Extinction of species due to Earth orbit changes?
Even small changes in the Earth's orbit or axis can increase the risk of extinction, at least for mammalian species. This was determined by a research group led by Jan van Dam from the University of Utrecht after evaluating around 80,000 fossil rodent teeth aged between 2.5 and 24.5 million years from a Spanish site.
Extinction events therefore returned every 1.2 million or every 2.4 million - times that can be reconciled with the so-called Milankovic cycles, which generally occur every 20,000 to 400,000 years. These fluctuations are particularly extreme at the times mentioned: Earth's orbit shifts to a greater extent in a rhythm of 2.4 million years, the Earth's axis varies more clearly in a cycle of around one million years. Depending on these earth parameters, the climate then reacts more strongly with cooling and changes in precipitation, which ultimately also affects the ecosystems. Species that cannot adapt quickly enough tend to go extinct; in periods when both cycles coincide, up to a third of the existing rodent species were affected.
The individual extinction waves wiped out up to five species of rodents over a period of 100,000 years. However, these losses were subsequently made up again by the immigration or evolution of new species, so that an average of 15 rodent representatives were regularly found locally again soon.
