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Paläontologische Zeitschrift

, Volume 81, Issue 4, pp 406–415 | Cite as

Enigmatic new mammals from the late Eocene of Egypt

  • Marcelo R. Sánchez-Villagra
  • Erik R. Seiffert
  • Thomas Martin
  • Elwyn L. Simons
  • Gregg F. Gunnell
  • Yousry Attia
Article

Abstract

A new mammalian genus and species from the earliest late Eocene of Egypt is represented by a lower jaw fragment and two isolated lower molars. A rare combination of features and the fragmentary nature of the materials make their taxonomic assignment to either Marsupialia or Chiroptera uncertain. The holotype of the new genus is the best-preserved specimen in the sample, a dentary fragment with two molars that have uncompressed trigonids, weak buccal cingulids, and a nyctalodont arrangement of the hypocristid. Some traits appear to more clearly support marsupial, as opposed to chiropteran, affinities for this species, including the very likely presence of four molars in the dentary. The enamel of an additional lower molar assigned to this species consists of a single layer of radial enamel without any prism decussation, an enamel type that characterizes marsupials as well as chiropterans. A second taxon is represented by two isolated upper molars. Some traits appear to more clearly support marsupial, as opposed to chiropteran, affinities for these species, including the orientation of pre- and postprotocristae, the moderately slender lingual portion of the trigon, and the absence of any talon expansion. As some of these features can be found in various bat clades, chiropteran affinities for these species cannot be ruled out, but we propose that the new taxa are more likely to represent specialized ‘didelphimorphian’ marsupials.

Keywords

Africa Fayum Metatheria Didelphimorphia Chiroptera Biogeography Enamel 

Kurzfassung

Aus dem untersten Ober-Eozän von Ägypten liegen ein Unterkiefer-Fragment und zwei isolierte untere Molaren einer neuen Säugetier-Gattung und -Art vor. Die ungewöhnliche Merkmalskombination und der fragmentarische Erhaltungszustand der Stücke lassen eine Zuordnung zu den Marsupialia oder Chiroptera möglich erscheinen. Das Unterkieferfragment (Holotyp) enthält zwei Molaren mit unkomprimierten Trigoniden, schwach entwickelten buccalen Cinguliden und einer nyctalodonten Anordnung des Hypocristids. Der Kiefer hat ursprünglich vermutlich vier Molaren besessen, was für eine Zuordnung zu den Marsupialiern spräche. Der Schmelz eines der neuen Art zugeordneten isolierten unteren Molaren besteht aus einer einfachen Lage von Radialschmelz (ohne Prismenüberkreuzung), ein Schmelztyp, der sowohl bei den Marsupialia als auch bei den Chiroptera vorkommt. Ein zweites Taxon ist durch zwei einzelne obere Molaren repräsentiert. Auch hier sprechen manche Merkmale eher für eine Zuweisung zu den Marsupialia, unter anderem die Anordnung der Prä- und Protocristae, der mäßig schlanke linguale Teil des Trigons und das Fehlen einer Talon-Ausweitung. Da einige dieser Merkmale auch bei verschiedenen Fledermäusen auftreten, kann eine Zugehörigkeit zu den Chiroptera nicht ausgeschlossen werden, obwohl wir zu der Auffassung tendieren, dass es sich bei beiden neuen Taxa eher um spezialisierte „didelphomorphe“ Beuteltiere handelt.

Schlüsselwörter

Afrika Fayum Metatheria Didelphimorphia Chiroptera Biogeographie Schmelz 

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Copyright information

© E. Schweizerbart’sche Verlagsbuchhandlung 2007

Authors and Affiliations

  • Marcelo R. Sánchez-Villagra
    • 1
  • Erik R. Seiffert
    • 2
  • Thomas Martin
    • 3
  • Elwyn L. Simons
    • 4
  • Gregg F. Gunnell
    • 5
  • Yousry Attia
    • 6
  1. 1.Paläontologisches Institut und MuseumUniversität ZürichZürichSwitzerland
  2. 2.Department of Anatomical SciencesSchool of Medicine, Stony Brook UniversityStony BrookUSA
  3. 3.Institut für PaläontologieUniversität BonnBonnGermany
  4. 4.Department of Biological Anthropology & AnatomyDuke University, and Division of Fossil Primates, Duke Primate CenterDurhamUSA
  5. 5.Museum of PaleontologyUniveristy of MichiganAnn ArborUSA
  6. 6.Egyptian Geological Museum, Misr el Kadima, Ethar el NabiCairoEgypt

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