“It’s not this organized, predictable world where progress is a thing in nature and the better adapted always ended up surviving.” “It’s a more complex evolutionary world than what pure Darwinism would tell us,” Juan Cantalapiedra, a co-author on the study and paleobiologist of the University of Alcalá in Madrid told Science News. However, over time, the larger species survived where smaller brethren did not. This means a species of brontothere stayed the same size until it branched into different species-some bigger, some smaller. Either they slowly swelled in size due to natural selection, grew in growth spurts followed by a plateau periods, or various species grew into varying sizes and the larger ones outlasting their smaller relatives.Īfter studying 276 individuals in the brontothere family to determine the most likely scenario, researchers from the Global Change Ecology and Evolution Research Group at the University of Alcalá in Spain concluded that the final explanation most likely contributed to the explosive growth of the brontotheres. There are three existing theories about how these creatures grew to such enormous proportions. Is an Apelike Humanoid Still Living Among Us?.Surviving the fiery end of the Cretaceous period in their burrows, mammals quickly inherited a (non-avian) dino-free planet known as the Cenozoic period, and scientists say they wasted no time taking advantage. The existence of mammals during the Age of Dinosaurs was one of prey- as small, squirrel-like creatures that scurried among the feet of lumbering giants. Then, after the dinosaurs’ own demise (the asteroid-sized curtain call known as the K-T Extinction), it became mammals’ turn to become the world’s new terrestrial giants. Studying 276 individuals in the brontotheres, researchers found that decreased competition among larger mammals led to the rise of giant “thunder beasts.”Īt the end of the Triassic period, small-sized dinosaurs roamed Earth alongside other groups of archosaurs-that is, until a widespread extinction event cleared the way for dinos to put on some serious size.
Brontotheres, the ancient North American ancestor of the horse, is a gigantism outlier, growing from around 40 pounds to four to five tons in 16 million years.The fossil record is filled with with land animals who grew to impossibly large sizes.
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