Guiclupea superstes, gen. et sp. nov., the youngest ellimmichthyiform (clupeomorph) fish to date from the Oligocene of South China

Abstract

A new ellimmichthyiform, Guiclupea superstes, gen. et sp. nov., from the Oligocene Ningming Formation of Ningming Basin, Guangxi Zhuang Autonomous Region, South China is described herein. With relatively large body size, parietals meeting at the midline, anterior ceratohyal with a beryciform foramen in the center, a complete predorsal scutes series of very high number and about equally-size scutes with radiating ridges on dorsal surface, first preural centrum unfused with first uroneural but fused with the parhypural, and first ural centrum of roughly the same size as the preural centrum, Guiclupea superstes cannot be assigned to the order Clupeiformes. The phylogenetic analyses using parsimony and Bayesian inference methods with Chanos/Elops as outgroup respectively suggests that the new form is closer to ellimmichthyiform genus Diplomystus than to any other fishes, although there are some discrepancies between the two criteria and different outgroups used. It shares with Diplomystus the high supraoccipital crest, pelvic-fin insertion in advance of dorsal fin origin, and the number of predorsal scutes more than 20. The new form represents the youngest ellimmichthyiform fish record in the world. Its discovery indicates that the members of the Ellimmichthyiformes had a wider distribution range and a longer evolutional history than previously known.

Taxic and morphological diversification during the early radiation of Clupeomorpha (Actinopterygii, Teleostei)

“…These skills could explain the diversity of environments, regions and ages that species inhabited, including clupeomorph complex palaeogeographical history (Murray & Wilson 2013; Chen et al . 2021). Although clupeomorph species inhabited marine, lacustrine, brackish water and freshwater environments, all the Late Cretaceous species used in the morphometric study were marine (Table S2; Fig.…”

“…2019; Chen et al . 2021). For example, a temperature rise can generate faster mutation rates plus the selection of short‐lived plankton generations that limits dispersal (Guinot & Cavin 2016).…”

“…2019; Chen et al . 2021), and partially discarding a spatial sampling bias. This Late Cretaceous morphological diversity could therefore be associated with high sea surface temperatures, the highest sea level ever known in the Earth's history, and the rise of numerous epicontinental seas (Guinot & Cavin 2016; Boukhalfa et al .…”