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Early Cretaceous multituberculate mammals from the Kuwajima Formation [Tetori Group], central Japan

100%

Kusuhashi N.

Acta Palaeontologica Polonica

2008

tom 53

nr 3

Hakusanobaatar matsuoi gen. et sp. nov. and Tedoribaatar reini gen. et sp. nov. are multituberculate mammals recovered from the Lower Cretaceous (Barremian to lower Aptian) Kuwajima Formation of the Tetori Group in the Shiramine district, Hakusan City, Ishikawa Prefecture, central Japan. Hakusanobaatar matsuoi is an eobaatarid multituberculate characterized by a P4 with cusp formula 3:5, and a P5 with cusp formula 2:6:?2. One of the specimens of H. matsuoi has the best preserved upper premolar series among known eobaatarid specimens. Based on the dentition of H. matsuoi, it is highly probable that the cimolodontan P4 is homologous with the “plagiaulacidan” P5. Tedoribaatar reini is also tentatively attributed to Eobaataridae, and shows a single−rooted p3 and loss of at least the permanent p2. On the basis of these apomorphic features, T. reini is considered to be the “plagiaulacidan” multituberculate that is most closely related to cimolodontans.

The choristoderan reptile Monjurosuchus from the Early Cretaceous of Japan

100%

Matsumoto R., Evans S. E., Manabe M.

Acta Palaeontologica Polonica

2007

tom 52

nr 2

The choristoderan reptile Monjurosuchus is described from the Lower Cretaceous Tetori Group of Japan on the basis of an associated specimen from the Kuwajima Formation, Ishikawa Prefecture, and more fragmentary remains from the contemporaneous Okurodani Formation, Gifu Prefecture. This is the first report of Monjurosuchus from Japan, but a long−necked choristodere, Shokawa, has already been recorded from these deposits. Monjurosuchus was first described from the Lower Cretaceous Jehol Biota of China, although it has only recently been recognised as a choristodere. As reconstructed, the Japanese Monjurosuchus differs from the type species, Monjurosuchus splendens, in the structure of the postorbital region, reduction of the quadratojugal, a slender parietal with a deep groove along the interparietal suture, and elongation of the jugal. As in M. splendens, the lower temporal fenestrae are closed. A cladistic analysis was performed in order to place Japanese and Chinese taxa, including the incompletely described Chinese long−necked Hyphalosaurus lingyanensis, into choristoderan phylogeny. The results support the monophyly of Neochoristodera and of a Sino−Japanese clade of long necked choristoderes. The placement of the European Tertiary Lazarussuchus remains problematic, but the analysis supports its placement within Choristodera rather than on the stem. The identification of Monjurosuchus from Japan provides an additional link between the fossil assemblages of the Tetori Group and those of the slightly younger Jehol Biota of China.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

1 Evans S. E.

1 Kusuhashi N.

1 Manabe M.

1 Matsumoto R.

1 2008

1 2007

Wyniki wyszukiwania

Early Cretaceous multituberculate mammals from the Kuwajima Formation [Tetori Group], central Japan

The choristoderan reptile Monjurosuchus from the Early Cretaceous of Japan