EVOLUTION AND EXTERNAL APPEARANCE 63 



are pertinent to our investigation, since Boyden and Gemeroy used it in 

 1950 to discover that ii per cent of all Cetacean and Artiodactyle 

 proteins were identical, while only about 2 per cent of the proteins of 

 either group agreed with those of other mammals. Moreover, study of 

 fossils has shown that a group of small, primitive mammals appeared in 

 the Cretaceous period (which began about 125 million years ago). These 

 animals which probably lived on land, and partly in trees, had charac- 

 teristics strongly reminiscent of primitive Carnivores and of primitiv^e 

 Insectivores. As yet, little is known about these small animals, the fossils 

 of which were discovered in the interior of Mongolia, but it is thought that 

 the mammalian line can be so constructed that both the Carnivores and 

 the Ungulates can be traced back to this group of primitive Creodonts- 

 cum-insectivores. Even modern insectivores, bats and apes are said to 

 be descended from these ancestors, and so are the Cetaceans whose line 

 of descent is close to that of the Carnivores and Ungulates, but especially 

 to the latter and quite particularly to the Even-toed Ungulates (Fig. 27). 



A glance at Fig. 27, will reveal a preponderance of stippled lines. These 

 indicate the absence of fossils, so that the picture may have to be modified 

 once new evidence comes to light. Meanwhile, it represents the best 

 interpretation of all the available data. From it, we can see clearly that the 

 first-known fossils of fully-fledged Cetaceans date back to the Eocene epoch 

 which l^egan roughly 45 million years ago. Cetacean fossils from that 

 epoch were first discovered in Louisiana in 1832, when a coluinn of 

 twenty-eight vertebrae was unearthed. They were classified as Basilosaunis, 

 i.e. King of the Reptiles. As early as 1839 Owen realized that Basilosaunis 

 was a mammal and not a reptile, and he renamed it ^euglodon, the 

 Greek for the yoke-shaped teeth of a skviU that had meanwhile been 

 discovered. 



In 1845 Albert Koch, a German collector, discovered a part of a skull 

 and a great nuinber of vertebrae. He joined up the vertebrae of two 

 animals and obtained a specimen 1 1 2 feet long which - ignorant of the 

 work of Owen - he called Hydrargos (Water Chief) and which he exhibited 

 as the 'Sea Snake', first in the Apollo Rooms on Broadway, New York, 

 and afterwards in a number of European cities. Later, it emerged that the 

 actual skeleton of the animal he was exhibiting could only have had a 

 length of 50 feet and that the skeleton belonged to a Cetacean (see Fig. 28) . 

 Further Cetacean skeletons from the Eocene, more or less complete, have 

 since been discovered in North America, Europe, Nigeria, New Zealand, 

 the Antarctic, and near Cairo in particular. 



All these skeletons belonged to a group of primitive Cetaceans, the 

 Archaeocetes, which were, however, not the direct ancestors of the two 

 extant sub-orders, and must be looked upon as a branch that died out 



