Saturday, May 26, 2007

Dinosaur bonanza

There have been a ton of fascinating dinosaur stories in the news lately, I've got some catching up to do. While I am now studying to be a zoologist (I like to think that I already am a zoologist, this past semester I got my first collecting permit for research in a national forest), paleontology was what first drew me into science, I hit the usual dinosaur phase when I was a kid, but never really grew out of it. That led to an interest in evolutionary biology, which led to a fascination with the diversity resulting from evolution, then an intense interest in the ecology that links organisms and their environments, and I guess it all snowballs, and thanks to a preschool infatuation with The Land Before Time, here I am.

Anyway, news!
First, researchers at the University of Alberta have analyzed CT scans ofvarious theropod skulls, comparing tyrannosaurids with non-tyrannosaurids (such as carnosaurs) to see if they could find any taxonomic trends. Some of the features analyzed were tooth-bending strength and the strength of the cranium and nasal bones.

The results: T. rex is once again shown to be an ultra-predator, with fused nasal bones that created superior strength and bite force. In addition to strengthening the skull, having fused nasals provided larger attachment area for muscles, allowing for immense forces to be applied by the jaws.

So just how strong was the T. rex? From the ScienceDaily press release:
A medium-sized T. rex had even more skull strength than a larger carnivorous creature, such as the Carcharadontosaurus saharicus, with a head nearly one and a half times as long. T. rex's neck power was similarly staggering. For instance, 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, says Snively. "We kept the muscle numbers down because we thought they couldn't possibly be that powerful, but Tyrrell museum colleagues showed that a T. rex's lower jaw could apply 200,000 newtons of force--that's like lifting a semi-trailer," he said. "All of the T. rex's features came together to give it the strongest bite of any land animal. The T. rex just blows everyone out of the water when it comes to strength.

What could be scarier than an animal that can carry a truck like a chew toy? One that can chase you on both land AND water! Earlier this week the Geological Society of America announced the discovery of a new dinosaur trackway in Spain. There are many known dinosaur trackways, but what makes this one noteworthy is that it gives us the strongest evidence to date that some dinosaurs could swim.

The 15 meter long trackway at the La Virgen del Campo track site in Spain’s Cameros Basin includes 6 asymmetrical pairs of scratch marks that were identifiable as belonging to a large theropod. Theropod tracks had previous been found in nearby areas known to be on the shoreline of the prehistoric lake. The prints were slightly S-shaped, and one of the authors of the paper, Loic Costeur of the Laboratoire de Planétologie et Géodynamique de Nantes, Université de Nantes, France, said that this is consistent with the marks left by a large animal clawing its way along sediment. The rippled patterns of the surrounding ground confirm that the prints were made at the bottom of a body of water.

You don't have to be big and fierce to leave your footprints on history, however: this week another interesting trackway discovery was announced, this one featuring a tiny print from a stegosaur hatchling. The prints were about the size of fifty-cent pieces, absolutely amazing when you consider that adult stegosaurs grew to 26-30 feet long and weighed up to 2 tons!

This makes me wonder about the growth rate of those creatures, how long did it take an animal the size of a human baby to reach the size of a bus? A lot of it has to do with metabolism, which is definitely an area of contention among paleobiologists. I'm not sure how much of an ontogenetic series of fossils there is for stegosaurs, I know they have pretty complete ones for some hadrosaurs, but you can't always generalize across species.

Anyway, that's today's dose of paleo-news!

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