Comments on Triassic pterosaurs with discussion about ontogeny and description of new taxa.

Alexander W.A Kellner

doi:10.1590/0001-3765201520150307

Alexander W.A Kellner

Open Access

https://doi.org/10.1590/0001-3765201520150307

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Abstract

Eudimorphodon ranzii was the first Triassic pterosaur to be described and several specimens have been referred to this taxon mainly based on the presence of multicuspid teeth. Since this dental feature has been observed in several other pterosaurs, the revision of some specimens assigned to Eudimorphodon shows that they represent new taxa as follows: Arcticodactylus cromptonellus (comb. nov.), Austriadraco dallavecchiai (gen. et sp. nov.) and Bergamodactylus wildi (gen. et sp. nov.). A preliminary analysis of pterosaur ontogeny resulted in the recognition of six distinct ontogenetic stages (OS1-6). According to this classification, the holotype of Arcticodactylus cromptonellus has reached OS2, and although being ontogenetically much younger than others, the conspicuous anatomical differences lead to its exclusion from Eudimorphodon. The holotypes of Austriadraco dallavecchiai, Bergamodactylus wildi and Carniadactylus rosenfeldi have reached at least OS5, which demonstrates that the anatomical differences among them cannot be explained by ontogeny. Moreover, Bergamodactylus wildi reaches about 60% of the maximized wingspan of Carniadactylus rosenfeldi and further concurs that these specimens collected in distinct Triassic Islands of Europe are not conspecific. The present study increases the diversity of Triassic flying reptiles and further pushes the origins of this clade back to at least the Middle Triassic.

Highlights

The pterosaur record from Triassic deposits is rather limited (Barrett et al 2008), the number of new specimens has increased throughout the years (Dalla Vecchia 2014)
In a cladistic analysis addressing the ingroup relationships of the Pterosauria, which included the main representatives of non-pterodactyloid and pterodactyloid taxa known at that time, Kellner (2001, 2003) pointed out that not all specimens referred to Eudimorphodon ranzii might belong to this species, which he restricted to the holotype (MCSNB 2888)
Some specimens assigned to the genus Eudimorphon and to the species Eudimorphodon ranzii have been reviewed, and based on significant anatomical differences assigned to new taxa: Arcticodactylus cromptonellus, Austriadraco dallavecchiai and Bergamodactylus wildi

Summary

INTRODUCTION

The pterosaur record from Triassic deposits is rather limited (Barrett et al 2008), the number of new specimens has increased throughout the years (Dalla Vecchia 2014). The observed elevation can be interpreted as a dorsal extension or process of the surangular This is true for the holotypes of Eudimorphodon ranzii (MCSNB 2888) and Carniadactylus rosenfeldi (MFSN 1797), and for MPUM 6009 for which such a structure has been reported (e.g., Wild 1978, Dalla Vecchia 2009, see discussion under Bergamodactylus). Regarding the ontogenetic stage of MPUM 6009, this individual has basically the same fused elements as observed in the holotype of Carniadactylus rosenfeldi (MFSN 1797): scapula and coracoid, proximal carpal series and the extensor tendon process of the first wing phalanx. Outcrops in the Friuli region and is slightly older than the Calcari di Zorzino Formation (see Dalla Vecchia 2003a: fig. 1)

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CONCLUSION