Dinosaurs and birds share small genomes

Stephen Withers
Thursday, 08 March 2007 09:42

Science - Biology

Flying animals such as birds have small genomes, but did that evolve along with the ability to fly? Recent research suggests not.

Bone cell size and genome size are known to be correlated, and a team from Harvard University and the University of Reading has estimated the cell sizes of various dinosaurs from fossilised bones. The researchers concluded that theropods - the group of dinosaurs that includes Tyrannosaurus rex and from which birds descended - had genomes of similar size to those of modern birds.

Bird-like characteristics - feathers, breathing structures, nesting and parental care - have been identified in dinosaurs, suggesting they were inherited by modern birds along with the small genome, rather than small genomes co-evolving with the ability to fly.

Small genomes also seem to correlate with higher metabolic rates, which ties in with the scenario that the first flying or gliding creatures launched themselves from trees or from a running start, both of which require a significant expenditure of energy. Carnivorous dinosaurs such as T-rex would also need to be fast moving to catch their prey.