Pristis sp.

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 : 51-53

Pristis sp.

Fig. 13A–F, M–R

Material examined

UNITED STATES OF AMERICA – Mississippi • 12 rostral spines; Catahoula Formation; MMNS VP-7787 (5 specimens), MMNS VP-7787.1 ( Fig. 13P–R ), MMNS VP-12070 ( Fig. 13M–O ), SC 2013.28.515 , SC 2013.28.516 , SC 2013.28.517 (3 specimens) • 28 isolated teeth; Catahoula Formation; MMNS VP-7748 (4 teeth), MMNS VP-8744 (2 teeth), MMNS VP-9211 (4 teeth), SC 2013.28.486 ( Fig. 13D–F ), SC 2013.28.487 to 28.489 , SC 2013.28.490 ( Fig. 13A–C ), SC 2013.28.491 (4 teeth), SC 2013.28.492 (3 teeth), SC 2013.28.493 (4 teeth), SC 2013.28.512 , SC 2013.28.527 .

Description

The rostral spines are composed entirely of dentine. These spines are elongated, antero-posteriorly narrow, and dorso-ventrally flattened but thick. The anterior and posterior margins are parallel along most of the spine length, but near the distal tip, the anterior margin converges towards the posterior margin to form a sharp point. The anterior margin is rounded except at the distal tip, which is a sharp edge. The posterior margin bears a furrow along its entire length. The dorsal and ventral surfaces are weakly convex except at the distal tip, where the surfaces are flat. Fine growth lines are visible near the base, and the basal surface has a somewhat D-shaped outline ( Fig. 13M, P ).

The teeth are tiny, measuring 1 mm in total height. Crown width (mesio-distal) averages 1.2 mm, with the smallest measuring 1.0 mm and the largest 1.8 mm in this dimension. Crown length averages 1.1 mm, with the smallest measuring 0.8 mm and the largest 1.5 mm in this dimension. The teeth are somewhat globular in appearance, with a crown that is convex in labial and profile views ( Fig. 13B, E–F ). In occlusal view, a transverse crest divides the crown into labial and lingual parts ( Fig. 13D ). The crest is generally blunt but can be sharp, and it does not reach the foot of the lateral crown. In labial view, the crest can be flat and weakly cuspidate with a pointed apex. The labial crown margin is weakly to strongly convex, and the labial face is convex to varying degrees. The lingual face exhibits an elongate medial protuberance (i.e., uvula) that extends onto the root, and this protuberance varies in width and length. The distal ends of the crown are lingually directed and form a roughly 70º angle with the medial lingual uvula ( Fig. 13A, D ). The angularity of the lateral crown projections varies from narrow and pointed to wide and rounded. The crown slightly overhangs the root labially, but the root extends beyond the lateral and lingual crown faces ( Fig. 13A, C, E ). In basal view, the root is bisected by a wide nutritive groove that is perforated (medially) by several small foramina. The root lobes are very short in profile view and have a cleaver-shaped basal outline, with a distinctive narrow process extending lingually. The oral root surface bears a pair of large foramina, one on each side of the medial uvula.

Remarks

Although all the rostral spines are ablated, they compare well to spines in the rostra of extant Pristis pectinata Latham, 1794 (MSC 43849, MSC 43850, SC 90.80.1) that we examined. Some of the Catahoula Formation spines have a sharp antero-distal margin and oblique striations on the dorsal and ventral surfaces. These features were observed on extant Pristis spines and have been reported on Eocene specimens, and they indicate that the Catahoula sawfishes used their spined rostrum to probe the sandy substrate for prey ( Cicimurri 2007; Ebersole et al. 2019). It is interesting to note that the figured specimens exhibit a distinct transition from sub-parallel margins to gently apically converging ( Fig. 13O, R ). Some rostral spines exhibiting this morphology reported from elsewhere have been assigned to Pristis brayi Casier, 1949 (see Hovestadt & Steurbaut 2023: 88). However, our examination of several extant Pristis spp. rostra demonstrates that the beginning of this constriction represents the point where the spine was exposed from the rostrum, with the proximal end set within a deep alveolus of the rostral cartilage (the distal end is exposed to wear). Ebersole et al. (2019) discussed the taxonomic uncertainty involved with the speciation of isolated Paleogene Pristis spines, and we herein follow these authors by leaving the Catahoula Formation specimens within open nomenclature. It cannot be ascertained whether similar rostral spines reported from middle Eocene deposits in Alabama ( Cappetta & Case 2016; Ebersole et al. 2019) are conspecific with the Catahoula Formation taxon, or if multiple Paleogene taxa are present.

The familial/generic assignment of teeth like those described above has been debated over the past several years, with alternating assignments to Rhinobatidae / Rhinobatos and Pristidae / Pristis (i.e., Cappetta & Case 2016; Ebersole et al. 2019; Adnet et al. 2020), but all sources agree that the morphology is assignable to Rhinopristiformes . Reinecke et al. (2023) provided a monograph that helped us make a more informed identification of these fossil teeth. The Catahoula Formation teeth are wider (mesio-distally) than long (labio-lingually). Additionally, the transverse crest, which ranges from low and rounded to sharp and cuspidate, has a straight to sinuous appearance (in occlusal view). Although the lateral crown margins are lingually directed and extend beyond the lingual medial uvula, we do not view these structures as lateral uvulae (sensu Cappetta 2012). Furthermore, in profile view the oral surface of the lingual medial uvula has a weakly to strongly sinuous outline, depending on the height of the transverse crest and the convexity of the uvula itself.

The features we observed on the Catahoula Formation teeth described above are consistent with those of fossil and extant representatives of Pristis ( Cappetta 2012; Carrillo-Briceño et al. 2015, 2016; Reinecke et al. 2023). These features include a sinuous transverse crest and a lack of lateral uvulae (in occlusal view), as well as the sinuous oral margin of the medial lingual uvula and slight labial overhang of the root (in profile view). Additionally, the basal root surface is cleaver-shaped with a distinctively lingually elongated projection.

In contrast, teeth of the extant rhinobatids Pseudobatos horkelii ( Müller & Henle, 1841) and Glaucostegus cemiculus ( Geoffroy Saint-Hilaire, 1817) have distinctive labial and lingual portions of the crown (see Reinecke et al. 2023: pls 13, 17) like the fossil teeth of Rhynchobatus we observed (see above). Although teeth of the extant Rhinobatos annandalei Norman, 1926 and Acroteriobatus annulatus (Smith in Müller & Henle, 1841) are similar to our Catahoula Formation specimens, they differ by having a straight transverse crest (occlusal view), a generally convex oro-lingual margin and a shorter, more oblique medial lingual uvula (profile view), a greater labial overhang of the root (profile view), and a shorter lingual projection of the root (basal view). These differences can be observed among the teeth shown by Reinecke et al. (2023: pls 1–4, 9–10, 5–16).

There are slight variations in tooth morphology within our Catahoula Formation sample that likely reflect some form of heterodonty. Narrow teeth with sharp and generally cuspidate transverse crests may represent anterior jaw positions, whereas teeth that are conspicuously wider than long with a low and rounded transverse crest may have been from lateral files.

Figures

Fig. 13. Pristis sp. (A–F, M–R), Rhynchobatus cf. pristinus (Probst, 1877) (G–L), and Anoxypristis sp. (S–X), teeth and rostral spines. A–C. SC2013.28.490, Pristis sp., tooth. A. Oro-lingual view. B. Labial view. C. Profile view. D–F. SC2013.28.486, Pristis sp., tooth. D. Oro-lingual view. E. Labial view. F. Profile view. G–I. SC2013.28.496, Rhynchobatus cf. pristinus, tooth. G. Labial view. H. Occlusal view. I. Profile view. J–L. SC2013.28.500, R. cf. pristinus, tooth. J. Labial view. K. Occlusal view. L. Profile view. M–O. MMNS VP-12070, Pristis sp., right rostral spine. M. Basal view. N. Posterior view.O. Dorsal view.P–R. MMNS VP-7787.1,Pristis sp., right rostral spine.P. Basal view.Q. Posterior view. R. Dorsal view. S–U. MMNS VP-12071, Anoyxpristis sp., right rostral spine. S. Basal view. T. Posterior view. U. Dorsal view. V–X. MMNS VP-12072.1, Anoxypristis sp., right rostral spine. V. Basal view. W. Posterior view. X. Dorsal view. Scale bars: A–F = 1 mm; G–L = 3 mm; M–X = 1 cm.