Aglaspida

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Aglaspida
Fossil range: Cambrian - ?Ordovician

Aglaspis spinifer

Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Superclass:	Aglaspida† Walcott, 1911

Families

Aglaspididae
Lemoneitidae
Beckwithiidae
?Strabopidae

The Aglaspida, more correctly termed Aglaspidida, were a group of small, horseshoe crab-like arthropods that were once regarded as being basal or ancestral horseshoe crabs. Now, though, they are regarded as a distinct group, possibly being close to the trilobites. The older idea that they link trilobites with Chelicerata has fallen out of favour.

Aglaspid fossils are found throughout the world, including North America (upper Mississippi valley, Missouri and Utah), Europe, and Australia.

As of 1997, Hou & Bergström split off Strabopidae (which were once regarded as being primitive eurypterids), including the genera Strabops, Paleomerus, Parapaleomerus, and Neostrabops, as its own distinct order/taxon, "Strabopida."

[edit] List of Genera

Aglaspella
Aglaspis
Aglaspoides
Angarocaris
Beckwithia
Borchgrevingkium
Craspedops
Cyclopites
Flobertia
Girardevia
Glypharthrus
Kodymirus
Neostrabops
Setaspis
Sinaglaspis
Strabops
Triopus
Tuboculops
Uarthrus

[edit] References

Hesselbo, SP. 1992. Aglaspidida (Arthropoda) from the Upper Cambrian of Wisconsin. Journal of Paleontology 66(6)885-923.
Raasch, GO. 1939. Cambrian Merostomata. Geological Society of America Special Paper 19, 146p.