The<scp>L</scp>eporid<scp>D</scp>atum: a late<scp>M</scp>iocene biotic marker

Abstract

Abstract Although L agomorpha (rabbits, hares and pikas) have a long evolutionary history in E urasia and A frica, including primitive genera of E urasia historically considered assignable at the family level to L eporidae, the predecessors of modern rabbits were absent throughout this vast region for most of the M iocene until late in that epoch. During the early and middle M iocene, crown group L eporidae differentiated in N orth A merica, then dispersed to northern A sia in the late M iocene around 8 Ma (million years before present) and afterward. They then spread widely and apparently rapidly throughout E urasia, reaching S outh A sia by 7.4 Ma and penetrating A frica about 7 Ma . The apparently abrupt introduction of L eporidae is a striking late M iocene event that we call the L eporid D atum. Perceived in terms of biochrons, the L eporid D atum includes localities in E urope and western A sia of late MN 11 ( M ammifères N éogènes system) age and younger, and precedes by less than one million years the B ahean‐ B aodean land mammal age boundary in C hina. The late M iocene spread of L eporidae throughout E urasia was a successful invasion in terms of the numerous occurrences and abundant fossils preserved. Where dating is sufficiently robust, the L eporid D atum is late M iocene, nowhere certainly more than ∼8 Ma . In contrast to this sudden and widespread invasion, rare older finds suggest two possible refinements to this scenario: stem lagomorphs close to modern L eporidae may have lingered into the middle M iocene of E urasia, or an independent, unsuccessful leporid invasion from N orth A merica may have preceded the 8 Ma datum. The L eporid D atum marks an important palaeoecological event for the O ld W orld and complements the significance of molecular dates for origins of modern genera.