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The oldest and youngest records of afrosoricid placentals from the Fayum Depression of northern Egypt

100%

Seiffert E. R.

Acta Palaeontologica Polonica

2010

tom 55

nr 4

Tenrecs (Tenrecoidea) and golden moles(Chrysochloroidea) are among the most enigmatic mammals alive today. Molecular data strongly support their inclusion in the morphologically diverse clade Afrotheria, and suggest that the two lineages split near the K−T boundary, but the only undoubted fossil representatives of each superfamily are from early Miocene (~20 Ma) deposits in East Africa. A recent analysis of partial mandibles and maxillae of Eochrysochloris, Jawharia, and Widanelfarasia, from the latest Eocene and earliest Oligocene of Egypt, led to the suggestion that the derived “zalambdomorph” molar occlusal pattern (i.e., extreme reduction or loss of upper molar metacones and lower molar talonids) seen in tenrecoids and chrysochloroids evolved independently in the two lineages, and that tenrecoids might be derived from a dilambdomorph group of “insectivoran−grade” placentals that includes forms such as Widanelfarasia. Here I describe the oldest afrosoricid from the Fayum region, ~37 Ma Dilambdogale gheerbranti gen. et sp. nov., and the youngest, ~30 Ma Qatranilestes oligocaenus gen. et sp. nov. Dilambdogale is the most generalized of the Fayum afrosoricids, exhibiting relatively broad and well−developed molar talonids and a dilambdomorph arrangement of the buccal crests on the upper molars, whereas Qatranilestesis the most derived in showing relatively extreme reduction of molar talonids. These occurrences are consistent with a scenario in which features of the zalambdomorph occlusal complex were acquired independently and gradually through the later Paleogene. Phylogenetic analysis places Dilambdogale and Widanelfarasia as sister taxa to the exclusion of crown afrosoricids, but derived features that these taxa share with early Miocene Protenrec hint at the possibility that both taxa might be stem tenrecoids. Late Paleocene Todralestes and Afrodon from Morocco are similarly placed as stem afrosoricids, indicating that African adapisoriculids (including Garatherium) might also be relevant to the origin of the tenrecoid and chrysochloroid clades.

Vampyravus orientalis Schlosser (Chiroptera) from the Early Oligocene (Rupelian), Fayum, Egypt — body mass, humeral morphology and affinities

51%

Gunnell G. F., Worsham S. R., Seiffert E. R., Simons E. L.

Acta Chiropterologica

2009

tom 11

nr 2

Vampyravus orientalis, from the Oligocene of Fayum, Egypt was the first fossil bat described from Africa. It is represented by a single, relatively large humerus from an unknown horizon in the Jebel Qatrani Formation. Based on regression analyses of skeletal proportions of modem bats, we developed a set of equations to estimate body mass of fossil bats from known skeletal elements in order to test the hypothesis that Vampyravus could have been within the body size range of other Fayum bats, including several recently described taxa from the Jebel Qatrani and underlying Birket Qarun Formations. Our findings indicate that only Witwatia could have had a body mass similar to Vampyravus. Witwatia is known only from Quarry BQ-2 (Late Eocene, Priabonian) in the Birket Qarun Formation. Therefore Vampyravus is between 2 and 7 million years younger, depending on where within the Jebel Qatrani Formation it was found. Also, a recently discovered distal humerus of Witwatia from BQ-2 demonstrates that this taxon differs substantially from Vampyravus in comparable morphology. Vampyravus is distinct from all other Fayum fossil bats. Vampyravus shares characteristics of the proximal and distal humerus with several extant bat groups including phyllostomids, some rhinolophoids, natalids, emballonurids, and rhinopomatids. The latter two families are represented by fossil forms in the Fayum. Although Vampyravus is much larger than either the Fayum emballonurid or rhinopomatid, relatively large size typifies many taxa representing modern bat groups in the Fayum, making it all the more conceivable that Vampyravus could belong to one of these families.

Ograniczanie wyników

1 Acta Chiropterologica

1 Acta Palaeontologica Polonica

2 Seiffert E. R.

1 Gunnell G. F.

1 Simons E. L.

1 Worsham S. R.

1 2010

1 2009

Wyniki wyszukiwania

The oldest and youngest records of afrosoricid placentals from the Fayum Depression of northern Egypt

Vampyravus orientalis Schlosser (Chiroptera) from the Early Oligocene (Rupelian), Fayum, Egypt — body mass, humeral morphology and affinities