The Troodon and the Dinosauroid
Dale Russell, discoverer of Stenonychosaurus (now called Troodon), then of the National Museum of Natural Sciences in Ottawa, Canada, postulated that late Cretaceous dinosaurs were well on the way to becoming intellectual animals, and would have succeeded if the dinosaurs had not suffered extinction. Stenonychosaurus had an opposable thumb, stood upright about three feet tall and had binocular vision. Russell commented:
It had all the ingredients of success that we see later in the development of the apes.
He believes that Stenonychosaurs were the “chief predators on Cretaceous mammals” and that there must have been quite a lot of them because, by the end of the Cretaceous, there were a lot of mammals, though they were small. These dinosaurs were obviously outwitting mammals, if Russell is right, and he thought evolution would have led them to have become intelligent Dinosaurs—Dinosauroids!
Jeff Hecht, a Massachusetts, USA, science and technology writer explained in issue 15 of Cosmos, June 2007 that Dale Russell’s idea of the dinosauroid began as a thought experiment. Scientists were beginning to realize dinosaurs were not as slow witted as reptiles, as they had supposed since Victorian times. Measurements of fossil dinosaurs showed steady increases in the encephalisation quotient (EQ) over millions of years. The EQ is a relative measure of an animal’s brain weight compared to that of an average animal of a related species and the same body weight. An EQ of 2.0 means the animal has a brain twice the weight of similar animals with the same weight. Russell wondered how the trend might have affected non avian dinosaurs had they survived to the present day. Could they have become intelligent, like us? Research has revealed intelligent behaviour in birds, as we now know, the closest living relatives of dinosaurs.
Hecht says we tend to think intelligence is a good thing that contributed to the evolutionary success of our species. So, what’s good for humans should have been good for dinosaurs. Yet some palaeontologists echo the late US evolutionary biologist Stephen Jay Gould, who doubted natural selection has any inherent preference for what we call intelligence. It would hardly be surprising as evolution is said not have any preferences at all because its direction depends upon the conditions pertaining at some particular time, and the characteristics of the animal itself. These can change from era to era. That said the overall tendency is for growth in brain size (Marsh’s law) and it is intelligence that need larger brains. Moreover, species seem to have developed characteristics that allow rapid evolution when it is needed, and that can give evolution direction!
Russell’s starting point was a fast, 60 kg, two legged predator called Troodon (Troodon formosus), which lived about 75 million years ago in Canada. The first Troodon skull showed that its brain, relative to its body size, was large for a dinosaur. Russell calculated that Troodon had an EQ that was nearly six times larger than the average of known dinosaurs, though small compared to modern humans. He extrapolated the figures to show that, if Troodon had survived and retained the same body size, its modern day descendants could have a brain volume of 1,100 cm3—comparable to that of some modern humans. Moreover, the placement of Troodon’s large eyes suggested it had binocular vision, and the outer two of its three fingers also appear to be opposable.
Russell decided that evolving a big brain would have reshaped the original dinosaur, and it is this reshaping that made it humanoid, and thus a dinosauroid. The back of its skull would have expanded to house the enlarged, bird shaped brain. The snout would have shrunk and the teeth would have disappeared, leaving a short, turtle like beak. To support the heavy head, Russell replaced the dinosaur’s long, horizontal neck with a short, upright one. That, in turn, required an upright posture, which would have made plausible the use of tools and weapons. As the body became upright, he expected the tail to diminish until it disappeared, as it did with our great ape relatives, but that the dinosauroid would retain reptilian traits of scaly skin and the lack of external genitals, and to have evolved live birth for its large headed young.
Russell’s colleague, Ron Sequin, sculpted a 1.3 metre tall dinosauroid for display beside a life sized model of Troodon. But it was, remember, a thought experiment, a serious conjecture based on careful scientific study, but it was not a testable scientific hypothesis, nor was it meant to be. Curious then that many people seem to have assumed it was, and dismiss Russell as some sort of nut!
Such criticisms are unwarranted and unfair. The speculation was sound and sensible. A testable hypothesis is that the dinosauroid actually did evolve, and destroyed itself in the KT extinction event. It was the Anthroposaurus sapiens!
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