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Additional Information
As with most early trilobites, Archaeaspis has an almost flat exoskeleton that is only thinly calcified, and has crescent-shaped eye ridges. As part of the Olenellina suborder, Archaeaspis lack dorsal sutures. The superfamily Fallotaspidoidea, to which Archaeaspis belongs can be distinguished from all other Olenellina by features of the cephalon and in particular the glabella.
The Campito Formation is a 1300 m thick upper Precambrian(?)Lower Cambrian sequence of siliciclastic rocks that crop out extensively in western Nevada and eastern California. The formation comprises two members: the Andrews Mountain Member and the gradationally overlying Montenegro Member. The Andrews Mountain Member consists of complexely interbedded, dark-colored feldspathic quartzites, siltstones and mudstones. The Montenergro Member is composed mostly of siltstones and mudstones.
Vendor: fossil soup - ZZ
SKU Number: SQ5388284
Rhombampyx yii trilobite from the Middle Ordovician, Meitan Formation, Zunyi, Guizhou, China.
The distinct oval/rhomboid dome where the anterior needle spine meets the head is the highly inflated glabella. It is slightly compressed but shows the distinctive bulbous shape unique to raphiophorids.
You can clearly see a thin, straight line pointing straight up from the top of the glabella. This is the base of the median snout spine.
The two elongated cheek spines can be seen on either side of the body. In life, these spines flared outward to stabilize the animal or deter predators, but post-mortem movement or burial compaction has curved it around the cephalon.
Full dimensions are listed below.