Biology:Kerygmachela

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Short description: Extinct gilled lobopod

Kerygmachela
Temporal range: Cambrian Stage 3
Kerygmachela kierkegaardi. MGUH 32054.jpg
Fossil of Kerygmachela kierkegaardi from the Sirius passet site
20191022 Kerygmachela kierkegaardi without lobopods.png
Reconstruction of Kerygmachela kierkegaardi based on later observations.[1]
Scientific classification edit
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: †Dinocaridida
Family: †Kerygmachelidae
Genus: †Kerygmachela
Budd, 1993
Species:
†K. kierkegaardi
Binomial name
†Kerygmachela kierkegaardi
Budd, 1993

Kerygmachela kierkegaardi is a kerygmachelid[2] 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 radiodont (Anomalocaris and relatives) and euarthropods.[3][1] 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 Denmark philosopher Søren Kierkegaard.[3][1]

Morphology

Eyes (deep blue), brain (light blue) and digestive system (yellow) of Kerygmachela.

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.[1] A small anterior-facing mouth is located below the head and bears a pair of stylet-like structures.[1] The head also possesses a median lobe-like projection that carries a pair of small, possible ocular structures (median eye).[1] 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.[3] Initially, 11 pairs of small legs (lobopods) were though to be evident just below the flaps,[3] but later observations suggest the lopobods were most likely absent, and the flaps were originated from ancestral lopobods instead.[5][2] The body ends with a single, stiff tail spine[1][2] that was formerly thought to be a pair of segmented cerci.[3][6]

Internally, Kerygmachela possesses a well-developed pharynx[1] 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.[1] Only the protocerebrum (the frontal-most cerebral ganglion) was evident from the brain region, thus all of the other head nerves were considered protocerebral.[1] On the other hand, a subsequent study of radiodont Stanleycaris might suggest a deutocerebral origin for the frontal appendage nerves.[8]

Paleoecology

The spiny frontal appendages suggests that Kerygmachela may have been a predator; however, fossils indicate a total size of approximately 175 mm and, with a relatively small mouth, suggest that it would have been restricted to very small prey.


References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 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. 
  2. ↑ 2.0 2.1 2.2 McCall, Christian R. A. (2023-12-13). "A large pelagic lobopodian from the Cambrian Pioche Shale of Nevada" (in en). Journal of Paleontology: 1–16. doi:10.1017/jpa.2023.63. ISSN 0022-3360. https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/large-pelagic-lobopodian-from-the-cambrian-pioche-shale-of-nevada/11B0704C49A7730AA3E8F46EB2CA1C95. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Budd, Graham E. (1993), "A Cambrian gilled lobopod from Greenland", Nature 364 (6439): 709–711, doi:10.1038/364709a0 
  4. ↑ 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. https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12168. 
  5. ↑ 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. https://onlinelibrary.wiley.com/doi/10.1002/spp2.1450. 
  6. ↑ Leanchoilia guts and the interpretation of three-dimensional structures in Burgess Shale-type fossils, Paleobiology, http://paleobiol.geoscienceworld.org/cgi/reprint/28/1/155 
  7. ↑ 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. 
  8. ↑ 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. https://doi.org/10.1016/j.cub.2022.06.027. 

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

  • Anomalocarid Homepage [1]
  • Palaeos - [2]

Wikidata ☰ Q138450 entry




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