Ajacicrepida ajax

Order Asaphida / Superfamily Asaphoidea / Family Ceratopygidae

aja, from the species name ajax; crepidus, Latin, base. Referring to the species ajax being the base of the

ajax, Greek for eagle, the Latin name of the Greek hero Aias, implying vigour like an eagle.

Arionellus ajax; Lisania ajax; Lisania mirabilis; Ajacicrepida mopanshanensis; Laticeratopyge laevis

A small trilobite with smooth dorsal shield. Cranidium gently convex, subtrapezoidal, anterior margin slightly arched forward; dorsal, occipital and anterior border furrows shallow or indistinct; glabella wide and long, gently convex, truncate-conical with broadly rounded front, no glabellar furrows, a small median glabellar node near the occipital furrow posteriorly; occipital ring gently convex, wide medially, narrowing laterally; fixigenae narrow in the palpebral area; palpebral lobes short; preglabellar field extremely narrow or absent; anterior border rather wide, with a small subtriangular posterior spine on the sagittal line; posterior wings longitudinally wide, subtriangular; posterior border furrow extremely shallow. Librigenae rather wide, with medium-length genal spines. Thorax of 9 segments, axis tapering backward; pleural ends with recurved pleural spines, pleural furrows wide and flat. Pygidium extremely short and transversely wide; axis short, of 2 rings, with rounded posterior end; first pair of macropleural ribs extending into a pair of lateral spines; border narrow. With growth, the glabella widens, the glabellar furrows shallower until absent, the anterior border widens, the pygidium becomes shorter and wider, and the lateral pygidial spines lengthen.

This species is the type species of the genus Ajacicrepida.