Biology:Tokummia
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
The genus name Tokummia named after Tokumm Creek which runs through the Marble Canyon where it was found. The species name katalepsis is a Greek word for "seizing", "gasping" or "holding".[1]
Morphology
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
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
Tokummia is placed in the family Protocarididae along with Branchiocaris, Protocaris and Loricicaris. Protocarididae is placed within the broader group Hymenocarina, which includes numerous arthropods with bivalved carapaces. Hymenocarina is placed within Mandibulata, which also includes myriapods (milipedes and centipedes), hexapods (including insects) and crustaceans,[1][3][4][5][6]
Cladogram of Hymenocarina, following Izquierdo-López and Caron, (2024):[7]
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References
- ↑ 1.0 1.1 1.2 1.3 Aria, Cédric; Caron, Jean-Bernard (26 April 2017). "Burgess Shale fossils illustrate the origin of the mandibulate body plan". Nature 545 (7652): 89–92. doi:10.1038/nature22080. PMID 28445464. Bibcode: 2017Natur.545...89A.
- ↑ "Ouch! U of T paleontologists identify 508-million-year-old sea creature with can opener-like pincers" (in en). https://www.utoronto.ca/news/ouch-u-t-paleontologists-identify-508-million-year-old-sea-creature-can-opener-pincers.
- ↑ Aria, Cédric; Caron, Jean-Bernard (2017-12-21). "Mandibulate convergence in an armoured Cambrian stem chelicerate". BMC Evolutionary Biology 17 (1): 261. doi:10.1186/s12862-017-1088-7. ISSN 1471-2148. PMID 29262772. Bibcode: 2017BMCEE..17..261A.
- ↑ Zeng, Han; Zhao, Fangchen; Niu, Kecheng; Zhu, Maoyan; Huang, Diying (2020). "An early Cambrian euarthropod with radiodont-like raptorial appendages" (in en). Nature 588 (7836): 101–105. doi:10.1038/s41586-020-2883-7. ISSN 1476-4687. PMID 33149303. Bibcode: 2020Natur.588..101Z. https://www.nature.com/articles/s41586-020-2883-7.
- ↑ 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). doi:10.1144/jgs2020-246. ISSN 0016-7649. Bibcode: 2021JGSoc.178..246A. https://doi.org/10.1144/jgs2020-246.
- ↑ Izquierdo-López, Alejandro; Caron, Jean-Bernard (2021). Zhang, Xi-Guang. ed. "A Burgess Shale mandibulate arthropod with a pygidium: a case of convergent evolution" (in en). Papers in Palaeontology 7 (4): 1877–1894. doi:10.1002/spp2.1366. ISSN 2056-2799. Bibcode: 2021PPal....7.1877I. https://onlinelibrary.wiley.com/doi/10.1002/spp2.1366.
- ↑ Izquierdo-López, Alejandro; Caron, Jean-Bernard (August 2024). "The Cambrian Odaraia alata and the colonization of nektonic suspension-feeding niches by early mandibulates" (in en). Proceedings of the Royal Society B: Biological Sciences 291 (2027). doi:10.1098/rspb.2024.0622. ISSN 1471-2954. PMID 39043240. PMC 11463219. https://royalsocietypublishing.org/doi/10.1098/rspb.2024.0622.
External links
- Fields, Lars (26 April 2017). Tokummia. Royal Ontario Museum.
- Fields, Lars (26 April 2017). Tokummia walkcycle. Royal Ontario Museum.
Template:Hymenocarina Wikidata ☰ Q29585082 entry
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