Biology:Kerygmachela
Kerygmachela kierkegaardi is a kerygmachelid[1] gilled lobopodian from the Cambrian Stage 3 aged Sirius Passet Lagerstätte in northern Greenland. Its anatomy strongly suggests that it, along with its relative Pambdelurion whittingtoni, was a close relative of radiodonts (Anomalocaris and relatives) and euarthropods.[2][3] The generic name "Kerygmachela" derives from the Greek words Kerygma (proclamation) and Chela (claw), in reference to the flamboyant frontal appendages. The specific name, "kierkegaardi" honors Danish philosopher Søren Kierkegaard.[2][3]
Morphology
The head of Kerygmachela possesses a pair of well-developed frontal appendages which correspond to those of other dinocaridids and siberiid lobopodians.[4] Each of them terminates in a series of long spines. A pair of sessile, slit-like compound eyes is located slightly behind the base of these appendages.[3] A small anterior-facing mouth is located below the head and bears a pair of stylet-like structures.[3] The head also possesses a median lobe-like projection that carries a pair of small, possible ocular structures (median eye).[3] The body is composed of 11 segments, each indicated by 4 dorsal turberculates associated with 11 pairs of lateral flaps with dorsal gill-like wrinkling.[2] Initially, 11 pairs of small legs (lobopods) were thought to be evident just below the flaps,[2] but later observations suggest the lopobods were most likely absent, and the flaps were originated from ancestral lopobods instead.[5][1] The body ends with a single, stiff tail spine[3][1] that was formerly thought to be a pair of segmented cerci.[2][6]
Internally, Kerygmachela possesses a well-developed pharynx[3] and a midgut with 8 pairs of arthropod-like digestive glands.[7] The brain have ramified nerves extended to the median lobe, frontal appendages and eyes.[3] Only the protocerebrum (the frontal-most cerebral ganglion) was evident from the brain region, thus all of the other head nerves were considered protocerebral.[3] On the other hand, a subsequent study of radiodont Stanleycaris might suggest a deutocerebral origin for the frontal appendage nerves.[8]
Paleoecology
The absence of walking limbs suggests that Kerygmachela was a freely swimming (nektonic) predator, using the body flaps to swim,[1][5] and the large frontal appendages to grasp prey.[9]
Phylogeny
After McCall 2023:[1]
| Total group Euarthropoda |
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References
- ↑ 1.0 1.1 1.2 1.3 1.4 McCall, Christian R. A. (2023-12-13). "A large pelagic lobopodian from the Cambrian Pioche Shale of Nevada" (in en). Journal of Paleontology 97 (5): 1009–1024. doi:10.1017/jpa.2023.63. ISSN 0022-3360. Bibcode: 2023JPal...97.1009M. https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/large-pelagic-lobopodian-from-the-cambrian-pioche-shale-of-nevada/11B0704C49A7730AA3E8F46EB2CA1C95.
- ↑ 2.0 2.1 2.2 2.3 2.4 Budd, Graham E. (1993), "A Cambrian gilled lobopod from Greenland", Nature 364 (6439): 709–711, doi:10.1038/364709a0, Bibcode: 1993Natur.364..709B
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Park, Tae-Yoon S.; Kihm, Ji-Hoon; Woo, Jusun; Park, Changkun; Lee, Won Young; Smith, M. Paul; Harper, David A. T.; Young, Fletcher et al. (2018-03-09). "Brain and eyes of Kerygmachela reveal protocerebral ancestry of the panarthropod head" (in en). Nature Communications 9 (1): 1019. doi:10.1038/s41467-018-03464-w. ISSN 2041-1723. PMID 29523785. Bibcode: 2018NatCo...9.1019P.
- ↑ Ortega-Hernández, Javier (2016). "Making sense of 'lower' and 'upper' stem-group Euarthropoda, with comments on the strict use of the name Arthropoda von Siebold, 1848" (in en). Biological Reviews 91 (1): 255–273. doi:10.1111/brv.12168. ISSN 1469-185X. PMID 25528950. Bibcode: 2016BioRv..91..255O. https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12168.
- ↑ 5.0 5.1 Lerosey-Aubril, Rudy; Ortega-Hernández, Javier (May 2022). Zhang, Xi-Guang. ed. "A new lobopodian from the middle Cambrian of Utah: did swimming body flaps convergently evolve in stem-group arthropods?" (in en). Papers in Palaeontology 8 (3). doi:10.1002/spp2.1450. ISSN 2056-2799. Bibcode: 2022PPal....8E1450L. https://onlinelibrary.wiley.com/doi/10.1002/spp2.1450.
- ↑ Leanchoilia guts and the interpretation of three-dimensional structures in Burgess Shale-type fossils, Paleobiology, http://paleobiol.geoscienceworld.org/cgi/reprint/28/1/155
- ↑ Vannier, Jean; Liu, Jianni; Lerosey-Aubril, Rudy; Vinther, Jakob; Daley, Allison C. (2014-05-02). "Sophisticated digestive systems in early arthropods" (in en). Nature Communications 5 (1): 3641. doi:10.1038/ncomms4641. ISSN 2041-1723. PMID 24785191. Bibcode: 2014NatCo...5.3641V.
- ↑ Moysiuk, Joseph; Caron, Jean-Bernard (2022). "A three-eyed radiodont with fossilized neuroanatomy informs the origin of the arthropod head and segmentation". Current Biology 32 (15): 3302–3316.e2. doi:10.1016/j.cub.2022.06.027. ISSN 0960-9822. PMID 35809569. Bibcode: 2022CBio...32E3302M.
- ↑ Haug, Joachim T.; Waloszek, Dieter; Maas, Andreas; Liu, Yu; Haug, Carolin (March 2012). "Functional morphology, ontogeny and evolution of mantis shrimp-like predators in the Cambrian" (in en). Palaeontology 55 (2): 369–399. doi:10.1111/j.1475-4983.2011.01124.x. ISSN 0031-0239. Bibcode: 2012Palgy..55..369H. https://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2011.01124.x.
Further reading
- Budd, G. E. (1999), "The morphology and phylogenetic significance of Kerygmachela kierkegaardi Budd (Buen Formation, Lower Cambrian, N Greenland)", Transactions of the Royal Society of Edinburgh 89 (4): 249–290, doi:10.1017/S0263593300002418
External links
Template:Lobopodia Template:Dinocaridida Wikidata ☰ Q138450 entry
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