A small azhdarchoid pterosaur from the latest Cretaceous, the age of flying giants

Abstract

Pterosaur fossils from the Campanian–Maastrichtian of North America have been reported from the continental interior, but few have been described from the west coast. The first pterosaur from the Campanian Northumberland Formation (Nanaimo Group) of Hornby Island, British Columbia, is represented here by a humerus, dorsal vertebrae (including three fused notarial vertebrae), and other fragments. The elements have features typical of Azhdarchoidea, an identification consistent with dominance of this group in the latest Cretaceous. The new material is significant for its size and ontogenetic stage: the humerus and vertebrae indicate a wingspan of ca 1.5 m, but histological sections and bone fusions indicate the individual was approaching maturity at time of death. Pterosaurs of this size are exceedingly rare in Upper Cretaceous strata, a phenomenon commonly attributed to smaller pterosaurs becoming extinct in the Late Cretaceous as part of a reduction in pterosaur diversity and disparity. The absence of small juveniles of large species—which must have existed—in the fossil record is evidence of a preservational bias against small pterosaurs in the Late Cretaceous, and caution should be applied to any interpretation of latest Cretaceous pterosaur diversity and success.

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

“…Taxonomic decisions regarding species do not necessarily need to rest on a phylogenetic analysis, as was also the case for previous taxonomic decisions regarding the specimen discussed here (UAVLP 24238) and others of the Pteranodon-complex (e.g., Bennett 1992, 1994. Similarly, a phylogenetic analysis is not necessary when a specimen is assigned to a pre-existing clade (e.g., Martin-Silverstone et al 2016). However, from all arguments presented by MartinSilverstone and colleagues against my interpretation of UALVP 24238, the most surprising one to me was the splitter label.…”

The toothless pterosaur Jidapterus edentus (Pterodactyloidea: Azhdarchoidea) from the Early Cretaceous Jehol Biota and its paleoecological implications

“…It is based on the analysis of Zhou et al [ 22 ], which is turn based on the previous analyses of Chinese pterosaurs by Andres and Ji [ 15 ] and Andres et al [ 8 , 23 ]. It has been updated with the taxonomy of Bennett [ 24 – 26 ], Lü et al [ 5 ], Martin-Silverstone et al [ 27 ], and Pinheiro and Rodrigues [ 28 ], as well as the addition several pterosaur species. This analysis incorporates all the characters and most of the species considered currently valid for pterosaurs, producing a matrix of 271 characters and 134 species.…”

Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators

“…Assumptions that azhdarchids were morphologically uniform have led to proposals that Maastrichtian pterosaurs were ecologically constrained at the end of the Cretaceous, and that their extinction represents the unspectacular end of a long, gradual pterosaurian decline (Unwin, 2005; Witton, 2013). The identification of clear distinctions in form and function within Azhdarchidae, along with the recent potential identification of the first small-bodied azhdarchid species from Campanian sediments (Martin-Silverstone et al, 2016), indicates that latest Cretaceous pterosaurs were not as ecologically homogenous as previously thought, and that their extinction may have coincided with their exploitation of niches previously unused in pterosaur evolution. Pterosaur extinction in the K/Pg event may thus have been more significant than traditionally considered.…”