We need to talk about the biggest break-up of all-time: the break-up of the supercontinent Pangea, and how, ultimately, when India smashed back into Asia, it traded one form of evolutionary isolation for another.

Toxodon was one of the last members of a lineage that vanished 11,000 years ago after thriving in isolation for millions of years. And its fossils would inspire a revolutionary thinker to tackle a bigger mystery than Toxodon itself:...