Pseudoarctolepis Explained

Pseudoarctolepis is an extinct genus of bivalved arthropod known from the Cambrian period. The type species, P. sharpi was described by Brooks & Caster in 1956 from specimens found in the Wheeler Shale of Utah.^[1] It is unusual among Cambrian arthropods for having a pair of wing-like structures projecting outwards from the carapace. A second species, P. semicircularis has been described from the Kaili Biota in South China, which differs from the type species in the fact that the wings are semicircular rather than blade-like.^[2] A possible related form has been reported from the Ordovician of Portugal.^[3] They were relatively large, with some carapaces of P. sharpi reaching 11cm (04inches) in length.^[4] The soft-bodied anatomy is poorly known, though the poorly preserved posterior anatomy of a specimen of P. sharpi is known, which consists of a narrow segmented abdomen, which ends with a pair of caudal rami. They are thought to have been actively swimming nektonic organisms. Affinities to the bivalved arthropod group Hymenocarina have been proposed, but the limited knowledge of the anatomy makes the referral tentative.^[5]

Notes and References

1. H. K. Brooks, and Kenneth E. Caster. “Pseudoarctolepis sharpi, n. Gen., n. Sp. (Phyllocarida), from the Wheeler Shale (Middle Cambrian) of Utah.” Journal of Paleontology, vol. 30, no. 1, 1956, pp. 9–14. JSTOR, . Accessed 12 Dec. 2022.
2. Yuan . Jinliang . Peng . Jin . Zhao . Yuanlong . August 2011 . New Bivalved Arthropods from Mid-Cambrian Kaili Biota of Southeastern Guizhou, Southwest China . Acta Geologica Sinica - English Edition . en . 85 . 4 . 758–764 . 10.1111/j.1755-6724.2011.00481.x. 129283273 .
3. Kimmig . Julien . Couto . Helena . Leibach . Wade W. . Lieberman . Bruce S. . June 2019 . Soft-bodied fossils from the upper Valongo Formation (Middle Ordovician: Dapingian-Darriwilian) of northern Portugal . The Science of Nature . en . 106 . 5–6 . 27 . 10.1007/s00114-019-1623-z . 31129730 . 253633957 . 0028-1042.
4. Robison, R. A. and Richards, B. C. 1981. Larger bivalve arthropods from the Middle Cambrian of Utah. University of Kansas Paleontological Contributions, 106, 1–28.
5. Lerosey‐Aubril . Rudy . Kimmig . Julien . Pates . Stephen . Skabelund . Jacob . Weug . Andries . Ortega‐Hernández . Javier . November 2020 . Zhang . Xi‐Guang . New exceptionally preserved panarthropods from the Drumian Wheeler Konservat‐Lagerstätte of the House Range of Utah . Papers in Palaeontology . en . 6 . 4 . 501–531 . 10.1002/spp2.1307 . 218995462 . 2056-2802.