Characteristics of Intelligent Dinosaurs. But a Thinking Dinosaur
"It is tempting to hope that the most original achievements of the mind are also the most recent."
Contents Updated: Tuesday, August 24, 1999
Anthroposaurs
Dr Brian Stableford is a biology graduate and lecturer in sociology at the University of Reading, England, but is better known as a writer of science fiction. He writes in The Science in Science Fiction that:
...certain difficulties stand in the way of the ever popular lizard-men who figure so frequently as science fictional villains. Reptiles, having no internal temperature control, are rather limited in the amount of brain activity they can indulge in...
That may be true of lizard-men but not of dinosaur-men or dinosauroids, to use the word coined by Dale Russell of the National Museum of Natural Sciences in Ottawa, Canada. Dinosauroids are intelligent creatures evolved from dinosaurs, and because dinosaurs had a physiology superior to lizards and in many ways superior to mammals, Dr Stableford’s complaint does not hold water. Our anthroposaur and Russell’s dinosauroid are Dr Stableford’s lizard-men precisely because they are all lizard-men could be.
Anthroposaur is the better term: it is more descriptive than Russell’s word, and Russell’s conception of dinosaur evolution was vastly different from that considered here. Russell imagined how dinosaurs might have evolved had they survived the Cretaceous-Tertiary (K-T) extinction and remained alive until today. They didn’t survive, so they couldn’t evolve. But the anthroposaurs could have evolved before the K-T catastrophe, as we shall see.
Stableford informally lists the characteristics of an intelligent organism.
If human beings did not walk upright, freeing their forelimbs to develop hands instead of paws, they could not have developed the kind of intelligence they have. Similarly intelligent beings must be sociable, because intelligence arises out of the need to communicate. The fact that most mammals and birds show a degree of intelligence not seen in reptiles is connected with the fact that they generally have more complicated social relationships, especially in connection with the rearing of young. The more sociable animals are, and the more able they are to interfere with and transform their environment, the more intelligent they become.
Stableford’s characteristics tally respectably with those deduced from our study of mankind’s emergence.
The ones which we have some chance of assessing rationally 65 million years after the death of the dinosaurs other than warm-bloodedness, are: intelligent terrestrial animals are bipedal, have an erect stance; are equipped with grasping hands having sensitive fingers and opposable thumbs; are equipped with binocular vision; own a large brain; are subject to social and parental guidance in childhood; are able to speak; are aggressive.
How do the dinosaurs measure up?
Bipedal
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.
Manipulative Hands
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. 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.
Binocular Vision
Binocular vision is, you will recall, the ability to direct both eyes simultaneously at an object. In considering the evolution of man it was coupled with manipulating hands in early primates and is considered basic to the development of intelligence. The importance of this ability for the growth of the brain is that it allows a better judgment of distance, valuable for leaping and throwing. It stimulates three dimensional thinking. The evolution of manufacturing levels of intelligence requires the development of hand and eye coordination. Without the ability to see stereoscopically, it seems unlikely that it would be possible to think stereoscopically and thereby to erect structures in the mind prior to building them on the ground. Many creatures alive today besides man have binocular vision, birds of prey like the owl, for instance, but they do not often combine it with grasping hands.
Binocular vision in tyrannosaurus was facilitated by the snout being very narrow so as not to impair its line of sight. But tyrannosaurus, as we have seen, had atrophied arms and the real evolutionary advantage comes when the binocular vision is combined with skillful hands. The stenonychosaurus had binocular vision combined with manipulative hands and fingers. Its eyes were large and well developed like the eyes of the ostrich (which has the largest eyes of any terrestrial creature alive today). This in itself is an interesting feature because it suggests that these dinosaurs were nocturnal or that they had evolved not long before from a nocturnal form.
Two points from this. First, it is further evidence, should anyone need convincing, that the dinosaurs were warm-blooded, because cold-blooded animals must be inactive at night. Second, what would they be hunting at night time that needed speed, agility, keen vision and grasping hands? None other than our predecessors, the mammals. It was not until the Cretaceous that we find signs that the mammals were hounded even into the night. They were terrorized, moreover, by creatures more cunning than themselves, as Desmond puts it. Yes, the mammals were small, but these dinosaurs were also small by dinosaur standards - stenonychosaurus was only about five feet long including its long tail. Here then is a dinosaur with keen senses, nimble and agile enough to hunt, by night, the supposedly superior mammals!
Brains
Let us turn now to the size of the dinosaurian brain. Carl Sagan writes, the entire evolutionary record on our planet, particularly the record contained in fossil endocasts, illustrates a progressive tendency toward intelligence. This is Marsh’s Law: brains grow from generation to generation. But it is not true of cold-blooded animals. Whereas a modern cat of the same body size as a sabre-toothed tiger of 30 million years ago has twice the brain volume, a modern crocodile has just the same volume of brain matter as an ancestor of comparable size 200 million years ago. The brains of even advanced cold-bloods like crocodiles violate Marsh’s law. But Marsh formulated his law from studying dinosaur brains!
The popular idea that the dinosaurs were dim witted, with brains no bigger than a ping-pong ball is only partly true. It appertains to the huge sauropods, ceratopsians and some carnosaurs - the dinosaurs well known to the layman. A triceratops’ body weighed 9000 times more than its brain, a hadrosaur’s body weighed 20,000 times more, and a brontosaurus’s weighed 100,000 times more. But it is not true of many others dinosaurs, the ones noted above with the grasping hands and binocular vision, the smaller, agile coelurosaurs and dromaeosaurs that lived late into the Cretaceous period. Knowing what we do about these, it is not so surprising that they had evolved large brains to coordinate their sophisticated movements and vision.
Deinonychus had the odd but effective habit of standing on one leg while slashing its victim with a vicious talon on the other. Such balancing tricks, even accepting that the creature would have its prey firmly in its grip, required remarkable brain development. The descendants of deinonychus, the family of dromaeosaurs, were agile, skilful predators with large brains. Few good fossils have been found but it has been conjectured that they were more common, and more successful, than the fossil record suggests, their habitats not being conducive to fossilization - just like the apes and hominids, mankind’s ancestors!
The body to brain ratio of the stenonychosaurus was 1000. This doesn’t signal much intelligence compared with a human being whose ratio is about 50, but it is comparable to a living flightless bird like the emu. It is also within a factor of about six of the ratio for a chimpanzee. Yet a bird-mimic dinosaur, the dromiceiomimus, had a brain bigger than an ostrich’s.
Birds, despite the derogatory expression bird brain, are remarkably intelligent. They are caring parents and often have a hierarchical social system epitomized by their pecking order. Large brained flightless birds such as the ostrich live together in flocks and also had some social organization suggesting that the dromiceiomimus did likewise.
Pterosaurs were flying dinosaurs. In modern day birds the ability to fly has required substantial development of their brains, particularly in the cerebellum region at the back of the brain and the cerebral region at the front of the brain. The cerebellum controls movement and balance while the cerebral region looks after coordination, both plainly important to a flying creature. The fascinating aspect of the pterosaurs was that their brains had developed exactly these features by convergent evolution. Like birds their olfactory sense had atrophied and instead they had well developed optic lobes. The optic lobes had been pushed by the growth of the cerebellum and cerebral regions to the sides and rear of the brain. Exactly the same had occurred in birds!
Even more similarities between the physiology of pterosaurs and birds could be listed but they are not relevant here. Suffice it to say that some pterosaurs were as small as a sparrow and that would be impossible for a cold-blooded or a naked warm-blooded creature. A cold-blooded vertebrate could hardly have generated the energy needed to fly. External insulation was needed for a warm-blood to maintain its high internal temperature. Pterosaur fossils have been found with clear impressions of fur on them. They must have looked like a cross between a fledgling bird and a bat, and they succeeded in holding their own against the birds for 90 million years until the cataclysm that marked the end of the Cretaceous era. But despite their obvious intelligence and fur coats, bat-like dinosaurs were not principle contenders for the honor of developing any sort of technology.
Sounds and speech
Let us come to the important question of vocal communication. Could the dinosaurs communicate by sounds?
All dinosaurs had sensitive middle ear bones and a notch in their skull where the tight ear drum stretched. Crocodiles and birds, both of which are related to the dinosaurs, have keen hearing so it is not surprising that dinosaurs also had acute hearing. Would they then make sounds? Birds do. And present day crocodiles can recognize each other by night by making a barking noise. There seems no reason to doubt that dinosaurs, known to have acute hearing, would also have done this.
But they had nothing akin to a larynx to enable them to make the sort of speech we do. Why should they? The cetaceans, our whales and porpoises, have sophisticated communication systems based on a host of sounds not made in the human way. Nor did carnivorous dinosaurs roar like lions, and herbivores did not bellow like bulls. Dinosaurs in films are given sounds that seem appropriate to monsters, not sounds such as they might have made.
Matsumi Suzuki, director of Tokyo's Institute of Sound, has worked out what kind of noises dinosaurs made by measuring the size and shapes of fossil skulls. Because he is not a palaeontologist, Suzuki drew heavily on the research of dinosaur specialists.
Many of the hadrosaurs had distinctive crests protecting their elaborately long nasal passages. David Weishampel, in 1981, had worked out the sounds made by these lambeosaurine dinosaurs of the late Cretaceous period. These reptiles, like parasaurolophus, had a large, hollow crest on their heads. Philip Currie of Alberta’s Tyrrell Museum suggested that these could have acted as a resonant chamber allowing the hadrosaurs to make sounds rather like a French horn. Weishampel concluded that they indeed acted as a resonating wind instrument. He calculated the frequencies and the harmonics. Suzuki has now reproduced the sound. It was more like a foghorn.
It is surmised that Charles Sternberg’s edmontosaurus had an inflatable sac on its snout that acted as a resonator enabling calls and signals to be made to other members of the herd to attract them or warn them. Elephant seals have a similar sort of arrangement. The nesting maiasaur of Montana could have made a deep base like sound by blowing air through its nasal passages.
Other dinosaurs produced sound by oscillating cartilages in their throats, but because cartilage does not fossilize, it had to be estimated from the cavities it left in the bones. The larger the cartilage, the slower the oscillation and the lower the frequency of sound. To check whether the method worked, he used it to get the sounds of living animals from their bones alone. It worked, so the sounds of the dinosaurs are unlikely to be far out.
Triceratops, a rhino-like herbivore with three horns, made a sound like the plaintive cry of a whale. Tyrannosaurus made sounds like indigestion and flatulence in a human stomach.
Hunting
Meat, being concentrated protein, we saw, is an important factor in the development of intelligence. The animal needs less bulky food and needs less time eating. So, it has more thinking time, time free to become cultural and inventive.
Tracks of up to six carnivorous dinosaurs all moving in parallel suggests that some of them hunted in packs. If, as Washburn suggested in man, sophisticated communication and language originated to coordinate group hunting activities, intelligent dinosaurs should be looked for among those types that hunted together. Carnivores also had the other attributes of intelligence discussed in this chapter. The hadrosaurs which could surely make conspicuous noises were not carnivores but, if herbivores could make sounds, hunting dinosaurs could also have developed a sophisticated range of whistling sounds for communication - like birdsong, perhaps.
Washburn’s hunting hypothesis is, of course, far from convincing but, if it were correct, it could apply equally to dinosaurs as to mankind. Plainly, the predatory dinosaurs were aggressive enough, if that were an important attribute for technological success. The skulls of the dinosaurs show that many had very well developed senses. The structure of their ears, indicates excellent hearing and the ability to hear high pitched noises, possibly initially the calls of their young and later the sounds of communication. Brain casts show highly developed olfactory bulbs showing the sense of smell was often good. Large orbits and pronounced optic lobes tell of excellent vision. Some were caring parents possibly having live young, had stereoscopic vision and manipulating hands. Many walked upright and some later dinosaurs had large and growing brains. Some also were fierce hunters and presumably correspondingly aggressive.
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