New remains of eocene and oligocene afrosoricida (Afrotheria) from Egypt, with implications for the origin(s) of afrosoricid zalambdodonty

Erik R. Seiffert, Elwyn L. Simons, Tomothy M. Ryan, Thomas M. Bown, Yousry Attia

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Abstract

Molecular estimates for the divergence of Chrysochloridae (golden moles) and Tenrecoidea (tenrecs) date back to near the K-T boundary, but at present the oldest undoubted fossil members of these clades are early Miocene in age (-20 Ma). The only Paleogene African genus that has been proposed as a possible stem tenrecoid is late Eocene (-34 Ma) Widanelfarasia from Egypt, heretofore known only from the lower dentition. Here we employ high-resolution computed tomography to reveal the morphology of the maxillary post-canine dentition of Widanelfarasia, and describe fragmentary dental and mandibular remains of early Oligocene Jawharia (gen. nov.) and Eochrysochloris (gen. nov.). The upper molar dentition of Widanelfarasia provides evidence for an intermediate morphological stage between moderate dilambdodonty and incipient zalambdodonty. Phylogenetic analysis employing the morphological character matrix of Asher and Hofreiter (2006) places Widanelfarasia within crown Tenrecoidea, but an alternative placement of that genus as a stem tenrecoid could not be statistically rejected. Additional support for the latter hypothesis, and for the hypothesis of convergent evolution of zalambdodonty within Afrosoricida, is provided by Eochrysochloris gen. nov., which shares apomorphic premolar features with Miocene Prochrysochloris and extant chrysochlorids, but retains a well-developed talonid basin on its lower molars. Jawharia gen. nov. is interpreted as an advanced stem tenrecoid that provides additional support for the hypothesis that tenrecoid zalambdodonty evolved from moderate dilambdodonty. Some of the apomorphic morphological features shared by Widanelfarasia and early Miocene Protenrec are also seen in Todralestes, from the oldest (late Paleocene) placental mammal-bearing locality in Africa. As such Todralestes may be a stem or crown afrosoricid, and, if so, the oldest known Afro-Arabian member of Afrotheria.

Original languageEnglish (US)
Pages (from-to)963-972
Number of pages10
JournalJournal of Vertebrate Paleontology
Volume27
Issue number4
DOIs
Publication statusPublished - Dec 12 2007

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All Science Journal Classification (ASJC) codes

  • Palaeontology

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