''Kerygmachela kierkegaardi'' is a kerygmachelid gilled lobopodian from the

Cambrian Stage 3 Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base nor top have been formally defined. The plan is for its lower boundary to correspond approxima ...

aged

Sirius Passet Sirius Passet is a Cambrian Lagerstätte in Peary Land, Greenland. The Sirius Passet Lagerstätte was named after the Slædepatruljen Sirius, Sirius sledge patrol that operates in North Greenland. It comprises six places in Nansen Land, on the eas ...

Lagerstätte A Fossil-Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that preserves an exceptionally high amount of palaeontological information. ''Konzentrat-Lagerstätten'' preserv ...

in northern

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

. Its anatomy strongly suggests that it, along with its relative '' Pambdelurion whittingtoni'', was a close relative of

radiodont Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and were used for a variety ...

(''

Anomalocaris ''Anomalocaris'' (from Ancient Greek , meaning "unlike", and , meaning "shrimp", with the intended meaning "unlike other shrimp") is an extinct genus of radiodont, an order of early-diverging stem-group marine arthropods. It is best known fro ...

'' and relatives) and euarthropods. The generic name "''Kerygmachela''" derives from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

words ''Kerygma'' (proclamation) and ''Chela'' (claw), in reference to the flamboyant frontal appendages. The specific name, "''kierkegaardi''" honors Danish philosopher

Søren Kierkegaard Søren Aabye Kierkegaard ( , ; ; 5 May 1813 – 11 November 1855) was a Danes, Danish theologian, philosopher, poet, social critic, and religious author who is widely considered to be the first existentialist philosopher. He wrote critical tex ...

Morphology

20191029 Kerygmachela brain and digestive system

The head of ''Kerygmachela'' possesses a pair of well-developed frontal appendages which correspond to those of other dinocaridids and siberiid lobopodians. Each of them terminates in a series of long spines. A pair of sessile, slit-like

compound eye A compound eye is a Eye, visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidium, ommatidia, which are tiny independent photoreception units that consist of a cornea, lens (anatomy), lens, and p ...

s is located slightly behind the base of these appendages. A small anterior-facing mouth is located below the head and bears a pair of stylet-like structures. The head also possesses a median lobe-like projection that carries a pair of small, possible ocular structures (median eye). 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. Initially, 11 pairs of small legs (lobopods) were thought to be evident just below the flaps, but later observations suggest the lopobods were most likely absent, and the flaps were originated from ancestral lopobods instead. The body ends with a single, stiff tail spine that was formerly thought to be a pair of segmented cerci. Internally, ''Kerygmachela'' possesses a well-developed pharynx and a midgut with 8 pairs of arthropod-like digestive glands. The brain have ramified nerves extended to the median lobe, frontal appendages and eyes. Only the protocerebrum (the frontal-most cerebral

ganglion A ganglion (: ganglia) is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system, this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system, there are ...

) was evident from the brain region, thus all of the other head nerves were considered protocerebral. On the other hand, a subsequent study of radiodont '' Stanleycaris'' might suggest a deutocerebral origin for the frontal appendage nerves.

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

External links

* Anomalocarid Homepag

*

Palaeos Palaeos.com is a web site on biology, paleontology, phylogeny and geology and which covers the history of Earth. The site is well respected and has been used as a reference by professional paleontologists such as Michael J. Benton, the professor of ...

Dinocaridida Prehistoric arthropod genera Cambrian arthropods Cambrian Greenland Fossils of Greenland Sirius Passet fossils Buen Formation Fossil taxa described in 1993 Søren Kierkegaard Cambrian genus extinctions {{paleo-arthropod-stub

Morphology

Paleoecology

References

Further reading

External links