Pentacarpellate Capsular Fruits of Ericaceous Affinity from the Paleocene of Wyoming, USA: Sandrawia Gen. Nov.

We describe a new fruit type of ericaceous affinity from Paleocene sediments of the Fort Union Formation of Wyoming, USA. The specimens are preserved in siltstones and sandstones as molds and casts, exhibiting excellent details of external and internal morphology. Observations via reflected light of surface-exposed specimens and microcomputed tomography scanning of subsurface fossils within hand specimens reveal that the fruits are pentacarpellate, loculicidal capsules bearing numerous small seeds in axile placentation near the apex of a central columella. The capsules are borne on a thick pedicel with a generally persistent pentamerous calyx. Morphological characters of Sandrawia scottii gen. et sp. nov. are consistent with placement in the order Ericales, with closest similarity to Ericaceae, but the combination of characters is distinct from that of any extant clade of the family. Although the Ericales were present in the Cretaceous, the evolution of extant genera within the Ericaceae seems to have occurred in the Cenozoic. Sandrawia represents an extinct Paleocene taxon at the generic and possibly subfamilial level.