Contents Updated: Thursday, August 05, 1999
The large long-necked dinosaurs such as brontosaurus and diplodocus have also been put through the sawmill of prejudice. It was felt that creatures weighing around 50 tons could not live on dry land. Water was needed to support such a bulk. The experts began to reconstruct them as long-necked crocodiles, their legs, like lizards', splayed on either side of their body. Early reconstructions of dinosaurs such as those at Crystal Palace in South London, England, looked crocodilian. Yet the earliest restorations had given the brontosaurus massive columnar legs like an elephant's. Nowadays physicists would agree that the thrust of the weight of huge bodies on dry land must be transmitted directly to the ground through sturdy, straight limbs.
Weight is related to volume which increases as the cube of the linear dimensions. The strength of the limbs however depends upon their cross section which increases only as the square of the linear dimension. As the weight of a body increases, its supports, its legs, have to thicken at a faster rate. Large terrestrial animals have to have legs like tree stumps. If the legs were splayed like a lizard's so that, on dry land, the body weight was suspended between the limbs rather than supported directly by them, the animal would be unable to raise itself from the ground without breaking its own legs. Such a reconstruction would have required the sauropods to be purely aquatic. The crocodile theorists accepted that the creatures sometimes had to move on land. But that was no problem to them - the sauropods must have slithered through the swamps in which they lived.
Blindness! The experts had lizards in their heads and could see nothing else. Sauropods manifestly had a differently shaped thorax from a crocodile precluding them from walking on splayed legs. The deep rib cage of the diplodocus would have required it either to slither in a deep trench to make space for its thorax or to slide along on its chest with its legs protruding sideways making little or no contact with the ground. Pillar-like legs supporting the heavy body on top was the only rational reconstruction for the sauropods.
The discovery of brontosaurus tracks at Glen Rose in Texas in 1938 settled the controversy. The stride of the monster was twelve feet but the left and right prints were separated width-ways by only six feet. Brontosaurus made footprints much closer together than a crocodile of equivalent size. Its legs were upright not splayed.
Such large animals must have needed vast amounts of internal energy simply to keep them on their feet. How could they have processed the huge quantities of food required by their high metabolisms when it must have been of fairly low grade and they had relatively small heads?
Paleontologists usually dismiss any thinking about the soft parts of dinosaurs because innards do not fossilize. All speculation about gastrointestinal tracts in the Dinosauria is futile, mocks Bakker, mimicking the orthodox thinkers. Because the sauropods were supposedly partly aquatic, had small heads and had weak teeth, orthodoxy dictated that their diet was soft - duckweed or algae. But is it reasonable to believe that these 50 ton animals had to live off duckweed or algae? Surely a huge maw in a huge head like a baleen whale would be needed for them to scoop up enough algae to sustain such huge bulk.
It must be more reasonable to assume that these dinosaurs were terrestrial browsers and ground their food in gizzards or fermented it in their stomachs or both. Modern birds have no teeth and do no chewing but they process often tough food perfectly effectively in their gizzards, and modern ruminants like cows and sheep predigest poor quality grasses by fermentation in their pre-stomachs to prepare it for further mastication. Birds like ostriches, though they have small heads and long necks similar to many dinosaurs, have both gizzards and fermentation processes to maximize absorbed energy. This compensates for the slow food intake implied by their small heads whilst maintaining their high metabolic rate. Brontosaurs most certainly did the same, and, in fact, their gizzard stones, worn smooth by grinding, have been found.
If dinosaurs were warm-blooded and especially if they were naked, they would have had to grow quickly or die of heat loss. Immature dinosaurs are rarely found. Maturity must have been reached quickly and early growth must have been rapid. Birds and mammals, today's warm-blooded animals, grow to maturity quickly. From a hatchling, an ostrich grows 150 pounds to adulthood in only nine months and an Alsatian dog is twenty times bigger at a year than it was at birth. (Humans are the exception, maturing slowly because of the time needed for them to fill their outsize brains with experience.)
Lizards have quite a different pattern of growth. They do not have a spurt of growth when young but increase in size constantly throughout their lives. Reptiles such as turtles and crocodiles take about ten times longer in the wild to put on the same weight as mammals.
The fossil record does not sustain such a growth pattern for dinosaurs. As bone grows it is supported by fibres of the protein, collagen. Fast growing bone has a random pattern of collagen fibres, rather like a felted fabric, whereas slow growing bone has a much more regular pattern of collagen put down in layers. The texture of all dinosaur bone is the irregular type typical of fast growth and warm blood.
Reconstructions like those at Crystal Palace in London depicted all dinosaurs as quadrupeds. Yet in the middle of the 19th century Thomas Huxley realized that some of the dinosaurs were bipedal. The discovery of excellent fossil skeletons of the iguanodon settled the matter.
Iguanodons were large erect herbivores 35 feet in length. Their front limbs were much smaller than the massive rear limbs showing they could not have been used for support and evidently were used for grasping branches as the great beasts browsed the trees. The carnivore, tyrannosaurus rex, was so bipedal that its forelimbs had atrophied until they were apparently quite useless. They consisted of two claws which were too short to reach the creature's mouth and so could not even have been used for feeding. Their purpose, it is surmised, was to provide leverage to lift the monster back on to its legs after it had been resting on its stomach.
Their tail however was important, stretching out backwards to provide a counterbalance to the creature's trunk when it moved. These dinosaurs lunged forwards with a sort of waddling effect as the tail swung from side to side. Ancient tracks confirm this picture.
T. rex was an eight ton monster. For it to stand on two limbs, was an effort that required a large amount of energy. Its head was so massive, unlike that of its earlier predecessor, allosaurus, that it needed enormous amounts of energy just to carry it. Is it feasible that such a creature could have had the defective physiological system and intermittent metabolism of a cold-blooded lizard?
One concludes from all this evidence that dinosaurs could not have had the physical make up of present day lizards. They were not just lumbering beasts (though some had a lumbering lifestyle like some mammals), they were sophisticated creatures that kept mammals suppressed for over 100 million years!
There are, of course, counter arguments against donosaurs being warm blooded and Nicholas Hotton has them.