A new millipede (Diplopoda, Helminthomorpha) from the Middle Triassic Luoping biota of Yunnan, Southwest China

Abstract

A new helminthomorph millipede,Sinosoma luopingensenew genus new species, from the Triassic Luoping biota of China, has 39 body segments, metazonites with lateral swellings that bear a pair of posterolateral pits (?insertion pits for spine bases), and sternites that are unfused to the pleurotergites. This millipede shares a number of characters with nematophoran diplopods, but lacks the prominent dorsal suture characteristic of that order. Other “millipede” material from the biota is more problematic. Millipedes are a rare part of the Luoping biota, which is composed mainly of marine and near-shore organisms. Occurrences of fossil millipedes are exceedingly rare in Triassic rocks worldwide, comprising specimens from Europe, Asia, and Africa, and consisting of juliform millipedes and millipedes that are either nematophorans or forms very similar to nematophorans.

The link between exceptional fossil preservation and palaeo‐redox conditions in the Middle Triassic Luoping Biota from South China

“…As definite terrestrial components of the Luoping Biota, the archosauromorph retile Pectodens , millipedes, and conifers suggest the proximity of the ancient coastline (Hu et al, 2011; Huang et al, 2018; Li, Fraser, Rieppel, Zhao, & Wang, 2017). Based on their preservation, the conifer remains may have been transported ~10 km into the Luoping Basin (Hu et al, 2011).…”

Diplopoda in the world fossil record

“…Diplopoda indet: Pickford & Andrews, 1981: 32; Slaughter, 1966: 79; Shear et al ., 1992: 136; Janossy, 1986: 20; Montoya et al ., 2001: 388; Rasnitsyn & Ross, 2000: 24; Röβler et al ., 2012: 819, Fig.12A; Ross et al ., 2016: 3; Huang et al ., 2018: 5, Fig.4; Riquelme & Hernández-Patricio, 2018: 643, Figs 3A-B, 642; Álvarez-Rodríguez et al ., 2023 (this work).…”

“…The fossil record of Diplopoda is limited to four species from the Triassic to Jurassic (Fig. 2): Tomiulus angulatus from the Lower Triassic Maltsevo Formation in Russia (Martynov, 1936), Hannibaliulus wilsonae from the Middle Triassic Grès à Voltzia Formation in France (Shear et al, 2009), Sinosoma luopingense from the Middle Triassic Guanling Formation in China (Huang & Hannibal, 2018) and the only species found in the Jurassic, Decorotergum warrenae from the Lower Jurassic Evergreen Formation in Australia (Jell, 1983).…”