A theoretical reptilian humanoid has also been the focus of a widely discussed thought experiment in speculative evolution. In particular, in 1982 paleontologist Dale Russell, curator of vertebrate fossils at the National Museum of Canada in Ottawa, conjectured a possible evolutionary path that might have been taken by the dinosaur Troodon (then called Stenonychosaurus) had they not all perished in the K/T extinction event 65 million years ago. The essence of this thought experiment was that bipedal predators (theropods) which existed at that time, such as Troodon, could have evolved into intelligent beings similar in body plan to humans. Over geologic time, Russell noted that there had been a steady increase in the encephalization quotient or EQ (the relative brain weight when compared to other species with the same body weight) among the dinosaurs. Russell had discovered the first Troodontid skull, and noted that, while its EQ was low compared to humans, it was six times higher than that of other dinosaurs. If the trend in Troodon evolution had continued to the present, its brain case could by now measure 1,100 cm3; comparable to that of a human. Troodontids had semi-manipulative fingers, able to grasp and hold objects to a certain degree, and binocular vision.
Description
Russel proposed that this Dinosauroid, like most dinosaurs of the troodontid family, would have had large eyes and three fingers on each hand, one of which would have been partially opposed. As with most modern reptiles (and birds), he conceived of its genitalia as internal. Russell speculated that it would have required a navel, as a placenta aids the development of a large brain case. However, it would not have possessed mammary glands, and would have fed its young, as birds do, on regurgitated food. He speculated that its language would have sounded somewhat like bird song.
Criticism
Russell's thought experiment has been met with criticism from other paleontologists since the 1980s, many of whom point out that Russell's Dinosauroid is overly anthropomorphic. Gregory S. Paul (1988) and Thomas R. Holtz Jr., consider it "suspiciously human" (Paul, 1988) and argue that a large-brained, highly intelligent troodontid would retain a more standard theropod body plan, with a horizontal posture and long tail, and would probably manipulate objects with the snout and feet in the manner of a bird, rather than with human-like "hands".
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