Genus. indet.

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 : 131

Gen. et sp. indet .

EXAMINED MATERIAL. — FSAC Bouj-141, 363 ( Fig.5C ), 364, 365, 366, 367, 368, 369, isolated centra.

DESCRIPTION

The centra are amphicoelous and their height is greater than their anterioposterior length ( Figs. 5B, C ). The crosssection is circular to slightly ovoid, with distinct growth rings. The surface of the centrum is ornamented by several longitudinal ridges of various sizes, separated by a thinner trabecular structure. In some centra, one or two weakly marked lateral fossae are present. Broken dorsal expansions indicate that neural arches were fused to the centrum. Bouj-363 is slightly different than other centra in having more marked longitudinal ridges of irregular size and orientation, well-marked small lateral pits and an irregularly circular cross-section.

REMARKS

Except Bouj-363, all centra show comparable ornamentation and size and probably correspond to the same taxon. The cylindrical shape, higher than long, and the ornamentation, formed by narrow longitudinal ridges of various sizes and trabeculae, is reminiscent of the abdominal centra of various perciforms like serranids, latids or scorpaenids. However, in these families, the ornamentation is formed by ridges of almost the same size, whereas the centra studied herein show an irregular alternation of narrow and larger ridges. Moreover, in latids and serranids the last abdominal centra show more marked lateral fossae ( Otero 2004; BK pers. obs.). In some Eocene scombrids (e.g., Scomberodon Van Beneden, 1871 , Scomberomorus Lacepède, 1801 , Paleocybium Monsch, 2004, Neocybium Leriche, 1908 and Sphyraenodus Agassiz, 1844 from Belgium and England), the anteriormost abdominal centra are higher than long, ornamented with longitudinal ridges of irregular size and with reduced or absent lateral fossae ( Leriche 1910; Monsch 2004; BK pers. obs.). The material from Gueran is considered as undetermined percomorph. Bouj-363 is interpreted as an anterior abdominal vertebra of the same taxon.

Figures

FIG. 5. — Actinopterygii and Testudines from the Sabkha of Gueran: A-G, Actinopterygii: Cylindracanthus sp., FSAC Bouj-356, rostrum in (A1) lateral and (A2) transversal views; B-E, Percomorpha indet.: B, FSAC Bouj-369,vertebra in (B1) lateral and (B2) transversal views; C, FSAC Bouj-363, vertebra in (C1) lateral and (C2) transversal views; D, FSAC Bouj-370, basioccipital in left lateral view; E, FSAC Bouj-371, fin spine in anterior view; F, Scombridae indet., FSAC Bouj-358, incomplete jawbone in labial view; G, Siluriformes indet., FSAC Bouj-372, right pectoral spine in anterior view; H-P, Testudines: H-L, Cheloniidae indet., FSAC Bouj-109,fragmentary costal in (H1) lateral transection, (H2) ventral, (H3) dorsal and (H4) medial transection views; I, FSAC Bouj-352,fragmentary lateral process of right hyoplastron in (I1) ventral and (I2) dorsal views; J, FSAC Bouj-351, subcomplete right hypoplastron in (J1) ventral and (J2) dorsal views; K, FSAC Bouj- 353, fragment of dermal plate, unlocated on the carapace, in dorsal view; L, FSAC Bouj-354, fragment of dermal plate, unlocated on the shell in (L1, L2) both faces; M, Dermochelyidae indet., FSAC Bouj-350, lateral pubic process of right pubis in (M1) ventral and (M2) dorsal views; N,? Podocnemidoidea indet., FSAC Bouj-196, fragment of right hypoplastron in (N1) dorsal and (N2) ventral views; O, Indeterminata (? Podocnemidoidea indet.), FSAC Bouj-95, fragment of dermal plate of carapace in (O1) dorsal and (O2) ventral views; P, Gueran turtles, pieces of the four fragments of Figure 5I, J, L and M, as preserved in view of conjunction in situ. Scale bars: 20 mm.