Alangium LAM.

Tiffney, Bruce H. & Manchester, Steven R., 2022, The Early Middle Eocene Wagon Bed Carpoflora Of Central Wyoming, U. S. A., Fossil Imprint 78 (1), pp. 51-79 : 65

Genus Alangium LAM.

Text-fig. 6a–e

M a t e r i a l. One chalcedony cast, DMNH EPI.47806.

D e s c r i p t i o n. Bilocular endocarp represented by two locule casts arranged in the form of a sandwich ( Text-fig. 6c–e ) with the intervening septum also silicified. Endocarp wall missing. Locules elliptical in face view ( Text-fig. 6a, b ), 13.8–16.3 mm long, 11.5–12.9 mm wide, each 3–4 mm thick, one slightly larger than the other; fruit 9.3 mm thick perpendicular to the septum. Septum ca. 1.5 mm thick, with about 16 regularly spaced peripheral circular depressions corresponding to the central vasculature ( Text-fig. 6c–e ).

D i s c u s s i o n. This distinctive cast was readily identified through comparison with similarly preserved specimens from the Clarno Formation of Oregon ( Manchester 1994). The Clarno specimens exhibit a range of preservation modes from permineralized examples with sufficient anatomical detail to verify the generic determination, to chalcedony locule cast “sandwiches” like the one figured here. The Wagon Bed specimen conforms to endocarps of section Marlea (ROXB.) BAILL. , which is also known from other Eocene localities including the Clarno Formation ( Manchester 1994), the London Clay ( Chandler 1961) and Messel ( Collinson et al. 2012) and from the Miocene Brandon Lignite ( Eyde et al. 1969). This specimen is distinctive in its large size in comparison to other Eocene species (length of 16 mm in this species vs. 10 mm in Clarno, 11 in London Clay, 6 mm in Messel). The modern genus includes about 20 species of small trees, shrubs and lianes of the Old World tropics, dominantly of southeast Asia ( Mabberley 2008). In sect. Marlea , A. scandens BLOEMB. is noted as a climber ( De Wilde and Duyfjes 2016).

Figures

Text-fig. 6. Cornaceae. Alangium (a–e), Mastixia (f–r). a–e: Alangium, DMNH EPI.47806. Scale bar = 1cm. b, e: Reflected light, palladium coated. a, c, d: Micro-CT scan surface rendering. a: Locule cast, face view of slightly larger locule. b: Face view of slightly smaller locule. c: Lateral view of the endocarp, the slightly enlarged left carpel separated from the smaller carpel by a longitudinal septal groove; the faint pitting in the groove suggestive of the septal vasculature. d, e: Views of either end of the endocarp, illustrating the size difference between the two carpels and the pitting in the septal groove suggestive of the septal vasculature. f–k: Mastixia USNM PAL772362. Scale bar = 1cm. f, g, j, k: reflected light,palladium coated; h, i: micro-CT scan surface rendering. f: Lateral view of endocarp, inferred dorsal germination valve groove facing the viewer. Note irregular, rugose, longitudinal ridges. g: Lateral view of endocarp, inferred germination valve with median longitudinal groove to left. h: Lateral view of endocarp reoriented with the same longitudinal groove to the right. i: Lateral view, rotated to ventral surface. j: View of one end of the endocarp, germination valve groove up. k: Opposite end view, with prominent radial ridges and intervening grooves, germination valve groove up. l–r: Mastixia USNM PAL 772363. Scale bar = 1cm. l: View of one face of endocarp, displaying a groove that may represent the surficial expression of the dorsal infold of a Mastixia-like germination valve. Surface badly eroded, reflected light, palladium coated. m: Opposite face of endocarp displaying extensive erosion and a central hole interpreted as feeding damage. n: Lateral view; m, n micro-CT scan surface renderings. o: A view of one end, displaying the prominent groove, reflected light, palladium coated. p: Opposite end to (o). q: View as in (o); p, q micro-CT scan surface renderings. r: Virtual transverse section showing curved locule (arrows).