dinosaurs, especially the herbivorous ones, have been the largest land animals ever. It seems natural that they would have fed on trees and huge cycads to satiate their gargantuan appetites. But would they have deigned to feast on the lowly grass? Yes, is the surprising answer from the latest research.
Fossilised dung -- called coprolites -- left by titanosaurs found from a hillside about 150 kilometres south of Nagpur, provides the evidence that grasses formed part of dinosaur diet. The fossils date back to about 65 million years back. Before the finding, the earliest fossils of grasses have been dated to about 55 million years ago but no older.
The plant evidence found in coprolites is based on microscopic bits of minerals that form in plants. When plants are eaten or decay, the mineral bits are released and pass through an animal's digestive system. Researchers, including Vandana Prasad of the Lucknow-based Birbal Sahni Institute of Paleobotany and Ashok Sahni of Punjab University, Chandigarh, were able to examine and date minerals from ancient grasses found in coprolites. The study appeared in Science (Vol 310, No 5751, November 18, 2005).
Their work "is the first unambiguous evidence that (grasses) originated and had already diversified during the Cretaceous (145-65 million years ago)," Dolores Piperno and Hans-Dieter Sues of the Smithsonian Institution's National Museum of Natural History wrote in a review accompanying the journal paper.
The finding is the first indication that grasses evolved before the dinosaurs went extinct.
Until now "it has been assumed that dinosaurs lived in virtually grass-free ecosystems," said Caroline A E Strmberg. Strmberg is a co-author of the paper and a researcher at the Swedish Museum of Natural History in Stockholm.