Part 4 (1/2)
What do we find among Dinosaurs? Thespesius, or Claosaurus, which may have walked where Baltimore now stands, was twenty-five feet in length and stood a dozen feet high in his bare feet, had a brain smaller than a man's clenched fist, weighing less than one pound.
Brontosaurus, in some respects the biggest brute that ever walked, was but little better off, and Triceratops, and his relatives, creatures having twice the bulk of an elephant, weighing probably over ten tons, possessed a brain weighing not over two pounds!
How much of what we term intelligence could such a creature possess--what was the extent of its reasoning powers? Judging from our own standpoint and the small amount of intellect apparent in some humans with much larger brains, these big reptiles must have known just about enough to have eaten when they were hungry, anything more was superfluous.
However, intelligence is one thing, life another, and the spinal cord, with its supply of nerve-substance, doubtless looked after the mere mechanical functions of life; and while even the spinal cord is in many cases quite small, in some places, particularly in the sacral region, it is subject to considerable enlargement. This is notably true of Stegosaurus, where the sacral enlargement is twenty times the bulk of the puny brain--a fact noted by Professor Marsh, and seized upon by the newspapers, which announced that he had discovered a Dinosaur with a brain in its pelvis.
In their great variety of size and shape the Dinosaurs form an interesting parallel with the Marsupials of Australia. For just as these are, as it were, an epitome of the cla.s.s of mammals, mimicking the herbivores, carnivores, rodents and even monkeys, so there are carnivorous and herbivorous Dinosaurs--Dinosaurs that dwelt on land and others that habitually resided in the water, those that walked upright and those that crawled about on all fours; and, while there are no hints that any possessed the power of flight, some members of the group are very bird-like in form and structure, so much so that it has been thought that the two may have had a common ancestry.
The smallest of the Dinosaurs whose acquaintance we have made were little larger than chickens; the largest claim the distinction of being the largest known quadrupeds that have walked the face of the earth, the giants not only of their day, but of all time, before whose huge frames the bones of the Mammoth, that familiar byword for all things great, seem slight.
For Brontosaurus, the Thunder Lizard, beneath whose mighty tread the earth shook, and his kindred were from 40 to 60 feet long and 10 to 14 feet high, their thigh bones measuring 5 to 6 feet in length, being the largest single bones known to us, while some of the vertebrae were 4-1/2 feet high, exceeding in dimensions those of a whale.
[Ill.u.s.tration: Fig. 19--A Hind Leg of the Great Brontosaurus, the Largest of the Dinosaurs.]
The group to which Brontosaurus belongs, including Diplodocus and Morosaurus, is distinguished by a large, though rather short, body, very long neck and tail, and, for the size of the animal, a very small head. In fact, the head was so small and, in the case of Diplodocus, so poorly provided with teeth that it must have been quite a task, or a long-continued pleasure, according to the state of its digestive apparatus, for the animal to have eaten its daily meal.
[Ill.u.s.tration: Fig. 20.--A Single Vertebra of Brontosaurus.]
An elephant weighing 5 tons eats 100 pounds of hay and 25 pounds of grain for his day's ration; but, as this food is in a comparatively concentrated form, it would require at least twice this weight of green fodder.
It is a difficult matter to estimate the weight of a live Diplodocus or a Brontosaurus, but it is pretty safe to say that it would not be far from 20 tons, and that one would devour at the very least something over 700 pounds of leaves or twigs or plants each day--more, if the animal felt really hungry.
But here we must, even if reluctantly, curb our imagination a little and consider another point: the cold-blooded, sluggish reptiles, as we know them to-day, do not waste their energies in rapid movements, or in keeping the temperature of their bodies above that of the air, and so by no means require the amount of food needed by more active, warm-blooded animals. Alligators, turtles, and snakes will go for weeks, even months, without food, and while this applies more particularly to those that dwell in temperate climes and during their winter hibernation practically suspend the functions of digestion and respiration, it is more or less true of all reptiles. And as there is little reason for supposing that reptiles behaved in the past any differently from what they do in the present, these great Dinosaurs may, after all, not have been gifted with such ravenous appet.i.tes as one might fancy. Still, it is dangerous to lay down any hard and fast laws concerning animals, and he who writes about them is continually obliged to qualify his remarks--in sporting parlance, to hedge a little, and in the present instance there is some reason, based on the arrangement of vertebrae and ribs, to suppose that the lungs of Dinosaurs were somewhat like those of birds, and that, as a corollary, their blood may have been better aerated and warmer than that of living reptiles. But, to return to the question of food.
From the peculiar character of the articulations of the limb-bones, it is inferred that these animals were largely aquatic in their habits, and fed on some abundant species of water plants. One can readily see the advantage of the long neck in browsing off the vegetation on the bottom of shallow lakes, while the animal was submerged, or in rearing the head aloft to scan the surrounding sh.o.r.es for the approach of an enemy. Or, with the tail as a counterpoise, the entire body could be reared out of water and the head be raised some thirty feet in the air.
Triceratops, he of the three-horned face, had a remarkable skull which projected backward over the neck, like a fireman's helmet, or a sunbonnet worn hind side before, while over each eye was a ma.s.sive horn directed forward, a third, but much smaller horn being sometimes present on the nose.
The little ”Horned Toad,” which isn't a toad at all, is the nearest suggestion we have to-day of Triceratops; but, could he realize the ambition of the frog in the fable and swell himself to the dimensions of an ox, he would even then be but a pigmy compared with his ancient and distant relative.
So far as mere appearance goes he would compare very well, for while so much is said about the strange appearance of the Dinosaurs, it is to be borne in mind that their peculiarities are enhanced by their size, and that there are many lizards of to-day that lack only stature to be even more _bizarre_; and, for example, were the Australian Moloch but big enough, he could give even Stegosaurus ”points” in more ways than one.
Standing before the skull of Triceratops, looking him squarely in the face, one notices in front of each eye a thick guard of projecting bone, and while this must have interfered with vision directly ahead it must have also furnished protection for the eye. So long as Triceratops faced an adversary he must have been practically invulnerable, but as he was the largest animal of his time, upward of twenty-five feet in length, it is probable that his combats were mainly with those of his own kind and the subject of dispute some fair female upon whom two rival suitors had cast covetous eyes. What a sight it would have been to have seen two of these big brutes in mortal combat as they charged upon each other with all the impetus to be derived from ten tons of infuriate fles.h.!.+ We may picture to ourselves horn clas.h.i.+ng upon horn, or glancing from each bony s.h.i.+eld until some skilful stroke or unlucky slip placed one combatant at the mercy of the other, and he went down before the blows of his adversary ”as falls on Mount Alvernus a thunder-smitten oak.”
[Ill.u.s.tration: Fig. 21.--Moloch. A Modern Lizard that Surpa.s.ses the Stegosaurs in All but Size. _From a drawing by J. M. Gleeson._]
A pair of Triceratops horns in the National Museum bears witness to such encounters, for one is broken midway between tip and base; and that it was broken during life is evident from the fact that the stump is healed and rounded over, while the size of the horns shows that their owner reached a ripe old age.
For, unlike man and the higher vertebrates, reptiles and fishes do not have a maximum standard of size which is soon reached and rarely exceeded, but continue to grow throughout life, so that the size of a turtle, a crocodile, or a Dinosaur tells something of the duration of its life.
Before quitting Triceratops let us glance for a moment at its skeleton.
Now among other things a skeleton is the solution of a problem in mechanics, and in Triceratops the head so dominates the rest of the structure that one might almost imagine the skull was made first and the body adjusted to it. The great head seems made not only for offence and defence; the spreading frill serves for the attachment of muscles to sustain the weight of the skull, while the work of the muscles is made easier by the fact that the frill reaches so far back of the junction of head with neck as to largely counterbalance the weight of the face and jaws. When we restored the skull of this animal it was found that the centre of gravity lay back of the eye. Several of the bones of the neck are united in one ma.s.s to furnish a firm attachment for the muscles that support and move the skull, but as the movements of the neck are already restricted by the overhanging frill, this loss of motion is no additional disadvantage.
[Ill.u.s.tration: TRICERATOPS PRORSUS Marsh Fig. 22.--Skeleton of Triceratops.]
To support all this weight of skull and body requires very ma.s.sive legs, and as the fore legs are very short, this enables Triceratops to browse comfortably from the ground by merely lowering the front of the head.