Dinosaur models on display

New Delhi, Sept. 5: Sixty-five million years after the dinosaurs went extinct, scientists have completed the second “census” of the diversity of discoverable dinosaurs, and predicted that hundreds are yet to be identified.

Scientists have so far been able to describe 527 dinosaur genera — species with similar characteristics. But dinosaur paleobiologist Peter Dodson at the University of Pennsylvania has now estimated the diversity of dinosaurs at 1,844 genera.

“We estimate that 71 per cent of discoverable dinosaur genera remain unknown to science,” Dodson and his colleague Steve Wang have said in a research paper to be published this week in the journal Proceedings of the National Academy of Sciences.

The researchers have said new genera of dinosaurs “will continue to be discovered for at least another century”.

But a leading Indian paleontologist has cautioned that India — among other regions in the world — would represent a “hole” in any census of dinosaur diversity because of lack of complete fossils from the country.

“We’ve never gone into expedition mode. Without a complete fossil, it’s difficult to identify or classify species in genera,” Ashok Sahni, a paleontologist with Punjab University, told The Telegraph.

In India, most dinosaur fossils found have been parts of limbs, teeth or bones, discovered mainly through the efforts of scientists not endowed with funding for prolonged expeditions.

Paleontologists estimate that the dinosaur fossils found in India might represent anywhere from 20 to 30 species. “But without complete fossils, different parts of the anatomy might represent the same species,” Sahni said.

Dodson’s first “census” of dinosaurs, completed in 1990, had classified 285 dinosaur genera. But a steady rise in the discovery of fossils through the 1990s prompted him to start another census to take into account the new findings.

In 1990, six countries — the US, Mongolia, China, Canada, England and Argentina — accounted for 75 per cent of known dinosaur genera. The new “census” shows the same six countries have the highest known diversities.