Darwin’s ‘Strangest’ Beast Finds Place on Tree
“Toxodon is perhaps one of the strangest animals ever discovered,” wrote Charles Darwin, a man who was no stranger to strangeness. He first encountered the creature in Uruguay on November 26th, 1834. “Having heard of some giant’s bones at a neighbouring farm-house…, I rode there accompanied by my host, and purchased for the value of eighteen pence the head of the Toxodon,” he later wrote.
The beast’s skeleton, once fully assembled, was a baffling mish-mash of traits. It was huge like a rhino, but it had the chiselling incisors of a rodent—its name means “arched tooth”—and the high-placed eyes and nostrils of a manatee or some other aquatic mammal. “How wonderfully are the different orders, at present time so well separated, blended together in different points of the structure of the toxodon!” Darwin wrote.
Those conflicting traits have continued to confuse scientists. Hundreds of large hoofed mammals have since been found in South America, and they fall into some 280 genera. Scientists still argue about when these mysterious beasts first evolved, whether they belong to one single group or several that evolved separately, and, mainly, which other mammals they were related too. “That’s been difficult to address because they have features that they share with a lot of different groups from across the mammalian tree,” says Ian Barnes from the Natural History Museum in London. “To some degree, people have circled around the same set of evidence for 180 years.”
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