Abstract
Like other soft-bodied organisms, ctenophores (comb jellies) produce fossils only under exceptional taphonomic conditions. Here, we present the first record of a Late Devonian ctenophore from the Escuminac Formation from Miguasha in eastern Canada. Based on the 18-fold symmetry of this disc-shaped fossil, we assign it to the total-group Ctenophora. Our phylogenetic analyses suggest that the new taxon Daihuoides jakobvintheri gen. et sp. nov. falls near Cambrian stem ctenophores such as ‘dinomischids’ and 'scleroctenophorans'. Accordingly, Daihuoides is a Lazarus-taxon, which post-dates its older relatives by over 140 million years, and overlaps temporally with modern ctenophores, whose oldest representatives are known from the Early Devonian. Our analyses also indicate that the fossil record of ctenophores does not provide strong evidence for or against the phylogenomic hypothesis that ctenophores are sister to all other metazoans.
Highlights
Like other soft-bodied organisms, ctenophores produce fossils only under exceptional taphonomic conditions
Ctenophores are one of the phylogenetically most important and controversial metazoan groups, and interest in their fossil record has been catalysed by new records of spectacularly preserved materials from Cambrian Lagerstätten from the 518-million-years-old Chengjiang B iota[1,2,3,4,5,6,7,8], the 505-million-years-old Burgess S hale[9,10,11] and other Burgess Shalelike deposits[12,13]
Based on morphological similarities of this Canadian fossil with stem-ctenophore fossils from the Cambrian Lagerstätte of the Chinese locality C hengjiang[7,39], we assess its affinity to stem-group ctenophores (‘dinomischids’, Siphusauctum, ‘scleroctenophorans’1,3,7,13) and early crown group ctenophores
Summary
Like other soft-bodied organisms, ctenophores (comb jellies) produce fossils only under exceptional taphonomic conditions. Ctenophores have long been known to be near the base of M etazoa[14], but some genetic and genomic studies have recently proposed that they are the most basal m etazoans[15,16,17,18,19,20,21], the ’ctenophores first’ hypothesis This has found some morphological support in a tentative Late Proterozoic stem-group representative of the ctenophores sensu lato[22]. While Cambrian Lagerstätten yielded several genera, ctenophore remains are much rarer in the Devonian; we are aware of only two studies, describing material from the German Hunsrück S late[40,41] This Early Devonian material, appears to belong to crown ctenophores morphologically similar to living forms such as Pleurobrachia, unlike the stem Cambrian taxa and the new Devonian stem taxon described here.
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