A new tetraradial olivooid (Medusozoa) from the lower Cambrian (Stage 2) Yanjiahe Formation, South China

Octapyrgites elongatus n. gen. n. sp., a relatively rare, tetraradial olivooid (Cnidaria, Medusozoa), is described from Bed 5 of the Yanjiahe Formation (Cambrian Stage 2) near Yichang, China. Although similar to Olivooides and Quadrapyrgites from the Fortunian Stage in consisting of a partially corr...

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Bibliographic Details
Published in:Journal of paleontology 2020-05, Vol.94 (3), p.457-466
Main Authors: Guo, Junfeng, Han, Jian, Van Iten, Heyo, Song, Zuchen, Qiang, Yaqin, Wang, Wenzhe, Zhang, Zhifei, Li, Guoxiang, Sun, Yifei, Sun, Jie
Format: Article
Language:English
Subjects:
Cambrian
Elongation
Embryogenesis
Embryonic development
Embryonic growth stage
Fossils
Hypotheses
Marine invertebrates
Medusozoa
Microscopy
Octapyrgites elongatus
Paleontology
Phylogenetics
Physical characteristics
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Symmetry
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Summary:Octapyrgites elongatus n. gen. n. sp., a relatively rare, tetraradial olivooid (Cnidaria, Medusozoa), is described from Bed 5 of the Yanjiahe Formation (Cambrian Stage 2) near Yichang, China. Although similar to Olivooides and Quadrapyrgites from the Fortunian Stage in consisting of a partially corrugated (longitudinal) periderm with a quadrate (transverse) apical portion and V-shaped apertural lobes, O. elongatus is substantially larger than other olivooids. The elongate apical region of O. elongatus is similar to four-sided Anaconularia anomala (Barrande, 1867), though with a flat tip that may have been an adaption for a sessile mode of life. As in other olivooids, embryonic development in O. elongatus may have been direct. Last, the paucity of olivooids and the absence of pentaradial cnidarians and carinachitids in Cambrian Stage 2 indicate a marked decline in the disparity of cnidarians near the Fortunian–Cambrian Age 2 boundary, when by contrast bilaterians underwent rapid diversification.
ISSN:0022-3360
1937-2337
DOI:10.1017/jpa.2019.101