the British authors of the study indicate that the inability to substitute other extinct species had been vulnerable to these animals. They were unable to react quickly to a catastrophe, as happened 66 million years ago, and recover.
Most experts believe that the impact of a meteorite in the area of modern Mexico at the end of the Mesozoic Era was the main cause of the extinction of the dinosaurs. Much more controversial is the theory that his death may have begun earlier, with the reduction of species.
Previous work on the issue did not take into account enough evolutionary dynamics as death and birth of species and did not have adequate statistical weight, the scientists write about Manabu Sakamoto, University of Reading.
in this new work itself is discussed in detail at the statistical level history of the race of all groups of dinosaurs, both ornitisquios as saurischians with suborders sauropodomorphs and theropods. They analyzed data covering 420 and 614 -respectively- systematic groups of dinosaurs.
The analysis largely supports the hypothesis that the rate of diversity had decreased in almost all dinosaurs before its ultimate demise, to even below the survival level. This occurred 24 million years before the meteorite impact.
If you look at the analysis of the major groups of dinosaurs separately even happened before, between 48 and 53 million years before the meteorite.
the only exceptions were herbivorous hadrosaurs (bipedal) and horned dinosaurs (dinosaurs horn), including whether there was a high rate of emergence of new species. It is likely that adaptation has enabled them to develop a very strong jaws and special teeth that allowed them to consume certain species of plants. 14 percent of the species of dinosaurs belonged to these two groups.
In addition, scientists tested the theory that there is a relationship between sea level and the rate of emergence of new species. Due to the rising water are isolated land masses with their populations, and this geographical isolation makes the emergence of new species.
It is unclear what caused the diversity of species between dinosaurs were reduced write the scientists. Some possible causes are increased volcanic activity, climate change or ecological interactions with groups of animals rapidly expanding.
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