Study: Mammals became 1,000 times bigger after dinosaurs expired

By on Nov 26, 2010 in Science, United States, Weird, World Comments

A recent study showed mammals became 1,000 times bigger than the dinosaurs after the latter expired which is about 65 million years ago, according to an article entitled The Evolution of Maximum Body Size of Terrestrial Mammals and was published in the Journal Science.

As published in international news sites on Thursday, mammals such as elephants and rhinoceros have grown to about 1,000 bigger than the dinosaurs; 25 million years after the latter died out on earth.

“When dinosaurs were around, the biggest mammals that are around are about 10 kilos,” University of Calgary paleontologist Jessica Theodor said, who is also one of 20 co-authors of the said article, which was published on the same day.

“What we found is that mammal body size immediately after the extinction of dinosaurs increased very quickly, the largest-size mammals that are around are 1,000 times bigger — they’re 10,000 kilos.” Theodor added.

The international study at the University of New Mexico in Albuquerque included about 20 scientists from the Australia, Canada, Finland, Israel, and the U.S., and was led by Felisa Smith.

The research team gathered all the fossil records to determine the largest animals during each time frame, and consulted existing literature and used tooth measurements to understand the possible body size of the mammals.

Indricotherium, which a relative of the rhinoceros, apparently grew about 17 tons (17,000 kilograms), and became the largest land mammal that ever lived, according to computer models the scientists created, as shown in the photo.

Theodor then suggests that the study revealed that the mammals grew larger during colder periods such as ice ages, because larger animals have less skin surface area compared to the volume of their bodies.

“Most of the very largest mammals eat vegetation off the top of trees, and you have to be fairly big to be able to do that,” the paleontologist added.

“Since you lose heat across your skin, bigger mammals have an easier time staying warm.” Theodor concluded.

Interestingly, researchers also say that no single group of mammals has dominated the largest size class throughout the time period.

In the end, the computer models was said to have suggested a previous theory is inaccurate; that the existence of large mammals was just a side-effect of an increase in the number and type of mammal species.



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