Suborder Trinucleina Subfamily Raphiophorinae | Class Trilobita | |
Genus LonchodomasAngelin, 1854 Similar Cyrtometopus, Illaenus, Pliomera, Cybele bellatula, Megistaspis | ||
Lonchodomas is a genus of trilobites, that lived during the Ordovician. It was eyeless, like all raphiophorids, and had a long straight sword-like frontal spine, that gradually transforms into the relatively long glabella. Both the glabellar spine and the backward directed genal spines are subquadrate in section. Lonchodomas has five thorax segments and the pleural area of the pygidium has two narrow furrows. Lonchodomas occurred in what are today Argentina, Canada (Newfoundland), Estonia, Latvia, Norway, the Russian Federation (St. Petersburg region) and the United States (Oklahoma, Virginia).
Contents
Distribution
Description
Like all raphiophorids, Lochodomas is eyeless. The headshield (or cephalon) and tailshield (or pygidium) are subtriangular in outline. Lonchodomas looks a lot like Ampyx but the glabella is diamond-shaped in outline, and it has a ridge along the midline (it is carinate). The glabella gradually transforms into the spine, which makes it difficult to determine where the spine begins. The long median glabellar spine is subquadrate in section and is directed horizontally forward, from the frontal tip of the glabella. The glabella has 2 pairs of muscle scars. The genal spines are also subquadrate in section. The thorax has 5 segments. The pleural regions of pygidium have 2 pairs of narrow pleural furrows.
