The earliest record of the genus Cola (Malvaceae sensu lato: Sterculioideae) from the Late Oligocene (28-27 Ma) of Ethiopia and leaf characteristics within the genus

摘要

A fossil leaf compression from the Late Oligocene (28-27 Ma) of northwestern Ethiopia is the earliest record of the African endemic moist tropical forest genus Cola (Malvaceae sensu lato: Sterculioideae). Based on leaf and epidermal morphology, the fossil is considered to be very similar to two extant Guineo-Congolian species but differences warrant designation of a new species. This study also includes a review of the fossil record of Cola, a comprehensive summary of leaf characteristics within several extant species of Cola, Octolobus, and Pterygota, and a brief discussion of the paleogeographic implications of the fossil species affinity and occurrence in Ethiopia.