Pictorial Guide to the Trilobite Order Harpetida

PICTORIAL GUIDE
TO THE ORDER HARPETIDA
last revised 14 July 2007 by S. M. Gon III

ORDER HARPETIDA

Click here to return to Harpetida Fact Sheet

Here is more detail on advanced Harpetida (Harpetidae) cephalic features:

Here are some representative Harpetida:

Entomaspididae Entomaspis	Harpididae Harpides	Harpetidae Harpes	Harpididae Dictyocephalites	Harpetidae Dolichoharpes	Harpetidae Eoharpes

Compare the pictorial format above with the descriptive narrative below:

ORDER HARPETIDA
Introduction: Recently split from the Ptychopariida (Ebach & McNamara 2002), advanced members (Harpetidae) easily distinguished by marginal sutures and lack of rostral plate, as well as the presence of the "harpetid brim."
Cephalon: semicircular to ovate; fringe inclined, consisting of vaulted inner genal roll, which is convex or flat, and an outer bilaminar brim, either flat, convex or concave, extending posteriorly to long, flat genal prolongations; facial sutures marginal, in Entomaspididae involving the eyes, but with anterior and posterior sections running close together toward otherwise marginal sutures; glabella convex, narrowing forwards, with 1 to 3 pairs of furrows, posterior pair isolating triangular basal lobes; occipital ring convex; alae typically present; preglabellar field broad, sloping down to flat or upwardly concave border; eyes commonly reduced to prominent tubercles, centrally located on genae, strong eye ridges present; external surface of cephalon may be tuberculose or granulose.
Thorax: with 12 or (frequently) more segments, pleurae flattened, with broad axial furrows.
Pygidium: subtriangular, elongate to short.
Families: Entomaspididae, Harpetidae, Harpididae (=Loganopeltidae).
Occurrence: Upper Cambrian to Late Devonian (Frasnian).
Representative Genera: Bohemoharpes, Brachyhipposiderus, Dolichoharpes, Dubhglasina, Entomaspis, Eoharpes, Harpes, Harpides, Kielania, Lioharpes, Loganopeltis, Hibbertia (formerly Paraharpes), Scotoharpes (formerly Aristoharpes)

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