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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.

Revealing body proportions of the enigmatic choristodere reptile Khurendukhosaurus from Mongolia

76%

Matsumoto R., Tsogtbaatar K., Ishigaki S., Tsogtbaatar C., Enkhtaivan Z., Evans S. E.

Acta Palaeontologica Polonica

2019

tom 64

nr 2

Khurendukhosaurus is an enigmatic genus of choristodere, recorded from the Lower Cretaceous of East Asia, Mongolia, and Siberian Russia. Until now, it was known only from isolated skull and postcranial elements, limiting comparison with other genera. Three major morphotypes have been recognised within Choristodera: longirostrine neochoristoderes with short-necks, and brevirostrine non-neochoristoderes with either short or long necks. The morphotype of Khurendukhosaurus was uncertain, although it had been inferred to be long-necked, based on cervical and caudal vertebral morphology shared with the Chinese Hyphalosaurus and on the results of phylogenetic analysis that placed it within a clade of Sino-Japanese long-necked taxa. Newly discovered material from the Mongolian type locality, Khuren-Dukh, preserves most major postcranial elements of a single individual. This specimen confirms that Khurendukhosaurus belongs to the long-necked morphotype, in having at least 13 cervical vertebrae. Moreover, a new phylogenetic analysis supports the placement of Khurendukhosaurus as a sister group of the Hyphalosaurus + Shokawa clade. Based on the new material, Khurendukhosaurus is estimated to have been roughly 1 m in total length, placing it at the upper end of the size range for long-necked choristoderes.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

2 Evans S. E.

2 Matsumoto R.

1 Enkhtaivan Z.

1 Ishigaki S.

1 Manabe M.

1 Tsogtbaatar C.

1 Tsogtbaatar K.

1 2019

1 2007

Wyniki wyszukiwania

The choristoderan reptile Monjurosuchus from the Early Cretaceous of Japan

Revealing body proportions of the enigmatic choristodere reptile Khurendukhosaurus from Mongolia