New soft-bodied panarthropods from diverse Spence Shale (Cambrian; Miaolingian; Wuliuan) depositional environments

Abstract

The Cambrian (Miaolingian; Wuliuan) Spence Shale Lagerstätte of northern Utah and southern Idaho is one of the most diverse Burgess Shale-type deposits of Laurentia. It yields a diverse fauna consisting of abundant biomineralized and locally abundant soft-bodied fossils, along a range of environments from shallow-water carbonates to deep-shelf dark shales. Panarthropods are the dominant component throughout the deposit, both in time and space, but whereas the trilobites and agnostoids are abundant, most of the soft-bodied taxa are only known from very few specimens. Additionally, the knowledge of soft-bodied panarthropods is currently largely limited to locations in the Wellsville Mountains of northeastern Utah. This contribution describes 21 new soft-bodied panarthropods from six locations, including the first occurrences of soft-bodied panarthropods in the High-Creek, Smithfield Creek, Spence Gulch, and Two-Mile Canyon localities. Additionally, we report the presence of bradoriids— i.e., Branchiocaris pretiosa Resser, 1929, Perspicaris? dilatus Robison and Richards, 1981, Naraoia? sp. indet., Thelxiope cf. T. palaeothalassia Simonetta and Delle Cave, 1975, and Tuzoia guntheri Robison and Richards, 1981—for the first time from the Spence Shale Lagerstätte; the first reported occurrence outside of the Burgess Shale for Thelxiope cf. T. palaeothalassia; and the first Wuliuan occurrence of Tuzoia guntheri. We also report on a new hurdiid carapace element and additional specimens of Buccaspinea cooperi? Pates et al., 2021, Dioxycaris argenta Walcott, 1886, Hurdia sp. indet., and Tuzoia retifera Walcott, 1912. This new material improves our understanding of the panarthropod fauna of the Spence Shale Lagerstätte and substantially increases our understanding of the distribution of the described taxa in time and space.

Large euarthropod carapaces from a high latitude Cambrian (Drumian) deposit in Spain

“…Remarks. Recent workers have referred Tuzoiidae to the order Tuzoiida [ 50 ], Hymenocarina [ 51 , 52 ] or left it uncertain [ 53 ]. The most recent phylogenetic analysis [ 51 ] recovered Tuzoia as an early diverging total-group mandibulate, as part of a clade comprising fuxianhuiids, hymenocarines and crown mandibulate groups pancrustaceans and myriapods.…”

“…[ 55 ]), though the tentative identification of process and notch adjacent to straight dorsal margin makes this assignment most likely. Within tuzoiids, the large size of the carapace is most comparable to material from the Drumian Jince Formation, Czechia [ 18 ] which can reach up to 180 mm in length, though specimens of ca 120 mm length from the Wuliuan Spence Shale, USA, have also been reported [ 52 ]. The fragment of carapace described here exceeds the size of most Tuzoia species, which with the exception of the Czech species are no taller than 100 mm ([ 54 ] fig.…”