Nature & Environment
Rats could evolve to be as big as sheep
By T.K. Randall
February 4, 2014 · 28 comments
How big can rats get ? Image Credit: CC BY-SA 2.0 Chris Barber
The extinction of several large mammal species could pave the way for super-sized rats.
Being highly adaptable, rats could soon grow to huge sizes if other larger mammal species disappear. The largest rodent species alive today is the capybara which can weigh up to 80kg, however in the past there have been even larger specimens - the extinct Josephoartegasia monesi for example grew to be the size of a large cow and weighed over a ton.
"In the Cretaceous Period, when the dinosaurs lived, there were mammals, but these were very small, rat and mouse-sized, because dinosaurs occupied the larger ecological niches," said geologist Dr Jan Zalasiewicz. "Only once the dinosaurs were out of the way did these tiny mammals evolve into many different forms, including some very large and impressive ones: brontotheriums, horses, mastodons, mammoths, rhinoceri and more."
If something similar happens in the future, animals like rats could become free to grow, spread and diversify. With gigantism being a common consequence of a smaller animal stepping in to fill the shoes of a larger species that has gone extinct, it is not outside the realm of possibility that we could be seeing rats the size of sheep or even bigger in the not-too-distant future.
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