Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco Author Zouhri, Samir Author Gingerich, Philip D. Author Khalloufi, Bouziane Author Bourdon, Estelle Author Adnet, Sylvain Author Jouve, Stéphane Author Elboudali, Najia Author Amane, Ayoub Author Rage, Jean-Claude Author Tabuce, Rodolphe text Geodiversitas 2021 2021-03-11 43 5 121 150 journal article 7746 10.5252/geodiversitas2021v43a5 e42658a2-0e15-4e90-9bc5-0d00cbcbd781 1638-9395 4605963 urn:lsid:zoobank.org:pub:697FC553-E37B-4EF9-97A4-950E4DEE246C 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.