Description

Description. The disassociated exoskeleton indicates that the sag. length of the cephalon (to the base of the anterior spine) is similar in length to the rest of the thorax + pygidium. Glabella with the shape of a narrow and elongate rhomb. There is no indication of lateral glabellar muscle impressions, nor of the lateral lobes developed by some species attributed to Lonchodomas. The maximum glabellar width is probably slightly less than half its length. The transverse convexity of the glabella is very low posteriorly, hardly elevated above the cheeks, and the occipital ring is hardly defined. An indistinct median crest runs along the anterior half of the glabella and is extended into a stout frontal spine of unknown length, which from its base probably had a prismatic cross section. Posterior border furrow shallows towards glabella; so far as it can be observed posterior border arches slightly forwards. Free cheeks not observed. Four thoracic segments clearly shown, and traces of the fifth, posterior segment to the left of the pygidium; thorax is probably subparallel sided, or with a gentle posterior taper. Transverse width of pleurae similar to that of axis, which is weakly convex; long (sag.) articulating half rings present. Pleural tips truncate; weak pleural furrows just posterior to median line and gently concave. Pygidium distinctive, just over twice as wide as long, with a moderately well-defined axis initially just over one-third anterior pygidial width, and this similar to its length, making a neat isosceles triangle as it tapers to border, axial furrows enclosing an angle of 50 degrees. Apart from half-ring, ring furrows not expressed. Distinct anterior pleural furrow elegantly concave laterally, and behind it one shallow but straight pleural furrow making a near right angle to the axial furrow and extending to border. Border itself is steeply downturned and of similar height along its length.

Common Names

Taxonomic Hierarchy

Kingdom: Animalia

Phylum: Arthropoda

Class: Trilobita

Order: Asaphida

Family: Raphiophoridae

Genus: Lonchodomas

Species: Lonchodomas shanensis (Reed, 1915)