Dinosaur extinction caused unexpected changes in plants and fruits
About 60 million years ago, the Cretaceous–Paleogene (K–Pg) extinction occurred, wiping away almost a third of all existing animals, including dinosaurs, from planet Earth. In recent years, scientists have been toying around with the idea of genetically reengineering some of the long-lost animals. Although still a far-fetched dream, researchers have now found that restoring the Jurassic Park would take a lot more than just reengineering the lost animals.
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A new paper published in the journal Proceedings of the Royal Society establishes that the mass extinction of animals also led to dramatic changes in vegetation and the way they behave. The study authored by Renske Onstein from the German Centre for Integrative Biodiversity Research and other researchers now shows that genetically reengineering any of the lost animals would require a total reengineering of their environment as well.
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“We used genetic data to reconstruct past relationships. Based on that information, we saw splitting and speciation happening,” Onstein said.
It is often thought that species thrive and evolution booms after an extinction. On the contrary, the researchers found dramatic occurrences in the wake of the extinction. The rate of species branching off into new ones was slowed down on average, a situation that the scientists were not able to explain.
“That’s the next question. Why did speciation slow down? I’m not sure, to be honest. We saw some groups where speciation actually increased, because other species went extinct and there was less competition, so they could really flourish. Other groups went down in speciation. We still need to get our heads around that,” Onstein said.
Further, there were drastic changes in vegetation after the extinction. The vegetation that persisted 25 million years after the extinction underwent serious changes in morphology. Some lost their defense mechanisms while others started growing much larger fruits.
The researchers divided the fruiting plants into two groups. The first group included plants that produced fruits smaller or equal to four centimeters in diameter. The other group included fruits with a diameter larger than four centimeters. The researchers noticed that several fruit types had increased in size within 25 million years after the extinction of dinosaurs.
“These large fruits probably still depended on large animals, but maybe not as large as these megaherbivores, which were over 1,000 kilograms. The fruits could probably also be dispersed by animals comparable to tapirs, 100 or 200 kilograms. Those kinds of animals were evolving during that time,” Onstein said.