modified on 2023-01-05
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