Creationist Reasons for the Extinction
If one were to seek a reason as to why so many of the great creatures that once roamed the earth are now extinct, then one might conjecture that the post-catastrophic world is not conducive to their survival. Firstly, there is evidence for a massive increase in the salinity of the oceans. As a comparative physiologist, I have always been fascinated by the fact that marine fishes (both the cartilaginous fishes as well as the bony fishes) are anatomically and physiologically adapted to a fresh water environment. Their internal salt concentration is approximately one third of that of seawater and their kidneys are adapted for the elimination of water although this function is not required in seawater. In fact, their low salt concentration causes them to lose water by osmosis so that they cannot afford to lose water via the kidneys. The cartilaginous fishes (sharks and rays) solve this problem by retaining urea (a toxin) to raise their osmolarity to a level higher than seawater so that they can gain water by osmosis, whereas bony fishes desalinate the seawater with salt pump in their gills. Obviously these organisms were adapted to much lower salinities in the past and only survive because of their ability to osmoregulate under these circumstances. The retention of toxin by a cartilaginous fish is an indication of an emergency solution to which they eventually adjusted. Only organisms that could either conform to the new conditions or regulate their salt content could survive. The more sensitive are now extinct.
Regarding the land organisms, it is enlightening that there are only two categories of organisms in terms of their ability to cope with the thermal environment in existence today. Terrestrial animals are either endothermic or ectothermic. Endothermic animals (largely mammals and birds) control their body temperatures by increasing their metabolic rates where environmental temperatures drop whereas ectothermic animals control their body temperatures by selectively utilizing external sources such as solar radiation. In the absence of solar radiation, the body temperatures of these animals is the same as that of their environment. We also speak of these categories as warm-blooded and cold-blooded animals.
In a world with climatic extremes one would have to belong to either one of these two categories to survive. There is evidence that the great reptiles of the past were probably neither endotherms nor ectotherms, but somewhere in between. The same probably holds true for many of the now extinct giant amphibians and mammal-like reptiles. Studies of bone to marrow ratios show that the dinosaurs and other creatures were thus in this intermediary condition and would thus require stable environmental conditions. The plant life of the lower stratigraphic record shows that the earth probably had a relatively warm climate prior to the catastrophe and the post-catastrophic climate was not suitable for the survival of the palaeoforms. Moreover, the large scale reduction in vegetation associated with the destruction means that many food sources were no longer available and precludes survival of these animals.
--From
http://www.amazingdiscoveries.org/a.../article/catastrophism-and-the-fossil-record/
There's nothing in scripture that says he had to take adult animals. He just had to be sure to take a boy and a girl.
