Sprecher
Beschreibung
The Big Sand Draw fruit and seed flora of the Paleocene Fort Union Formation in the southern Wind River Basin of Wyoming, USA, was initially collected in the 1960s. However, the specimens were only preliminarily studied because of the difficulty of understanding the morphology of disseminules preserved predominantly as moulds. We investigated 161 hand specimens of the highly fossiliferous sideritic sandstone, ranging from 1 to 12 cm in maximum dimension, using a GE Phoenix V|tome|xm 240 micro-CT scanner, and processed resulting image stacks with VG Studio-Max, Amira, and Meshlab software. While some disseminules were exposed at the surface, the majority of the samples contained one or more (up to 45) fruits or seeds hidden inside that were revealed only by this X-ray methodology. Our current inventory of the fruit and seed flora includes about 55 morphotypes. These include Ditaxocladus (Cupressaceae), Palaeosinomenium (Menispermaceae), Eotrochion (Trochodendraceae), Platanus (Platanaceae), Hexagonokaryon (Fagaceae), Cranea (Betulaceae), Kingsboroughia (Sabiaceae), Cyclocarya (Juglandaceae), Acer (Sapindaceae), Ampelocissus (Vitaceae), Cornus (Cornaceae), Langtonia, Mastixia, Mastixiopsis (Mastixiaceae), cf. Rehderodendron (Styracaceae), Sandrawia (Ericaceae), Iodes, and Palaeophytocrene (Icacinaceae). At least 30 additional, morphologically distinctive fruit and seed taxa remain unplaced within the Eudicots. The technology allowing us to "see inside" the samples has revealed greater species richness and more details of morphology than were previously known and, together with co-occurring leaf impressions, contributes to an improved understanding of the forest composition, paleoenvironment and biogeographic affinities of this flora. This work also informs us that specimens traditionally bypassed in fieldwork may be paleobotanically significant.