High-crowned teeth appear in Patagonia first
South American herbivores evolve teeth for gritty, open-country food millions of years before anyone else.
- When
- —
- Duration
- 8.9 million years
- Known to
- ± 2 million years
- Era
- Oligocene, Cenozoic
Hypsodonty — tall-crowned teeth with a long wear reserve — is the standard adaptation to abrasive diets, and it appears in South American native ungulates far earlier than in North American horses. The likeliest cause is not grass but grit: volcanic ash from the Andean arc coating the vegetation and wearing teeth down. The case is a useful warning that a trait usually read as a signal of grassland can be produced by something else entirely.