And the changes are not limited to the Flora. It is in the very ground in which they grow. For continental drift has been at work since at least the Paleozoic, and the changes are proving to be of greater significance. According to Geologists, the Cenozoic can currently be divided into six smaller periods:
- Paleocene (= "early dawn of the recent")
- Eocene (= "dawn of recent life")
- Oligocene (= "but little of recent")
- Mioscene (= "living species still in a minority"), it is to this period that many of our mountains owe their existence.
- Pliocene (= "more living than extinct species")
- Pleistocene (= "a great majority of living species")
From the time of the Cretaceous Period, mammals have deviated from the paths of the earlier Reptiles. Not only were mammals warm-blooded, but with few exceptions, did not engage in the laying of eggs. For every major class of mammal, The Record of the Rocks has an ancestral fossil to match:
- Eohippus > horses
- Oxyclactylus > giraffes, camels
- Tetrabelodon > elephants
- Titanotherium > rhinoceros
- Smilodon > cats
As each period goes by, from the Eocene to the Pleistocene, the fossils show a progression of development that tends to reflect an ongoing increase in brain size and capacity for intelligence.
And so it seems to go until the Pleistocene, when the temperature proceeded to drop until finally the Earth entered a period of glacialization now known as the "Ice Ages". It is only with the recession of the last Ice Age, that we finally start coming across the Earliest Traces of Human Development.
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