Tuesday, September 30, 2008

Extinct: You Calling Me Chicken?

Aerosteon riocoloradensis, an enormous carnivorous dinosaur that apparently breathed like a bird, is the next installment in our Extinct series. There have been a couple of big stories recently on bird-like dinosaurs. First, there was the discovery of this chicken-sized dinosaur, and now we have the revelation that Aerosteon (means "air bones"), a giant predatory dinosaur, possessed a respiratory system similar to that of modern birds. This discovery represents more evidence in the now well-accepted (and amazing) theory that dinosaurs evolved into birds

Aerosteon, discovered in Argentina in 1996, lived about 85 million years ago and was approximately 25 feet long and 8 feet high. That's roughly the size of a bulldozer. Using computed tomography (CT) analysis researchers including paleontologists Paul Sereno (who also discovered SuperCroc, maybe a later post) and Jeffrey Wilson demonstrated hollow bones and air sacs in the dinosaur. They hypothesize that this giant might have breathed like modern birds, using air sacs to transfer air to its lungs as birds do, instead of the expansion/contraction lung system that humans use. This system provides more efficient breathing for birds allowing them to achieve high altitude flight. Aerosteon might have used such a system to regulate heat, as Wilson says here: "It's a way to lower core body temperature by getting rid of air".

I have always found the idea that dinosaurs, the monster kings of earth for hundreds of millions of years, became birds breathtaking. Dinosaurs and birds, two great exciters of human imagination, are one. That's extraordinary.

Also extraordinary are efforts to reverse engineer dinosaurs. By manipulating DNA, researchers are giving chickens teeth and tails and scales. Amazing stuff. As famous paleontologist Jack Horner says "‘I have to admit that I’ve certainly imagined walking up on a stage to give a talk, and having a little dino chicken walk up behind me."

There was a great Discovery channel show on this subject recently, I will look out for the clip and post it here.

(image credit: Todd Marshall c 2008, courtesy of Project Exploration)