Джон Остром: Динозаврлар туралы түсініктерді өзгерген палеонтолог

American paleontologist

John Harold Ostrom (February 18, 1928 – July 16, 2005) was an American paleontologist who revolutionized the modern understanding of dinosaurs. Ostrom's work inspired what his pupil Robert T. Bakker has termed a "dinosaur renaissance". Beginning with the discovery of Deinonychus in 1964, Ostrom challenged the widespread belief that dinosaurs were slow moving lizards (or "saurians"). He argued that Deinonychus, a small two legged carnivore, would have been fast moving and warm blooded. Further, Ostrom's work made zoologists question whether birds should be considered an order of Reptilia instead of their own class, Aves. Prior to Ostrom's work, the development of birds was generally believed to have split off early on from that of dinosaurs. Ostrom showed more bird like traits common in dinosaurs and proved that birds themselves are in fact a group of coelurosaurian theropods, a descendant of dinosaurs. The first of Ostrom's broad based reviews of the osteology and phylogeny of the primitive bird Archaeopteryx appeared in 1976.

Ostrom was born in New York on February 18, 1928 and grew up in Schenectady. As a pre medical undergraduate student at Union College, he originally aimed to prepare for medical school in order to become a physician like his father. However, an elective course in geology and George Gaylord Simpson's book The Meaning of Evolution inspired him to change his career plans. He earned his bachelor's degree in biology and geology from Union College in 1951. Ostrom enrolled at Columbia University as a graduate student with Ned Colbert as his advisor. In 1951 Simpson invited Ostrom to spend the summer as a field assistant in the San Juan Basin of New Mexico. Ostrom also worked as a research assistant with Colbert, who was the Curator of Vertebrate Paleontology at the American Museum of Natural History (AMNH), Ostrom earned his doctorate in geology (vertebrate paleontology) in 1960 with a thesis on North American hadrosaurs that was based on the skull collection housed at the AMNH. In 1952 Ostrom married Nancy Grace Hartman (d. 2003). They had two daughters, Karen and Alicia.

Ostrom taught for one year at Brooklyn College in 1955 before joining the faculty at Beloit College the following year. In 1961 he accepted a professorship at Yale University, where he remained throughout his career. As a new professor at Yale, Ostrom was named the assistant curator for vertebrate paleontology at the Peabody Museum of Natural History. He became full professor and curator in 1971. Throughout his career, Ostrom led and organized fossil hunting expeditions to Wyoming and Montana. He worked in the Cloverly Formation Site in Montana and Wyoming from 1962 to 1966. Late in 1964, he discovered Deinonychus fossils near the town of Bridger, Montana. In 1966 John H. Ostrom helped to establish Dinosaur State Park in Rocky Hill, Connecticut ("because the governor was besieged by letters from schoolchildren swayed into dino mania by Ostrom".). Ostrom edited the American Journal of Science, published over a dozen books for both scientific and lay audiences. He was the recipient of numerous awards and honors. Despite lobbying to preserve it, a shopping mall was built on the site of the Charles O. Wolcott Quarry in 2000. Ostrom died from complications of Alzheimer's disease in July 2005 at the age of 77 in Litchfield, Connecticut.

Ostrom's work first achieved international attention with his studies of the unique hadrosaur nasal apparatus, which had not been convincingly explained by the early 1960s. By examining the olfactory apparatuses of modern reptiles and drawing comparisons via comparative morphology, Ostrom concluded that hadrosaurs likely developed an acute sense of smell by a lengthening of the nasal passages into long chambers that wound around the skull and were protected by bony crests. He speculated in a subsequent paper that hadrosaurs had need for such an acute sense of smell as a defense against larger carnivorous dinosaurs, of which the hadrosaur body plan had little in the way of armor and speed. This hypothesis led Ostrom to further conclude that ecology of hadrosaurs was more likely to be that of dry ground such as conifer forests, rather than swampy, aquatic environments, thought to be the case at the time. This idea was further justified by a 1922 paper that Ostrom rediscovered in 1964, which described the stomach contents of a mummified specimen of the hadrosaur Anatosaurus, which included conifer needles, twigs, fruit and seeds, plant matter that would be consumed in a terrestrial environment.

Due in large part to his earlier research on hadrosaurs—and his conclusion that they were likely upright, terrestrial animals rather than sluggish, swamp bound lizards—Ostrom was one of the first paleontologists to grasp the implications of the amount of energy it would take such large animals (and their still larger predators, such as Tyrannosaurus rex) to stand and move erect. At the first North American Paleontological Convention, held at the Chicago Field Museum in 1969, Ostrom spoke out against the accepted wisdom that Mesozoic climates were universally tropical and that such warm climates would be necessary to sustain large animals with lizard like metabolisms. Ostrom supported this view by noting the correlation of erect posture and locomotion with high metabolism and body temperature in modern mammals and birds, stating that this relationship cannot be accidental. Ostrom's reappraisal of dinosaurs as endothermic was considered radical at the time, but its ability to resolve outstanding contradictions in dinosaur physiology immediately drew many followers, and would be supported by many future discoveries. In his 1973 paper in Nature, "The Ancestry of Birds", Ostrom argued for a coelurosaurian (Theropoda) ancestry of birds, based on the skeletal anatomy of Archaeopteryx. He suggested that dinosaurs, far from becoming extinct, had evolved into a wide variety of descendants in the form of birds. Ostrom's work led to a revolution in the classification of fossils and the understanding of dinosaur bird lineages. In considering the possible evolution of flight, Ostrom theorized that birds might have evolved the ability for powered flight as a result of cursorial, or ground upward movement such as leaping up to capture prey. This position was opposed to the arboreal hypothesis in which activities such as gliding down from trees were suggested to have been a precursor to flight.

In 1970, John Ostrom gave Microvenator celer its formal name (meaning "fast small hunter"). Also in 1970, he named Tenontosaurus tilletti (meaning "tendon lizard"). The largest discovered example of this species is 23 feet long and had an estimated live weight over 1000 pounds. In 1998, Catherine Forster named a fossil Rahonavis ostromi (meaning "Ostrom's menace from the clouds") in honour of John Ostrom. The fossil is that of a primitive winged creature with a two foot wingspan, feathers and a sickle shaped claw on its second toe designed for slashing prey, similar to Deinonychus and Archaeopteryx. In 2017, Ostromia (a new genus named for the Haarlem specimen, formerly of Archaeopteryx) was named in his honor.