Hemipristis curvatus Dames, 1883

Ebersole, Jun A., Cicimurri, David J. & Stringer, Gary L., 2019, Taxonomy and biostratigraphy of the elasmobranchs and bony fishes (Chondrichthyes and Osteichthyes) of the lower-to-middle Eocene (Ypresian to Bartonian) Claiborne Group in Alabama, USA, including an analysis of otoliths, European Journal of Taxonomy 585, pp. 1-274 : 66-67

Hemipristis curvatus Dames, 1883

Fig. 24

Hemipristis curvatus Dames, 1883: 140 , pl. 3, fig. 4a–b.

Hemipristis wyattdurhami White, 1956: 134 , text-pl. figs 40–47, pl. 11, fig. 4.

Hemipristis serra – Woodward 1889: 451 .

Hemipristis wyattdurhami – Thurmond & Jones 1981: 63 , fig. 29.

Material examined

UNITED STATES OF AMERICA – Alabama • 6 isolated teeth; Claiborne Group; ALMNH PV1989.4.189, ALMNH PV1989.4.220, ALMNH PV1989.4.221, MSC 2376.1–2, MSC 2377.

Description

Upper anterior teeth have high, triangular crown. Mesial cutting edge elongate, slightly convex, bearing four large serrae basally but otherwise smooth; basal serrae decrease in size towards crown foot. Upper half of the distal edge smooth, vertical, whereas basal half bears five large serrae decreasing in size towards the crown foot. Mesial edge and upper half of the distal edge form conspicuous cusp that is slightly distally inclined. Root has a large lingual boss bisected by a nutritive groove. Upper lateral teeth have broad-based crown bearing distally curving cusp. Mesial cutting edge very convex, smooth except for one-or-two medially located serrae. Apical one-third of distal edge smooth, forms distally inclined cusp along with mesial edge. Lower two-thirds of distal edge formed into heavily serrated oblique heel; five-to-eight serrae present that decrease in size basally. Root bilobate; very short and highly diverging lobes separated by V-shaped interlobe area; wide, shallow lingual nutritive groove.

Remarks

Woodward (1889: 451) originally reported a tooth collected from Eocene deposits in Clarke County, AL as Hemipristis serra Agassiz, 1843 , noting, however, that the specimen was “doubtfully of this species.” This specimen was later reexamined by White (1956) and referred to a new species, Hemipristis wyattdurhami , a taxon that Cappetta (1987) later designated as a junior synonym of H. curvatus Dames, 1883 . Teeth of H. serra attain much larger sizes than those of H. curvatus , and the mesial cutting edge on the upper teeth and lower lateral teeth of H. serra bear more denticles than do teeth of H. curvatus . In contrast, the mesial edge on H. curvatus teeth in these jaw positions are smooth or with few very weak denticles. H. serra is also widely regarded as a Neogene taxon (see Cappetta 2012).

Stratigraphic and geographic range in Alabama

The specimens in our sample were collected from the Gosport Sand at site ACh-21. Middle Bartonian, Zone NP17.

Figures

Fig. 24. Hemipristis curvatus Dames, 1883, teeth. A–C. MSC 2377, lower anterior tooth, Gosport Sand. A. Labial view. B. Lingual view. C. Mesial view. D–F. ALMNH PV1994.4.220, upper lateral tooth, Gosport Sand. D. Labial view. E. Lingual view. F. Mesial view. G–I. ALMNH PV1994.4.221, upper lateral tooth, Gosport Sand. G. Labial view. H. Lingual view. I. Mesial view. J–L. ALMNH PV1994.4.189, lower lateral tooth, Gosport Sand. J. Labial view. K. Lingual view. L. Mesial view. Scale bars = 5 mm.