Physogaleus secundus ( Winkler, 1876 )

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 : 95-99

Physogaleus secundus ( Winkler, 1876)

Fig. 34

Trigonodus secundus Winkler, 1876: 20 .

Trigonodus tertius Winkler, 1876: 21 .

Physodon secundus – Leriche 1905: 189 , pl. 8, figs 6, 17, 18.

Carcharias (Physodon) secundus – Priem 1908: 109 .

Carcharias (Physodon) tertius – Leriche 1922: 183 .

Galeorhinus sp. cf. G. falconeri – White 1956: 144–145 , fig. 149.

Galeorhinus cf. falconeri – Thurmond & Jones 1981: 67–68 .

Rhizoprionodon secundus – Bor 1980: 7, pl. 1, fig. 2.

Physogaleus secundus – Cappetta 1980a: 37 , pl. 5.

Physogaleus tertius – Cappetta 1980a: 38 .

Scoliodon secundus – Kruckow & Thies 1990: 57 .

Abdounia recticona – Maisch et al. 2014 : figs 3, 5–6.

Material examined

UNITED STATES OF AMERICA – Alabama • 786 isolated teeth; Claiborne Group ; ALMNH PV1989.4.125b, ALMNH PV1989.4.219c (3 specimens), ANSP 23415 , ANSP 23420 , GSA-V713, MMNS VP-8191, MMNS VP-8214 (2 specimens), MSC 1424.12 , MSC 188.82 , MSC 188.128 , MSC 188.217 , MSC 2381.1 , MSC 2381.3 , MSC 34405.3 , MSC 34405.5 , MSC 34405.7 – 10 , MSC 34405.13 , MSC 34405.15 , MSC 34408.1 , MSC 34408.5 – 7 , MSC 34408.9 , MSC 34408.11 – 13 , MSC 35736.1 – 2 , MSC 35765.1 – 21 , MSC 35770.1 – 72 , MSC 35771.1 – 12 , MSC 36168, MSC 36179, MSC 37116, MSC 37120.1 – 4 , MSC 37139, MSC 37151, MSC 37156, MSC 37165, MSC 37187.1 – 5 , MSC 37188, MSC 37201, MSC 37245.1 – 6 , MSC 37247.1 – 8 , MSC 37262.1 – 4 , MSC 37275.1 – 7 , MSC 37283, MSC 37298, MSC 37327.1 – 72 , MSC 37353.3 , MSC 37456.1 – 12 , MSC 37509.1 – 17 , MSC 37557.1 – 11 , MSC 37610.1 – 3 , MSC 37613.1 – 4 , MSC 37633.1 – 2 , MSC 37639.1 – 2 , MSC 37659.1 – 2 , MSC 37661, MSC 37669.1 – 6 , MSC 37899, MSC 38198.1 – 3 , MSC 38428, MSC 38467.1 – 2 , MSC 38481.1 – 81 , MSC 38510.1 – 4 , MSC 38529, MSC 38545, MSC 38627, MSC 38832, MSC 38861, MSC 38968.1 – 2 , NJSM 24027 (2 specimens), SC 2012.47.57, SC 2012.47.58, SC 2012.47.59 (2 specimens), SC 2012.47.60 (56 specimens), SC 2012.47.61 (2 specimens), SC 2012.47.62 (2 specimens), SC 2012.47.63 (2 specimens), SC 2012.47.64 (2 specimens), SC 2012.47.65 (63 specimens), SC 2012.47.66, SC 2012.47.67, SC 2012.47.68 (8 specimens), SC 2012.47.161, SC 2012.47.173 (2 specimens) , SC 2012.47.182 (9 specimens), SC 2012.47.208 (27 specimens), SC 2012.47.209 (26 specimens), WSU 5041 (143 specimens), WSU CC 444, WSU CC 511 (2 specimens), WSU CC 529 (3 specimens), WSU CC 530.1 (2 specimens), WSU CC 531 (3 specimens), WSU CC 534 (2 specimens), WSU CC 582 (3 specimens).

Description

Anterior teeth with triangular crown; mesial and distal edges slightly convex. Lingual crown face convex; labial face nearly flat; enameloid smooth. Mesial cutting edge smooth to very weakly denticulated basally. Distal cutting edge smooth apically, denticulated basally. Distal heel contiguous or only weakly differentiated from cutting edge. Up to four denticulations on distal heel that decrease in size basally. Upper part of mesial and distal cutting edges form triangular, slightly distally directed cusp. Root bulky, bilobate, with low, elongated lobes; pronounced lingual boss bears nutritive groove, which contains large nutritive foramen. Weakly U-shaped interlobe area. Lateral teeth wide, with more convex mesial cutting edge, short distal cutting edge, cusp distally directed. Indistinct denticulation sometimes present at base of mesial edge. Conspicuous distal heel bearing one-to-four denticles, decreasing in size basally; distal heel separated from cutting edge by pronounced notch. Root wider, more labiolingually compressed than on anterior teeth. Root lobes generally rounded, widely diverging; interlobe area from flat to weakly concave. Conspicuous nutritive groove on lingual root boss; multiple foramina located on labial root face. Basal root face flattened. Gynandric heterodonty evident, with male lower anterior teeth being taller, mesiodistally thinner, more sigmoidal than female teeth.

Remarks

Winkler (1876) erected Physogaleus secundus and P. tertius within the same publication, but Kent (1999a) viewed these two taxa as conspecific because he believed the characteristics distinguishing them ( P. tertius with taller main cusp and larger overall size) were likely the result of gynandric and/or ontogenetic heterodonty. We agree with Kent (1999a) that the two species are conspecific, and because both taxa were named within the same publication, P. secundus has priority because it was listed first.

We assigned Claiborne teeth to P. secundus based on the number of denticles on the mesial cutting edge and distal heel cusplets. The anterior teeth of P. secundus generally have one-to-two mesial and distal cusplets, lateral teeth generally have up to four on the distal heel, and mesial denticles, if present, lack definition and tend to be restricted to the crown base. In contrast, the lateral teeth of Physogaleus alabamensis comb. nov. have up to 12 distal cusplets and well-defined mesial denticles that can extend almost two-thirds the height of the crown. Furthermore, P. alabamensis comb. nov. anterior teeth have three or more sets of mesial denticles and distal cusplets. Maisch et al. (2014: fig. 3, 5–6) identified an Abdounia recticona (recognized here as Pseudabdounia recticona gen. et comb. nov.) tooth from the contact of the Tallahatta and Lisbon formations in Choctaw County. Although this tooth has a superficial resemblance to Pseudabdounia recticona gen. et comb. nov., we refer it to Physogaleus secundus because the denticles are rounded, not triangular and divergent as seen on the former taxon, and the mesial denticles are irregular and not clearly defined.

Although superficially similar to Galeorhinus , teeth of P. secundus and P. alabamensis comb. nov. lack a thickened labial crown base. Physogaleus lateral teeth could be confused with Galeocerdo , but they can be differentiated by the lack of serrations on the main cusp (see Galeocerdo clarkensis and Galeocerdo eaglesomei below). On the P. secundus and P. alabamensis comb. nov. teeth examined, these cusplets are nearly always absent above the distal notch, and denticles rarely extend more than two-thirds the height of the crown on the mesial edge.

Stratigraphic and geographic range in Alabama

The specimens in our sample were collected from the Meridian Sand Member of the Tallahatta Formation and the lower Tallahatta Formation at site ADl-1, the Tallahatta Formation at site AMo-8, the contact of the Tallahatta and Lisbon formations at sites ACh-14, ACov-1, ACov-11, and ACon-6, the basal Lisbon Formation at site ACov-11, the “upper” Lisbon Formation at site ACh-8, the basal Gosport Sand at site ACl-4, and the Gosport Sand at sites ACh-21 and ACl-15. Upper Ypresian to middle Bartonian, zones NP12 to NP17.

Family Galeocerdidae Herman et al., 2010

Figures

Fig. 34 (opposite page). Physogaleus secundus (Winkler, 1876), teeth. A–C. MSC 37116, lateral tooth, Tallahatta/Lisbon formation contact zone, courtesy of Bruce Relihan. A. Labial view. B. Mesial view. C. Lingual view. D–F. MSC 2381.3, lateral tooth, Gosport Sand. D. Labial view. E. Mesial view. F. Lingual view. G–I. MSC 35770.1, anterolateral tooth, lower Tallahatta Formation. G. Labial view. H. Mesial view. I. Lingual view. J–L. MSC 35771.1, lateral tooth, lower Tallahatta Formation. J. Labial view. K. Mesial view. L. Lingual view. M–O. MSC 35770.3, lateral tooth, lower Tallahatta Formation. M. Labial view. N. Mesial view. O. Lingual view. P–R. MSC 37245.1, lateral tooth, basal Lisbon Formation. P. Labial view. Q. Mesial view. R. Lingual view. S–U. MSC 37188, lateral tooth, Tallahatta/ Lisbon formation contact zone, courtesy of T. Prescott Atkinson. S. Labial view. T. Mesial view. U. Lingual view. V–X. MSC 37201, lateral tooth, Meridian Sand Member of the Tallahatta Formation. V. Labial view. W. Mesial view. X. Lingual view. Y–AA. MSC 37245.3, anterolateral tooth, basal Lisbon Formation. Y. Labial view. Z. Mesial view. AA. Lingual view. BB–DD. MSC 37245.2, lower anterior tooth, basal Lisbon Formation. BB. Labial view. CC. Mesial view. DD. Lingual view. EE– GG. MSC 35770.2, lower anterior tooth, lower Tallahatta Formation. EE. Labial view. FF. Mesial view. GG. Lingual view. HH–JJ. MSC 37156, anterolateral tooth, Tallahatta/Lisbon formation contact zone, courtesy of James Lowery. HH. Labial view. II. Mesial view. JJ. Lingual view. KK–MM. MSC 37298, lateral tooth, basal Lisbon Formation. KK. Labial view. LL. Mesial view. MM. Lingual view. NN–PP. MSC 37557.2, anterolateral tooth, basal Gosport Sand. NN. Labial view. OO. Mesial view. PP. Lingual view. QQ–SS. MSC 37557.1, anterolateral tooth, basal Gosport Sand. QQ. Labial view. RR. Mesial view. SS. Lingual view. Scale bars = 5 mm.