Nurhachius luei, a new istiodactylid pterosaur (Pterosauria, Pterodactyloidea) from the Early Cretaceous Jiufotang Formation of Chaoyang City, Liaoning Province (China) and comments on the Istiodactylidae

Xuanyu Zhou,Rodrigo V Pêgas,Maria E.C Leal,Niels Bonde

doi:10.7717/peerj.7688

Abstract

A new istiodactylid pterosaur, Nurhachius luei sp. nov., is here reported based on a complete skull with mandible and some cervical vertebrae from the lower part of the Jiufotang Formation of western Liaoning (China). This is the second species of Nurhachius, the type-species being N. ignaciobritoi from the upper part of the Jiufotang Formation. A revised diagnosis of the genus Nurhachius is provided, being this taxon characterized by the presence of a slight dorsal deflection of the palatal anterior tip, which is homoplastic with the Anhangueria and Cimoliopterus. N. luei sp. nov. shows an unusual pattern of tooth replacement, with respect to other pterodactyloid species. The relationships within the Istiodactylidae and with their closest taxa are investigated through a phylogenetic analysis by parsimony.

Highlights

Istiodactylid pterosaurs are characterized by rhombic teeth with lancet-shaped crowns, long skulls with short pre-antorbital portions of the rostrum, and nasoantorbital fenestrae representing over 50% of the total skull length and height (Howse, Milner & Martill, 2001; Andres & Ji, 2006; Lü et al, 2013)
For the comparisons we present, the following taxa/specimens were analyzed first-hand: N. ignaciobritoi, Liaoxipterus brachyognathus holotype (CAR-0018), Hongshanopterus lacustris holotype (IVPP V14582) and Haopterus gracilis holotype (IVPP V11726)
A phylogenetic analysis was performed based on the data matrix by Holgado et al (2019) modified with the inclusion of characters by Lü, Xu & Ji (2008), Witton (2012), Andres, Clark & Xu (2014), and new characters; and the addition of the following taxa: Archaeoistiodactylus linglongtaensis, Kunpengopterus sinensis, Liaoxipterus brachyognathus and N. luei sp. nov

Summary

Introduction

Istiodactylid pterosaurs are characterized by rhombic teeth with lancet-shaped crowns, long skulls with short pre-antorbital portions of the rostrum, and nasoantorbital fenestrae representing over 50% of the total skull length and height (Howse, Milner & Martill, 2001; Andres & Ji, 2006; Lü et al, 2013). The group was originally named by Howse, Milner & Martill (2001) in order to accommodate, only Istiodactylus latidens. The Istiodactylidae were phylogenetically defined by Andres, Clark & Xu (2014) as the least inclusive clade containing Nurhachius and Istiodactylus. Four pterosaur genera and five species (all represented by a single specimen) have been referred to the Istiodactylidae sensu Andres, Clark & Xu (2014) in the literature, namely.

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