National Geographic reports: “T. Rex Protein “Confirms” Bird-Dinosaur Link”. We know dino bones and bird bones are morphologically similar. The hypothesis is strong enough that recent dinosaur screen directors have been showing some of their dinosaurs to move and chirrup and behave in bird-like ways and grow feathers, rather than lumbering around and dragging their tails like cold-blooded reptiles.
A paleobiology team led by Chris Organ has been going a step further – into molecular similarities. They have been extracting collagen protein fragments from fossilised dinosaur bone found in Hell Creek, and comparing them to various critters of today.
A new study of ancient proteins retrieved from a Tyranosaurus rex fossil confirms the long-hypothesized evolutionary connection between dinosaurs and modern birds, experts say. The finding is the first molecular evidence that birds, not lizards or other reptiles, are the closest living relatives of dinosaurs, the researchers note. A close relationship between the two groups was already widely suspected, based on similarities in skeletal features.
“The amazing part of this study is that we could establish the dinosaur-bird connection using only 89 total amino acids [the building blocks of proteins],” Asara said. “With only a small amount of sequence data”, he continued, “we can take an unidentified or fragmented fossil bone and not only identify the species but also help place it in evolution.”
The report refers to this article in Science Vol. 320. no. 5875, p. 499, “Molecular Phylogenetics of Mastodon and Tyrannosaurus rex”, by Chris Organ et al. The work extends the dinosaur/bird work done last year. In the current paper, the dinosaur proteins are compared to 21 species as a starting point to placing dinosaurs in the biological family tree on a molecular basis rather than purely by anatomical features. The technique’s validity, while contested, is supported by the team’s recent data demonstrating the molecular relationship between mastodons and modern elephants.
For the current work, Organ, Asara and colleagues compared collagen protein from several dozen species. The goal: placing T. rex on the animal kingdom’s family tree using molecular evidence.
“Most of the collagen sequence was obtained from protein and genome databases, but we also needed to sequence some critical organisms, including modern alligator and modern ostrich, by mass spectrometry,” says Asara.
“We determined that T. rex, in fact, grouped with birds–ostrich and chicken–better than any other organism that we studied,” he says. “We also showed that it groups better with birds than modern reptiles, such as alligators and green anole lizards.”