Ancient Arctogaea

The remaining insectivores, the Dilambdodonta, are first found in the Lower Eocene; the living families are of com paratively modern introduction. The erinaceoids first appear in the Oligocene of Europe, North America and Mongolia. The shrews and moles have a similar distribution, whilst the primitive family of lepticids is confined to the Oligocene and Eocene of North America. Thus the Dilambdodonta appear originally to have been of northern origin, occurring throughout the whole of Arctogaea and entering the southern peninsulas at some late period. Galeopithecus has perhaps ancestors in the Eocene of North America and of Europe.

Carnivora.

In Basal Eocene times Europe and North Amer ica were inhabited by primitive carnivores belonging to sub-orders the majority of which were not related to any living form. These extinct groups, the Acreodi and pseudo-Creodi, are represented in Europe, Mongolia, and North America in the Eocene and Oligocene, and one or two members of the latter group reached northern Africa in Oligocene times. One form at any rate lived on in India to the Miocene but none ever reached South America. The ancestors of the true carnivores, which fall within the family Miacidae, occur in Basal Eocene and Eocene rocks in Europe, Mongolia and North America. From this family there arose a whole series of forms from which the civets (Viverridae), rac coons (Procyonidae), dogs (Canidae) and Mustelidae arose.

The Viverridae are represented in the Eocene of Europe al though not in that of America. They have a long history in the European Tertiary and appear in the Upper Miocene and later deposits of northern India : from a viverrid stock the Hyaenidae seem to have originated. The first forms known, both of the existing genus itself and of the intermediate genus Ictitherium, occur in the Pontian Lower Pliocene fauna, which stretches with minor modifications in its character from China to Portugal: no member of the group reached America.

The mustelids first appear in exceedingly similar forms of weasels in the Oligocene of Europe, Mongolia and North America. During its later history the group appears to have been European and North American, the otters and badgers being Old World and occurring in late Miocene or Pontian times in the Oriental region.

The Canidae (dogs) have a long, very elaborate and still incom pletely understood evolutionary history both in the Old and New Worlds. One interesting feature is an early separation of the dhole-like dogs from the others, dating from Oligocene times. The Oligocene forms of this group are entirely North American, but a single member at any rate seems to occur in the Upper Miocene of Europe. The living representatives are

South American, African and Oriental, regions which were certainly not inhabited by members of this group until late Tertiary times.

The Procyonidae are first represented by Lower Miocene forms in North America, and no members of the group appear to have reached Mongolia or Europe. An apparent exception is provided by two animals, Aelurus (the panda), now living in the Himalaya, first known from Upper Pliocene deposits in west Europe, and Aeluropus (the giant panda), living in Tibet, found fossil in the Pleistocene of Burma. The ancestry and affinities of these forms are however still uncertain.

The amphicyonine dogs, which are represented in the Oligo cene of North America, occur during Miocene times in both Europe and North America ; from this group the Ursidae (bears) appear to have arisen, Ursavus being from the Middle Miocene of France and possibly related forms occur in Europe, India, China and North America. They first appear in South America in Pleistocene times.

The Felidae (cats) belong to two independent groups, the Machaerodontinae (sabre-tooth cats) and the Felinae (true cats). Both families occur in the Oligocene of North America and Europe, and their descendants are found in these localities at every horizon between that and the Pleistocene. At this stage the former became extinct, whilst the latter has living representatives in both sub-regions. The Middle Miocene of central Africa contains the remains of a feline, and the Oriental region has been inhabited by both sabre-tooth and true cats since Miocene times. Cats of both types first appear in South America in Pliocene deposits. The group appears to be of northern origin and to have colonised the southern projections of Arctogaea during the Miocene at a time when many migrations were taking place.

The Proboscidea

first appear in Upper Eocene rocks in Egypt as a small animal, Moerit/zerium, which presents the first traces of their characteristic specialisations. In the Lower Oli gocene of Egypt this animal is still found and is there accompanied by its descendant Palaeomastodon. This genus gave origin to the later Proboscidea, its immediate descendants being included under the somewhat vague term "mastodon." Mastodons appear in the Lower Miocene of North Africa, Baluchistan and Europe and by Mid-Miocene times had reached China and North Amer ica. Subsequently in Upper Pliocene times mastodons of special type migrated southwards and lived on into Pleistocene times in South America.