Stories tagged Tyrannosaurus 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?

Aug
25
2007

Just out for a jog: Can you run at 18 mph?  (photo by mcdlttx on flickr.com)
Just out for a jog: Can you run at 18 mph? (photo by mcdlttx on flickr.com)
For the younger Science Buzz readers – it’s very important that you understand how cool the Tyrannosaurus Rex is. Super cool. The adults reading this, of course, already know this fact. It’s one of those things you just pick up, and it sticks with you – like riding a bike, or what it feels like to be hungover. You never forget.

However, kids, as you go through your little lives, you will also occasionally encounter those doubting Thomases and sassy Williams who will try to lead you astray, who will try to tell you that the Tyrannosaurus Rex did not, in fact, evolve with the sole purpose of being a reptilian Fonzie. Ignore them! (The major difference between the tyrannosaur species and Arthur Fonzarelli is a simple lack of thumbs. This is barely enough to scientifically distinguish the two.)

These doubters and killjoys will tell you, among other things, that the lizard king was not a running, hunting, killing machine, but more of a flat-tired Cretaceous garbage truck – a scavenger, not a hunter. Part of this argument has to do with dinosaur’s velocity; to be a successful hunter, the T. Rex would have to be able achieve a decent top-speed, if only for a short while. In Jurassic Park, you might remember, the T. Rex was shown galloping along at about 30 mph. The joyless haters have argued that for the tyrannosaurus to reach anything like this speed, the majority of its body mass would have had to have been in its leg muscles, which was almost certainly not the case. The Rex, they say, would more likely have lumbered around looking for already-dead animals to feast off of.

This argument, however, is modeled on the body structure of extant bipedal animals (like flightless birds). Scientists at the University of Manchester have pointed out that the tyrannosaurs weren’t really built like the bipedal animals living today, and have recently developed a new and probably more accurate method of measuring their top speed.

The Manchester researchers developed a computer program that uses the given muscle and bone structure of an animal, and slowly works out the creature’s optimum movement patterns and top speed. They fed data for five dinosaur species (including the T. Rex), as well as that of several existing bipedal animals, into their supercomputer. The scientists had to make an educated guess as to the muscle strength and density of the dinosaurs, but used the same modeling techniques for the dinosaurs as they did for the living animals.

The computer took about a week to work out what each animal’s optimum running gait and posture would be, but finally yielded some interesting results. According to the program, an athletic human’s top speed should be about 18 mph, and an ostrich’s about 35 mph. Both of these are pretty accurate, if just slightly on the slow side (Some Olympic track and field athletes can reach about 29, and ostriches can get to about 40). For the dinosaurs, they found that the famous velociraptor could probably reach about 24 mph, the compsognathus 40 (pretty good for such a little guy), an allosaurus 21, and that the tyrannosaurus rex could do about 18 mph.

18 mph. I think that’s pretty respectable. More than respectable, actually - it’s cool. I mean, I’m fairly cool, and I can’t run 18 mph. And while I’m willing to cede that the tyrannosaurus might have scavenged as the opportunity presented itself, I think 18 mph is more than enough to ambush a hadrosaur or triceratops now and again. At the very least. Also, let’s not be too judgmental over the whole scavenging thing. Who doesn’t, really? I ate half of a potato chip off of my floor this morning. Does that make me a scavenger? No, it makes me an efficient consumer. And it certainly doesn’t mean that I’m not a hunter. Come to my neighborhood and count the rats, and we’ll see who’s a hunter.

May
20
2007

I am often complimented on the condition and arrangement of my teeth. In particular, I have a very specialized space, or "gap," in between the central incisors of my upper jaw, something frequently admired by friends and strangers alike. This "gap" is a near-perfect adaptation the requirements of my diet - it makes short work of chocolate chip cookies, and I think "evisceration" is the most accurate term to describe its effect on burritos, and other soft food items. It is a source of great personal pride.

However, as they have in so many other ways, the long-dead Tyrannosaurids (the family of the T. Rex) have once again put me to shame.

Comparing CT scans of fossilized Tyrannosaur skulls with those of non-Tyrannosaur theropods (two-legged meat eaters), a group of Canadian scientists have recently shown that "fused, arch-like nasal bones are a unique feature of tyrannosaurids."
Tyrannosaur Nasal Bones: T-rex nasal bones and how they fit onto the skull. (Credit: Dr. Eric Snively, University of Alberta)
Tyrannosaur Nasal Bones: T-rex nasal bones and how they fit onto the skull. (Credit: Dr. Eric Snively, University of Alberta)

What's so special about "fused, arch-like nasal bones" you ask? Everything, says University of Alberta researcher Dr. Eric Snively. Previous estimates for the bite strength of Tyrannosaurids (long assumed to be one of history's top biters, second only to new-metal star Fred Durst) have been so high that the act of biting could have crushed the Tyrannosaur's own head. The fused nasal bones, however, would have allowed a Tyrannosaur to employ the massive strength of its head and neck with out harming itself. Larger theropods, such as the carcharadontosaurus and giganotosaurus, would have been unable to match the skull strength of even a medium sized tyrannosaur.

So where does this now place the T. Rex in the old hunter/scavenger debate? Dr. Snively and the coauthors of this research describe the T. Rex's jaws as a "zoological superweapon." But scavengers often display massive bone-crunching teeth and jaws (check out the archaeotherium and the hyenadont in the SMM's Dino's and Fossils gallery, if you get the chance - both have some impressive jaws, and both were probably at least occasional scavengers. While you're at it, take a look at our moveable T. Rex skull and jaws). Or does this research just plant the T. Rex more firmly in the category of "opportunist?"

Oh, also, here are a couple of fun bits of trivia from ScienceDaily's article:

"In a split second, a T. rex could toss its head at a 45 degree angle and throw a 50kg person five metres in the air. And that's with conservative estimates of the creature's muscle force."

"[Tyrrell museum researchers] showed that a T. rex's lower jaw could apply 200,000 newtons of force--that's like lifting a semi-trailer."

All pretty impressive, I guess, but, still, you should see me tear through a box of Twinkys. Grr.

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:

Mar
29
2005

We recently reported on the discovery of a Tyrannosaurus Rex femur bone with preserved fleshy tissue inside. Thanks to Science Magazine we can bring you some close up photos of these unique finds. Some of the photos here are of a modern ostrich. Try comparing the Tyrannosaurus Rex finds with those of a modern bird like the ostrich (pictured below).

Tyrannosaurus Rex Vascular Canals