Washington, July 28 - After the dinosaurs, mammals too have to contend with a shrinking genome, according to evidence buried in the chromosomes of animals and plants.

There was a shrinking in the genomes of the dinosaurs before they went extinct. This trend continues today in the case of mammals, say Indiana University-Bloomington (IU-B) scientists.

The finding might seem counter-intuitive, given that the last 65 million years have seen mammals expand in diversity and number, not to mention dominance in a wide variety of ecological roles.

But it is precisely their success in numbers that could have led to the contraction of their genomes.