Cucumericrus
Extinct genus of arthropod From Wikipedia, the free encyclopedia
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 Temporal range: | |
|---|---|
| |
| Trunk appengade of Cucumericrus decoratus | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Stem group: | Arthropoda |
| Genus: | †Cucumericrus Hou, Bergstrom & Ahlberg, 1995 |
| Type species | |
| Cucumericrus decoratus Hou, Bergstrom & Ahlberg, 1995 | |
Description
Cucumericrus known from a few poorly preserved specimens.[1][2] Only fragments of trunk cuticle and corresponded appendages had been revealed, while important taxonomic features such as head structures 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]
Taxonomic affinities
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]
See also
- Caryosyntrips, another stem-arthropod with similar uncertainties.
- Parapeytoia, a megacheiran once thought to be similarly leg-bearing radiodont.
- Erratus, a basal deuteropod with similar component of trunk appendages.
References
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