Tastes Like Chicken
And the answer is: like chicken. With a hint of frog and notes of newt.
It's not that many people have been asking what Tyrannosaurus rex tasted like. But in a feat that demolishes longstanding beliefs about how long biological molecules can resist the ravages of geology and time, scientists have isolated tiny amounts of the protein collagen from the leg bone of a T. rex that died 68 million years ago. After Bob Harmon, a preparator at the Museum of the Rockies in Bozeman, Mont., noticed the dinosaur's foot bone sticking out of a cliff in Montana's Hell Creek geological formation one day in 2000, paleontologists excavated the rex over the course of three summers, freeing it from 1,000 cubic yards of rock. In 2005, they announced that they had found well-preserved soft tissue, blood vessels and cells inside its thigh bones.
Now the scientists have gone a big step further. They have isolated collagen, the main protein in bone, from the fossil and determined the sequence of the amino acids that constitute it. (Amino acids link up into proteins like beads link up into necklaces.) The sequence it matches most closely, the researchers report today in the journal Science, is that of modern-day chickens, followed closely by frog and newt.
The match lends molecular support to the hypothesis that birds and dinosaurs are closely-related evolutionary cousins. That idea had rested on anatomy and, in particular, the similarity between the bones of birds and dinos such as T. rex. But different species can evolve similar anatomy even though they are unrelated. The molecular match is stronger evidence that the crow hopping around some roadkill can claim rex as an ancestor.
The discovery that proteins endure for 68 million years (300,000 years, the age of some bits of collagen obtained from a frozen mammoth, had been thought to be the longest biological molecules could survive) means scientists will be able to sic molecular techniques on other puzzles of evolution. "It opens the door to all sorts of investigations," says Mary Schweitzer of North Carolina State University, who first found cells in the Montana rex's thigh bones. It should now be possible, for instance, to more accurately infer the evolutionary relationships among extinct animals; until now, family trees have been constructed from the shapes of bones and teeth, a not-always-reliable technique. Paleontologist John Horner (the model for the dinosaur scientist in Jurassic Park) says the find will also change how he and other fossil hunters do their work. In the future, he says, they will keep newly-excavated bones isolated from the environment so that bacteria cannot degrade any surviving proteins. If more dinos give up their proteins, it may one day be possible to say whether cute little compsognathus is related to blood-thirsty velociraptors and solve other mysteries of dino genealogy.