ADVANTAGES

Most plants produce seeds, which would have largely survived the catastrophe and began growing when conditions improved. Ferns came back first, in what is called a , as ferns are a . Crocodiles, modern birds (which included ), mammals, and amphibians also survived, and all could have found refuge in burrows, swamps, and shoreline havens, lived in tree holes and other crevices that they were small enough to hide in, and all could have eaten the catastrophe’s detritus. In general, freshwater species fared fairly well, especially those that could eat detritus. Also, the low-energy requirements of ectothermic crocodiles would have seen them survive when the mesothermic/ dinosaurs starved. The primary determinants seem to have been what could survive on detritus or energy reserves and what could not, and what could find refuge from the initial conflagration. While there may have been some evidence of dinosaur decline before the end-Cretaceous extinction (it was gradually growing colder), and the may have caused at least some local devastation, the complete extinction of non-avian dinosaurs, ammonites, marine reptiles, and others that would have been particularly vulnerable to the bolide event’s aftermath has convinced most dinosaur specialists that the bolide impact alone was sufficient to explain the extinction and no other hypothesis explains the pattern of extinction and survival that the bolide hypothesis does. In general, the key to surviving the end-Cretaceous extinction was being a marginal species, and all of those on center-stage paid the ultimate price. The end-Cretaceous extinction's toll was nearly 20% of all families, half of all genera, and about 75% of all species, and marked the end of an era; the Mesozoic ended and made way for the Age of Mammals, also called the , which used to have the .

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