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Historic Background of Reptiles (9th Part)

© Janat Khatoon

Many theories have been advanced to account for the immense dying of the dinosaurs. Some of them are almost persuasive, some seem pretty desperate. Without going into the merits of these, it can be said that this great anomaly remains to confound them all: it was not a single species of animals that disappeared so unaccountably, it was several orders of reptiles. It was a broad spectrum of animal life occupying all sorts of environments and habitats. Some of the creatures were tiny, some gigantic, some ordinary reptiles, some among the most bizarre animals that ever lived. If too-great size, and thus too-great surface to volume ratio in times of rising temperatures killed off the sauropods, then what struck down the pterosaurs, most of which were wispy aerialists that lived in wholly different ways? If mammals are up the eggs of the terrestrial dinosaurs, what plagued the live bearing ichthyosaurs that ranged the open seas? And so it goes. The fact is the event has not been accounted for. We know only that a vast and far-flung fauna was wiped out and replaced by a fauna of mammals leaving the world of today with only remnants of the once great orders.

The dinosaurs were by no means the only Mesozoic reptiles that burgeoned and spread and then because extinct. Of the others, some made ventures into alleys that went quickly blind; others like the ichthyosaurs and plesiosaurs were successful radiation that endured far longer than modern mammals have been on earth. Most of them were stocks that went back into the sea, and more will be said of them in the chapter on water reptiles. The grand days of the crocodilians were the Mesozoic days, when one kind reached a length of fifty feet; and crocodile architecture was paralleled in astonishing detail by that of that phytosaurs, a completely separate branch from the Permian reptile stem. The crocodiles continued; the phytosaurs, although in their own time they appeared to be just as promising, are gone, for reasons we do not know, and in all likelihood never will.