The Relationships of Cuspicephalus Scarfi Martill and Etches, 2013 and Normannognathus Wellnhoferi Buffetaut Et Al., 1998 to Other Monofenestratan Pterosaurs
Total Page：16
File Type：pdf, Size：1020Kb
Contributions to Zoology, 84 (2) 115-127 (2015) The relationships of Cuspicephalus scarfi Martill and Etches, 2013 and Normannognathus wellnhoferi Buffetaut et al., 1998 to other monofenestratan pterosaurs Mark P. Witton1, 2, Michael O’Sullivan1, David M. Martill1 1 School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth, PO1 3QL, UK 2 E-mail: [email protected] Key words: Cuspicephalus scarfi, Jurassic, Monofenestrata, Normannognathus wellnhoferi, Pterosauria, Wukongo- pteridae Abstract Discussion ....................................................................................... 122 Cuspicephalus scarfi .............................................................. 122 The evolution of pterodactyloid pterosaurs occurred in a ‘modular’ Normannognathus wellnhoferi ............................................ 123 fashion with ‘pterodactyloid’-type crania and cervical vertebrae Significance of Cuspicephalus scarfi interpreted evolving in pterodactyloid sister taxa – early monofenestratan as a wukongopterid ................................................................ 125 pterosaurs – before later postcervical modifications marked the Acknowledgements ....................................................................... 125 development of the true pterodactyloid condition. This means of References ...................................................................................... 126 evolution creates problems for distinguishing isolated pterodac- tyloid crania from those of non-pterodactyloid monofenestratans, and has led to uncertainty over the affinities of two Late Jurassic Introduction European pterosaurs known only from skulls, Cuspicephalus scarfi Martill and Etches, 2013 and Normanno gnathus well- nhoferi Buffetaut et al., 1998. Some aspects of their cranial The origin of the Pterodactyloidea is currently a hot anatomy suggest affinities to early pterodactyloids – specifically topic in pterosaur research. Whereas a clear morpho- the Germanodactylidae – while others indicate a relationship with logical divide once separated pterodactyloids from a group of non-pterodactyloid monofenestratans, the Wukongop- other pterosaurs, new discoveries have revealed major teridae. Here, we characterise the skulls of Jurassic monofenes- tratans to provide greater insight into the identity of these ptero- stages of their early evolution. These include the pur- saurs. We find a suite of characters indicating thatCuspicephalus ported earliest known member of the Pterodactyloidea is a wukongopterid, notable for being a particularly large and long (Andres et al., 2014) and ‘transitional’ taxa bridging snouted member of the group, as well as the youngest, and the pterodactyloid-like anatomy to earlier pterosaurs (Lü et Norman- first European record of this clade. The affinities of al., 2010; Tischlinger and Frey, 2014). Perhaps the most nognathus are less clear however. We consider its previous al- location to the Germanodactylidae doubtful, and note some significant of these ‘transitional’ species is the Callovi- similarities it shares with ctenochasmatoid pterodactyloids, but an-Oxfordian Tiaojishan Formation species Darwinop- the only known specimen is probably too fragmentary for confi- terus modularis Lü et al., 2010, a small pterosaur with dent referral to any specific clade within Monofenestrata. anatomy ‘intermediate’ between that of pterodactyloids and their historically recognised sister group, the Rham- phorhynchidae (Lü et al., 2010). The anatomy of Dar- Contents winopterus is noted for its ‘modular’ nature, combining ‘pterodactyloid-grade’ head and neck anatomy with Introduction .................................................................................... 115 et al. Europe’s possible non-pterodactyloid non-pterodactyloid postcervical features (Lü , Darwinopterus monofenestratans .................................................................... 117 2010). and the Pterodactyloidea appear Institutional abbreviations .................................................... 118 to form a monophyletic clade, the Monofenestrata, Material and methods .................................................................. 119 named after the combined nasal and antorbital opening Systematic declaration .......................................................... 119 common to all members of this group (Lü et al., 2010). Comparative anatomy ........................................................... 119 Another recent discovery, a privately-owned complete Results ............................................................................................. 119 Cranial characteristics of the Wukongopteridae ............ 119 skeleton from the latest Kimmeridgian Painten Forma- Cranial characteristics of the ‘Painten tion of Germany, apparently represents a grade of pro-pterodactyloid’ ................................................................ 122 monofenestratan between Darwinopterus and the Downloaded from Brill.com10/06/2021 05:36:39AM via free access 116 Witton et al. – Affinities of pterosaursCuspicephalus and Normannognathus Pterodactyloidea (Tischlinger and Frey, 2014). As in cervical vertebrae with more plesiomorphic, non-ptero- Darwinopterus, its skull and neck possesses typical dactyloid-like postcervical anatomy (Wang et al., 2010, ‘pterodactyloid’ features while its postcranial skeleton, Hone, 2012; Andres et al., 2014). The purported early despite being relatively pterodactyloid-like, retains clear istiodactylid Archaeoistiodactylus linglongtaensis Lü hallmarks of an earlier pterosaur bauplan. This specimen and Fucha, 2010 is also probably a wukongopterid has not been named because of its lack of public acces- (Martill and Etches, 2010; Witton, 2013) or a close rela- sion and, following Tischlinger and Frey (2014), is tive of this group (Sullivan et al., 2014). It is highly hereafter referred to as the ‘Painten Pro-pterodactyloid’. likely that the Tiaojishan wukongopterids are oversplit Since Darwinopterus was described, a number of (Lü et al., 2012; Witton, 2013). similar taxa have been identified from the Tiaojishan The characterisation of non-pterodactyloid monofen- Formation. These include two other Darwinopterus estratans has solely used relatively complete skeletons species, D. robustodens Lü et al., 2011a and D. linglong- unambiguously demonstrating their distinctive, ‘modu- taensis Wang et al., 2010; as well as Kunpengopterus lar’ anatomy. Problems arise when applying these means sinensis Wang et al., 2010, Wukongopterus lii Wang et of identifying wukongopterids to more fragmentary al., 2009 and Changchengopterus pani Lü, 2009. These Jurassic pterosaur material, however. Non-pterodactyloid taxa are considered to form a clade, the Wukongopteri- monofenestratan skeletons are distinctive, but their in- dae (Wang et al., 2010), diagnosed by their combination dividual ‘modules’ are not strongly apomorphic, instead of relatively derived pterodactyloid-like skulls and showing plesiomorphic anatomies which are very simi- Fig. 1. A, MJML K1918, holotype skull of the long-snouted pterosaur Cuspicephalus scarfi Martill and Etches, 2013; B, MGCL 59’583, holotype of Normannognathus wellnhoferi Buffetaut et al., 1998. Scale bars represent 50 mm (A) and 10 mm (B). Fig. 2. Simplified stratigraphic distribution of Monofenestratan groups at the Jurassic/ Cretaceous boundary, and the stratigraph- ic position of the two species discussed herein, Normannognathus welln hoferi and Cuspicephalus scarfi. Phylogeny largely based on Lü et al. (2010, 2012), but the position of the ‘Painten Pro-pterodacty- loid’ is inferred from recent work by Tischlinger and Frey (2014). 1, Monofen- estrata; 2, Pterodactyloidea. Abbreviations of geologic ages: Aal, Aalenian; Alb, Al- bian; Apt, Aptian; Bar, Barremian; Baj, Bajocian; Bat, Bathonian; Ber, Berriasian; Cal, Callovian; Hau, Hauterivian; Kim, Kimmeridgian; Oxf, Oxfordian; Tit; Titho- nian; Val, Valanginian. Downloaded from Brill.com10/06/2021 05:36:39AM via free access Contributions to Zoology, 84 (2) – 2015 117 lar to those of other Jurassic pterosaur clades. This (Andres pers. comm.), and we accordingly await publica- raises questions over how precisely incomplete monofen- tion of this before discussing this specimen further. estratan fossils can be classified if evidence of a com- MJML K1918, the holotype of the long-snouted bined pterodactyloid/non-pterodactyloid bauplan is pterosaur Cuspicephalus scarfi Martill and Etches, 2013 absent: do they represent wukongopterids, pterodacty- from the Kimmeridgian Kimmeridge Clay of Dorset, loids, or something else entirely? Lü et al. (2010) vali- UK (Fig. 1A) represents a second possible non-ptero- dated this concern when performing separate cladistic dactyloid monofenestratan. Known from a nearly com- analyses of the cranial and cervical, and postcervical plete skull, Martill and Etches (2013) noted some simi- anatomy of Darwinopterus modularis. The head and larities in cranial and dental features between MJML neck ‘modules’ were found to nest deeply within the K1918 and the wukongopterid Darwinopterus, but Pterodactyloidea while the postcervical module plotted concluded that ‘a close relationship cannot be proved’ as the sister taxon to the Rhamphorhynchidae (Lü et al., (Martill and Etches, 2013: p. 285). This was in part 2010). This problem has also been borne out in other because the specimen also bears several similarities to studies where classifying isolated monofenestratan