What Is the Earliest-Known Dinosaur?
Since the fossil record for dinosaurs is rather incomplete, we do not have fossils from the very first dinosaur that ever lived. However, based on the age of the specimens that we do have, that first dinosaur may well have lived in the earlier portions of the Triassic Period.
The earliest dinosaurs for which we do have well-documented fossils are found in Late Triassic Ischigualasto Formation in northern Argentina. Skeletons discovered in these rock layers include the meat-eating dinosaurs Herrerasaurus and Eoraptor, as well as the plant-eating dinosaur Pisanosaurus. Some of the rock layers from this formation are composed of ancient volcanic ash, which has yielded a radioisotopic age of 228 million years ago.
Other possible candidates include dinosaur remains from Late Triassic rock layers of the Petrified Forest in Arizona, the Wolfville Formation in Nova Scotia, and some rock formations in Brazil. But unfortunately, no radioisotopic dates have been obtained from rock layers in these units. Based on other kinds of fossils found in these formations, such as fossil pollen and other kinds of vertebrates, it appears that dinosaurs from these rock layers are slightly younger than the skeletons of Herrerasaurus, Eoraptor, and Pisanosaurus from the Ischigualasto Formation.
This video is part of a series, "Dinosaurs Explained," produced by the American Museum of Natural History. In the series, Museum paleontologists answer the most frequently asked questions about dinosaurs.
To watch the videos, go to www.amnh.org/explore/amnh-tv. Click on the "Dinosaurs Explained" Tab on the left side of the page. In the playlist, start with the first question and play each video consecutively for a mini-course in dinosaur fossils.
Episode 1: What Is and Is Not a Dinosaur?
• What Is and Is Not a Dinosaur?
Episode 2: Who Discovered the First Dinosaur Fossils?
• Who Discovered the First Dinosaur Fos...
Episode 3: How Do Dinosaurs Get Their Names?
• How Do Dinosaurs Get Their Names?
Episode 4: Are Any Dinosaurs Still Alive Today?
• Are Any Dinosaurs Still Alive Today?
Episode 5: How Many Kinds of Dinosaurs Are There?
• How Many Kinds of Dinosaurs Are There?
Episode 6: Where in the World Did Dinosaurs Live?
• Where in the World Did Dinosaurs Live?
Episode 7: What Is the Earliest-Known Dinosaur?
• What Is the Earliest-Known Dinosaur?
Episode 8: What Were the Biggest and Smallest Dinosaurs?
• What Were the Biggest and Smallest Di...
Episode 9: What Did Dinosaurs Eat?
• What Did Dinosaurs Eat?
Episode 10: How Fast Were Dinosaurs?
• How Fast Were Dinosaurs?
Episode 11: How Intelligent were Dinosaurs?
• How Intelligent Were Dinosaurs?
Episode 12: Did Dinosaurs Fight?
• Did Dinosaurs Fight?
Episode 13: How Did Dinosaurs Reproduce?
• How Did Dinosaurs Reproduce?
Episode 14: Did Dinosaurs Travel in Herds or Packs?
• Did Dinosaurs Travel in Herds or Packs?
Episode 15: What Was Dinosaur Skin Like?
• What Was Dinosaur Skin Like?
Episode 16: How Fast Did Dinosaurs Grow, and How Long Did They Live?
• How Fast Did Dinosaurs Grow, and How ...
Episode 17: What Color Were Extinct Dinosaurs?
• What Color Were Extinct Dinosaurs?
Episode 18: Were Dinosaurs Warm-Blooded?
• Were Dinosaurs Warm-Blooded?
Episode 19: How Did All Dinosaurs Except Birds Go Extinct?
• How Did All Dinosaurs Except Birds Go...
Episode 20: Can We Clone Extinct Dinosaurs From DNA Preserved in Their Fossils?
• Can We Clone Extinct Dinosaurs From D...
Episode 21: What Is a Fossil?
• What Is a Fossil?
Episode 22: How Do We Know Where to Look for Dinosaur Fossils?
• How Do We Know Where to Look for Dino...
Episode 23: How Are Dinosaur Fossils Discovered and Collected?
• How Are Dinosaur Fossils Discovered a...
Episode 24: How Are Dinosaur Fossils Prepared in the Laboratory?
• How Are Dinosaur Fossils Prepared in ...
Episode 25: How are skeletal mounts of dinosaurs in museum exhibits built?
• How are skeletal mounts of dinosaurs ...
Episode 26: Where are all the dinosaur fossils kept once they're prepared?
• Where are all the dinosaur fossils ke...
Episode 27: How Do We Know Which Kind of Dinosaurs Were Most Closely Related?
• How Do We Know Which Kind of Dinosaur...
Episode 28: How do we know how long ago dinosaurs lived?
• How do we know how long ago dinosaurs...
Episode 29: In what kind of environments did dinosaurs live?
• In what kind of environments did dino...
Episode 30: How does studying dinosaurs benefit humanity?
• How does studying dinosaurs benefit h...
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