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Pierre Teilhard de Chardin – Phenomenon of Man

Let us begin by focussing our attention on the younger and more progressive branch of the mammals - the placentals, herbivores and the rodents who get their food directly from the vegetable kingdom, the insectivores similarly predatory on the arthropoda, the carnivores battening on both these groups and the omnivores who dine at every table.  These are the four dominant radiations ….

Now let us consider these four stems separately.  They subdivide splitting up easily into subordinate units.  Take for instance the richest of them at present – the herbivores.  According to the two different ways in which the extremities of the limbs are transformed into feet for running (by the hyper development of two fingers or the single median one), we see this group separating into two great families, the Artiodactyla and the Perissodactyla, each formed by a collection of large and distinct lineages.  In the Perissodactyla we find the obscure crowd of tapirs, the short but astonishing branch of the Titanotheridae, the Chalicotheridae with digging claws which man in his early days may possibly have seen, the Rhinocerotidae horned and hornless, and lastly the solipedal Equidae, imitated in South America by a completely independent phylum.

In the Artiodactyla we find Suidae, the Camelidae, the Cervidae and the Antilopidae – to say nothing of less vigorous stems which are nevertheless as differentiated and as interesting to the paleontologist.  And we have not mentioned the abundant and robust group, the Proboscidia.  Conforming to the rule of the suppression of the peduncles, the early history of each of these groups is lost in the mists of the past.

But once they appeared we can follow each one of them through the principal phases of their geographical expansion; also through their successive sub-divisions into sub-verticals which proceed almost indefinitely; and lastly by the exaggeration due to orthogenesis of certain skeletal characteristics dental or cranial, which generally end up by making them monstrous or delicate.

Nor is this all.  For we can distinguish, superimposed on this florescence of genera and species issued from the four fundamental radiations, another network corresponding to attempts made here and there to abandon life on the ground and take to the air, the water, or even to an underground existence.  Besides forms specialised for running there are arboreal and even flying forms, and burrowing forms.

The Cetacean and Sirenia seem to have developed surprisingly quickly from the carnivores and the herbivores.  Others (such as the chiroptera, moles and mole rates) are derived from the oldest elements of the placental group, the insectivores and the rodents both dating from the end of the Secondary era.