Anoxypristis sp.

Fig. 39 A–I

Anoxypristis aff. mucrodens – Cappetta & Case 2016: 62–63, pl. 10, figs 9–12.

Material examined

UNITED STATES OF AMERICA – Alabama • 18 isolated teeth; Claiborne Group; ALMNH PV1985.87.10, ALMNH PV1985.87.9, ALMNH PV1992.56.4 (2 specimens), MMNS VP-8946 (3 specimens), MMNS VP-8952 (3 specimens), MSC 35791, MSC 37289, MSC 37310, MSC 37333, MSC 37422, MSC 37643, MSC 37658, WSU CC 549.

Description

Rostral spines dorsoventrally flattened and symmetrical in either of these views. Spines have a slight ventral bend and weakly convex dorsal and ventral faces. Anterior and posterior edges straight and rounded basally, becoming sharp and tapering gently to a rounded point. No posterior groove present. Spine slightly wider basally, where transverse growth lines visible dorsally and ventrally. Growth lines visible ventrally almost to the spine apex. Faint mediolateral striations visible on ventral face. Spine base ovate and with weak central depression. Entire spine lacks an enameloid covering.

Remarks

The Anoxypristis rostral spines in our sample were differentiated from those of Pristis by having thin anterior and posterior edges, as opposed to a wide and flat or grooved posterior edge on Pristis spines. Anoxypristis spines can be differentiated from those of Propristis (see below) in being anteroposteriorly narrower and much more elongated, with a correspondingly more pointed apex. Anoxypristis spines in our sample are similar to a specimen assigned by Case & Cappetta (1990) to Anoxypristis aff. mucrodens, but we refrain from speciating these specimens because the range of variation in rostral spine morphology is inadequately known within the two Eocene species of Anoxypristis, including A. fajumensis (Stromer, 1905a) and A. mucrodens (White, 1926). The spines in our sample differ from those of Mesopristis osonensis Farrés, 2003 from the middle Eocene of Spain in their lack a distinctive V-shaped basal concavity. The concavity occurring on M. osonensis spines fits over a thin projection emanating from the base of the alveolus of the rostrum, forming a tongue-and-groove articulation.

Stratigraphic and geographic range in Alabama

The specimens in our sample were collected from the lower Tallahatta Formation at site ADl-1, the contact of the Tallahatta and Lisbon formations and the basal Lisbon Formation at site ACov-11, and the basal Gosport Sand at site ACl-4. Upper Ypresian to middle Bartonian, zones NP14 to NP17.