Batomorphi, Cappetta, 1980

Cicimurri, David J., Ebersole, Jun A., Stringer, Gary L., Starnes, James E. & Phillips, George E., 2025, Late Oligocene fishes (Chondrichthyes and Osteichthyes) from the Catahoula Formation in Wayne County, Mississippi, USA, European Journal of Taxonomy 984 (1), pp. 1-131 : 72-74

Batomorphi fam., gen. et sp. indet.

Fig. 22A–L

Material examined

UNITED STATES OF AMERICA – Mississippi • 326 poorly preserved isolated teeth; Catahoula Formation ; SC 2013.28.394 to 28.398 , SC 2013.28.399 (2 specimens), SC 2013.28.400 (49 specimens), SC 2013.28.401 (19 specimens), SC 2013.28.402 (16 specimens), SC 2013.28.403 (17 specimens), SC 2013.28.404 (218 specimens) • 9 dermal thorns; Catahoula Formation ; MMNS VP-6650.1 ( Fig. 22G–I ), MMNS VP-6650.2 ( Fig. 22D–F ), MMNS VP-8066.1 ( Fig. 22J–L ), MMNS VP-8066.2 , SC 2013.28.405 , SC 2013.28.518 , SC 2013.28.520 , SC 2013.28.521 , SC 2013.28.528 • 43 caudal spines; Catahoula Formation ; MMNS VP-7035 (13 specimens), MMNS VP-7035.1 ( Fig. 22A–C ), SC 2013.28.480 , SC 2013.28.481 , SC 2013.28.482 , SC 2013.28.483 (16 specimens), SC 2013.28.484 , SC 2013.28.485 (9 specimens) .

Description

Several thorn-like denticles measuring up to 3.5 mm in antero-postero length and 2.5 mm in medio-lateral width consist of a rather small crown atop a taller and wider base. The crown is small, conical, and covered with smooth enameloid. Some of these denticles (i.e., Fig. 22D–F ) have a high conical base that bears numerous widely spaced radiating furrows. Although the furrows reach the crown foot, they do not extend to the base of the crown. Other similar denticles ( Fig. 22G–I ) are laterally compressed with broad and nearly vertical sides that bear fine vertical striations. Both types of denticles have a circular to sub-rectangular basal outline ( Fig. 22E, H ), and the basal surface is weakly convex ( Fig. 22D, G ). An additional denticle morphotype is comprised of a triangular, highly distally inclined crown and very thin base ( Fig. 22J–L ). Smooth enameloid is limited to the dorsal surface of the crown. The base is flared outward from the crown, has a roughly triangular outline, and the basal surface is weakly concave. The caudal spines in our sample are elongated, distally tapering, and dorso-ventrally flattened ( Fig. 22A–C ). The dorsal surface is covered by enameloid except for the distal end, where the element was embedded in soft tissue. The proximal end is also wide and spatulate, whereas the distal tip is sharply pointed. The ventral surface lacks enameloid and has a single robust, rounded medial ridge that parallels the spine length ( Fig. 22B ). The right and left lateral surfaces bear a single row of denticles. The closely spaced denticles are enameloid-covered, sharply angled proximally, and sharply pointed ( Fig. 22A ). Denticle size is consistent except for the distal tip, where they quickly decrease in size.

Remarks

The 326 highly worn symphyseal and lateral teeth represent elements from durophagous ray dentitions. These include complete and broken specimens with tooth crowns that have been worn through in vivo use down to, and beyond, the lingual transverse ridge. Many specimens have also been modified through post mortem transport, as they are polished and have rounded edges and corners. Thus, their taxonomically significant features, like crown ornamentation, shape of the lingual transverse ridge, and nature of the root lobes, are not preserved. We could therefore not determine whether the specimens represent “ Rhinoptera ” sp., “ Myliobatis ” sp., or “ Aetomylaeus ” sp., but they are included here for completeness and to document the overall abundance of durophagous ray teeth.

One thorn-like denticle morphology (not shown), represented by SC 2013.28.405, is comparable to a denticle from the Chattian Chandler Bridge Formation of South Carolina that Cicimurri & Knight (2009) assigned to Dasyatidae (see their fig. 8e). MMNS VP-8066 ( Fig. 22J–L ) is reminiscent of dermal thorns referred to Bathytoshia centroura ( Mitchill, 1815) by Purdy et al. (2001). Other denticles like those shown in Fig. 22D–F and G–I (also including SC 2013.28.520, SC 2013.28.521 and SC 2013.28.528) are similar to each other and are believed to represent the same taxon. It is possible these represent one of the rhinopristiform fishes we identified by teeth (i.e., Rhynchobatus ).

Although there is slight variation in the gross morphology of the caudal spines, the shape of the lateral denticles is consistent, and the specimens could represent the same taxon. Unfortunately, we cannot say with certainty to which species they belong, but it is likely they represent one (or more) of the taxa within Dasyatidae or Myliobatidae we identified by their teeth.

Figures

Fig. 22. Elasmobranchii indet., remains: Myliobatiformes gen. et sp. indet. (A–C), Batomorphi fam., gen. et sp. indet. (D–L), and Galeomorphii fam., gen. et sp. indet. (M–U). A–C. MMNS VP-7035.1, Myliobatiformes gen. et sp. indet., caudal spine. A. Dorsal view. B. Ventral view. C. Right profile view. D–F. MMNS VP-6650.2, Batomorphi fam., gen. et sp. indet., dermal denticle. D. Profile view. E. Apical view. F. Basal view. G–I. MMNS VP-6650.1, Batomorphi fam., gen. et sp. indet., dermal denticle. G. Profile view.H.Apicalview.I. Basal view.J–L. MMNSVP-8066.1, Batomorphi fam.,gen. et sp. indet., dermal denticle. J. Profile view. K. Apical view. L. Basal view. M–O. MMNS VP-7750, Galeomorphii fam., gen. et sp. indet., placoid scale. M. Profile view. N. Apical view. O. Basal view. P–R. MMNS VP-7753, Galeomorphii fam., gen. et sp. indet., symphyseal tooth. P. Distal view. Q. Lingual view. R. Labial view. S–U. MMNS VP-8741.1, Galeomorphii fam., gen. et sp. indet., symphyseal tooth. S. Distal view. T. Lingual view. U. Labial view. Scale bars: A–C = 2 cm; D–L = 5 mm; M–U = 1 mm.