The Cambridge natural history, Vol. 10 (of 10)Beddard, Frank E. (Frank Evers)
Science
The Cambridge natural history, Vol. 10 (of 10)
Beddard, Frank E. (Frank Evers)
Animals; Mammals
The Ethiopian region has also its Anthropoids, the Gorilla and the
Chimpanzee, but they belong to genera or a genus different from those which
include the Oriental forms. There are five peculiar genera of
Cercopithecidae. The Lemurs restricted to this region are _Galago_,
_Perodicticus_ and _Arctocebus_. The peculiar Insectivorous families
Macroscelidae and Chrysochloridae are only found here, besides many other
peculiar genera. Africa is especially the home of Antelopes, and the
Giraffe is not found now outside its borders. The Elephant and the
Rhinoceroses are of different species from those of India. There are many
peculiar Rodents and Ungulates.
* * * * *
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CHAPTER III
THE POSSIBLE FORERUNNERS OF THE MAMMALIA
The relationship of Mammals to Vertebrates lying below them in the scale,
their origin in fact, is a much-debated question, with many attempted
solutions. To enter into this large question in detail would involve a
great deal of useless statement of arguments founded upon misleading or
upon quite inaccurate "facts." It will perhaps be sufficient if we reflect
here the current view most in vogue at the present, _i.e._ that which would
refer the Mammalia to reptiles belonging to the extinct Permian and
Triassic group of the Theromorpha (also called Anomodontia). These have
been explored lately to a very large extent, and chiefly by Professor
Seeley.[45] The very fact that a genus _Tritylodon_, only known by the
forepart of the skull, has been called Mammalian and Anomodont by various
authors, shows at least the difficulty of differentiating the two groups
when the material for study is imperfect. As a matter of fact these
Theromorpha are without doubt reptiles; they show, for example, a lower jaw
formed out of several distinct pieces, of which the articular articulates
with a fixed quadrate on the skull. They possess the characteristic
reptilian bones, the "transverse," the pre- and post-frontals, and there
are various other points of structure which leave no room for doubt as to
their truly reptilian nature. There are, however, numerous indications of
an evolution in the mammalian direction in all parts of the skeleton, to
the more important of which some reference will be made here. It may be as
well to clear the {91} ground by mentioning the fact that among the
Theromorpha four distinct types of reptiles are included, which are
considered to form four orders, _i.e._ the Pareiasauri, the Theriodontia,
the Anomodontia (Dicynodontia), and the Placodontia.
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