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

Ehiro, Masayuki; Sasaki, Osamu; Kano, Harumasa; Nagase, Toshiro

doi:10.1016/j.palwor.2019.03.001

Cited by 13 publications

(17 citation statements)

References 26 publications

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“…A recent study re-identified several ammonoid fossils from the type section of the Osawa Formation as Hellenites tchernyschewiensis , H. inopinatus , Neocolumbites grammi , N. insignis , Procolumbites ussuriensis , and P. subquadratus in its lower part; therefore, the lower Osawa Formation can be correlated to the N. insignis zone of South Primorye 60 . It is possible that Utatsu-Tatezaki, the other ichthyosauromorph-bearing “ Columbites – Subcolumbites zone” locality, which is the type locality of Utatsusaurus , also includes N. insignis (upper lower Spathian) and Subcolumbites (middle Spathian) subzones because no large missing parts have been recognized between the underlying Hiraiso Formation and Osawa Formation 32 , 61 , 62 . As evidenced by Smith et al 3 and this study, some medium (~ 2.5 m) to large (~ 5 m) ichthyopterygians were present during the early Spathian, shortly after the P–T boundary (approximately 3 Mys 53 ), thus, it is not surprising that lower Spathian marine reptiles exist among Japanese collections.…”

Section: Discussionmentioning

confidence: 99%

Early Triassic ichthyopterygian fossils from the Russian Far East

Nakajima

Shigeta

Houssaye³

et al. 2022

Sci Rep

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Ichthyopterygia is a major clade of reptiles that colonized the ocean after the end-Permian mass extinction, with the oldest fossil records found in early Spathian substage (late Olenekian, late Early Triassic) strata in the western USA. Here, we describe reptilian remains found in situ in the early Spathian Neocolumbites insignis ammonoid zone of South Primorye in the Russian Far East. Specimen NSM PV 23854 comprises fragmentary axial elements exhibiting a combination of morphological characteristics typical of Ichthyopterygia. The cylindrical centra suggest that the specimen represents a basal ichthyopterygian, and its size is comparable to that of Utatsusaurus. Specimen NSM PV 24995 is represented by a single limb bone, which is tentatively identified as an ichthyopterygian humerus. With a body length of approximately 5 m estimated from the humeral length, NSM PV 24995 represents one of the largest specimens of early Spathian marine reptiles known to date. Such size variation among the earliest ichthyopterygians might suggest an explosive diversification in size immediately after the end-Permian mass extinction. Both vertebrae and humerus specimens exhibit an extremely cancellous inner structure, suggesting a high degree of aquatic adaptation in ichthyopterygians, despite their short history of evolution in the ocean.

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Section: Discussionmentioning

confidence: 99%

Early Triassic ichthyopterygian fossils from the Russian Far East

Nakajima

Shigeta

Houssaye³

et al. 2022

Sci Rep

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“…Our knowledge of Early Triassic thylacocephalans has largely been expanded on both taxonomy and paleogeographic distribution due to recent discoveries from South China (Ji et al, 2017), Japan (Ehiro et al, 2015, 2019), and North America (Charbonnier et al, 2019) (Table 1). Thylacocephalans are thought to have reached one of the highest diversity levels in the Early Triassic, despite a few questionable taxonomic assignments.…”

Section: Discussionmentioning

confidence: 99%

“…Microcaris Pinna, 1974, Ferrecaris Calzada and Mañé, 1993, Kitakamicaris Ehiro and Kato in Ehiro et al, 2015, and Miyagicaris Ehiro et al, 2019.…”

Section: Systematic Paleontologymentioning

confidence: 99%

“…Multiple localities have been reported with records spanning from Europe, Central and East Asia, Madagascar, and Australia (see Schram, 2014 and Braig et al, 2019 for a review). Recently, as abundant materials were reported from Japan, South China, Italy, and North America, the Triassic appears to have been the period with the highest taxonomic richness of thylacocephalans (Table 1; Ehiro et al, 2015, 2019; Ji et al, 2017; Teruzzi and Muscio, 2018; Charbonnier et al, 2019).…”

Section: Introductionmentioning

confidence: 98%

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New Thylacocephala (Crustacea) assemblage from the Spathian (Lower Triassic) of Majiashan (Chaohu, Anhui Province, South China)

Tintori

Jiang

et al. 2020

J. Paleontol.

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Here we report and describe a new assemblage of Thylacocephala (Crustacea) from the late Spathian (Early Triassic) of Chaohu, Anhui Province, South China. The assemblage consists of at least three species from different genera: the small-sized Microcaris rectilineatus n. sp. appears the most abundant, while the large-sized Ankitokazocaris sp. and Diplacanthocaris chaohuensis n. gen. n. sp. are rare. A morphometric analysis of the carapace outline separates Diplacanthocaris chaohuensis n. gen. n. sp. from other genera. Along with Ankitokazocaris chaohuensis Ji et al., 2017 and Kitakamicaris sp. from the horizon 28 m above this assemblage, four different genera of Thylacocephala occur in the Chaohu Fauna. With additional materials reported from Japan and North America, the Early Triassic is now known as the period when Thylacocephala reached their highest diversity and widest geographical distribution. Thylacocephala quickly diversified shortly after the Permian–Triassic mass extinction, probably because of their ability to survive in a relatively low-oxygen environment. Thylacocephalan fossils from Chaohu are found in dense concentrations, suggesting they might have constituted a food source for the fishes and marine reptiles in the Chaohu Fauna. UUID: http://zoobank.org/b24e82a7-ea9a-49dc-9c6c-8ad8262db276

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“…2017), and, based on their highly incomplete fossil record, the group seems to have reached its peak diversity and widest distribution in low palaeolatitudes during the Triassic (Ehiro et al . 2015, 2019; Ji et al . 2017; Charbonnier et al .…”

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confidence: 99%

Upper Ordovician Thylacocephala (Euarthropoda, Eucrustacea) from Bohemia indicate early ecological differentiation

Roy

Rak

Budil

et al. 2021

Papers in Palaeontology

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Thylacocephala is a clade of marine bivalved euarthropods generally considered to belong to Eucrustacea, although their affinities within this group remain unsettled. Detailed thylacocephalan anatomy and tagmosis is poorly known, and the majority of taxa have been described based only on the valves of the carapace. While some thylacocephalans are considered to have been fully nektic, others probably had a nekto-benthic mode of life. The group makes its last appearance in the Upper Cretaceous of Lebanon, while the previously oldest definite record is from the Silurian of Wisconsin, USA. This paper describes two new thylacocephalans, Pseudoprotozoea irenae gen. et sp. nov. and Bohemiacaris libori gen. et sp. nov. from the Sandbian (Upper Ordovician

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

Cited by 13 publications

References 26 publications

Early Triassic ichthyopterygian fossils from the Russian Far East

Early Triassic ichthyopterygian fossils from the Russian Far East

New Thylacocephala (Crustacea) assemblage from the Spathian (Lower Triassic) of Majiashan (Chaohu, Anhui Province, South China)

Upper Ordovician Thylacocephala (Euarthropoda, Eucrustacea) from Bohemia indicate early ecological differentiation

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