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Extinct genus of arthropod From Wikipedia, the free encyclopedia
Tuzoia (from Mount Tuzo, a mountain in the Canadian Rockies) is an extinct genus of large bivalved arthropod known from Early to Middle Cambrian marine environments from what is now North America, Australia, China, Europe and Siberia. The large, domed carapace reached lengths of 180 millimetres (7.1 in), making them amongst the largest known Cambrian arthropods.
Tuzoia Temporal range: | |
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Carapace of Tuzoia retifera | |
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Life restoration | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Order: | †Hymenocarina |
Family: | †Tuzoiidae |
Genus: | †Tuzoia Walcott, 1912 |
Type species | |
Tuzoia retifera Walcott, 1912 | |
Species | |
The largest carapaces of Tuzoia are known to reach 18 cm (7.1 in) in length, suggesting a total body length of approximately 23 cm (9.1 in).[1] Along the sides of the carapace a spiked ridge is present, and the edges and midline of the carapace are also spiked in many species. These spines likely functioned to aid stability while swimming. The carapaces are marked with a reticulate (net-like) pattern, which was likely to increase the structural integrity of the valves while remaining lightweight.[2][3] The head had a anterior/ocular sclerite at the top, a single pair of large stalked eyes, and a pair of segmented antennae. The head also bore pairs of cephalic appendages, which have curved setae. The first two limb pairs, dubbed the "cephalothoracic legs" have 7 podomeres, with spinose endites, with the legs ending in a terminal claw. The basipods are greatly elongated, and bears 5 to 6 endites, which become spinose at their ends. It is unclear whether exopods are present on these limbs. There are likely 10 pairs of trunk legs excluding the cephalothoracic legs. These had seven podomeres, the first with a spinose endite, with the limb ending in a terminal claw, and a similarly elongated basipod, which had a spine proximal to that of the first podomere. These limbs likely had paddle-shaped exopods. The body terminates with a large tail fan.[1]
Tuzoia was likely an actively swimming organism. It had historically been considered a pelagic organism, due to their wide distribution. However, the soft tissues described in 2022 suggest an alternative interpretation as an animal that swam close to the seafloor (nektobenthic) as a predator or a scavenger. Tuzoia was likely capable of walking along the seafloor with the carpace flexing outwards to allow the legs to contact the substrate.[1]
They were formerly considered to be the only members of the family Tuzoiidae until 2022, when a new genus Duplapex was described from the Cambrian of China, which differs from Tuzoia by having a flat carapace. Their phylogenetic position was long uncertain due to the lack of soft tissue remains, a close relationship with Isoxys was proposed based on similarities of their carapaces.[4] However soft tissues described in 2022 suggest instead that Tuzoia was a member of Mandibulata, as the earliest diverging member of a paraphyletic Hymenocarina, and that similarities to isoxyids may be due to retained plesiomorphies.[1]
After Vannier et al., 2007, and subsequent literature:[2][5]
Indeterminate remains are also known from the Buchava Formation and Jince Formation of the Czech Republic.[2][9] As well as the Sinsk Lagerstatte of Siberia.[10][5]