Dino evolution 2.0

  • Article by: BILL WARD , Star Tribune
  • Updated: June 14, 2012 - 9:25 AM

Dinosaurs went away 65 million years ago, but what we know about them is still changing.

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Brachiosaurus, velociraptor, T.Rex and triceratops

Photo: Tom Wallace, Star Tribune

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Remember all that cool stuff you learned about dinosaurs in school 20 (or 50) years ago? Well, don't. It's likely to be incomplete at best, incorrect at worst.

In elementary school, when we were all enthralled by dinosaurs, we learned that they were cold-blooded, slow-moving reptiles wiped out because they failed to adapt. Wrong, probably wrong and wrong.

When "Jurassic Park" came out, we gawked at velociraptors hunting in packs, a dilophosaurus spitting venom and a T. rex that couldn't see humans if they stood still -- all of it as big a pile of poop as the triceratops dung in the film.

"Nearly everything that we thought we knew about dinosaurs has changed in the last 20 years," said Macalester Assistant Prof. Kristi Curry Rogers, one of the nation's foremost vertebrate paleontologists. "They were not cold-blooded and slow-moving but almost certainly active, warm-blooded biological superlatives."

Turns out the little ones taking in the Minnesota Zoo's "Dino-Saurs" exhibit this summer know more about these animals than do their parents or grandparents, thanks in part to the PBS show "Dinosaur Train" and the continuing work of Curry Rogers and her peers.

"The kids are pulling Mom and Dad through the exhibit and telling them everything they know," said Christine Ness, the zoo's interpretive naturalist. "They're telling our volunteers how to pronounce the names, because they know."

What all of us understand about these animals is evolving even more quickly than they did during 160 million years of roaming the Earth. Starting with the fact that they did evolve, and thrive, across what began as the planet's sole land mass, Pangea, before it morphed into today's continents.

"The public has had this perception that [dinosaurs] were failures," Curry Rogers said, "that they were outcompeted or outdone by us, the mammals. Now there's a realization that dinosaur diversity was almost at its highest at the moment that dinosaurs went extinct.

"They weren't being outcompeted. The reason they went extinct is this unpredicted impact event [a meteorite] in the Yucatan. Whether they died in 24 hours from a global infrared blast or it took longer, a few days or a few thousand years, until that moment dinosaurs were doing great."

More bird than reptile

Even more knowledge has been gleaned over the past few decades about what kind of animals dinosaurs were and how they lived.

The consensus today, Curry Rogers said, is that dinosaurs were hatched from surprisingly small eggs, no larger than a softball, and developed very rapidly. Sauropods grew to 60 to 75 feet long in 12 to 15 years, "which means that they were pretty efficient at extracting their food supply.

"All of them [grew] faster than any reptile ever recorded and not as fast as any birds. They gave birds their bump up. Birds get that fast growth from their dinosaur ancestors."

Besides sometimes flying (pterodactyls) and sporting downy feathers (tyrannus and others), many dinosaurs had other bird-like traits.

"We now think that the meat-eating ones [theropods] had bird-like lungs, and they and long-necked ones [sauropods] breathed like birds," said Curry Rogers, who co-authored a recent Scientific American article on sauropods. "I do a lot of work with bones and teeth, and all of that tells us they're more like mammals and birds than things we think of as reptiles."

Dinosaurs were regarded as reptiles in the early 1980s when a second-grader named Kristi Curry read an article in the Weekly Reader about Jack Horner discovering nest, egg and hatchling fossils of a duck-billed dinosaur at Montana's Egg Mountain.

That not only prompted an 8-year-old schoolgirl to decide what she wanted to be when she grew up but also kicked off what became known as the dinosaur renaissance, which was further fueled by the 1993 megahit "Jurassic Park" and continues to this day.

Just 'look at the right rocks'

The learning evolution never seems to end: The oviraptor, whose name means "egg thief" because the first remains were atop a nest in Mongolia, turns out to have been brooding those eggs. The brachiosaurus, long considered to have walked like a giraffe, couldn't have done so without damaging its vertebrae and generally kept its neck down and grazed near the ground. Velociraptors, as tall as pro basketball players in "Jurassic Park," were the size of large chickens and did not hunt in packs.

The big surprise for Ness as the exhibit was going up was the wide time frame for these (mostly) big guys. "We're closer in time to T. rex," she said, "than T. rex was to the stegosaurus."

Every year, new species -- more than 60 during the past decade -- are being discovered; the 400 excavated so far are perhaps a third of the actual total, Curry Rogers said.

"No matter where you go, if you look at the right rocks you can almost certainly find dinosaur bones. The amazing thing is that every time it rains, there's the potential for something new to be discovered."

And for the rest of us to unlearn something we thought we already knew.

  • BRACHIOSAURUS

    Then: They walked like giraffes and ate from the treetops. Now: That would have damaged the vertebrae, so they primarily grazed much closer to the ground.


    VELOCIRAPTOR

    Then: They hunted in packs and could open doors (as in "Jurassic Park"). Now: They probably were loners but a bone in their wrist would have let them open a door.


    T.REX

    Then: These fierce animals were the ultimate carnivores. Now: Over the course of their lives, many of these carnivores lost their teeth and became plant-eaters.


    TRICERATOPS

    Then: They were cold-blooded reptiles. Now: Check out the beak on this guy. We now think dinosaurs were warm-blooded and more like birds than reptiles.


    DINO-SAURS!

    What: Fifteen animatronic replicas, including T. rex, a giganotosaurus and a stegosaurus robot.

    Where: Northern Trail, Minnesota Zoo, 13000 Zoo Blvd., Apple Valley.

    When: Through Sept. 3.

    How much: $4 ($3.50 for members), plus zoo admission.

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