Isoxys minor Luo et al. 2008

By oilshale

• November 1, 2021

Taxonomy

Kingdom: Animalia
Phylum: Arthropoda Latreille 1829
Class: incertae sedis
Order: incertae sedis
Family: incertae sedis
Genus: Isoxys
Species: Isoxys minor
Author Citation Luo et al. 2008

Geological Time Scale

Eon: Phanerozoic
Era: Paleozoic
Period: Cambrian
Sub Period: None
Epoch: Series 2 Epoch
International Age: Stage 4

Stratigraphy

Wulongqing Formation

Provenance

Acquired by: Purchase/Trade

Dimensions

Length: 20 mm

Location

Gaoloufang (Village)
Guandu (District)
Yunnan (Province)
China

• cambrian
• gaoloufang
• guanshan biota
• isoxys minor
• shitangshan
• tff-oilshale-ar1515
• wulongqing
• yunnan

Comments

Taxonomy according to fossilworks.org

Vannier et al. 2006 assume that Tuzoia and the also Cambrian genus Isoxys are possibly representatives of the class Thylacocephala.

The fossil probably shows rare soft part preservation of the frontal appendages and the stalked eyes.

Emmended diagnosis for the genus Isoxys by Garcia-Bellido 2009, p. 1224: ”Arthropod with one pair of cephalic appendages and a uniform series of at least 13 pairs of biramous appendages. Long, narrow body covered almost entirely by a bivalved, very thin unmineralized carapace. Prominent, stalked, spherical to pear-shaped lateral eyes protrude beyond the anterior margin of the carapace. Each valve armed with prominent cardinal spines. Dorsal outline straight or slightly projecting to form a weak to well-developed cusp (small circular node may be present below this cusp) anterior of mid-length. Ventral outline semicircular, weakly preplete (valve is highest anterior to its mid-length) to postplete (highest posterior to its mid-length). Simple perimarginal features (very narrow to more inflated rim).  No flattened ⁄ concave marginal features. Narrow to broad doublure may be present. Carapace folded along the dorsal line (valves conjoined by a narrow band of cuticle; absence of articulating hinge). Internally, midgut glands may be present. External ornament may be expressed as uniform micro-reticulation or longitudinal striae. (Modified from Vannier and Chen 2000, p. 311)."

Line drawing from Huang et al. 2014:

Identified by oilshale using Huang et al. 2014.

References:

Garcia-Bellido, D.C., Paterson, J.R., Edgecombe, G.D., Jago, J.B., Gehling, J.G. and Lee, M.S.Y. (2009). The bivalved arthropods Isoxys and Tuzoia with soft-part preservation from the Lower Cambrian Emu Bay Shale Lagerstätte (Kangaroo Island, Australia). Palaeontology, 52: 1221-1241.  https://doi.org/10.1111/j.1475-4983.2009.00914.x

Huang, D.Y., Wang, Y.N. (2014). The soft anatomy of Isoxys minor from the Guanshan fauna, lower Cambrian of Southwest China. Palaeoworld. http://dx.doi.org/10.1016/j.palwor.2014.10.006

Hu, S.X., Zhu, M.Y., Luo, H.L., Steiner, M., Zhao, F.C., Li, G.X., Liu, Q., Zhang, Z.F. (2014). The Guanshan Biota. Yunnan Science and Technology Press, Kunming, 204 pp. (in Chinese, with English summary).

H.-L. Luo, L. Yong, S.-X. Hu, X.-P. Fu, S.-Q. Hou, X.-Y. Liu, L.-Z. Chen, F.-J. Li, J.-Y. Pang and Q. Liu. (2008). Early Cambrian Malong Fauna and Guanshan Fauna from Eastern Yunnan, China 1-134.

Vannier, J. and Chen, J.Y. (2000). The Early Cambrian colonization of pelagic niches exemplified by Isoxys (arthropoda). Lethaia 33, 295–311.

Vannier, J., Chen, J.-Y., Huang, D.-Y. and Wang, X.-Q. (2006). Thylacocephalan arthropods: Their early Cambrian origin and evolutionary significance. Acta Paleontologica Polonica, 51:201–214.