Striatolamia macrota (Agassiz, 1843)

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 : 32-35

Striatolamia macrota (Agassiz, 1843)

Fig. 11

Otodus macrotus Agassiz, 1843: 273 , pls 32, 27–28, 30.

Lamna elegans Agassiz, 1843: 289 , pl. 35, figs 1–5, pl. 37a, figs 58–59.

Otodus striatus Winkler, 1874a: 8 , pl. 1, figs 7–9.

Odontaspis macrota striata var. semistriata Leriche, 1942: 13–14 , pl. 1, figs 6–8.

Odontaspis elegans – Woodward 1889: 361 .

Odontaspis macrota var. rossica – Jaekel 1895: 11 , pl. 1, figs 8–17.

Odontaspis macrota – Eastman 1901: 105 , pl. 14, figs 4. — White 1956: 147–148. — Thurmond & Jones 1981: 48.

Lamna striata – Priem 1901: 484 , pl. 11, figs 29–30.

Odontaspis (Synodontaspis) macrota – Casier 1958: 18 .

Striatolamia macrota – Applegate 1968: 32–36 , pls 1–3.

Odontaspis macrota striata var. semistriata – Thurmond & Jones 1981: 48 , fig. 14. Eugomphodus macrotus – Kruckow & Thies 1990: 35 .

Striatolamia cf. striata – Clayton et al. 2013 : fig. 2m–o.

Sylvestrilamia teretidens – Clayton et al. 2013 : fig. 2p–q.

Isurolamna inflata – Cappetta & Case 2016 : pl. 6, fig. 5.

Material examined

UNITED STATES OF AMERICA – Alabama • 2123 isolated teeth; Claiborne Group ; ALMNH PV1989.2.421 (13 specimens), ALMNH PV1989.4.1.2.5 (6 specimens), ALMNH PV1989.4.10.2.5, ALMNH PV1989.4.105.2, ALMNH PV1989.4.118.2 (4 specimens), ALMNH PV1989.4.126b (3 specimens), ALMNH PV1989.4.144.1 (3 specimens), ALMNH PV1989.4.144.4 (6 specimens), ALMNH PV1989.4.15.4, ALMNH PV1989.4.16.1.4 (8 specimens), ALMNH PV1989.4.16.2b (2 specimens), ALMNH PV1989.4.160.1 (5 specimens), ALMNH PV1989.4.161.5 (5 specimens), ALMNH PV1989.4.165 (2 specimens), ALMNH PV1989.4.17.3a (3 specimens), ALMNH PV1989.4.17.4 (4 specimens), ALMNH PV1989.4.173, ALMNH PV1989.4.175b (5 specimens), ALMNH PV1989.4.176.3, ALMNH PV1989.4.177b (2 specimens), ALMNH PV1989.4.182 (2 specimens), ALMNH PV1989.4.20.2 (3 specimens), ALMNH PV1989.4.22.4 (9 specimens), ALMNH PV1989.4.27.3 (8 specimens), ALMNH PV1989.4.31.1, ALMNH PV1989.4.32.1 (2 specimens), ALMNH PV1989.4.33.1(2specimens), ALMNH PV1989.4.34.4(5specimens), ALMNH PV1989.4.38.4 (4 specimens), ALMNH PV1989.4.52.3, ALMNH PV1989.4.55.2 (4 specimens), ALMNH PV1989.4.6.1.2 (4 specimens), ALMNH PV1989.4.62, ALMNH PV1989.4.63.1.1 (2 specimens), ALMNH PV1989.4.69 (2 specimens), ALMNH PV1989.4.7.2 (2 specimens), ALMNH PV1989.4.71.2, ALMNH PV1989.4.77.1 (7 specimens), ALMNH PV1989.4.77.1.3, ALMNH PV1989.4.86 (3 specimens), ALMNH PV1989.4.94.3 (2 specimens), ALMNH PV1989.4.98 (2 specimens), ALMNH PV1992.28.13 (2 specimens), ALMNH PV1992.28.18a (5 specimens), ALMNH PV1992.28.22, ALMNH PV1992.28.27 (3 specimens), ALMNH PV1992.28.34a (2 specimens), ALMNH PV1992.28.45 (3 specimens), ALMNH PV1993.2.422 (2 specimens), ALMNH PV2000.1.43.1a (4 specimens), ALMNH PV2000.1.43.2a (21 specimens), ALMNH PV2000.1.43.5a, ALMNH PV2000.1.43.5d (9 specimens), ALMNH PV2000.1.44.2, ALMNH PV2000.1.44.5 (2 specimens), ALMNH PV2013.1.388, ALMNH PV2013.3.127, ALMNH PV2013.3.136b (5 specimens), ALMNH PV2013.4.166, ALMNH PV2013.4.53 (2 specimens), ALMNH PV2013.4.55 (2 specimens), ALMNH PV2016.3.262b (10 specimens), ALMNH PV 2016.4.26 (5 specimens), ALMNH PV 2016.4.29, ANSP 23404 , ANSP 23405 , ANSP 23406 , GSA-V697 (13 specimens), GSA-V700 (2 specimens), GSA-V707, GSA-V708 (4 specimens), GSA-V711, GSA-V712 (4 specimens), GSA-V714 (4 specimens), GSA-V715, GSA-V717 (7 specimens), MMNS VP-8219 (7 specimens), MMNS VP-8228 (85 specimens), MSC 188.2 , MSC 188.11 – 14 , MSC 188.16 – 19 , MSC 188.21 – 22 , MSC 188.29 , MSC 188.36 , MSC 188.39 , MSC 188.41 – 45 , MSC 188.49 , MSC 188.78 , MSC 188.111 MSC 188.121 , MSC 188.178 , MSC 188.193 , MSC 188.202 , MSC 188.254 , MSC 188.328 , MSC 1424.1 , MSC 1424.10 , MSC 1424.22 – 25 , MSC 2372.1 – 2 , MSC 2372.4 , MSC 2372.6 – 10 , MSC 2372.10 , MSC 2372.12 , MSC 2372.14 , MSC 2372.16 – 19 , MSC 2372.22 – 23 , MSC 2373.1 – 6 , MSC 2375.2 , MSC 2375.6 , MSC 2375.39 , MSC 12675.3 – 4 , MSC 12675.7 MSC 12697.1 – 2 , MSC 12708.1 – 9 , MSC 33246, MSC 33248, MSC 33251, MSC 33253, MSC 33254, MSC 33256, MSC 33259, MSC 33261, MSC 33273, MSC 33275, MSC 33276, MSC 33277, MSC 33285, MSC 33286, MSC 33287, MSC 33288, MSC 33289, MSC 33290, MSC 33292, MSC 33297, MSC 33313, MSC 33314, MSC 33325, MSC 33327, MSC 33331, MSC 33335, MSC 33337, MSC 33339, MSC 33341, MSC 33353, MSC 33357, MSC 33365, MSC 33370, MSC 33372, MSC 33379, MSC 33381, MSC 33382, MSC 33385, MSC 33386, MSC 33400, MSC 33401, MSC 33405, MSC 33406, MSC 33409, MSC 33411, MSC 33417, MSC 33418, MSC 33424, MSC 33425, MSC 33426, MSC 33431, MSC 33434, MSC 33435, MSC 33437, MSC 33438, MSC 33440, MSC 33441, MSC 33442, MSC 33443, MSC 33447, MSC 33451, MSC 33453, MSC 33456, MSC 33459, MSC 33460, MSC 33465, MSC 33466, MSC 33468, MSC 33469, MSC 33470, MSC 33472, MSC 33474, MSC 33482, MSC 33486, MSC 33491, MSC 33493, MSC 33501, MSC 33502, MSC 33505, MSC 33506, MSC 33508, MSC 33512, MSC 33522, MSC 33523, MSC 33524, MSC 33531, MSC 33534, MSC 33538, MSC 33539, MSC 33540, MSC 33541, MSC 33545, MSC 33546, MSC 33547, MSC 33555, MSC 33557, MSC 33560, MSC 33562, MSC 33564, MSC 33566, MSC 33569, MSC 33572, MSC 33575, MSC 33577, MSC 33580, MSC 33584, MSC 33585, MSC 33589, MSC 33591, MSC 33592, MSC 33593, MSC 33597, MSC 33598, MSC 33599, MSC 33639, MSC 33640, MSC 33641, MSC 33644, MSC 33645, MSC 33649, MSC 33651, MSC 33652, MSC 33657, MSC 33659, MSC 33660, MSC 33661, MSC 33665, MSC 33667, MSC 33668, MSC 33674, MSC 33675, MSC 33676, MSC 33692, MSC 33694, MSC 33699, MSC 33704, MSC 33710, MSC 33716, MSC 33718, MSC 33724, MSC 33727, MSC 33732, MSC 33734, MSC 33737, MSC 33843, MSC 33859, MSC 33861, MSC 33863, MSC 33867, MSC 33871, MSC 33872, MSC 33876, MSC 33879, MSC 33880, MSC 33885, MSC 33886, MSC 33891.1 – 11 , MSC 33892.1 – 10 , MSC 33893.1 – 10 , MSC 33894.1 – 10 , MSC 33895.1 – 10 , MSC 33896.1 – 10 , MSC 33897.1 – 10 , MSC 33898, MSC 33898.1 – 10 , MSC 33899.1 – 10 , MSC 33900.1 – 9 , MSC 33901.1 – 10 , MSC 33902.1 – 10 , MSC 33903.1 – 10 , MSC 33904.1 – 10 , MSC 33905.1 – 10 , MSC 33906.1 – 10 , MSC 33907.1 – 10 , MSC 33908.1 – 9 , MSC 33909.1 – 10 , MSC 33910.1 – 10 , MSC 33911.1 – 10 , MSC 33912.1 – 11 , MSC 33913.1 – 10 , MSC 33914.1 – 16 , MSC 33915.1 – 328 , MSC 33917, MSC 33920, MSC 33921, MSC 33923, MSC 33936, MSC 33937, MSC 33939, MSC 33940, MSC 33941, MSC 33945, MSC 33946, MSC 33949, MSC 33951, MSC 33954, MSC 34403.1 – 86 , MSC 35739.1 – 24 , MSC 35792, MSC 35793.1 – 10 , MSC 35794.1 – 10 , MSC 35795.1 – 10 , MSC 35796.1 – 10 , MSC 35797.1 – 10 , MSC 35798.1 – 10 , MSC 35799.1 – 18 , MSC 35810, MSC 35890.1 – 10 , MSC 36903, MSC 37118, MSC 37128, MSC 37129, MSC 37140, MSC 37191.1 – 13 , MSC 37202.1 – 5 , MSC 37252.1 – 18 , MSC 37253.1 – 3 , MSC 37267.1 – 3 , MSC 37278.1 – 2 , MSC 37285.1 – 20 , MSC 37314.1 – 2 , MSC 37329.1 – 19 , MSC 37393.1 – 6 , MSC 37400, MSC 37495.1 – 299 , MSC 37511.1 – 15 , MSC 37521.1 – 25 , MSC 37527.1 – 7 , MSC 37537.1 – 2 , MSC 37562.1 – 34 , MSC 37578, MSC 37579, MSC 37580.1 – 4 , MSC 37581.1 – 5 , MSC 37582, MSC 37583, MSC 37585.2 , MSC 37599.1 – 6 , MSC 37612.1 – 4 , MSC 37614.1 – 2 , MSC 37615, MSC 37619, MSC 37640.1 – 2 , MSC 37642.1 – 2 , MSC 37644, MSC 37646.1 – 2 , MSC 37668, MSC 37685, MSC 37686, MSC 37697, MSC 38474.1 – 2 , MSC 38499.1 – 14 , MSC 38557.1 – 2 , MSC 38613, MSC 38614, MSC 38615, MSC 38617, MSC 38618, MSC 38619, MSC 38620, MSC 38621, MSC 38622, MSC 38623, MSC 38624, MSC 38625, NJSM 24018 (2 specimens), SC 2012.47.163 (10 specimens), SC 2012.47.180, SC 2012.47.207 (24 specimens), SC 2012.47.79, SC 2012.47.80 (47 specimens), SC 2012.47.81, SC 2012.47.82 (17 specimens), SC 2012.47.83, SC 2012.47.257 (3 specimens), SC 2012.47.260, WSU 5 , WSU 21 , WSU 5025 , WSU 5029 (7 specimens), WSU 5033 , WSU 5034 (17 specimens), WSU 5043 (59 specimens), WSU CC 447 , WSU CC 455 , WSU CC 539 .

Description

Anterior teeth with a long, slender, pointed crown that is sigmoidal in profile view, with upper anteriors more so than lower anteriors. Lingual crown face strongly convex and bears numerous longitudinal ridges extending to nearly 75% of cusp height. Labial face flat, smooth. Anterior teeth with single pair of minute, often indistinct, lateral cusplets. Root holaulacorhize with deep U-shaped interlobe area separating thin, rounded, and divergent lobes. Shallow nutritive groove located on pronounced lingual root boss. Upper third anterior teeth may have a slight mesial bend. Lateral teeth with broad-based triangular crown that quickly tapers apically; crown labiolingually narrower than on anterior teeth. Lingual crown ornament reduced on lateral teeth, generally very faint and confined to the medial portion of the face. Lateral teeth usually with one pair of low, broadly triangular, diverging lateral cusplets, but reduced second pair occasionally observed. Main cusp on lower lateral teeth erect; those on lower files is distally inclined. Root holaulacorhize and flattened basally. Shallow nutritive groove located on lingual root protuberance. Interlobe area shallow, V-shaped. Root lobes shorter and wider than on anteriors.

Remarks

Clayton et al. (2013) referred a large number of specimens in their sample from the basal Lisbon Formation in Covington County (site ACov-11) to Striatolamia cf. striata (Winkler, 1874) and Sylvestrilamia teretidens ( White, 1931) . Although morphologically similar, the teeth of Sylvestrilamia teretidens are described as being smaller in size and not as sigmoidal as those of Striatolamia (see Cappetta 2012). A reexamination of these specimens has shown all to belong to S. macrota . Clayton et al. (2013) referred their Striatolamia teeth to S. striata because of their small size and coarse lingual ornamentation, which was seen as a contrast to the larger and more finely ornamented S. macrota . However, examination of several thousand specimens from the Claiborne Group, as well as a sample from the Bartonian Tupelo Bay Formation (temporally equivalent to the Gosport Sand) of South Carolina (housed at SC), shows that tooth size and crown ornament is highly variable within the formations, with S. striata - type teeth occurring with S. macrota teeth. Several extremely large (up to 6.0 cm in apicobasal height) Striatolamia specimens have been recovered from the Lisbon Formation and Gosport Sand in Alabama ( Fig. 11 BB– GG), and overall these teeth are more robust than their smaller counterparts, have a wider crown base, and often have conspicuous lingual crown ornamentation. Specimens of this size are rare in Alabama, but they also occur in South Carolina. It appears that, assuming all of the Claibornian teeth represent S. macrota , there is an increase in maximum tooth size from the early Eocene to the late-middle Eocene. This phenomenon was also observed by Cappetta (2012), who noted a size increase in S. macrota teeth throughout the temporal range of the taxon, and Malyshkina & Ward (2016) also noted size differences between their sample of early and middle Eocene S. macrota teeth from Uzbekistan. We attribute the variation we observed within the Claiborne formations of Alabama to ontogeny and phyletic increase in tooth size from stratigraphically older units to younger units.

Cappetta & Case (2016) assigned four teeth from the ACov-11 site to Isurolamna aff. inflata ( Leriche, 1905) . This species, however, is considered a nomen dubium because Leriche (1905) failed to figure a specimen or designate a holotype. The tooth figured by Cappetta & Case (2016: pl. 6, fig. 5) does bear a superficial resemblance to Isurolamna affinis Casier, 1946 by having a thin, lingually bent crown, and a nutritive foramen as opposed to nutritive groove. However, our large sample from the ACov-11 does not contain any material that can unequivocally be identified as Isurolamna , but certain ablated Striatolamia anterior teeth in our sample resemble the tooth they figured.

Striatolamia was originally placed within the Odontaspididae , with some suggesting that the macrota - type morphology should be included within Carcharias (see Ward 1980; Welton & Zinsmeister 1980; Long 1992; Purdy 1998). Cappetta & Nolf (1981), however, recognized Striatolamia as a distinct genus, citing differences between with the lateral cusplets of Striatolamia and the Recent Carcharias taurus Rafinesque, 1810 . Cappetta & Nolf (1981) placed the taxon within the Mitsukurinidae , a view later followed by Siverson (1995), who suggested Striatolamia has an affinity to certain Cretaceous members of this family. Although Long (1992) and Cunningham (2000) illustrated the morphological similarities between Striatolamia and C. taurus, Siverson (1995) proposed that these similarities could be the result of convergent evolution. Herein we follow Cappetta & Nolf (1981) and Siverson (1995) in placing Striatolamia within the Mitsukurinidae .

Stratigraphic and geographic range in Alabama

The specimens in our sample were derived from the Meridian Sand Member of the Tallahatta Formation and the lower Tallahatta Formation at site ADl-1, the contact of the Tallahatta and Lisbon Formations at sites ACh-14, ACov-1, ACov-11, and ACon-6, the “upper” Lisbon Formation at sites ACh-8 and ACl-3, the basal Gosport Sand at sites ACl-4, AMo-4, and AWa-2, and the Gosport Sand at sites ACh-21 and ACl-15. Upper Ypresian to middle Bartonian, zones NP12 to NP17.

Figures

Fig. 11. Striatolamia macrota (Agassiz, 1843), teeth. A–C. MSC 33541, lateral tooth, lower Tallahatta Formation. A. Labial view. B. Lingual view. C. Mesial view. D–F. MSC 37191.5, lateral tooth, Tallahatta/Lisbon formation contact zone, courtesy of T. Prescott Atkinson. D. Labial view. E. Lingual view. F. Mesial view. G–I. MSC 2375.6, lateral tooth, Gosport Sand. G. Labial view. H. Lingual view. I. Mesial view. J–L. MSC 33591, anterior tooth, lower Tallahatta Formation. J. Labial view. K. Lingual view. L. Mesial view. M–O. MSC 37252.15, anterior tooth, basal Lisbon Formation. M. Labial view. N. Lingual view. O. Mesial view. P–R. MSC 37521.10, anterior tooth, Gosport Sand. P. Labial view. Q. Lingual view. R. Mesial view. S–U. MSC 33341, tooth, lower Tallahatta Formation. S. Labial view. T. Lingual view. U. Mesial view. V–X. MSC 37252.17, tooth, basal Lisbon Formation. V. Labial view. W. Lingual view. X. Mesial view. Y–AA. MSC 37562.14, tooth, basal Gosport Sand. Y. Labial view. Z. Lingual view. AA. Mesial view. BB–DD. ALMNH PV2016.4.26, tooth, large morphology, Gosport Sand. BB. Labial view. CC. Lingual view. DD. Mesial view. EE–GG. MSC 37129, anterior tooth, Tallahatta/Lisbon formation contact zone, large morphology, courtesy of James Lowery. EE. Labial view. FF. Lingual view. GG. Mesial view. Scale bars = 1 cm.