New Material of the Pterosaur Gladocephaloideus Lü et al., 2012 from the Early Cretaceous of Liaoning Province, China, with Comments on Its Systematic Position.

Junchang Lü,Caizhi Shen,Martin Kundrát,Anthony Fiorillo

doi:10.1371/journal.pone.0154888

Junchang Lü, Caizhi Shen + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0154888

Copy DOI

Abstract

Although there are nine genera of ctenochasmatoids reported from the Jehol Biota, at present each is known from a specimen that has either a skull or a relatively complete postcranial skeleton. A nearly complete juvenile specimen of Gladocephaloideus from the Lower Cretaceous Jiufotang Formation of Sihedang, Lingyuan of Liaoning Province is the most complete ctenochasmatoid preserved to date with a skull and postcranial skeleton. Based on the holotype (IG-CAGS 08–07) and the nearly complete new specimen (JPM 2014–004), the diagnosis of Gladocephaloideus is amended: approximately 50 teeth in total with sharp tips; small nasoantorbital opening, occupying approximately 13% of total skull length; ratio of prenarial rostrum length to skull length approximately 0.63; deep groove along the mid-line of the mandibular symphysis; length to width ratio of the longest cervical vertebra = 4.1; ratio of femur length to tibia length = 0.61; tibia as long as the wing-phalange 1. Phylogenetic analysis recovers Gladocephaloideus within the clade Ctenochasmatidae. Gladocephaloideus has a closer relationship to the Chinese Pterofiltrus rather than to other ctenochasmatid pterosaurs. Microstructure of limb bones implies that JPM 2014–004 represents an early juvenile of Gladocephaloideus jingangshanensis, and that the type specimen is not a fully grown specimen either. We assume that the holotype may equate to the late juvenile or sub-adult developmental stage of Gladocephaloideus.

Highlights

Ctenochasmatoidea is a group of pterosaurs within the suborder Pterodactyloidea and has been defined as the clade containing Cycnorhamphus suevicus, Pterodaustro guinazui, their most recent common ancestor, and all of its descendants [1]
A ctenochasmatoid pterosaur distinguished by the following unique combination of characters: rostrum relatively slender, the distal end of the parietal crest large; about 50 teeth in total, and all the teeth with sharp tips; nasoantorbital opening small, reaching approximately 13% of skull length; ratio of prenarial rostrum length to skull length approximately 0.63; deep groove along the mid-line on the dorsal surface of the mandibular symphysis; length to width ratio of the longest cervical vertebra = 4.1; ratio of femur length to tibia length = 0.61; tibia as long as wing-phalange 1; length ratio of metatarsal III to tibia about 0.4
Phylogenetic analysis shows that Gladocephaloideus is more closely related to Pterofiltrus than to other ctenochasmatoids, and they form a clade

Summary

Introduction

Ctenochasmatoidea is a group of pterosaurs within the suborder Pterodactyloidea and has been defined as the clade containing Cycnorhamphus suevicus, Pterodaustro guinazui, their most recent common ancestor, and all of its descendants [1]. A new specimen of a nearly complete juvenile assigned to Gladocephaloideus from the Lower Cretaceous Jiufotang Formation of Sihedang, Lingyuan of Liaoning Province (Fig 1) is a significant addition as the most complete ctenocahsmatid yet recovered from this formation. It provides new details about skeletal anatomy and development of the genus. Gladocephaloideus was initially assigned to the family Gallodactylidae [11], based on an incomplete skeleton with skull and lower jaw preserved. Based on the new specimen, the phylogenetic analysis places Gladocephaloideus within the clade Ctenochasmatidae, and suggests that it does not belong to Gallodactylidae. The new specimen (JPM 2014–004) represents much earlier juvenile stage of Gladocephaloideus jingangshanensis

Methods

Results

Discussion

Conclusion