New data on the winged fruits of Carpolithus prangosoides Berry from the Eocene of western Tennessee and Kentucky.

Abstract

We reexamined the morphology of the winged fruits Carpolithus prangosoides Berry (later synonym: Terminalia vera Berry) from the Eocene Claiborne Formation of southeastern North America, based on original and more recently collected specimens from several localities in Tennessee and Kentucky, USA. Physical and virtual sections of the fossils allow for more detailed documentation of wing morphology. The fruits are ellipsoidal, with five main lateral wings which bear radiating reticulate venation that forms loops near the margin. None of the fruits show pedicel or style remnants, but a basal pedicel scar was observed at the end opposite to the prominent, persistent sepals, indicating that the perianth was epigynous. A comparison with all known families having fin-winged fruits was conducted to assess possible affinities of C. prangosoides. Although no modern genus was found to match these fossils, the available characters, including the five sepals, suggest that it belongs to the Eudicot clade, likely in the Pentapetalae. However, the prior suggestion of combretaceous affinity is rejected based on differences in wing number and venation. We reviewed other North American reports of combretaceous fossils, concluding that only a few of them are reliable records for the family.