The rise and retreat of odd-toed ungulates

A rapid Eocene arrival

The earliest sampled perissodactyls occur during the PETM on northern landmasses, but those first fossils do not reveal an exact place or time of origin.

First appearances are fossil observations, not exact origination dates.

Browsers in a greenhouse world

Eocene brontotheres radiate in North America and Asia while western European Palaeotherium medium provides a separate leaf-browsing sample; one ecology is not assigned to every lineage.

Cooling changes the guild

Marine records resolve stepwise ice growth, while the Hampshire mammal sequence separates turnover, a hiatus and later immigrant appearances; together they do not prove one simple cause.

Specialists and survivors

Living horses, tapirs and rhinoceroses are a narrow remnant of former perissodactyl diversity, and even Coelodonta species show that extinct rhinoceros ecology was not uniform.