Review of taxonomy, geographic distribution, and paleoenvironments of Azhdarchidae (Pterosauria)

Abstract

The taxonomy, geographic distribution, and paleoenvironmental context of azhdarchid pterosaurs are reviewed. All purported pteranodontid, tapejarid, and azhdarchid specimens from the Cenomanian Kem Kem beds of Morocco are referred to a single azhdarchid taxon, Alanqa saharica. The four proposed autapomorphies of Eurazhdarcho langendorfensis from the lower Maastrichtian Sebeş Formation of Romania are based on misinterpretations of material and this taxon is likely a subjective junior synonym of Hatzegopteryx thambema. Among 54 currently reported azhdarchid occurrences (51 skeletal remains and 3 tracks) 13% are from lacustrine deposits, 17% from fluvial plain deposits, 17% from coastal plain deposits, 18% from estuarine and lagoonal deposits, and 35% from costal marine deposits. Azhdarchids likely inhabited a variety of environments, but were abundant near large lakes and rivers and most common in nearshore marine paleoenvironments.

A Medium-Sized Robust-Necked Azhdarchid Pterosaur (Pterodactyloidea: Azhdarchidae) from the Maastrichtian of Pui (Haţeg Basin, Transylvania, Romania)

“…We are happy to admit that, ideally, superior discoveries are required before we can adequately test the possibility that the sympatric azhdarchids discussed here and elsewhere (Vremir et al, 2013a;Vremir et al, 2014;Dyke et al, in prep. ) are individual variants or age classes of the same taxon, However, we do not agree with Averianov's (2014) primary assumptions: that sympatric azhdarchids should be assumed to be conspecific by default and that small and midsized specimens must automatically be assumed to be juveniles of the giant taxa found in the same strata. Averianov's (2014) philosophical approach to taxonomic lumping is demonstrated both by his adoption of Martill and Naish's (2006) now abandoned and very much out of date proposal that Thalassodromeus sethi, Tupuxuara longicristatus, and Tup.…”

“…) are individual variants or age classes of the same taxon, However, we do not agree with Averianov's (2014) primary assumptions: that sympatric azhdarchids should be assumed to be conspecific by default and that small and midsized specimens must automatically be assumed to be juveniles of the giant taxa found in the same strata. Averianov's (2014) philosophical approach to taxonomic lumping is demonstrated both by his adoption of Martill and Naish's (2006) now abandoned and very much out of date proposal that Thalassodromeus sethi, Tupuxuara longicristatus, and Tup. leonardii are synonymous, and by his assumption that scattered azhdarchid remains recovered from diverse horizons and localities should all belong to the same species (Azhdarcho lancicollis), despite differences in morphology and size.…”

“…It should be noted that Averianov (2014) argued that Eurazhdarcho is merely a juvenile of Hatzegopteryx thambema and that all characters proposed as diagnostic for the former are erroneous. We are happy to admit that, ideally, superior discoveries are required before we can adequately test the possibility that the sympatric azhdarchids discussed here and elsewhere (Vremir et al, 2013a;Vremir et al, 2014;Dyke et al, in prep.…”

Late cretaceous continental and marine vertebrate assemblages from the Laño quarry (Basque-Cantabrian Region, Iberian Peninsula): an update

“…because of close resemblances with Azhdarcho lancicollis from the Turonian of Uzbekistan in Central Asia, mainly on the basis of jaw morphology and general size (Buffetaut, 1999). Azhdarchid remains are relatively common in the latest Cretaceous continental sites of Europe (Company et al, 1999;Barrett et al, 2008;Buffetaut, 2008;Averianov, 2014) and new taxa have recently been described (Ősi et al, 2005;Vremir et al, 2013 and references). Pending a full description of this material, the Laño pterosaur is provisionally referred to Azhdarchidae indet.…”

Cretornis hlavaci Frič, 1881 from the Upper Cretaceous of Czech Republic (Pterosauria, Azhdarchoidea)

“…A small ventral pneumatic foramen on distal humerus surface is present in non-azhdarchid azhdarchoid Radiodactylus langstoni from the Albian of Texas, USA (Murry et al, 1991;Andres and Myers, 2013). A distinct cleft-like pneumatic foramen is present on the distal end of the humerus in Montanazhdarcho minor (McGowen et al, 2002 and personal observation of MOR 691 by AA) from the Campanian of Montana, USA, originally described as azhdarchid but reinterpreted as non-azhdarchid azhdarchoid (Averianov, 2014). In Cretornis hlavaci there is no pneumatic foramen on the distal end of humerus, which is consistent with the azhdarchoid condition.…”