Apankura

Apankura Temporal range:
Reconstruction of A. machu
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subclass:	†Euthycarcinoidea
Genus:	†Apankura Vaccari et al., 2004
Species:	†A. machu
Binomial name
†Apankura machu Vaccari et al., 2004

Apankura machu is a Cambrian euthycarcinoid from the Santa Rosita Formation of Argentina. It was at one point the only Cambrian euthycarcinoid. However, Mosineia and Mictomerus are likely older.

Description

Apankura is roughly 4 cm long, and has large mandibles, a trait previously unknown from euthycarcinoids. The antennae are uniramous like other euthycarcinoids, with a possible buccal complex present behind the mandibles. No post-mandibular oral appendages are present. The pre-abdomen is composed of five tergites, with 11 uniramous limb pairs, with the tergites showing "segment decoupling" where there are more limbs than tergites. The pre-abdomen also has 11 sternites, each roughly 3 times wider than long. The pre-abdominal limbs match other euthycarcinoids, although they taper distally and lack setae. The apodemes are preserved as several dark rods. The post-abdomen is incomplete but composed of at least six segments, all lacking limbs, with the gut preserved as a dark line in the centre. A circular structure on the second post-abdominal segment is of unclear function, although it may be a gonopore. Apankura is unique among euthycarcinoids due to the reduced anterior pre-abdominal limbs, a longer post-abdomen and relatively few limb podomeres.

Etymology

Apankura derives from a Quechua word meaning "crab", whilst machu derives from a word meaning "grandfather" in reference to the age of the fossils.