Dinosaurs: General Information

Dinosaur experts answer some tough questions from students.

By Bill Hammer, Don Lessem, Tim Rowe
  • Grades: 3–5, 6–8, 9–12

The following questions were answered by dinosaur expert Don Lessem, paleontologist Tim Rowe, and paleontologist Bill Hammer.


Q: What is a dinosaur exactly?
A: Dinosaurs are a group of animals descended from reptiles and the ancestors of birds. They were different from their reptile ancestors in that they have an S shaped neck and feet held directly beneath their bodies, and several other features. They lived on land, grew both big and small, and died out 65 million years ago. Pterodactyls and other flying reptiles are pterosaurs, not dinosaurs, since dinosaurs didn't fly. But pterodactyls did live in dinosaur time. (Don Lessem)

Q: How many different kinds of dinosaurs were there?
A: We know of about 300 kinds now, half of those from a single tooth or bone. We do find a reliably new kind of dinosaur every seven weeks on average though! That means that half of all dinosaurs have been named since I was a kid which is not all that long ago — only 30 years — not 65 million. There were probably thousands of kinds of dinosaurs, but we haven't found most of them yet. We don't get a great sample because fossils are usually only made in lowland areas where bones get covered over by mud even though dinosaurs lived all over. And we only find fossils where rock from dinosaur time is now near the surface. Lots of places have dinosaurs but they are deep in the ground. And in lots of places the weather wasn't right to turn dinosaurs into fossils. (Don Lessem)

A: The count is over 650 species of dinosaurs, although not all of these are valid. These species occur in over 400 genera. There are many more species of plant-eating dinosaurs named than carnivores because carnivores were fewer in number. (Bill Hammer)


Q: How long did most dinosaurs live?
A: We don't know. Big animals, including us, tend to live a long time. Dinosaur bones sometimes show rings of growth, but we don't know if they are laid down every year or how often. Surely it took years for the biggest dinosaurs to grow to full size. (Don Lessem)

Q: Where did dinosaurs live?
A: Dinosaurs lived everywhere on Earth, including the South Pole, which had no ice then. (Don Lessem)

Q: Why do people say some dinosaurs have small brains?
A: Some dinosaurs had brains the size of peas. Others had the biggest brains of any animals of their time compared to their size. Dinosaurs weren't stupid, at least they were smarter than modern reptiles and some almost as smart as many birds. (Don Lessem)

Q: Do we have any living dinosaurs today, like the coelacanth or komodo dragon?
A: Those are living dinosaurs only in the sense of being ancient animals which are still alive, but none are actually dinosaurs. Komodo dragons grow to huge sizes and eat kids when they can get them. They kill by their germ-infested slobber when they bite. Fortunately they are only on one island in Indonesia, far away. Coelacanths are huge fish long thought extinct, which were found by fisherman in the Indian Ocean in the 1930's. (Don Lessem)

Q: Were the dinosaurs in Jurassic Park depicted accurately?
A: Yes, I thought by and large the dinosaurs from Jurassic Park were the best ever done. The Triceratops and T. rex in particular looked very much like what scientists think they might have, except that T. rex's teeth might well have closed in its mouth not hung out, and the arms were a little long. But there were still many inaccuracies, and interesting ones. The dinosaurs were bigger, faster and smarter overall than we think they were — sort of like dinosaurs on steroids. The gamekeeper says velociraptor was "as smart as a chimp, as fast as a cheetah and they can remember." I don't know about remembering but its more likely they were dumber than ostriches (by brain size compared to body size) and slower than us. They were only as big as standard poodles! The spitter is dilophosaurus, a dinosaur that was really the first big meat-eater, 20 feet long and as far as we know didn't spit poison or have a neck frill that fanned out. Most of the dinosaurs in the movie are Cretaceous not Jurassic animals. (Don Lessem)

A: The accuracy of Michael Crichton's rendering of dinosaurs in Jurassic Park varies (I have not read The Lost World). He certainly goes overboard on velociraptor with the sort of intelligence he gives it, and in the film its size was about 3 times the size of actual specimens. Velociraptor is a close relative of modern day birds, but it has a somewhat smaller brain and thus its behavior patters were no more complex that what one would find in a bird today. You might keep in mind that Crichton's books are science fiction, and that he is not one to let the truth get in the way of a good story. (Tim Rowe)


Q: Can people remake a dinosaur using a robot? Can they be life size?
A: Yes, full-sized robot dinosaurs have been made. The best was a T. rex made for the movie Jurassic Park. I saw it being made, and it could do all sorts of complicated computer driven movements. But it wasn't nearly as scary as the real thing would be. (Don Lessem)

Q: Which dinosaur would have made the best pet?
A: Great question! I'd choose a triceratops to mow my lawn (though grass wasn't around in dinosaur times), a T. rex to cut my steak, and an ornithomimid (an ostrich-like dinosaur) to ride around on. But the best for inside the house might be a compsognathus, a little meat-eater about the size of a big chicken. I just hope it could be house-trained! (Don Lessem)

Q: What are your favorite dinosaurs?
A: My favorite dinosaurs are troodon, the smartest, and T. rex, my first dinosaur love. (Don Lessem)

Q: If you depended on a dinosaur for transportation, which one would you choose and why?
A: I think a gallimius would be best for a racing dinosaur, but hard to stay in the saddle. Triceratops would be a nice comfortable slow ride and you could hold onto his frill so you wouldn't fall off. (Don Lessem)

Q: Do you know anything about Champ, who supposedly lives in Lake Champlain? Do you think he is real? Many have compared him to the Loch Ness monster.
A: I know about Champ — the supposed sea monster in Lake Champlain. Like Nessie, the Loch Ness Monster, Champ is thought by some people to be a dinosaur-aged leftover, a sea reptile called a plesiosaur. I wish this were true, but I don't think it's possible. Why would this animal live on in only one or two places 65 million year after it disappeared everywhere else? It would need to have several dozens to have a breeding population to stay around that long. Plus, people only see bits of one and then never find a bone or make a clear picture of it. I think it a wonderful fantasy that there is a Champ. (Don Lessem)

  • Part of Collection:
  • Subjects:
    Animal Behavior and Structure, Dinosaurs, Paleontology and Fossils
  • Skills: