Waukeshaaspis eatonae n. gen. n. sp.: A specialized dalmanitid (Trilobita) from the Telychian of southeastern Wisconsin

Abstract

A new dalmanitid trilobite is described from the early Silurian (Telychian) Waukesha Biota in Wisconsin, USA, best known for its variety of exceptionally preserved arthropods. Waukeshaaspis eatonae new genus new species is the most common trilobite found in the Waukesha Biota, numbering ∼200 specimens, allowing a thorough description of the dorsal exoskeleton. This new taxon has a combination of characters unique to the Dalmanitidae, including a distinct embayment on the posterior margin of the pygidium. Embayments are rare for dalmanitids, most species having instead a caudal spine. The lengthening of the genal spines might have served a similar function to that which a caudal spine would have served, allowing the embayment to fulfill a different function, related to keeping an opening when enrolled. The abundance at the preservation site suggests physiological tolerance at the habitation site.