Mass extinction would favor the survival of smaller animals.
(Mirror Daily, United States) – Mass extinction would affect massive animals more than it would small ones according to a recent study. Lauren Sallan, an environmental scientist at the University of Pennsylvania, has explained that the study she participated in studied fish fossils and found evidence which suggested that evolution did not replace large vertebrates for many years after they became extinct.
The fish fossils analyzed were over 350 million years old and showed evidence that some fish species from that time period were killed in a mass extinction called the Hangenberg event. However it was found that the mass extinction killed larger species of fish while the smaller ones managed to survive.
Sallan’s findings also suggest that the smaller species of fish had an advantage that their larger counterparts did not possess: they bred at a considerably faster pace than the larger species. The differences observed after the mass extinction in the ecosystem were astounding. Most fish species left were of small size.
The researchers explain that what was left was an ocean consisting of sharks that measured mostly less than a meter and species of fish and tetrapods that only measured roughly 10 centimeters. Still, these small species are responsible for every other species that came after them.
The changes in the body sizes of animals over the course of time have been debated by paleontologists before and there are several theories trying to explain how and why these changes happened. Cope’s rule is one of these theories and relies on the premise that animal species tend to grow larger over time in order to become better hunters as well as to avoid predation. Another theory suggests that species become larger in the presence of increased amounts of oxygen.
A theory known as the Lilliput Effect states that there is an inevitable incline towards small body size after a mass extinction. Many scientists believe that we are either on the verge of a sixth mass extinction, with some going as far as to say that we are already in the middle of one. The main cause of this current mass extinction is the human population and its actions, according to a report published earlier this year.
However, while humans are mostly responsible for this phenomenon, scientists have stated that if aggressive conservation efforts were to be made a true mass extinction could still be avoided. But in order for such efforts to be successful, the efforts to conserve already threatened species would have to be greatly intensified as soon as possible.
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