Original paper
Euthycarcinoid ecology and evolution
Braddy, Simon J.
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 312 Heft 1 (2024), p. 15 - 30
87 references
published: Aug 28, 2024
published online: Jul 23, 2024
manuscript accepted: Apr 30, 2024
manuscript received: Mar 9, 2024
ArtNo. ESP155031201002, Price: 29.00 €
Abstract
The diversity, ichnology, ecology and evolution of the euthycarcinoids, an enigmatic group of Cambrian to Triassic aquatic and amphibious mandibulate arthropods, is reviewed. Euthycarcinoids are stem myriapods and possibly evolved from juvenile fuxianhuiids via neotony; spawning in tidal pools, individuals acquiring sexual maturity early had a selective advantage. Euthycarcinoids first came onto land either to feed on early land plants, tidal infauna, algae or microbial mats or to scavenge dead animals washed up by the tide. Alternatively, it was to protect their eggs from aquatic predators or because they were left stranded on the tidal flats and migrated from pool to pool to maintain moisture. A new family, Apankuridae nov. is proposed for Cambrian taxa with a barrel-shaped preabdomen and six postabdominal segments. A Middle Cambrian putative euthycarcinoid from shallow lagoon or intertidal facies in Russia is reinterpreted as a phyllocarid crustacean. Cambrian and Siluro-Devonian euthycarcinoids average ca. 8 cm long, but taxa halve in size as they pass into the Carboniferous, probably due to competition. Potential synapomorphies of taxa include a mid-dorsal crest or carina, different length tergites, axial and pleural lobes, preabdominal epimera, postabdominal epimera, setae on the abdominal appendages, smaller posterior appendages, a longer telson and terminal moveable telson spine. Sottyxerxids are interpreted as more closely related to myriapods than euthycarcinids, due to their multi-segmented trunk and homopodous legs; a long ghost range (Silurian to Carboniferous) is predicted by their relatively poor fossil record. Kampecarids are interpreted as intermediate between sottyxerxids and myriapods, based on their legless collum and tail segments.
Keywords
Cambrian • Kampecarid • Myriapod • Sottyxerxid • terrestrial