The youngest ophiocistioid: a first Palaeozoic‐type echinoderm group representative from the Mesozoic

Abstract

Articulated ophiocistioids are rare as fossils, enigmatic in terms of their phylogenetic position, and have been considered to be an exclusively Palaeozoic echinoderm group. Apart from articulated body fossils, the fossil record of Ophiocistioidea is otherwise dependent on isolated microfossils. However, it has been demonstrated that disarticulated jaw elements (goniodonts) of ophiocistioids can be diagnostic at genus and species level and can be used to fill gaps in the non‐articulated fossil record. The Late Triassic Cassian Formation of Italy is regarded as one of the most important strata of early Mesozoic invertebrates worldwide. A fossil assemblage from a locality near Misurina, South Tyrol, yielded various echinoderms, including a stem group echinoid representative and a new ophiocistioid, Linguaserra triassica sp. nov. The new taxon is described and placed within linguaserrid ophiocistioids. The evolutionary history of the group is briefly discussed in relation to other taxa of the Ophiocistioidea and Echinoidea. Linguaserra triassica not only represents the first documented occurrence of this ‘Palaeozoic’ echinoderm class from Mesozoic strata but also establishes the stratigraphically youngest record of goniodonts or ophiocistioid teeth in the world.

A possible Cambrian stem-group gnathiferan-chaetognath from the Weeks Formation (Miaolingian) of Utah

“…A potentially important clue might be the calcitic composition of the teeth, although as noted this may well be diagenetic. Certainly among metazoans, calcitic teeth are unusual, with the most notable instances being in the echinoids (e.g., Wang et al, 1997; Stock et al, 2014) and extinct ophiocistioids (e.g., Reich et al, 2018). Moreover, in the former group, the teeth can on occasion show a fibrous microstructure (Reich and Smith, 2009, text-fig.…”

A Total-Evidence Dated Phylogeny of Echinoids and the Evolution of Body Size across Adaptive Landscape

“…Traditionally, the Permo-Triassic extinction event was considered to have played a major role in shaping the macroevolutionary history of echinoids, with only one or two lineages crossing the boundary (Kier 1977; Smith 1984; Smith and Hollingworth 1990; Erwin 1994; Twitchett and Oji 2005). However, recent work on echinoids and other echinoderm groups, suggests that the end-Permian extinction had a lower impact on echinoderm macroevolution (Thuy et al 2017; Reich et al 2018; Thompson et al 2018). Our topology and divergence times are in line with these findings, indicating that multiple lineages of echinoids survived the end-Permian mass extinction, including members of Miocidaridae, Serpianotiaridae, Triadotiaridae and the three main clades of crown group echinoids (cidaroids, aulodonts and carinaceans).…”

Echinoids from the Tesero Member (Werfen Formation) of the Dolomites (Italy): implications for extinction and survival of echinoids in the aftermath of the end-Permian mass extinction

“…A potential source of “hidden diversity” comes from this disarticulated material (Twitchett & Oji, 2005; Pietsch et al, 2019) as echinoid coronal plates, like the ossicles of other echinoderm groups, display morphological features characteristic of both higher, and lower, taxonomic levels (Gordon & Donovan, 1992; Nebelsick, 1992; Nebelsick, 1995; Nebelsick, 1996; Donovan, 2001; Thompson & Denayer, 2017). Analysis of disarticulated material in Triassic strata has provided novel insight into the diversity and distribution of a number of echinoderm groups during the end-Permian extinction event (Thuy, Hagdorn & Gale, 2017; Reich et al, 2018).…”