†Tuzoia tylodesa Luo et Hu, 2006

By oilshale

• September 28, 2021

Taxonomy

Kingdom: Animalia
Phylum: Arthropoda Latreille 1829
Class: incertae sedis
Order: Tuzoida Simonetta and Delle Cave, 1975
Family: Tuzoiidae Raymond, 1935
Genus: Tuzoia
Species: Tuzoia tylodesa
Author Citation Luo et Hu, 2006

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: 28 mm

Location

Gaoloufang Village
Chenggong District, Kunming Town
Yunnan Province
China

• cambrian
• gaolufang
• kunming
• stage 4
• tff-oilshale-ar2513
• tuzoia
• tylodesa
• wulongqing

Comments

Taxonomy from Vannier et al. (2007, p. 458).

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

Revised diagnosis for the genus Tuzoia Walcott, 1912 in Vannier et al. (2007, pp. 458–459): “Large bivalved arthropod (valve length up to approx. 180 mm; Chlupác and Kordule, 2002). Carapace thin, nonmineralized, and relatively flexible, folded dorsally (no true articulated hinge) into two hemispherical valves. Valve outline amplete or slightly preplete/postplete (L:H ratio between 1.3 and 1.6). Straight or slightly convex dorsal margin with or without spines. Anterior and posterior cardinal processes (acp and pcp, respectively) pointed in most species. Acp usually more prominent than pcp and with underlying notch. Posterior margin typically with a mid-posterior spine (mps) and a posteroventral spine (pvs). Angle between dorsal margin and pvs between 20° and 40°, most frequently 30°. In some species, additional small marginal spines (sms) and crenulation, especially ventrally, their length decreasing towards the front. Well-marked to vestigial lateral ridge along the entire length of the valves, usually at mid-distance between dorsal and ventral margin on a direct line with mps. In some species, lateral ridge armed with a series of 7–10 thin and broad-based, probably flimsy, spines (spines projecting almost perpendicular to the sagittal plane of the carapace). Valve surface with well-marked reticulate pattern (size of polygonal fossae decreasing towards lateral ridge, cardinal areas, and along margins). A pair of large, stalked lateral eyes and short antennae protruding through anterior notch. Eye stalks at least three times longer than the eye itself. Gut with possible digestive glands.”

General morphology of Tuzoia Walcott, 1912 from Vannier et al. (2007, p. 446):

Description of Tuzoia tylodesa by Luo et al., 2006, p. 468: “Bivalved arthropod. Valves hemi-elliptical in lateral view. The holotype is about 15 mm in length and 8 mm in height.  The ratio of length / height is 1:0.55. The maximum length and height of each valve of the largest individual is 35 mm and 20 mm. Hinge-line straight, with a triangular process at each end. The anteroventral part expands forward slightly, forming a triangular marginal spine. Posteroventral part straight, bearing serrated spines on the dorsal side. 4-5 short, triangular spines present at the dorsal margin. Lateral ridge strong, convex towards the ventral side. Surface of the two valves are covered by sparse, node-like structure, ranging from 0.5-1.0 mm in diameter.”

Identified by oilshale using Luo et al., 2006.

References:

LUO, H.L., FU, X.P., HU, S.X., LI, Y., CHEN, L.Z., YOU, T. & LIU, Q., (2006): New bivalved arthropods from the early Cambrian Guanshan fauna in the Kunming and Wuding area. Acta Palaeontologica Sinica 45, 460–472.

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.

Vannier, J., Caron, J.-B., Yuan J.-L., Briggs, D. E. G., Collins, D., Zhao Y.-L., Zhu M.-Y. (2007): Tuzoia: Morphology and Lifestyle of a Large Bivalved Arthropod of the Cambrian Seas. Journal of Paleontology 81 (3), 445–471.

Zhao, J., Li, Yujing, Selden, Paul A. and Cong, Peiyun (2020): New occurrence of the Guanshan Lagerstatte (Cambrian Series 2, Stage 4) in the Kunming area, Yunnan, southwest China, with records of new taxa. ALCHERINGA: AN AUSTRALASIAN JOURNAL OF PALAEONTOLOGY, VOL. 44, NO. 3, 343–355 DOI: 10.1080/03115518.2020.1781257.
Izquierdo-López A, Caron J-B. (2022): The problematic Cambrian arthropod Tuzoia and the origin of mandibulates revisited. R. Soc. Open Sci. 9: 220933. https://doi.org/10.1098/rsos.220933.