Zegdoumyidae (Rodentia, Mammalia), stem anomaluroid rodents from the Early to Middle Eocene of Algeria (Gour Lazib, Western Sahara): new dental evidence

A new and primitive species of Protophiomys (Rodentia, Hystricognathi) from the late middle Eocene of Djebel el Kébar, Central Tunisia

“…Another mammal-bearing locality from North Africa, Aznag, Morocco, dating from the middle middle Eocene (middle Lutetian), has yielded one isolated rodent incisor . The material is meagre but the study of the enamel microstructure of this tooth has revealed a Schmelzmuster transitional from the pauciserial to the uniserial condition, a primitive type of enamel which is typical to that found in zegdoumyids from Algeria and Tunisia (e.g., Martin, 1993;Marivaux et al, 2011). A few teeth, tentatively referred to Protophiomys (P. cf.…”

“…In contrast, the Black Crow locality from Sperrgebiet (close to the Silica localities; Pickford et al, 2008) displays a diverse assemblage including macro-and micromammals, which are undoubtedly of Eocene affinity. This locality has notably yielded a zegdoumyid rodent (Glibia namibiensis [Zegdoumys namibiensis sensu Marivaux et al, 2011]), but so far no hystricognaths. Although the Paleogene fossil record of North and Sub-Saharan Africa is far from being well-documented, there is currently no evidence of hystricognaths on that landmass during the early Paleogene.…”

“…These localities have yielded only zegdoumyid anomaluroids, a group of rodents endemic to Africa that is not closely related to the clade Hystricognathi ( Vianey-Liaud et al, 1994;Marivaux et al, 2004Marivaux et al, , 2011Marivaux, unpublished new data). Another mammal-bearing locality from North Africa, Aznag, Morocco, dating from the middle middle Eocene (middle Lutetian), has yielded one isolated rodent incisor .…”

Four mammal fossil calibrations: balancing competing palaeontological and molecular considerations

“…No taxa presently considered as putative Caviomorpha-Phiomorpha crown members are known from earlier Lutetian (Middle Eocene) mammal faunas. However, the Lutetian is particularly poorly sampled for small mammal fossils in Africa, a potential geographic origin for this clade (Gheerbrant and Rage, 2006;Marivaux et al, 2011). Hence, the absence of any hystricognaths from the better sampled Early Eocene faunas Coster et al, 2012) provides a more appropriate soft maximum of basal Ypresian age (56.0 Ma).…”

“…Meredith et al (2011) employed several calibrations based on reference fossil taxa that have not been subject to any formal phylogenetic analysis, matrix-based or otherwise (e.g., the tree shrew Eodendrogale and an undescribed putative Mormoopid bat). In other cases the placement of the reference taxon has been contradicted by matrixbased analyses, such as for the putative anomaluroid, Pondaungimys (see Marivaux et al, 2011) and the putative procyonid, Pseudobassaris (see Finarelli, 2008). Instead, I included the four new calibrations alongside the primary calibration set from Phillips et al (2009) when the same clade is included (Amniota, Sauropsida, Theria, Marsupialia, Australasian marsupials, Petauroidea, Xenarthra, Primates, Carnivora, Erinaceidae-Soricidae, Paenungulata, Perissodactyla, Suina-Ruminatia, and Whippomorpha).…”