Stories tagged T. rex

Aug
10
2009

Typical T. rex?: Image modified slightly by JGordon.
Typical T. rex?: Image modified slightly by JGordon.Courtesy ArthurWeasley
Oh, paleontologists… with your grabby little claws… always grabbing for the juiciest headlines… late to the table of the hard sciences, where your neighbors long ago grew fat and respected.

JK, of course. You’re a spunky young science, paleontology, and I love you for it. And who doesn’t want headlines? Why do you think I keep lighting fireworks off on my roof? If you’ve got something as loved, feared, and debated as the mighty Tyrannosaurus rex as your specialty, why not be a little provocative?

And so it went with a couple of paleontologists based out of Beijing and Munich. They’re all, “Ahem. Ahem. Is this thing on? Hello? We think, ah, that the Tyrannosaurus rex probably ate a lot of baby dinosaurs, and not so many fearsome adult dinosaurs. And, um, we…”

And then the press is all, “Say what?! Are you trying to say that the T. rex was just a big, dumb baby-eater? You are?”

Scientists: “Sort of, but not exactly.”

Press: “Print it!”

And so we have a new contender in the “Fearsome Hunter vs. Giant Scavenger” ring: Fearsome Baby-Hunter!

The idea, say the scientists, is that it’d be a lot easier to go around eating weak little babies than to go around fighting big triceratops and stuff, so that’s probably what T. rex did. (T. rex and other large, two-legged meat eaters.)

That part makes sense. Even if you’re as big and strong as the T. rex certainly was, eating something that can’t hurt you or run away from you pays off a lot more than eating something that can hurt seriously damage you, and takes a lot of energy to get. If you were a dinosaur, babies would probably be your favorite food. They’d be like the equivalent of individual serving yogurts. (Fun, delicious, and easy to eat.) That doesn’t mean that there were no epic dino-battles… they would have just been rare, I guess.

The paleontologists go on to say that T. rex-like dinosaurs specialized in baby eating so much, that it could explain the lack of immature dinosaurs in the fossil record. Juveniles would have been eaten whole, or at least in large chunks, their predators digesting the bones and everything. This would also explain, the claim, the low occurrence of bite marks on fossilized adult dinosaur bones—they just weren’t getting bitten much, if they made it to adulthood.

That’s where some of the theory falls apart for me. Why would an organism expend so much energy growing and maintaining a body the size of T. rex’s if its main prey was small and weak? Also, did dinosaurs just leave their young lying around for any old predator to eat? Unless a predator were small and sneaky (and whatever else T. rex was, it wasn’t small and sneaky), and could grab baby dinos on the sly, one would think that it would run into some protective parent dinosaurs pretty often. And then they’d have to fight, which defeats the purpose of going after little dinosaurs in the first place.

The lack of scarred adult bones seems to be incidental too. If a dinosaur died from whatever scarred its bones, I’d assume that it would be totally eaten (either by its killer, or later, by scavengers) before it fossilized. And maybe the type of wound that would leave scars on a bone would likely kill the attacked animal. And if the creature didn’t die, if it healed totally, it still might get eaten later on. And most animals don’t fossilize anyway.

And do we need a reason why there aren’t more baby dinosaur skeletons? They survive to adulthood, no baby skeletons. They get eaten, no skeleton. (Babies were bound to have been eaten, even without large dinosaurs specializing in eating them.) Even if they died of other causes, I wonder if their parents would eat the body themselves, or at least push it out of a nest, or leave it behind (where it would get eaten).

I wonder, too, if the ratio of baby dinosaurs to adults is similar in periods and areas without large theropods. (Theropods are the group of two-legged meat eaters T. rex belonged to.) If it’s the same, then the reason for so few specimens would have to be low fossilization rates, or a sampling problem, or just that everything was eating baby dinosaurs, not just theropods (which is a much less interesting claim to make).

Anyone care enough to offer an opinion?

Apr
13
2007

Two years ago, everyone was talking about the work of paleontologist Mary Schweitzer: she noticed that thin slices of a 68-million-year-old fossil femur from a Tyrannosaurus rex looked like they still contained soft tissue. (See photos of the bone.) Using antibodies to the collagen protein, she showed that the bone still contained intact collagen molecules—the main component of cartilage, ligaments, and tendons.

Hello, dinos?: A new study shows that preserved collagen from a 68-million-year-old Tyrannosaurus rex is similar to that of chickens. (Photo courtesy Danelle Sheree)
Hello, dinos?: A new study shows that preserved collagen from a 68-million-year-old Tyrannosaurus rex is similar to that of chickens. (Photo courtesy Danelle Sheree)

She used antibodies to a type of collagen extracted from chickens. The fact that the antibodies stuck suggested that T. rex collagen is similar to that of birds. And when she compared the preserved soft tissue to that of modern animals, the closest match was an emu—a flightless bird.

To learn more about the collagen in the T. rex bones, Schweitzer worked with John Asara, a chemist at Harvard University, to analyze it using mass spectrometry.

The Economist describes the technique this way:

This technique identifies molecules (or fragments of molecules) from a combination of their weight and their electric charges. Knowing the weights of different sorts of atoms (and of groups of atoms that show up regularly in larger molecules, such as the 20 different amino acids from which proteins are assembled) it is usually possible to piece together fragments to form the profile of an entire protein.

When Asara compared the profile he'd created to proteins from living animals, the closest matches were to chickens and ostriches. (Schweitzer and Asara's study was published in the April 13, 2007, issue of the journal Science.)

Many paleontologists already believed, based on fossil bones, that birds are dinosaurs or their descendants. But this new paper provides even more evidence of the fact.

Buzz stories on the subject from last year:

Recent news articles: