Cambrian helcionelloids (univalved molluscs) from the Korean Peninsula: systematic revision and biostratigraphy

Oh, Yeongju; Lee, Dong‐Chan; Lee, Dong Hoon; Lee, Jeong-Gu

doi:10.1080/03115518.2021.1929479

Cited by 5 publications

(1 citation statement)

References 29 publications

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“…This species is similar to Helcionelloidea indet. (Oh et al, 2021), which belongs to series 2 with a high stratigraphic position, the latter"s shell being moderately coiled and considerably compressed laterally; 21.8 mm long, 10.3 mm wide and 15.1 mm tall. The apical end is blunted and smooth with a triangular outline.…”

Section: Measurements In μMmentioning

confidence: 99%

Helcionelloids from the Cambrian Fortunian of the Northern Yangtze Platform, China

ZHANG,

PANG,

YANG

et al. 2023

Acta Geologica Sinica (Eng)

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A study on the morphological characteristics of helcionelloids and its microstructure from the Nanjiang area (north Sichuan, China) at the northern Yangtze Platform is taken to understand its position in the phylogeny. Helcionelloids fossils from the Kuanchuanpu Formation of the Changtanhe–Maolinzi section include 7 genera and 11 species. There are distinct differences on the degree of shell bending, the apical morphology and apex position, the outline of the apeture, and the height of the shell, which constitute an important identification feature. Though the helcionelloid apices have varying degrees of rotation towards the aperture, they have no any evident distortion. A pair of basally symmetrical muscle scars are discovered on the shells of helcionelloids (such as Bemella simplex), showing distinct difference comparing with those of the stem‐group gastropod (e.g., Pelagiella). The prismatic shell layer of helcionelloids has been observed, which are common components in Cambrian molluscs. They are significantly different from the dense layer microstructure found in contemporary molluscs. The microstructures, muscle scars and morphological characteristics demonstrate that the helcionelloid is a stem‐group of molluscs.

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Section: Measurements In μMmentioning

confidence: 99%

Helcionelloids from the Cambrian Fortunian of the Northern Yangtze Platform, China

ZHANG,

PANG,

YANG

et al. 2023

Acta Geologica Sinica (Eng)

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Palaeobiogeography of the family Nisusiidae (Cambrian rhynchonelliform brachiopods) using the ‘area‐transition count’ method and systematic revision of Korean species

Lee

et al. 2022

Papers in Palaeontology

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Nisusiidae is a rhynchonelliform brachiopod family that was widely distributed in low‐latitude regions during the middle Cambrian (Stage 3 of Series 2 to the Drumian Stage of the Miaolingian Series). Cladistic analysis of 24 nisusiid species including two species from South Korea (Nisusia paucicostellata and Nisusiidae gen. et sp. indet.) demonstrates that the nisusiids consist of two sister clades (Clade 1 and 2) whose common ancestor was derived from a paraphyletic ‘basal’ group. Non‐spinose taxa are all included in Clade 1, while spinose Nisusia species are found throughout the three groups including Clade 1, indicating paraphyly of Nisusia. The optimized ancestral area(s) are assigned to internal nodes of the taxon area cladogram using both the Fitch algorithm and the DIVALIKE+J model of BioGeoBEARS, and then the relationship between cladogenetic area transition types and palaeogeographical areas is examined using the ‘area‐transition count’ method. Of 10 possible cladogenetic area transitions, which are combinations of range contraction (C), expansion (E), switch (S) and no range change (N), six (CC, CE, CN, EN, NN and NS) are observed in the two optimization results. It is proposed that the nisusiids originated in Laurentia as a strongly spinose form and dispersed into high‐latitude peri‐Gondwana during Stage 3 and then strongly diversified into other areas during Stage 4, and that non‐spinose forms evolved later, mainly in Laurentia. The nisusiid palaeobiogeographical pattern is interpreted to reflect distributional range changes that were probably caused by palaeo‐oceanic currents with the aid of island arcs as stepping stones, and pumice, produced by volcanic activity, as the means of dispersal.

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Redlichia nobilis Walcott, 1905, the oldest trilobite in South Korea: age and morphologic restoration by strain analysis

et al. 2021

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Cambrian helcionelloids (univalved molluscs) from the Korean Peninsula: systematic revision and biostratigraphy

Cited by 5 publications

References 29 publications

Helcionelloids from the Cambrian Fortunian of the Northern Yangtze Platform, China

Helcionelloids from the Cambrian Fortunian of the Northern Yangtze Platform, China

Palaeobiogeography of the family Nisusiidae (Cambrian rhynchonelliform brachiopods) using the ‘area‐transition count’ method and systematic revision of Korean species

Redlichia nobilis Walcott, 1905, the oldest trilobite in South Korea: age and morphologic restoration by strain analysis

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