Propristis schweinfurthi Dames 1883

Propristis schweinfurthi Dames, 1883

Fig. 39 J–R

Propristis schweinfurthi Dames, 1883: 136, pl 3, figs 1a–c, 2.

Amblypristis cheops Dames, 1883: 106, text fig.

Pristis schweinfurthi Priem 1905: 636, text-fig. 6.

Pristis (Eopristis) reinachi Stromer 1905a: 52, pl. 4, figs 15, 15a.

Material examined

UNITED STATES OF AMERICA – Alabama • 10 isolated teeth; Claiborne Group; ALMNH PV 1989.4.2 (3 specimens), ALMNH PV1989.4.110, ALMNH PV1989.4.118.1 (2 specimens), MSC 2392.6, MSC 2392.8, MSC 37392.1 – 2.

Description

Rostral spines short, anteroposteriorly wide, dorsoventrally very thin. Spines asymmetrical, with sharp and sinuous anteroposterior cutting edge at spine apex. Dorsal and ventral faces taper to a point anteriorly and posteriorly. Spine base slightly concave in dorsal and ventral views, with faint growth line striations. Striations extend less than halfway up the spine and terminate where the spine is worn. Spine base elliptical in basal view; anterior and posterior edges pointed. Basal edge is granular with a shallow anteroposterior sulcus.

Remarks

The genus Propristis contains two species, the Eocene Propristis schweinfurthi Dames, 1883 and the Miocene Propristis mayumbensis Dartevelle & Casier, 1943. The teeth in our sample appear to be conspecific with those referred to P. schweinfurthi (see Dames 1888: 107; Cappetta 2012: fig. 386; Zalmout et al. 2012: fig. 5q–r) and are only slightly older (Bartonian) than the type specimens from the Priabonian of Egypt (Dames 1883). Propristis schweinfurthi was originally named for a partial rostrum, but later Dames (1888) named the species Amblypristis cheops for a number of isolated pristid rostral teeth from the same locality. Stromer (1905a), however, designated A. cheops a junior synonym of P. schweinfurthi, as he determined that specimens of the former belonged to the rostrum of the latter.

Propristis rostral spines are easily distinguished from Pristis and Anoxypristis by their wider and shorter dimensions, and more extensive cutting edge. In contrast to the latter two genera, the spines of Propristis were set into shallow, closely spaced depressions on the margins of the rostral cartilage, as opposed to deep alveoli formed by broad projections of rostral cartilage. The spines of Propristis overlapped each other and formed an irregular, continuous cutting edge (Fraas 1907).

Stratigraphic and geographic range in Alabama

The specimens in our sample are known only from the basal Gosport Sand at site ACl-4 and the Gosport Sand at site ACh-21. Middle Bartonian, Zone NP17.

Order Myliobatiformes Compagno, 1973

Suborder Myliobatoidei Compagno, 1973

Family Dasyatidae Jordan, 1888