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.
The dinosaur renaissance was a scientific revolution that began in the late 1960s and led to renewed academic and popular interest in dinosaurs. It was initially spurred by research indicating that dinosaurs may have been active warm-blooded animals, rather than sluggish cold-blooded lizard-like reptilians as had been the prevailing view and description during the first half of the twentieth century.
This new view of dinosaurs was championed particularly by John Ostrom, who argued that birds evolved from coelurosaurian dinosaurs, and Robert Bakker, who argued that dinosaurs were warm-blooded in a way similar to modern mammals and birds. Bakker frequently portrayed his ideas as a "renaissance" akin to those in the late nineteenth century, referring to the period in between the Dinosaur Wars and the dinosaur renaissance as "the dinosaur doldrums".
Deinonychus (/daɪˈnɒnɪkəs/ dy-NON-ih-kəs; from Ancient Greek δεινός (deinós) 'terrible' and ὄνυξ (ónux), genitive ὄνυχος (ónukhos) 'claw') is a genus of dromaeosaurid theropod dinosaur with one described species, Deinonychus antirrhopus. This species, which could grow up to 3.4 meters (11 ft) long, lived during the Early and Late Cretaceous Period, about 115–93.9 million years ago (from the mid-Aptian to Cenomanian stages). Fossils have been recovered from the U.S. states of Montana, Utah, Wyoming, and Oklahoma, in rocks of the Cloverly Formation and Antlers Formation, though teeth that may belong to Deinonychus have been found much farther east in Maryland.
Paleontologist John Ostrom's study of Deinonychus in the late 1960s revolutionized the way scientists thought about dinosaurs, leading to the "dinosaur renaissance" and igniting the debate on whether dinosaurs were warm-blooded or cold-blooded. Before this, the popular conception of dinosaurs had been one of plodding, reptilian giants. Ostrom noted the small body, sleek, horizontal posture, ratite-like spine, and especially the enlarged raptorial claws on the feet, which suggested an active, agile predator.
Robert Thomas Bakker (born March 24, 1945) is an American paleontologist who helped reshape modern theories about dinosaurs, particularly by adding support to the theory that some dinosaurs were endothermic (warm-blooded). Along with his mentor John Ostrom, Bakker was responsible for initiating the ongoing "dinosaur renaissance" in paleontological studies, beginning with Bakker's article "Dinosaur Renaissance" in the April 1975 issue of Scientific American. His specialty is the ecological context and behavior of dinosaurs.
Bakker has been a major proponent of the theory that dinosaurs were warm-blooded, smart, fast, and adaptable. He published his first paper on dinosaur endothermy in 1968. His seminal work, The Dinosaur Heresies, was published in 1986. He revealed the first evidence of parental care at nesting sites for Allosaurus. He also observed evidence in support of Eldredge and Gould's theory of punctuated equilibrium in dinosaur populations. Bakker currently serves as the Curator of Paleontology for the Houston Museum of Natural Science.