Firstly, not all crocodile families did survive - in fact, quite a number did become extinct, particularly the large-bodied ones.Ī number of reasons have been suggested to explain why the other groups of crocodiles did survive. The question is often asked as to why and how they survived this mass extinction when non-avian dinosaurs did not. Fossils found around the Traps show that life was resilient in this environment, including dinosaur life.Ĭrocodiles and alligators are often viewed as the great survivors from the dinosaur age, and also mistakenly as living dinosaurs. The Deccan eruptions certainly affected local flora and fauna, but evidence suggests that it may have had little direct affect on global extinctions. These could cause catastrophic changes to the climate including prolonged winters, seasonal changes, global warming and aridity, along with other impacts such as acid rain, and chemical changes to the ocean surfaces. Large scale eruptions would have resulted in several trillion tonnes of ash and toxic gases, such as sulphur dioxide and carbon dioxide, being pumped into the air. Other sites of possible massive volcanic eruptions have been found in Cameroon and the Coral Sea.
#Mesozoica species list series
They were formed over a few million years near the end of the Cretaceous when huge volumes of lava were released in a series of eruptions. In particular, the Deccan Traps in India cover an area of 800,000 square kilometres. The end of the Cretaceous was one of the most intense periods of volcanic activity in Earth's history with a number of sites showing evidence of large scale eruptions.
They argue that much of the evidence put forward to support the meteorite impact theory could have been due to volcanic activity instead. Some suggest that the extinction occurred over an extended period of time due to massive volcanism. Not all scientists agree that a meteorite impact caused the end-Mesozoic extinction. All these would devastate the biosphere, with massive initial fatalities followed by collapse of food chains. Research shows that the effects would include global firestorms, high magnitude earthquakes, tsunamis, acid rain, heating of the atmosphere, and debris and dust that cause prolonged winter. These includes more sites around the world with iridium, possible impact craters, tsunami sediment deposits, shocked quartz and carbon soots.Ī large meteorite (about 10-kilometre-wide) hitting the Earth would be catastrophic. This theory gained momentum as further research turned up a variety of supportive evidence from rock layers dating to about 66 million years old. Iridium is scarce on Earth and considered to be meteoric in origin. This layer yielded extensive amounts of the mineral element iridium. The idea was first proposed by Alvarez and Alvarez in 1979 based on their analysis of a clay layer in Italy (known as the Gubbio clay layer). Many scientists believe that the impact of one or more meteorites was the major cause of the end-Mesozoic extinction.
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