From what Bakker and Ostrom discovered during the 1970s, dinosaurs offer remarkable possibilities for the development of intelligence. We have seen that dinosaurs fulfilled the requirement of bipedalism early on—the reason for their supremacy was their upright, bipedal stance. Bipedalism gave dinosaurs a head start on mammals in the race for intelligence because it was the very basis of their evolutionary emergence. Like the hominids, having discovered that they could run on their hind legs, they must eventually have realized that their forelimbs were freed for the manipulation of objects.
What, then, of grasping hands? To be of maximum use this means that one of the digits, the thumb, should be opposed enabling its tip to touch the tip of the other digits. Is there evidence that the dinosaurs were able to grasp things? The answer is that opposed digits were very common in dinosaurs. Even the Tyrannosaurids and other large carnivores had an opposed toe rather like perching birds, but T rex’s forelimbs, we noted, had degenerated into crutches to help it get out of bed.
The feathered dinosaur, the archaeopteryx, certainly had grasping hands, as did its near relatives the coelurosaurs, and surely used them for grasping insects and climbing trees. A related but later dinosaur that seemed to have evolved a high degree of coordination of hands and arms was the deinonychus. Its “hands [were] better adapted for grasping and holding than any other dinosaur” (Desmond). Deinonychus had long, grasping hands with wrist joints that rotated so that the hands could turn towards each other enabling the animal to grasp its prey in both hands. Wilford’s comment is that “only humans and certain other mammals can do this”.
The Late Cretaceous, the period we are chiefly interested in, was full of examples. Some descendants of deinonychus formed a whole group called the dromaeosaurs all of which had opposable fingers and were obviously capable of a high degree of coordination.
One of the descendants of deinonychus was a dinosaur discovered by Dale Russell called the stenonychosaurus—now recognized as being Troodon formosus. This animal had manipulating fingers, but also had a complex of advanced features, including binocular vision, that make it rather special. Plainly some dinosaurs combined a bipedal gait with sensitive, manipulative hands.
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