Tokummia
| Tokummia Temporal range:
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Order: | †Hymenocarina |
| Family: | †Protocarididae |
| Genus: | †Tokummia |
| Species: | †T. katalepsis
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| Binomial name | |
| †Tokummia katalepsis Aria & Caron, 2017
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Tokummia is a genus of fossil hymenocarine arthropod, known only by one species, Tokummia katalepsis, from the middle Cambrian (508 million years old) Burgess Shale as found in a quarry in Marble Canyon in Canada.[1]
Etymology[edit]
The genus name Tokummia named after Tokumm Creek which runs through the Marble Canyon where it was found. The species name katalepsis means Greek word for "seizing", "gasping" or "holding".[1]
Morphology[edit]
Tokummia has a cylindrical body, with the anterior half covered by a 8.78 cm (3.46 in) long bivalved carapace. At the front of the animal, there are a pair of antennae, possible eyes, mouthparts (mandibles, maxillule and maxilla) and prominent pincer-like maxillipeds. These shows the oldest record of arthropod pincers. Posterior to the maxillipeds are 50 leg-bearing trunk segments. Each of its biramous leg has 5-segmented basipods, followed by an exopod (flap-like outer branch) and 7-segmented endopod (leg-like inner branch). The anterior 10 leg pairs have basipodal endites (inner spines) while the remaining leg pairs have widen exopods. The trunk terminated with a pair of caudal rami.[1]
Paleobiology[edit]
Tokummia is suggested to be a bottom feeder, being able to walk on the sea floor, and to occasionally swim, and used its pincers to catch prey.[2]
Taxonomy[edit]
According to the original description of Tokummia, hymenocarines like Tokummia, Branchiocaris, Canadaspis and Odaraia are stem group Mandibulata, the group includes myriapods, hexapods and crustaceans,[1] and this theory is supported in multiple subsequent studies.[3][4][5][6]
References[edit]
- ^ a b c d Aria, Cédric; Caron, Jean-Bernard (26 April 2017). "Burgess Shale fossils illustrate the origin of the mandibulate body plan". Nature. 545 (7652): 89–92. Bibcode:2017Natur.545...89A. doi:10.1038/nature22080. PMID 28445464. S2CID 4454526.
- ^ "Ouch! U of T paleontologists identify 508-million-year-old sea creature with can opener-like pincers". University of Toronto News.
- ^ Aria, Cédric; Caron, Jean-Bernard (2017-12-21). "Mandibulate convergence in an armoured Cambrian stem chelicerate". BMC Evolutionary Biology. 17 (1): 261. Bibcode:2017BMCEE..17..261A. doi:10.1186/s12862-017-1088-7. ISSN 1471-2148. PMC 5738823. PMID 29262772.
- ^ Zeng, Han; Zhao, Fangchen; Niu, Kecheng; Zhu, Maoyan; Huang, Diying (2020). "An early Cambrian euarthropod with radiodont-like raptorial appendages". Nature. 588 (7836): 101–105. Bibcode:2020Natur.588..101Z. doi:10.1038/s41586-020-2883-7. ISSN 1476-4687. PMID 33149303. S2CID 226248177.
- ^ Aria, Cédric; Zhao, Fangchen; Zhu, Maoyan (2021-03-22). "Fuxianhuiids are mandibulates and share affinities with total-group Myriapoda". Journal of the Geological Society. 178 (5). Bibcode:2021JGSoc.178..246A. doi:10.1144/jgs2020-246. ISSN 0016-7649. S2CID 233952670.
- ^ Izquierdo‐López, Alejandro; Caron, Jean‐Bernard (2021). Zhang, Xi‐Guang (ed.). "A Burgess Shale mandibulate arthropod with a pygidium: a case of convergent evolution". Papers in Palaeontology. 7 (4): 1877–1894. Bibcode:2021PPal....7.1877I. doi:10.1002/spp2.1366. ISSN 2056-2799. S2CID 236284813.
External links[edit]
- Fields, Lars (26 April 2017). Tokummia. Royal Ontario Museum.
- Fields, Lars (26 April 2017). Tokummia walkcycle. Royal Ontario Museum.
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