free debate

July 29, 2009

Prehistoric Proteins

For a long time, I considered the idea of collecting DNA or proteins from fossils to be all Hollywood. I've never seen Jurassic Park, but the premise just sounds wrong. Collecting dinosaur DNA from 100 million year old blood in the body of a mosquito preserved in amber? Highly unlikely.

However, a couple of new discoveries have popped up lately that make the idea of collecting molecular fossils less science fiction. The first of these dealt with finding the color of an extinct type of bird.

The Moa was a giant flightless bird, rather like an emu. They lived on New Zealand up until humans arrived near the 13th century AD, and are now extinct. There were no records of how these birds were colored. Reconstructions were made based on the moa's living relatives, emus and kiwi birds, but they were just educated guesses, rather than solid data.
Nicholas Rawlence, of the University of Adelaide, has developed a new technique that answers the question of the moa's coloration. They can extract mitochondrial DNA from fossilized feather shafts, and use that information to determine exactly what color the feathers were: in the case of the moa, brown with white tips. This technique can be applied to the remains of other extinct bird fossils found on New Zealand, answering other questions of how many species there were, and how factors like climate affected them.
Still, moa fossils are not nearly as old as dinosaur fossils (a few hundred thousand years, vs. 10s to 100s of millions of year). A second story I found is more intriguing, because they did find traces of genetic material... in a T-Rex.

The T-Rex in question was a very well preserved specimen from 68 million years ago. The initial analysis done on it found traces of collagen in the fossil bone. This finding was controversial, and many attributed the finding to contamination or statistical error. A new study, however, returned the same results: peptides of collagen do exist in the bone. It's an exciting new discovery, and might help, with more data, to determine how dinosaurs are related to each other, and to their living descendants: birds.
The odds of ever getting a full strand of DNA from a dinosaur fossil is extremely low. They are simply too fragile to last for 100 million years. Jurassic Park will stay a fictional idea. However, as these two findings show, there is some potential in finding bits of genetic material in the fossils, which may help clear up questions on coloration, speciation, extinction, and more.

Credit: Discovery Channel- Feathers Revealing Extinct Moa's True Colors
Science Daily- Reexamination of T-Rex Verifies Disputed Biochemical Remains