The animated adventure Ice Age: Dawn of the Dinosaurs is bound to mislead countless youth when it comes to dinosaur history. Dinosaurs were long gone by the time the Ice Age rolled around. At least Manny the wooly mammoth, the movie’s reluctant hero, pays lip service to that fact. He says to one rampaging dino: “I liked you better when you were extinct!”

And when did the dinosaurs make their final goodbye? To get the scoop, we spoke to our Land of the Lost expert Thomas R. Holtz Jr., a paleontologist at the University of Maryland’s Department of Geology who specializes in carnivorous dinosaur evolution and adaptation and focuses on Tyrannosaurus rex and its relatives.

When I was a kid, the idea seemed to be that 65 million years ago a meteor crashed into Earth and made dinosaurs extinct. True or false?

That’s by far the best-supported hypothesis: At the end of the Cretaceous period an asteroid about the size of Manhattan hit the Earth in the Yucatan peninsula. We’ve got the crater, we’ve got debris, and elsewhere in the world, we’ve got the die-off in both land and sea creatures. It seems it was a catastrophic extinction triggered by a great impact. The only dinosaurs to survive were the ancestors of modern birds.

A controversial April 2009 study proposes that some dinosaurs survived the Cretaceous period, living almost a half-million years in what is now New Mexico and Colorado. What’s your take on this?

In the American West, one particular researcher [Jim Fassett] and some colleagues said they have evidence that dinosaur remains were found above the normal extinction layer. The difficulty is that the geological evidence is not certain: They may simply have very late materials [from before the extinction]. Dating rock layers in geologically complex regions like the American West can be tricky. It may also be that the material was excavated and redeposited with new materials by river channels. They haven’t found dinosaur footprints—something that had to be made by a living creature—above the extinction layer, and right now it’s very isolated materials, not lots of bones. So at present they [only] have ambiguous evidence.

In the film, dinosaurs survive well into the last Ice Age by living in a subterranean jungle populated by 20-foot-tall venus flytraps and weasels who think they’re pirates. You probably don’t think that’s likely, either.

Yes, and given that the animals are all talking, it seems clear it’s all fantastical.

So if this isn’t the best movie for an accurate depiction of dinosaurs, what would you recommend?

A movie that has dinosaurs that’s going to be accurate, not a fantasy, won’t have anyone for people to relate to—because, well, they’re dinosaurs. In terms of visual accuracy, though, some of the dinosaurs in Jurassic Park are the best reconstructions that have appeared onscreen. The movie’s T. rex is probably the most accurate T. rex we’ve seen.

What did the movie get right?

Well, the shape of T. rex, the size, the movements—pretty much everything matched up really well with what we know.

Any glitches?

One of the few problems was that T. rex’s hands were facing downward. You’d have to twist the joints to get them like that, because as we know now, the hands were facing inward. People thought at the time that they faced downward, though, so it’s only an error in hindsight. Otherwise it worked really well.

It was good enough to give everyone nightmares.

Right! If you can do that, you know you did something right.

-Matthew Hill

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