Tech UPTechnologyWhen mammals replaced dinosaurs

When mammals replaced dinosaurs

grandes-mamiferosWhen dinosaurs became extinct 65 million years ago, mammals began to grow, multiplying their size by a thousand in some cases. It is the case ofDeinotherium, a distant relative of elephants that disappeared 2.7 million years ago and weighed 17.00 kilograms.

Dinosaurs disappearand suddenly no one else eats the vegetation. That supposes agreat availability of food, and mammals begin to eat, and if you are a herbivore it is more efficient to be large “, explains Jessica Theodor, a biologist at the University of Calgary (Canada) and co-author with 19 other researchers of the article published today in the journalScience. Mammals, whose weight until then oscillated between 3 grams and 15 kilograms, began to consume this food andin some cases they reached up to 17 tons of weight.

For the study, Theodor and his colleagues first analyzed preserved mammalian fossils from all successive periods. In order to demonstratehow much mammals grew after the extinction of the dinosaurs, the researchers collected data on the maximum size of each major group of land mammals from each continent, including perissodactyls (odd-toed ungulates such as horses and rhinos), proboscideans (including elephants, mammoths, and mastodons) , xenarthros (anteaters, tree-dwelling sloths, and armadillos), as well as a large number of other extinct animal groups.

The results give clues about what factors define the size limits of land mammals: the amount of space available for each animal and the climate in which they live. According to scientists, the colder the climate, the larger the animals , because larger animals conserve heat better.

In addition to confirming the extraordinary growth that mammals experienced when the dinosaurs disappeared, the study shows that this evolution took place relatively quickly. “The dinosaurs became extinct 65 million years ago and in 25 million years the ecosystem was reprogrammed to respond to the growing demand for these ever-larger animals, which is, in geological terms, a short period, a truly evolution. fast, “emphasizes Theodor.

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