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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.

Synonym: †Archotuba conoidalis Hou et al., 1999, †Cambrorhytium sp. Chen & Zhou, 1997 Quote from ‘The Cambrian Fossils of Chengjiang, China: The Flowering of Early Animal Life, Second Edition’: Hou Xian-Guang et al., p. 136: “This species is relatively common with hundreds of known specimens, which are essentially the remains of the tubes of the animal. All of the specimens are preserved as compressed fossils, in which a whitish color, sometimes with rusty patches. No proboscis or other soft parts of the animal have been discovered. The tube is shaped like an elongated cone. Large individuals can reach 5cm in length and 6mm in diameter for the wide opening, with a sharply pointed posterior end. The surface of the tube is smooth and and lacks ornamentation, but a few specimens show sparsely distributed annulations. Parts of the intestine can be seen through the tube as a dark longitunal structure running down the midline of the fossil. Archotuba is monospecific. A. elongata was originally reported as Selkirkia? elongata Luo & Hu, 1999. Chengjiang material recorded under the name Cambrorhytium sp. nov. of Chen & Zhou, 1997 and the species Archotuba conoidalis Hou et al., 1999 are considered to be the same species as A. elongata. A. elongata shows similarities to the other Cambrian tube-dwelling genera Selkirkia and Paraselkirkia and phylogenetic position of A. elongata remains problematic. It was originally assigned to Priapulida (Luo et al. 1999; Hou et al. 1999), but others have suggested that it might be related to cnidarians (Chen Jun-yuan & Zhou 1997; Chen Jun-yuan 2004; Huang 2005).” This species is often found fixed to other creatures, and even clustered together with its own kind in similar orientations. A sessile lifestyle would suggest against an assignment to Priapulidae. However, if indeed they were sedentary like the cnidarians, no tentacles have been preserved to support such a conjecture. References: Luo Hui‐lin, Hu Shi‐xue, Chen Liang‐zhong, Zhang Shi‐shan & Tao Yong‐he (1999): Early Cambrian Chengjiang Fauna from Kunming Region, China. 129 pp, 32 pls. Yunnan Science and Technology Press, Kunming [in Chinese, with English summary]. The Cambrian Fossils of Chengjiang, China: The Flowering of Early Animal Life, Second Edition’: Hou Xian-Guang, David J. Siveter, Derek J. Siveter, Richard J. Aldridge, Cong Pei-Yun, Sarah E. Gabbott, Ma Xiao-Ma, Mark A. Purnell, Mark Williams (DOI:10.1002/9781118896372). Luo Hui‐lin, Hu Shi‐xue, Chen Liang‐zhong, Zhang Shi‐shan & Tao Yong‐he (1999): Early Cambrian Chengjiang Fauna from Kunming Region, China. 129 pp, 32 pls. Yunnan Science and Technology Press, Kunming [in Chinese, with English summary]. Chen Jun‐yuan & Zhou Gui‐qing (1997): Biology of the Chengjiang fauna. Bulletin of the National Museum of Natural Science, 10, 11–106. Hou Xian‐guang, Bergström, J., Wang Hai‐feng, Feng Xiang‐ hong & Chen Ai‐lin (1999): The Chengjiang Fauna. Exceptionally Well‐Preserved Animals from 530 Million Years Ago. 170 pp. Yunnan Science and Technology Press, Kunming, Yunnan Province, China [in Chinese, with English summary]. Chen Jun‐yuan (2004): The Dawn of Animal World. 366pp. Jiangsu Science and Technology Press, Nanjing, Jiangsu Province, China [in Chinese]. Chen Jun‐yuan & Zhou Gui‐qing (1997): Biology of the Chengjiang fauna. Bulletin of the National Museum of Natural Science, 10, 11–106. Huang Di‐ying (2005): Early Cambrian worms from SW China: morphology, systematics, lifestyles and evolutionary significance. PhD thesis, University Claude Bernard Lyon 1, France, 247 pp.

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): Identified by oilshale using Luo et al., 2006. References: P’an, K., (1957): On the discovery of Homopoda from South China. Acta Palaeontologica Sinica 5, 523–526. 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., 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

Gangtoucunia, a member of the Guanshan fauna, is a genus of worm-like creatures originally assigned to the Archaeopriapulids for uncertain reasons. However, according to studies by Zhang et al, 2022, these are creatures with cnidarian affinity within the subphyllum Medusozoa. Emended diagnosis from Zhang et al., 2022 p. 2: "Elongated, tubular polypoid cnidarian that secreted an organophosphatic dwelling tube. The external surface of the tube is transversely annulated with dense and irregular growth lines and has a basal, discshaped holdfast. The tube is elongate with a slight, gradual proximal tapering. The polyp has a single whorl of circumoral tentacles of unknown total length. The polyp body is externally smooth. Internally, the gut is divided by numerous longitudinal septa that partition an elongate gut extending along the preserved length of the body." References: Luo H L, Hu S X, Chen L Z, et al. Early Cambrian Chengjiang Fauna from Kunming Region, China (in Chinese with English summary). Kunming: Yunnan Science and Technology Press, 1999. 129 S. X. HU, M. Y. Zhu, M. Steiner, H. L. Luo, F. C. Zhao and Q. Liu. 2010. Biodiversity and taphonomy of the Early Cambrian Guanshan biota, eastern Yunnan. Science China Earth Sciences 53(12):1765-1773 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. Zhang G, Parry LA, Vinther J, Ma X. 2022 Exceptional soft tissue preservation reveals a cnidarian affinity for a Cambrian phosphatic tubicolous enigma. Proc. R. Soc. B 289: 20221623. https://doi.org/10.1098/rspb.2022.1623