MUSEUM NOTES

Southland Times, Issue 23773, 22 March 1939, Page 16

MUSEUM NOTES

AGE OF MAMMALS The opening of the next great period in the life of the earth, the cainozoic period, was a period of upheaval and extreme volcanic activity. It was ,at this time that the vast masses of the Alps and Himalayas and the mountainous backbones of the Rockies and the Andes were thrust up, and that the rude outlines of our present oceans and continents appeared. It is now estimated that between 40 and 80 million years have elapsed from the beginning of the cainozoic period to tire present time.

At the outset of the period the climate of the world was cold but it grew gradually warmer until a fresh phase of great abundance was reached, after which conditions grew hard again and the earth passed into a series of extremely cold cycles, the glacial ages, from which it is apparently slowly emerging.

With the opening of the cainozoic period the grasses appear and for the first time there is pasture in the world; and with the full development of the once obscure mammalian type appear a number of interesting grazing animals and of carnivorous types which prey on these. At first these mammals seem to differ only in a few characteristics from the herbivorous and carnivorous reptiles that ages before had flourished and then vanished from the earth. But the differences between the life of the mesozoic and cainozoic periods are far profounder than the resemblances. The most fundamental of all these differences lies in the mental life of the two periods, and it arises essentially out of the continuing contact of parent and offspring which distinguishes mammalian, and in a lesser degree, bird life, from the life of the reptile. With very few exceptions the reptile abandons its egg to hatch alone. The young reptile has no knowledge whatever of its parent; its mental life such as it is, begins and ends with its own experiences. It may tolerate the existence of its fellows, but it has no communication with them; it never imitates, never learns frpm them, and is incapable of concerted action with them. Its life is that of an isolated individual. But with the suckling and cherishing of young which was distinctive of the new mammalian and avian strains, arose the possibility of learning by imitation, of communication, by warning cries and other concerted action, of mutual control and instruction. EARLIEST FORMS The earliest mammals of the cainozoic period are but little superior in brain size to the more active dinosaurs, but towards modern times we find, in every tribe and race of mammalian animals, a steady universal increase in brain capacity. For instance, we find at a comparatively early stage that rhinoceroslike beasts appear, and one, the titanotherium lived in the earliest division of this period. It was probably very like a modern rhinoceros in its habits and needs but its brain capacity was not one-tenth of that of its living successor. The difference between the reptile world and the world of our human minds is one our sympathies seem unable to pass, for we cannot conceive in ourselves the swift uncomplicated urgency of a reptile’s instinctive motives, its appetites, its fears and hates. But the mammals and birds have self-re-straint and consideration for other individuals, a social appeal, and a selfcontrol that is, at its own lower level, after our own. We can in consequence establish relations with almost all sorts of them. When they suffer they utter cries and make movements which arouse oui 1 feelings, and we can make understanding pets of them with mutual recognition. They can be tamed to self-restraint towards us, domesticated and taught. That unusual growth of brain which is the central fact of cainozoic times marks a new communication and interdependence of individuals and foreshadows the development of human societies which began with the monkeys, apes and sub-men. As the cainozoic period went on the resemblance of its flora and fauna to the plants and animals which inhabit the' world today, increased. The big clumsy uintatheres and titanotheres, big clumsy brutes like nothing living, disappeared. On the other hand a series of forms led up by steady degrees from the grotesque and clumsy predecessors to the giraffes, camels, horses, elephants, deer, dogs, lions and tigers of the existing world. The evolution of the horse is particularly legible upon the geological record and we have today a fairly complete series of forms from the small tapir-like ancestor about the size of a hare that lived in early cainozoic, times.

Another line of development that has been pieced together with precision is that of the llamas and camels.