Tethylamna, Cappetta & Case, 2016

Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, Geodiversitas 43 (5), pp. 121-150 : 127

Tethylamna cf. twiggsensis ( Case, 1981)

EXAMINED MATERIAL. — 50 isolated teeth, figured material includes FSAC Bouj-331, 332, 333, 334, 335 and 336.

DESCRIPTION

Numerous teeth are attributed to odontaspidid Tethylamna cf. twiggsensis. This species is easily recognizable by a pair of double flat cusplets on anterior ( Fig. 3A, F ) and lateral teeth ( Fig. 3 C-E).

REMARKS

The range of this species is currently restricted to the latest Lutetian-late Priabonian and its geographic distribution extends to paleotropical seas between tropical eastern Pacific, Caribbean and oriental Neotethys ( Casier 1971; Case 1981; Case & Borodin 2000; Case & Cappetta 1990; Ward & Wiest 1990; Adnet et al. 2007; Underwood et al. 2011; Cappetta & Case 2016). Originally described from the late Eocene of Georgia, United States ( Case 1981), distinction between the middle and the late Eocene representatives are sometimes controversial. The Bartonian teeth have lateral cusplets less pronounced compared to those from Priabonian ( Underwood et al. 2011) explaining why they are often referred to confer twigssensis. These Bartonian samples could corresponds to intergradual change from the possible ancestor T. dunni of Cappetta & Case (2016) recovered from the Lutetian of Alabama, USA toward those of Priabonian, including type of species ( Case 1981).

Figures

FIG. 3. — Elasmobranchii from Sabkha of Gueran collected around the Archaeocete whale carcasses.(A-F) Tethylamna cf.twiggsensis: A, FSAC Bouj-331 anterior lower tooth in labial view; B, FSAC Bouj-332 anterolateral lower tooth in labial view; C, FSAC Bouj-333 lateral lower tooth in (C1) labial and (C2) lingual views; D, FSAC Bouj-334 posterior lower tooth in labial view; E, FSAC Bouj-335 lateral lower tooth in (E1) labial and (E2) lingual views; F, FSAC Bouj-336 anterior upper tooth in (F1) labial and (F2) lingual views. G-I, Galeocerdo cf. eaglesomei; G, FSAC Bouj-337 anterior tooth in (G1) labial and (G2) lingual views; H, FSAC Bouj- 338 anterolateral tooth in lingual view; I, FSAC Bouj-339 lateral tooth in (I1) labial and (I2) lingual views. Scale bar: 10 mm.