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Diversity of the adapisoriculid mammals from the early Palaeocene of Hainin, Belgium

100%

De Bast E., Sige B., Smith T.

Acta Palaeontologica Polonica

2012

tom 57

nr 1

Adapisoriculidae are an enigmatic group of small mammals known from the late Cretaceous of India, and from the early Palaeocene to early Eocene of Europe and Africa. Based on their primitive dental morphology, they have been classified as didelphids, nyctitheriids, leptictids, mixodectids, tupaiids, and palaeoryctids. While the latest hypothesis based on dental morphology suggests an affinity with Lipotyphla, postcranial remains indicate a close relationship with Euarchonta. Here, we present new adapisoriculid dental remains from the early Palaeocene locality of Hainin (Belgium). Adapisoriculidae are particularly abundant in Hainin, where they represent about one third of the mammalian fauna, offering new insights into both their specific and generic phylogenetic interrelationships. We describe three new species (Afrodon gheerbranti sp. nov., Bustylus folieae sp. nov. and Proremiculus lagnauxi gen. et sp. nov.) and document the previously unknown lower dentition of Bustylus marandati. The diversity of dental morphologies observed in the Hainin fauna suggests different interrelationships than previously suggested. In particular, the genus Proremiculus is considered morphologically intermediate between Afrodon and Remiculus, and the latter is no longer recognised as the sister group of Adapisoriculus. Although the highest diversity of adapisoriculids occurs in Europe, the oldest and most primitive members of the family were found in India and Africa, respectively. The geographic origin of the family could thus be located in any of these three continents, depending on the importance attributed to each of these factors. The coexistence of primitive and derived adapisoriculids at Hainin might indicate a very quick diversification in Europe, probably starting around the K−T boundary.

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

80%

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.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

1 De Bast E.

1 Seiffert E. R.

1 Sige B.

1 Smith T.

1 2012

1 2010

Wyniki wyszukiwania

Diversity of the adapisoriculid mammals from the early Palaeocene of Hainin, Belgium

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