New records of Burgess Shale-type taxa from the middle Cambrian of Utah

Abstract

Abstract.-Cambrian strata of the Laurentian craton contain numerous examples of Burgess Shale-type faunas. Although displaying a more or less concentric distribution around the cratonal margin, most faunal occurrences are in present-day western North America, extending from the Northwest Territories to California. Nevertheless, the soft-bodied and lightly skeletalized fossils in most of these Lagerstätten are highly sporadic. Here, we extend knowledge of such Middle Cambrian occurrences in Utah with reports of four taxa. An arthropod from the Marjum Formation, Dytikosicula desmatae gen. et sp. nov., is a putative megacheiran. It is most similar to Dicranocaris guntherorum, best known from the younger Wheeler Formation, but differs primarily in the arrangement of pleurae and overall size. Along with a specimen of ?Yohoia sp, a new species of Yohoia, Y. utahana sp. nov., is described. It differs from the type and only known species, Y. tenuis, principally in its larger size and shorter exopods; it is the first description of this genus from outside the Burgess Shale. A new species of a stem-group lophotrochozoan from the Spence Shale, Wiwaxia herka sp. nov., possesses a palisade of dorso-lateral spines that are more robust and numerous than the type species of Wiwaxia, W. corrugata. Another notable taxon is Eldonia ludwigi from the Marjum Formation, which is interpreted as a primitive ambulacrarian (assigned to the cambroernids) and a new specimen of the ?cnidarian Cambrorhytium from the Wheeler Shale is illustrated.

Orthrozanclus elongata n. sp. and the significance of sclerite-covered taxa for early trochozoan evolution

“…3c). The two dorsal rows of spines in Wiwaxia are highly variable in their number, size, spacing, and orientation, both within and between species 8,15,25 , so do not form a distinct region of the scleritome architecture. As such, the peripheral sclerite zones in Orthrozanclus (Fig.…”

A cryptic record of Burgess Shale‐type diversity from the early Cambrian of Baltica

“…); 10*, File Haidar – Borgholm Formation boundary, Östergotland, Sweden (this study); 11, Wiwaxia corrugata , Burgess Shale, British Columbia, Canada (Walcott ); 12, Wiwaxia herka , Utah, USA (Conway Morris et al . ); 13, Buchava Formation, Czech Republic (Fatka et al . ); 14, Georgina Basin, Australia (Southgate & Shergold ; Porter ); 15, Llanos Basin, Colombia (Smith et al .…”

New reconstruction of the Wiwaxia scleritome, with data from Chengjiang juveniles

“…W. papilio sp. nov. is distinguished from W. corrugata based on the low number ribs on its sclerites; detailed comparison with other species is hampered by the shortage of comparative material 1 5 .…”

“…The distinctive mid-Cambrian organism Wiwaxia is best known for its stalked carbonaceous sclerites, which together comprise an imbricated dorsal scleritome. Articulated scleritomes have previously been reported from five localities spanning 15 million years 1 2 3 4 5 6 . The constitution of the Wiwaxia scleritome is remarkably conserved, notwithstanding species-level variety in sclerite proportions and orientation.…”