Cucumericrus Temporal range: | |
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Trunk appengade of Cucumericrus decoratus | |
Scientific classification ![]() | |
Kingdom: | Animalia |
Stem group: | Arthropoda |
Genus: | † Cucumericrus Hou, Bergstrom & Ahlberg, 1995 |
Type species | |
Cucumericrus decoratus Hou, Bergstrom & Ahlberg, 1995 |
Cucumericrus ("cucumber-leg") is an extinct genus of stem-arthropod. The type and only species is Cucumericrus decoratus, with fossils discovered from the Maotianshan Shales of Yunnan, China. [1]
Cucumericrus is known from a few poorly preserved specimens. [1] [2] Only fragments of trunk cuticle and corresponding appendages had been revealed, while features, such as head structures, which are important to determining its taxonomy, are unknown. [2] [3] The trunk cuticle possess irregular wrinkles [1] and may had been soft in life. [4] Each of the trunk appendage compose of a dorsal flap-like element and a ventral stubby leg with unknown distal region, [1] structurally comparable to the trunk appendages of gill lobopodians (dorsal flaps and ventral lobopods) and euarthropod biramous appendages (flap-like exopod and limb-like endopod). [3] [5] Anterior margin of the flap lined with ray-like structures, similar to the body flaps of some radiodonts. The legs have been interpreted as somewhere between annulated lobopod legs and segmented arthropod legs. [4] [5]
Cucumericrus was originally described as a radiodont alongside Parapeytoia , a genus with somewhat similar trunk appendages, but later revealed to be a megacheiran [6] [7] [8] [9] being misinterpreted as a leg-bearing radiodont at that time. [1] The radiodont affinity of Cucumericrus remain questionable, since the presence of legs is unknown from any other radiodonts and no other radiodont key features (e.g. frontal appendages; oral cone; head sclerites) had been discovered. Only a few phylogenetic analysis including Cucumericrus, either resolving it in a polytomy between euarthropods and other radiodonts (alongside Caryosyntrips ) [10] [11] or closer to euarthropods (as a basal deuteropod) than radiodonts. [12]