Premaxillary crest variation within the Wukongopteridae (Reptilia, Pterosauria) and comments on cranial structures in pterosaurs

Abstract

Cranial crests show considerable variation within the Pterosauria, a group of flying reptiles that developed powered flight. This includes the Wukongopteridae, a clade of non-pterodactyloids, where the presence or absence of such head structures, allied with variation in the pelvic canal, have been regarded as evidence for sexual dimorphism. Here we discuss the cranial crest variation within wukongopterids and briefly report on a new specimen (IVPP V 17957). We also show that there is no significant variation in the anatomy of the pelvis of crested and crestless specimens. We further revisit the discussion regarding the function of cranial structures in pterosaurs and argue that they cannot be dismissed a priori as a valuable tool for species recognition.

Rebuttal of Martin-Silverstone et al. 2017, ‘Reassessment of Dawndraco kanzai Kellner 2010 and reassignment of the type specimen to Pteranodon sternbergi Harksen, 1966’

“…To my knowledge, there are no figured specimens of Pteranodon (or related species) combining complete posterior regions of skulls and pelves where argumentation for sexual dimorphism could be made (Kellner and Tomida 2000). Perhaps, further preparation of the pelvic region of UALVP 24238, combined with some alternative ways of assessing the size of the pelvic canal in flattened material (e.g., 3-D reconstruction based on CT-scans) might help in this matter (see discussion in Cheng et al 2017). To further demonstrate difficulties of gender differentiation within pterosaurs, although Bennett (1992) considered the possibility that the anhanguerids Anhanguera and Tropeognathus might represent males and females of the same species, this was latter refuted by both, morphology (Kellner and Tomida 2000) and phylogeny (Kellner 2003, Andres et al 2014.…”

“…In one of the few pterosaur bonebeds (which include some eggs, demonstrating the likelihood of the presence of females), where different individuals can confidently be assigned to the same species, there are morphological evidences suggesting that the expression of the cranial crests (but not their presence, see Cheng et al 2017) might be sexually dimorphic (Wang et al 2014a). In my opinion, this has still to be demonstrated for Pteranodon or Pteranodon-like taxa.…”

“…Cranial crests made by the frontals have since been reported in other pterosaurs such as Guidraco and Ludodactylus (Frey et al 2003, Wang et al 2012 and proximal caudals with duplex centra were reported in Anhanguera (Kellner & Tomida 2000). That said, regarding the cranial crest, a highly controversial topic these days (see Cheng et al 2017), I hardly believe that Guidraco or Ludodactylus should be classified into the genus Pteranodon, but just would like to stress that diagnoses can change with the advent of new specimens or more information. That seems also to be the case for the Pteranodon-complex.…”

New anatomical information of the wukongopteridKunpengopterus sinensisWang et al., 2010 based on a new specimen

“…In the last ten years, important new pterosaur discoveries have been made in several regions of China, mostly coming from the Late Jurassic Tiaojishan Formation and the Early Cretaceous Jehol Group (e.g., Wang et al, 2009 ; Wang et al, 2012 ; Wang et al, 2014b ; Wang et al, 2015 ; Lü et al, 2010 ; Lü et al, 2011a ; Lü et al, 2011b ; Cheng et al, 2012 ; Cheng et al, 2015 ; Cheng et al, 2017 ; Jiang et al, 2014 ; Jiang et al, 2016 ; Rodrigues et al, 2015 ). Among the most exciting discoveries done recently are the Wukongopteridae, whose members combine characters from both, basal non-pterodactyloids and derived pterodactyloids (e.g., Wang et al, 2009 ; Lü et al, 2010 ; Cheng et al, 2016 ).…”

“…So far, six specimens of this non-pterodactyloid clade have been described and referred to three genera and five species ( Wang et al, 2009 ; Wang et al, 2010 ; Lü et al, 2010 ; Lü et al, 2011a ). In addition, there is Changchengopterus pani , known from two individuals ( Lü, 2009 ; Zhou & Schoch, 2011 ), that is regarded as a potential wukongopterid ( Wang et al, 2009 ; Cheng et al, 2017 ), and another three undetermined specimens ( Lü et al, 2011b ; Cheng et al, 2016 ; Cheng et al, 2017 ). Furthermore, there are several undescribed fossils scattered throughout many collections in China that most certainly belong to this clade.…”