Sprecher
Beschreibung
Numerous lignitized fruits and seeds have been recovered from commercial clay pits of the middle Eocene Cockfield Formation of the Claiborne Group. One fruit type, comprising five specimens, previously studied with reflected light and scanning electron microscopy, was further investigated with Keyance shadow effect microscopy and micro-CT scanning technology to elucidate the inner morphology. The fossils are lenticular endocarps, nearly circular in apical view. Four, five, or seven cylindrical locules, most or all with an enlarged seed, are arranged in a ring in the interior of the endocarp. Near the upper part of the endocarp are subapical extra-locular cavities alternating with the locules. Near the equatorial rim of the endocarp are lateral extra-locular cavities, equal in number to the locules. The exact means of emergence of the radicle is uncertain, but it appears that the radicle penetrates a small opening at the apex of the locule or pushes through the very thin upper layer of the locule. The characters of the fossil are mostly shared with those of fruits of the subfamily Spondioideae of the family Anacardiaceae. The fossils, however, do not match any single modern or fossil genus, especially differing in the method of germination. Therefore, a new genus of Anacardiaceae is proposed. This new genus, along with other extant genera, including Cyrtocarpa, Dracontomelon, and Lannea, and extinct genera, including Pentoperculum, Pseudosclerocarya, and Spondicarya, known from the Eocene of North America and Europe, shows that fruits of Anacardiaceae, especially Spondioideae, were already diverse and widespread by the Eocene.