John Ostrom: Modern popular interest in dinosaurs, as well as the best-selling book and hit film Jurassic Park, owes much to the patient and scholarly work of a little-known American palaeontologist and Yale University professor, John Ostrom, who has died aged 77.
His research also led him to propose the formerly dismissed theory that birds are descended from feathered varieties of the ancient creatures. Before Ostrom's discoveries, dinosaurs were regarded as slow, cold-blooded and dim-witted reptiles that vanished from the Earth about 65 million years ago, leaving behind a few fossils. But, in 1963, he published a paper challenging the notion and suggesting they were speedy, upright and more like "bi-pedal buffaloes" than swamp-loving laggards.
Ostrom was able to reinforce this view with a discovery the following year. On the last day of a summer fieldwork study in Montana, while plodding along a ridge, he and his assistant noticed an inexplicable sight: some large, sharp claws protruding from an eroded mound. "We both nearly rolled down the slope in our rush to the spot," he recalled.
They carefully exposed the remains of a strong two-legged creature with a curving 4-in claw, like a sickle, on each forelimb. Ostrom called the 125 million-year-old fossil deinonychus ("terrible claw" in Greek) and suggested it was a predator that ran fast and upright, killing prey by slashing with its deadly claws. This would mean, he concluded, that it had a high metabolism and was warm-blooded.
Ostrom's investigation at the Montana site also uncovered an ancient mini-drama. Four other claw creatures were positioned around the much larger skeleton of a herbaceous dinosaur called tenontosaurus, leading Ostrom to imagine a fierce fight, in which the large creature killed four of a pack of the deinonychus before succumbing itself.
This, in turn, led to a modern story of mass appeal. In 1991, the terrible-claw creatures became the prototype for the vicious velociraptors of Michael Crichton's best-selling thriller Jurassic Park. Two years later, when director Steven Spielberg turned the story into a worldwide cinema success, he used a range of computer-created monsters, of which deinonychus was the star.
The deinonychus discovery provoked a scientific debate over the revolutionary idea that at least some dinosaurs, such as deinonychus or tyrannosaurus rex, were closer to mammals and birds than to cold-blooded reptiles. This, in turn, led to a revival of the hypothesis, developed by British scientist TH Huxley in 1868, that dinosaurs were direct ancestors of modern birds. Ostrom became a leading proponent of this theory after his second significant discovery, in a museum in the Dutch city of Haarlem.
In 1970, Ostrom saw a fossil identified as a pterosaur, a gliding reptile, but he questioned the label. Its source was the same Bavarian quarries that had yielded the remains of archaeopteryx, a mixture of bird and dinosaur which was recognised as the first bird, from about 150 million years ago.
The museum specimen, now named Haarlem archaeopteryx, persuaded Ostrom to study bird flight evolution. He discovered more than two dozen similarities between deinonychus and birds, and, in 1973, further examination of the Haarlem fossil led him to propose that here were the origins of birds.
This idea, he recalled, was at first regarded as "crazy" and it took nearly 30 years to find general academic acceptance. The crucial point was reached in 1996, with the discovery in China of a feathered dinosaur fossil. On seeing the photographs of it, Ostrom said he became "literally weak in the knees". But he knew he was vindicated.
John Harold Ostrom, born February 18th, 1928; died July 16th, 2005