Page:Popular Science Monthly Volume 66.djvu/242

238 Leaving this parental order, in the Permian and Lower Trias, we first see in the older offspring, the Anomodontia, reptiles of varied size and description, carnivorous and herbivorous in habit, most abundantly found in South Africa, in Asia and in Europe, and not at all as yet in America, either North or South. The high degree of fitness for different habits, or radiation, of the Anomodonts is distinguished from that of any other reptiles at any time by its numerous analogies to the radiation of the mammals, namely, into very large and very small forms, into carnivorous and herbivorous, into terrestrial and possibly into aquatic types; in fact, some of these animals, if seen on land to-day might readily be mistaken for mammals.

The second offspring of the Cotylosauria, on the contrary, the Diaptosauria, are essentially and unmistakably saurians; that is, if seen about us to-day they would undoubtedly at first be described as lizards. They were still more broadly cosmopolitan in range, being scattered over both Americas (Pelycosauria, Proganosauria), Europe (Protorosauria, Rhynchosauria), Asia (Rhynchosauria) and Africa (Proganosauria, Rhynchosauria). They are also found highly diversified in type, but all their analogies of fitness are with the reptiles and not with the mammals. It is of prime importance that more of these diaptosaurs be found, and that those already known in the museums should be more critically examined. What we already know, however, enables us to establish the following facts: first, that the parentage of these animals is more probably among the cotylosaurs than among the anomodonts, and second that already in the Permian they had formed a sufficiently large number of branches to be regarded as a fully evolved radiation.

In the Triassic the offspring of the anomodonts and of the diaptosaurs appear as the third generation from the cotylosaurs.

The recurrent difficulty arises that the actual points of contact or transition from the anomodonts are wanting, and we must continue to reason by the ideal reconstruction of the hypothetical linking forms. Such reasoning connects the Testudinata (turtles and tortoises), the Sauropterygia, or marine plesiosaurs, and, singularly enough, our own ancestors, the primordial mammals, with the group of anomodonts and not at all with that of the diaptosaurs. Here in the Upper Permian and Lower Trias we must await both discovery and the closest critical analysis, but if this still hypothetical affiliation be confirmed by discovery, as I personally am sanguine it will be, then it will be true to say that the mammals, and hence man, are much more nearly affiliated to the anomodonts than to either the lizards or snakes, which are both on the great Diaptosaur branch. Our presence on the great Anomodont branch and remoteness from the creeping and crawling