Popular opinion holds ground sloths are extinct because they were  too inept to survive.  Polite critics often point to sloth teeth as one example of their maladaptation, foregoing the customary jabs at their supposed beach bum lifestyle and grooming habits. This came to mind recently when we received some photos from Daniela Kalthoff, PhD, a researcher at the Swedish Museum of Natural History.  She’s studying the microstructure of sloth teeth and offered us some amazingly detailed images of a Megalonychid tooth to aid our research (left).

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