Lonchodomas clavulus

Lonchodomas Temporal range: Ordovician PreЄ Є O S D C P T J K Pg N
Lonchodomas mcgeheei, from the Bromide Formation, Carter County, Oklahoma
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Trilobita
Order:	Asaphida
Suborder:	Trinucleina
Family:	Raphiophoridae
Subfamily:	Raphiophorinae
Genus:	Lonchodomas Angelin, 1854
Species
L. rostratus (Sars, 1835) (type species) synonym Ampyx rostrata L. carinatus Cooper, 1953 L. clavulus Whittington, 1965 L. mcgeheei (Decker, 1931) synonym Ampyx mcgeheei L. retrolatus Ross jr. & Barnes, 1967 L. suriensis Harrington & Leanza, 1957 L. volborthi (Schmidt, 1894)

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).

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.