Pristis, Linck, 1790

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 : 110-111

Pristis sp.

Fig. 39 S–GG

Pristis lathami – Holman & Case 1988: 328 . — Cappetta & Case 2016: 63–64, pl. 11, figs 1–2.

Material examined

UNITED STATES OF AMERICA – Alabama • 247 isolated teeth; Claiborne Group ; ALMNH PV1989.4.108 (36 specimens), ALMNH PV1985.87.11, ALMNH PV1985.87.12, ALMNH PV1985.87.13, ALMNH PV1985.87.14, ALMNH PV1985.87.15, ALMNH PV1985.87.16, ALMNH PV1985.87.17, ALMNH PV1985.87.18, ALMNH PV1985.87.19, ALMNH PV1985.87.20, ALMNH PV1985.87.21, ALMNH PV1985.87.22, ALMNH PV1985.87.23, ALMNH PV1985.87.24, ALMNH PV1985.87.25, ALMNH PV1985.87.26, ALMNH PV1985.87.27, ALMNH PV1985.87.28, ALMNH PV1985.87.29, ALMNH PV1985.87.30, ALMNH PV1985.87.31, ALMNH PV1985.87.32, ALMNH PV1985.87.53, ALMNH PV1985.87.54, ALMNH PV1985.87.6, ALMNH PV1989.4.10.1 (3 specimens), ALMNH PV 1989.4.14 (2 specimens), ALMNH PV1989.4.151.2 (4 specimens), ALMNH PV1989.4.17.2 (7 specimens), ALMNH PV1989.4.46, ALMNH PV1989.4.57, ALMNH PV1989.4.75.1, ALMNH PV1989.4.78 (2 specimens), ALMNH PV1989.4.92 (2 specimens), ALMNH PV1990.7 , ALMNH PV1992.28.12, ALMNH PV1992.28.20 (2 specimens), ALMNH PV1992.28.8 (2 specimens), ALMNH PV1992.28.8 (2 specimens), ALMNH PV1992.56.4 (22 specimens), ALMNH PV1993.2.488, ALMNH PV2000.1.43.13 (2 specimens), MMNS VP-5640 (23 specimens), MMNS VP-8221 (6 specimens), MSC 2150.2 , MSC 2150.4 , MSC 2175.30 , MSC 2392.1 – 3 , MSC 2392.9 , MSC 2395.5 , MSC 33249, MSC 33364, MSC 33378, MSC 33390, MSC 33528, MSC 33548, MSC 33570, MSC 33646, MSC 33650, MSC 33666, MSC 33691, MSC 33888, MSC 33890, MSC 33905, MSC 34406.1 – 5 , MSC 34621, MSC 35737.1 – 3 , MSC 35790.1 – 5 , MSC 37134.1 – 6 , MSC 37169, MSC 37182.1 – 3 , MSC 37277, MSC 37334.1 – 8 , MSC 37437.1 – 25 , MSC 37439, MSC 37458, MSC 37525, MSC 37617, MSC 38399, MSC 38628, MSC 38788, NJSM 24030 (2 specimens), SC 2012.47.169 (2 specimens), SC 2012.47.93 (9 specimens), WSU 5026 .

Description

Rostral spines attain large sizes, some reaching 10cm in length. Rostral spines long, slender.Spines generally straight, may curve ventrally; dorsal and ventral surfaces slightly convex anteroposteriorly. Anterior spine edge rounded; posterior edge generally concave, with sharp dorsal and ventral edges. Apical portion of anterior edge sharp, slightly convex, forms sharp point with posterior edge. Anterior and posterior edges nearly parallel, slightly wider basally. Longitudinal striations sometimes visible on basal portion of the spine. Growth bands perpendicular to spine length visible on some spines. Medial margins of rostral spines flat to slightly concave. Some spines with flat posterior margin. Rostral spines lack enameloid.

Remarks

Cappetta (2012) and Cappetta & Case (2016) recognized the following species of Eocene Pristis : P. amblodon Cope, 1869 ; P. brayi Casier, 1949 ; P. lathami Galeotti, 1837 ; P. olbrechtsi Dartevelle & Casier, 1959 ; P. pickeringi Case, 1981 ; and P. prosulcatus Stromer, 1905a . Cappetta & Case (2016) noted two morphologies of Pristis rostral spines from the ACov-11 locality that they assigned to “ Pristis sp. 1” and “ Pristis sp. 2.” The two morphologies were differentiated based on supposedly unique ornamentation and by being “thicker”, and the authors suggested that a new species may be represented. Pristis lathami Galeotti, 1837 is the name most frequently assigned to isolated Eocene Pristis rostral spines (see Cappetta 2012; Cappetta & Case 2016), but we refrain from speciating any of the isolated Claiborne spines because of the variation observable on fossil and extant Pristis rostral spines, and our lack of knowledge of the post-rostrum skeletal morphology of the extinct species. Variation in spine shape may be the result of several factors, including ontogeny, in vivo wear and, potentially, heterodonty. Pristis rostral spines are not replaced but instead increase in size over the lifespan of the animal ( Slaughter & Springer 1968). Spines of older animals are large, dorsoventrally thicker, have deeper posterior grooves, and are often more worn than their smaller/younger counterparts. There is also potential for heterodonty in our sample based on preserved specimens at MSC and SC, where the spines in the rostra of extant Pristis tend to be shorter at the posterior end of the rostrum than those located more anteriorly. Due to this range of variation, it is our opinion that a conservative approach be taken when identifying isolated fossil Pristis rostral spines because one or more of the described species are likely nominal. We also believe that the absence of a posterior groove is not related to ontogeny, as the posterior margin of both small and large spines may be flat or slightly concave.

It is interesting to note that certain spines in our sample exhibit faint striations on the dorsal and ventral surfaces, oblique to the anterior/posterior edges, near the spine tip. These are identical to what was described by Cicimurri (2007) on middle Eocene spines from South Carolina and has been observed on spines of extant species ( Allen 1999). The sharp anterior edge, pointed tip, and faint dorsal/ventral striations are believed to be the result of the sawfish using the spined rostrum to probe the sea floor in search of prey animals.

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 at sites ACh-14 and ACov-11, the basal Lisbon Formation at site ACov-11, the basal Gosport Sand at sites ACl-4 and AMo-4, and the Gosport Sand at site ACh-21. Upper Ypresian to middle Bartonian, zones NP14 to NP17.

Figures

Fig. 39. Pristidae Bonaparte, 1838, rostral spines. A–I. Anoxypristis sp. A–C. MSC 35791, basal Tallahatta Formation. A. Anterior view. B. Ventral view. C. Basal view. D–F. MSC 37658, Tallahatta/ Lisbon formation contact zone, courtesy of Bruce Relihan. D. Anterior view. E. Ventral view. F. Basal view. G–I. MSC 37643, basal Gosport Sand. G. Posterior view. H. Dorsal view. I. Basal view. — J–R. Propristis schweinfurthi Dames, 1883. J–L. MSC 2392.8, Gosport Sand. J. Anterior view. K. Dorsal view. L. Basal view. M–O. MSC 2392.6, Gosport Sand. M. Anterior view. N. Dorsal view. O. Basal view. P–R. MSC 37392, basal Gosport Sand. P. Anterior view. Q. Dorsal view. R. Basal view. — S–GG. Pristis sp. S–U. MSC 37169, Tallahatta/Lisbon formation contact zone, courtesy of James Lowery. S. Posterior view. T. Dorsal view. U. Basal view. V–X. MSC 33528, lower Tallahatta Formation. V. Posterior view. W. Dorsal view. X. Basal view. Y–AA. MSC 33548, lower Tallahatta Formation. Y. Posterior view. Z. Ventral view. AA. Basal view. BB–DD. MSC 35737.1, lower Tallahatta Formation. BB. Posterior view. CC. Ventral view. DD. Basal view. EE–GG. MSC 2392.1, Gosport Sand. EE. Posterior view. FF. Dorsal view. GG. Basal view. Scale bars = 1 cm.