A Middle–Late Eocene vertebrate fauna (marine fish and mammals) from southwestern Morocco; preliminary report: age and palaeobiogeographical implications

Abstract

Recent field work in the southern Moroccan Sahara (‘Western Sahara’), south of the city of ad-Dakhla, has led to the discovery of several new fossiliferous sites with fossil vertebrates in sedimentary deposits previously reported for the Mio-Pliocene. The sedimentology and geological setting of the studied area are briefly reported here, and at least three units have been identified in successive stratigraphical sequences according to their fossil content. The first preliminary list of vertebrate associations is reported and consists mainly of isolated teeth belonging to selachian and bony fishes, a proboscidean tooth currently assigned to ?Numidotherium sp. and many remains of archaeocete whales (Basilosauridae). At least 48 species of selachians are presently identified; many of them are new and others are recorded in the late Middle Eocene (Bartonian) and Late Eocene (Priabonian) of Wadi Al-Hitan (Egypt) or Wadi Esh-Shallala Formation (Jordan) as in other African localities (e.g. Otodus cf. sokolowi, ‘Cretolamna’ twiggsensis, Xiphodolamia serrata, Misrichthys stromeri, Hemipristis curvatus, Galeocerdo cf. eaglesomi, Propristis schweinfurthi), probably indicating a Late Eocene age for unit 2 of the bedrock successions. The evolutionary trend noticeable on the proboscidean tooth is in agreement with such an assumption, by comparison with the close relative species known from the Eocene of Egypt, Libya and Algeria. Indeed, the faunal associations from the Dakhla area clearly demonstrate the erroneous age of these deposits, previously thought to be Mio-Pliocene. It suggests a correlation in age (late Middle Eocene–Late Eocene) and a similar environment with the famous marine deposits from Egypt and Jordan. It opens new opportunities to understand the biogeography and the surprising similarity of landscape between West and Northeast Africa during the Bartonian–Priabonian period.

A new Priabonian Chondrichthyans assemblage from the Western desert, Egypt: Correlation with the Fayum oasis

“…1 in Underwood et al, 2011) and Southwestern Morocco (Carcharhinus sp. in Adnet et al, 2010). Contrary to Adnet et al (2007) who suspected an origination in eastern Tethys during the Late Eocene, these modern carcharhinids frequented the North The species displays a moderate but well marked dignathic heterodonty.…”

“…The teeth are different from those of the Early Eocene species O. sigei Cappetta, 1986 in having a lower crown and root lobes more massive and closer. This genus seems to be rather common in worldwide tropical sea during the Middle-Late Eocene period because it is recovered in shallow water deposits from Southwestern Asia (Adnet et al, 2008), India (see Adnet et al, 2008), Egypt (Strougo et al, 2007;Underwood et al, 2011) and Morocco (Tabuce et al, 2005;Adnet et al, 2010). Similar to the unnamed species of Fayum (Underwood et al, 2011, Fig .…”

Evolutionary history of the devilrays (Chondrichthyes: Myliobatiformes) from fossil and morphological inference

“…Three new taxa belonging to mobulids have been recognized in the dental remains recovered south of Ad Dahkla in the so‐called ‘Western Sahara’, currently in south‐western Morocco. The preliminary report of these faunas (Adnet et al ., 2010) suggested a late Middle Eocene–Late Eocene age, although Underwood et al . (2011) referred these faunas to the Late Eocene only, based on common occurrences with the well‐dated Fayum area.…”

“…Occurrences: Widely recorded in Palaeogene deposits from north Europe to East and West Africa (e.g. Herman, 1979; Cappetta, 1987; Noubhani & Cappetta, 1997; Kozlov, 2001; Strougo, Cappetta & Elnahas, 2007; Van Den Eeckhaut & De Schutter, 2009; Adnet, Cappetta & Tabuce, 2010; Underwood et al ., 2011),…”

Los Rajiformes (Chondrichthyes, Batomorphii) del Plioceno Inferior de la Formación Arenas de Huelva, Suroeste de España

“…En el continente africano, han sido descritos rhinobatos para el Eoceno medio/superior del suroeste de Marruecos (Adnet et al, 2010). En Europa, el género Rhinobatos se ha reconocido para el Mioceno de la región de Montpellier, Francia (Cappetta, 1970), así como en el Mioceno terminal de la Cuenca de Alvalade, Portugal (Balbino, 1995).…”