Washington, April 25 : Genetic sequencing by scientists has shown link of Tyrannosaurus rex with birds like chickens and ostriches, thus providing further evidence for the theory that dinosaurs' closest living relatives are modern-day birds.
Molecular analysis, or genetic sequencing, of a 68-million-year-old Tyrannosaurus rex protein from the dinosaur's femur confirms that T. rex shares a common ancestry with chickens, ostriches, and to a lesser extent, alligators.
The dinosaur protein was wrested from a fossil T. rex femur discovered in 2003 by paleontologist John Horner of the Museum of the Rockies. The bone was found in a fossil-rich stretch of land in Wyoming and Montana.
The new research results represent the first use of molecular data to place a non-avian dinosaur in a phylogenetic tree, a "tree of life," that traces the evolution of species.
According to Chris Organ, a researcher at Harvard University, "These results match predictions made from skeletal anatomy, providing the first molecular evidence for the evolutionary relationships of a non-avian dinosaur."
"Even though we only had six peptides - just 89 amino acids from T. rex, we were able to establish these relationships," he added.
For the study, Organ, John Asara from Harvard Medical School and colleagues compared collagen protein from several dozen species. The goal was 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," said Asara.
According to Asara, "We determined that T. rex, in fact, grouped with birds - ostrich and chicken - better than any other organism that we studied.
"We also showed that it groups better with birds than modern reptiles, such as alligators and green anole lizards," he added.
The scientists also report that a similar analysis of 160,000- to 600,000-year-old collagen protein sequences derived from a mastodon bone establishes a close phylogenetic relationship between that extinct species and modern elephants.