Brachycarcharias lerichei

Brachycarcharias lerichei (Casier, 1946)

Fig. 13

Otodus vincenti Winkler, 1876: 25.

Lamna lerichei Casier, 1946: 80, pl. 2, figs 7a–b.

Odontaspis substriata var. atlasi Arambourg, 1952: pl. 12, text fig. 18.

Odontaspis atlasi Nolf, 1972: 115, pl. 1, figs 4–6.

Lamna vincenti – Woodward 1899: 10, pl. 1, figs 21–22.

Odontaspis vincenti – Arambourg 1952: 85, pl. 85, fig. 19.

Cretolamna lerichei – Case 1994a: 115, pl. 4, figs 62–71, 74–77.

“ Carcharias ” vincenti – Baut & Genault 1995: 205, pl. 5, figs 3–4.

Serratolamna lerichei – Kent 1999a: 21, pl. 2.2, figs j–k.

Brachycarcharias lerichei – Cappetta & Nolf 2005: 241, pl. 2.

Isurolamna lerichei – González-Rodríguez et al. 2013: 30.

Isurolamna inflata – Cappetta & Case 2016: pl. 6, figs 6–7.

Material examined

UNITED STATES OF AMERICA – Alabama • 1370isolated teeth; Claiborne Group; ANSP 23407, ANSP 23408, ALMNH PV1989.4.208b (3 specimens), ALMNH PV1992.28.24, ALMNH PV2000.1.43.1a (2 specimens), ALMNH PV2000.1.43.5b, ALMNH PV2016.3.262a (3 specimens), MMNS VP-8218 (9 specimens), MMNS VP-8229 (116 specimens), MSC 12675.1, MSC 12708.5, MSC 188.32, MSC 2372.2, MSC 2375.1, MSC 2375.3, MSC 2375.5, MSC 33252, MSC 33258, MSC 33260, MSC 33264, MSC 33266, MSC 33267, MSC 33268, MSC 33270, MSC 33271, MSC 33279, MSC 33281, MSC 33282, MSC 33284, MSC 33296, MSC 33298, MSC 33299, MSC 33300, MSC 33301, MSC 33304, MSC 33307, MSC 33308, MSC 33309, MSC 33312, MSC 33320, MSC 33322, MSC 33336, MSC 33346, MSC 33349, MSC 33352, MSC 33354, MSC 33356, MSC 33358, MSC 33359, MSC 33369, MSC 33375, MSC 33376, MSC 33383, MSC 33384, MSC 33387, MSC 33388, MSC 33391, MSC 33392, MSC 33393, MSC 33395, MSC 33397, MSC 33398, MSC 33407, MSC 33410, MSC 33414, MSC 33416, MSC 33419, MSC 33423, MSC 33427, MSC 33428, MSC 33429, MSC 33432, MSC 33439, MSC 33446, MSC 33448, MSC 33454, MSC 33457, MSC 33458, MSC 33462, MSC 33473, MSC 33477, MSC 33478, MSC 33479, MSC 33480, MSC 33484, MSC 33485, MSC 33487, MSC 33488, MSC 33489, MSC 33490, MSC 33492, MSC 33498, MSC 33500, MSC 33504, MSC 33509, MSC 33514, MSC 33517, MSC 33518, MSC 33521, MSC 33527, MSC 33530, MSC 33532, MSC 33533, MSC 33535, MSC 33537, MSC 33542, MSC 33544, MSC 33550, MSC 33551, MSC 33554, MSC 33556, MSC 33561, MSC 33568, MSC 33571, MSC 33576, MSC 33578, MSC 33581, MSC 33582, MSC 33588, MSC 33594, MSC 33595, MSC 33596, MSC 33638, MSC 33642, MSC 33647, MSC 33648, MSC 33654, MSC 33662, MSC 33664, MSC 33669, MSC 33671, MSC 33678, MSC 33679, MSC 33680, MSC 33681, MSC 33683, MSC 33687, MSC 33689, MSC 33690, MSC 33696, MSC 33697, MSC 33698, MSC 33708, MSC 33709, MSC 33711, MSC 33712, MSC 33713, MSC 33714, MSC 33715, MSC 33717, MSC 33719, MSC 33720, MSC 33721, MSC 33722, MSC 33725, MSC 33726, MSC 33730, MSC 33731, MSC 33733, MSC 33735, MSC 33736, MSC 33738, MSC 33857, MSC 33859, MSC 33860, MSC 33862, MSC 33864, MSC 33866, MSC 33868, MSC 33874, MSC 33881, MSC 33884, MSC 33887, MSC 33889, MSC 33892, MSC 33893, MSC 33906, MSC 33918, MSC 33919, MSC 33924, MSC 33927, MSC 33929, MSC 33930, MSC 33942, MSC 33944, MSC 33947, MSC 33953, MSC 33955, MSC 34404.1 – 29, MSC 35626.2 – 10, MSC 35627.1, MSC 35627.3 – 5, MSC 35627.7 – 10, MSC 35628.2 – 10, MSC 35629.1 – 4, MSC 35629.7 – 10, MSC 35630.1 – 10, MSC 35631.1 – 10, MSC 35632.1 – 9, MSC 35633.1 – 5, MSC 35633.7 – 10, MSC 35634.1 – 10, MSC 35635.3 – 10, MSC 35636.1 – 8, MSC 35637.1 – 10, MSC 35638.1 – 3, MSC 35638.5 – 10, MSC 35639.1 – 10, MSC 35640.1 – 10, MSC 35641.1 – 10, MSC 35642.1 – 10, MSC 35643.1 – 10, MSC 35644.1 – 2, MSC 35644.4 – 10, MSC 35645.2 - 10, MSC 35646.1 – 5, MSC 35646.7, MSC 35646.9 – 10, MSC 35647.1 – 4, MSC 35647.6 – 8, MSC 35647.10, MSC 35648.1 – 2, MSC 35648.5 – 10, MSC 35649.1 – 10, MSC 35650.1 – 5, MSC 35650.7 – 10, MSC 35651.1 – 3, MSC 35651.5 – 10, MSC 35652.1 – 6, MSC 35652.8 – 10, MSC 35653.1 – 7, MSC 35653.9 – 10, MSC 35654.1 – 6, MSC 35654.8 – 10, MSC 35655.2 – 7, MSC 35655.9 – 10, MSC 35656.1 – 10, MSC 35657.1 – 10, MSC 35658.1 – 10, MSC 35659.1 – 10, MSC 35660.1 – 8, MSC 35661.1 – 10, MSC 35662.2 – 10, MSC 35663.2 – 10, MSC 35664.1 – 10, MSC 35665.1 – 7, MSC 35665.9 – 10, MSC 35666.1 – 10, MSC 35667.1 – 2, MSC 35667.4 – 10, MSC 35668.1 – 10, MSC 35669.1 – 10, MSC 35670.1 – 10, MSC 35671.1 – 10, MSC 35672.1, MSC 35672.3 – 10, MSC 35673.1 – 10, MSC 35674.1 – 10, MSC 35675.2 – 7, MSC 35676.1 – 2, MSC 35676.4 – 6, MSC 35676.8 – 10, MSC 35677.1 – 5, MSC 35677.7 – 10, MSC 35678.1, MSC 35678.3 – 10, MSC 35679.1 – 10, MSC 35680.1 – 10, MSC 35741.1 – 12, MSC 35741.14, MSC 35762.1 – 2, MSC 35782, MSC 37074.3, MSC 37183, MSC 37189.1 – 29, MSC 37199.1 – 24, MSC 37261.1 – 3, MSC 37284.1 – 18, MSC 37284.21 – 22, MSC 37284.25 – 32, MSC 37284.34 – 39, MSC 37284.40, MSC 37325.1 – 11, MSC 37325.14 – 24, MSC 37325.26, MSC 37325.28, MSC 37328, MSC 37401.1 – 3, MSC 37508.1 – 4, MSC 37510.2, MSC 37510.4 – 5, MSC 37561.3 – 15, MSC 37561.18 – 24, MSC 37561.26 – 27, MSC 37561.29, MSC 37561.31 – 40, MSC 37584.1 – 6, MSC 37600.1 – 4, MSC 38531.1 – 2, NJSM 24019 (3 specimens), SC 2012.47.78 (3 specimens), SC 2012.47.86, SC 2012.47.87, SC 2012.47.88 (151 specimens), SC 2012.47.89 (2 specimens), SC 2012.47.205 (18 specimens), SC 2012.47.210 (63 specimens), WSU 5024, WSU 5030 (85 specimens), WSU 9, WSU CC 535.2, WSU CC 537.2, WSU CC 540 (2 specimens), WSU CC 541, WSU CC 542.

Description

Anterior teeth with tall, narrow, weakly to strongly sigmoidal main cusp. Mesial and distal cutting edges sharp, continuous, bi-convex, reaching base of main cusp. Main cusp with flat and smooth labial face, whereas lingual face very convex or may bear faint parallel striations, which are restricted to lower one-third of cusp. Generally, one pair of large and sharply pointed lateral cusplets present, but indistinct second pair observed on some specimens. Root holaulacorhize with deep U-shaped interlobe area separating elongated and rounded lobes. Deep nutritive groove located on prominent lingual root boss. Lateral teeth differ from anterior teeth by having lower, more triangular, and labiolingually thinner main cusp that is also distally inclined. Most lateral teeth devoid of ornamentation, but some specimens show indistinct lingual striations that are restricted to the base of the main cusp. Lateral teeth with oneto-three pairs of triangular lateral cusplets, with first pair the largest. Upper lateral teeth with a distinct distal inclination. Lower lateral teeth with an erect crown and slight lingual bend. Root on lateral teeth holaulacorhize with shallow V-shaped interlobe area separating short, wide, diverging lobes. Shallow nutritive groove occurs on pronounced lingual root protuberance.

Remarks

The Brachycarcharias lerichei teeth in our sample were differentiated from those of B. twiggsensis by their smaller overall size, narrower main cusp, smaller lateral cusplets compared to main cusp size, and the teeth generally only bear a single pair of lateral cusplets. The B. lerichei teeth were distinguished from those of B. atlasi by having much less distinct lingual ornamentation on the main cusp and absence of ornamentation on lateral cusplets, by generally having only a single pair of lateral cusplets on lateral teeth, and wider, more triangular cusplets on anterior teeth. In addition, the root is often more labiolingually robust on the teeth of B. atlasi. Several other morphologically similar genera that can be found within Claiborne strata in Alabama including Hypotodus, Striatolamia, Tethylamna, and Jaekelotodus (see below). Brachycarcharias lerichei anterior teeth have cutting edges that reach the base of the main cusp, but edges on Hypotodus and Striatolamia stop well short of the cusp base. Additionally, anterior teeth of Striatolamia are always ornamented, the ornament is always coarser than on B. lerichei teeth, and the cusplets are diminutive. Anterior teeth of Jaekelotodus are more robust and have smaller lateral cusplets than B. lerichei. Tethylamna anterior teeth are comparably much larger and robust than those of B. lerichei and they are always smooth on their lingual face (B. lerichei teeth can, at times, exhibit weak longitudinal ridges). Tethylamna lateral teeth are also larger and broader than those of B. lerichei, and the lateral cusplets are almost always distally directed (as opposed to diverging on B. lerichei). The lateral teeth of B. lerichei have larger and more divergent cusplets compared to Hypotodus, and the single pair of cusplets on the latter taxon are medially oriented. Lateral teeth of Jaekelotodus are conspicuously hooked and have smaller lateral cusplets than those of B. lerichei. The lateral teeth of Striatolamia are more strongly ornamented than B. lerichei, and cusplets are comparatively wider and more blunt, and the root lobes are wider.

The B. lerichei teeth in our sample appear to be highly variable with respect to lingual crown ornamentation (as it may be present or absent) and development of lateral cusplets (as two pairs are occasionally present, depending on jaw position and ontogenetic age). This variability has also been documented in the morphologically similar dentitions of the extant Lamna nasus (Bonnaterre, 1788), leading some to question whether the placement of the species within Brachycarcharias is necessary (see Purdy & Francis 2007). Despite questions regarding the generic placement of this species, the use of Brachycarcharias has gained favor and is followed herein.

Cappetta & Case (2016) reported three teeth in their sample from site ACov- 11 in Covington County, AL as belonging to Isurolamna aff. inflata (Leriche, 1905). We did not encounter this genus within our large sample of teeth from the same site, and it is our opinion that those specimens are not Isurolamna. Within our Lisbon sample of B. lerichei, we did observe several ablated lateral teeth that superficially resemble Isurolamna.

Stratigraphic and geographic range in Alabama

The specimens in our sample were derived from the Meridian Sand Member of the Tallahatta Formation and lower Tallahatta Formation at site ADl-1, the contact of the Tallahatta and Lisbon formations at sites ACh-14, ACov-11, and ACon-6, the basal Lisbon Formation at site ACov-11, the “upper” Lisbon Formation at site ACl-3, 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.