Additional thylacocephalans (Arthropoda) from the Lower Triassic (upper Olenekian) Osawa Formation of the South Kitakami Belt, Northeast Japan

Masayuki Ehiro, Osamu Sasaki, Harumasa Kano, Toshiro Nagase

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The Lower Triassic Osawa Formation in the South Kitakami Belt, Northeast Japan, consisting mostly of mudstone of shallow-marine environment, was deposited during the late Olenekian (ca. 250 Ma), and is an important unit through which to examine the biotic recovery process after the end-Permian mass extinction. The Osawa Formation is the only unit in Japan that yields thylacocephalans (Arthropoda). Three species belonging to three genera have been reported before: Ankitokazocaris bandoi, Kitakamicaris utatsuensis and Ostenocaris sp. In addition to the known species, some thylacocephalans, including one new genus and three new species, are described in the present paper: Ankitokazocaris tatensis n. sp., Concavicaris parva n. sp., Miyagicaris costata n. gen. n. sp. and Ostenocaris? sp. Although Thylacocephala have a rather long stratigraphic range (from Silurian to Cretaceous) and are known from a wide geographical region, there are only about thirty genera in this group. The Osawa thylacocephalan fauna comprises at least five genera, making it one of the most diverse in the world at the generic level. During the Triassic Period, the Thylacocephala diversified and spread widely throughout low-latitude regions.

Original languageEnglish
Pages (from-to)320-333
Number of pages14
JournalPalaeoworld
Volume28
Issue number3
DOIs
Publication statusPublished - 2019 Sep 1

Keywords

  • Biotic recovery
  • Early Triassic
  • Osawa Formation
  • South Kitakami Belt
  • Thylacocephala

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Stratigraphy
  • Palaeontology

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