Although of modest size, this creature was one of the most unusual of all dinosaurs and provides entirely new insight on the classification of predaceous dinosaurs and on the surprisingly sophisticated capabilities possessed by some theropods.
Osteology of Deinonychus antirrhopus...
John Ostrom frasi celebri
In comparing the hadrosaurs with other dinosaurian herbivores, it is striking that they alone lack any obvious defensive or protective adaptations. They possessed no horns, no claws, no sharp teeth, they carried no clubbed or spiked tail, and they had no bony armor. They certainly were not constructed for rapid flight and they cannot be considered giants for their time. In short, the hadrosaurs appear to have been quite defenseless — a most improbable plight. As an alternative it seems increasingly probable that they depended upon the relative security of lakes, swamps, or rivers and thereby escaped from their enemies.
The cranial crests of hadrosaurian dinosaurs
In my opinion, the foot of Deinonychus is perhaps the most revealing bit of anatomical evidence pertaining to dinosaurian habits and capabilities to be discovered in many decades. Grandiose statements of this kind are, of course, easily rejected, but the functional implications of the pes of Deinonychus are not so easily discarded – especially in view of the other remarkable adaptations of this animal. Deinonychus must have been anything but "reptilian" in its behavior, responses and way of life. It must have been a fleet-footed, highly predaceous, extremely agile and very active animal, sensitive to many stimuli and quick in its responses. These in turn indicate and unusual level of activity from a reptile and suggest an unusually high metabolic rate.
Osteology of Deinonychus antirrhopus...