Welcome to Brainstuff, a production of iHeart Radio, Hey brain Stuff, Lauren Bobo bomb Here. Mammoths, mastodons, and sabretooth cats weren't the only giants roaming ancient America. The Palistocene was a global epoch that kicked off two point six million years ago. It lasted right up until Earth's most recent ice age, ended about eleven thousand, seven hundred years before the present day. When you live in a cold environment, being big has
its advantages. Large animals tend to conserve body heat more easily than smaller ones, and this is one of the major reasons why colossal mammals were so widespread during the frigid Pleistocene. Castroides was very much a product of its time.
The largest rodent in Pleistocene North America, this very big beaver grew to more than seven ft long from tail to snout that's over two meters, and could have weighed as much as two hundred and twenty pounds or a hundred kilos or more, rivaling the American black bear in size.
Casteroids utterly dwarfed the beavers that live today. Modern Eurasian and American beaver species clock in it just around three ft long, a bit less than a meter, and weigh somewhere between twenty nine and seventy seven pounds that's about thirteen to thirty five kilos. Proportionately, Casteroids had a narrower tail and shorter legs, albeit with bigger hind feet than it's extant relatives. We also know that it didn't eat the same foods. Woody plants are a crucial part of
every living beaver's diet. The critters used chisel like incisors that's their front teeth to gnaw through bark and take down trees. But even though casteroids incisors grew to be a whopping six inches or fifteen centimeters long, the teeth had duller edges. By comparison, dental differences would have made it a lot harder for casteroids to eat tree bark, and indeed, it looks like this was not really on
their menu. Using isotropic signatures in casteroid's teeth from Ohio and the yukon En study found that the giant beaver mostly ate softer aquatic plants. The findings say a lot about the rodents ecological niche and why it might have died out For starters casteroids probably didn't build dams, not that there's anything unusual about that. The earliest known beavers appeared during the Eocene epoch, which lasted between about fifty
six and thirty four million years ago. New evidence suggests that the wood harvesting specialists came along much later, perhaps around twenty million years ago. In all likelihood, these bark fanciers used wood as a food source before any of them started constructing dams. Since casteroids fed on aquatic plants, its survival would have depended on wetland habitats. The animal
was highly successful for a time. Casteroids fossils representing at least two distinct species have been documented in the Great Plains, the Great Lakes, the American South Alaska, and numerous Canadian provinces. Unfortunately, for the mega sized beaver, North America became warmer and drier after the Last Ice Age ended, wetlands grew scarcer as a result. Today's beavers used their logging skills to reshape the land around them so that it meets their
own needs. With some well placed wood in the nearest stream, a determined beaver can engineer brandon new ponds. Yet, if casteroids didn't harvest wood or build dams. It couldn't have followed suit. So theoretically, the decline in natural wetlands left the giant beaver more susceptible to extinction. The last of these creatures perished around ten thousand years ago. Today's episode was written by Mark man Scene and produced by Tyler Clang. For more and listen lots of other big topics, visit
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