| Kerygmachela | |
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| Fossil ofKerygmachela kierkegaardi from the Sirius passet site | |
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| Reconstruction ofKerygmachela kierkegaardi based on later observations.[1] | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Family: | †Kerygmachelidae |
| Genus: | †Kerygmachela Budd, 1993 |
| Species: | †K. kierkegaardi |
| Binomial name | |
| †Kerygmachela kierkegaardi Budd, 1993 | |
Kerygmachela kierkegaardi is akerygmachelid[2]gilled lobopodian from theCambrian Stage 3 agedSirius PassetLagerstätte in northernGreenland. Its anatomy strongly suggests that it, along with its relativePambdelurion whittingtoni, was a close relative ofradiodont (Anomalocaris and relatives) andeuarthropods.[3][1] Thegeneric name "Kerygmachela" derives from theGreek wordsKerygma (proclamation) andChela (claw), in reference to the flamboyant frontal appendages. Thespecific name, "kierkegaardi" honorsDanish philosopherSøren Kierkegaard.[3][1]
The head ofKerygmachela possesses a pair of well-developed frontal appendages which correspond to those of otherdinocaridids andsiberiid lobopodians.[4] Each of them terminates in a series of long spines. A pair of sessile, slit-likecompound 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 thought 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 segmentedcerci.[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 cerebralganglion) 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 radiodontStanleycaris might suggest a deutocerebral origin for the frontal appendage nerves.[8]
The spiny frontal appendages suggests thatKerygmachela 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.
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| TheCambrian explosion |
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Fossil localities |
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