Illigera fruits (Hernandiaceae) from the Miocene of Alum Bluff, northwestern Florida

Abstract

The Middle Miocene Alum Bluff flora in northwestern Florida provides a valuable opportunity for comprehending former floristic diversity and the development of modern temperate forest in southeastern North America. The flora previously was understood to be dominated by deciduous subtropical to temperate taxa. Here, we present newly discovered winged fruits of the tropical genus Illigera (Hernandiaceae). The new fossil species, Illigera berryi Hai Zhu, Manch. et T.A. Lott is the first confirmed thermophilic macrofossil record from the flora and enriches the known floristic diversity. This occurrence expands the paleogeographic distribution of Illigera in North America southeastward and extends the known fossil history of the genus from the Eocene to the Middle Miocene. Combined with previously recognized fossil occurrences from the Eocene of western North America and eastern Asia, the fossil evidence indicates that Illigera had a wide distribution in the Cenozoic, and suggests that the genus may have originated from the Northern Hemisphere.