Abstract The immense size of many pterosaurs is now well known to academics and laymen alike, but truly enormous forms with wingspans more than twice those of the largest modern birds were not discovered until 83 years after the first pterosaur fossils were found. These remains were discovered in an expedition to the Cretaceous chalk deposits of Kansas led by O.C. Marsh in 1870: initially revealing animals with 6.6 m wingspans, Marsh eventually found material from animals estimated to span 7.6 m. Marsh's record breaking pterosaur – the largest flying animal known for nearly 80 years – was equalled by a supposed wing bone described by C.A. Arambourg in 1954 , and then surpassed with the discovery of the 10 m span azhdarchid Quetzalcoatlus northropi by D. Lawson in 1972. Subsequent fragmentary azhdarchid discoveries suggest even larger forms: reinterpreting Arambourg's ‘wing bone’ as a cervical vertebra suggests an animal with an 11–13 m wingspan, while the Romanian taxon Hatzegopteryx thambema is a particularly large and robust form with a 12 m wingspan. Giant pterosaur footprints are also known, with the largest footprints recording walking azhdarchids of comparable size to those suggested by body fossils.

The Cretaceous Pierre Shale Group in eastern South Dakota and western Wyoming contains numerous fossils, including the flying reptile Pteranodon , 19 specimens of which are described herein. Pteranodon specimens have been found in the two lower formations of the Pierre Shale Group: 4 in the basal Gammon Ferruginous Formation, and 15 in the overlying Sharon Springs Formation. Of these specimens, 64% are associated forelimb elements. Two factors, or a combination thereof, explain the abundance of associated forelimb elements: (1) predatory preference of the muscle mass in the chest over the wing membrane, which may not have offered much nutrient to the predators; and (2) the strong wing membrane, which would have secured the wing elements while the muscle mass would have fallen away. In either case, the wing membrane may have served as a protective layer over the forelimb bones until burial. Two Pteranodon specimens contain vertebrae of the fish Enchodus , which appear to be stomach contents, the first documented Pteranodon stomach contents from South Dakota.

Abstract: Four specimens of the pterosaur Pteranodon exhibit patterns of irregular alternating light and dark bands on the lateral surfaces of the upper jaw anterior to the nasoantorbital fenestra. Examinations reveal that the maxilla and premaxilla of Pteranodon consisted of two thin sheets of bone interconnected by regularly spaced septa with the spaces contained within presumably pneumatized, resulting in a structure analogous to modern honeycomb sandwich panels. The alternating light and dark bands resulted from waves of bone deposition moving anteriorly along the external surface of the lateral sheet of bone and laying down thin laminae of new bone while bone was simultaneously resorbed from the internal surface of the lateral sheet to maintain its thickness. The specimens that exhibit the bands were immature males and no banding was found in mature specimens or immature females. Therefore, the presence of the bands in immature males is interpreted as correlated with the enlargement and reshaping of the rostrum as males approached and attained sexual maturity.

Abstract Previous cladistic studies of pterosaur relationships suffer from restricted numbers of taxa and characters, incomplete data sets and absence of information on characters, tree structure and the robustness of trees. Parsimony analysis of a new character data set (60 characters, 20 terminal taxa, 93.75% complete) yielded six trees. In the strict consensus tree Preondactylus is the most basal taxon followed, stepwise, by the Dimorphodontidae and the Anurognathidae. Beyond this basal group, more derived pterosaurs (Campylognathoididae (Rhamphorhynchidae + Pterodactyloidea)) share a suite of characters principally associated with elongation of the rostrum. The Pterodactyloidea consists of four major clades. The Ornithocheiroidea is the most basal taxon consisting, stepwise, of Istiodactylus, the Ornithocheiridae, Nyctosaurus and the Pteranodontidae. The remaining taxa, Ctenochasmatoidea, Dsungaripteroidea and Azhdarchoidea, are weakly united in a clade of non-ornithocheiroid pterodactyloids, but their inter-relationships are difficult to resolve. Cycnorhamphus is the basal-most ctenochasmatoid, while the remaining taxa (Pterodactylus, Lonchodectidae, Ctenochasmatidae) form an unresolved trichotomy. The Dsungaripteroidea (Germanodactylus + Dsungaripteridae) is strongly supported by features of the skull and dentition. The Azhdarchoidea (Tapejara [Tupuxuara + Azhdarchidae]) is united by cranial characters such as elevation of the antorbital region, and relative shortening of the wing finger. The pattern of pterosaur evolution suggested by the results of this analysis is broadly similar to traditional ideas, but has greater resolution, more complexity and reveals several previously unrecognized ‘events’.

Abstract A cladistic analysis based on 39 terminal taxa and 74 characters (several multistate) using PAUP (Phylogenetic Analysis Using Parsimony) (3.1.1 for Macintosh and 4.0b10 for Microsoft Windows) presents a new hypothesis of pterosaur inter-relationships. This study suggests that the most primitive taxon is the Anurognathidae, followed by Sordes and all remaining pterosaurs. Dendrorhynchoides is confirmed as a member of the Anurognathidae, being closely related to Batrachognathus. Preondactylus occupies a more derived position than Sordes, which questions its previous assignment as the most primitive pterosaur. The hypothesis of rhamphorhynchoid paraphyly is confirmed, with the Rhamphorhynchidae more closely related to the Pterodactyloidea than to more basal forms. The Pterodactyloidea shows a basal dichotomy: the Archaeopterodactyloidea and the Dsungaripteroidea. The Archaeopterodactyloidea is formed by Pterodactylus + Germanodactylus and a clade formed by Gallodactylidae + Ctenochasmatidae. The Nyctosauridae occupies the basal position within dsungaripteroids and is followed by the Pteranodontoidea and the Tapejaroidea. Pteranodontoids have Pteranodon at the base, followed stepwise by Istiodactylus, Ornithocheirus and the Anhangueridae. Tapejaroids are composed of the Dsungaripteridae at the base followed by the Tapejaridae and the Azhdarchidae. Major trends within pterosaur evolutionary history are: general increase in size (wing span and body); increase of wing metacarpal and pteroid; decrease of proportional length of the second and third wing phalanx relative to the first; gradual increase of rostrum (anterior to external nares); and anterior shift of the skull-mandible articulation. Cranial crests are present in most pterodacty-loids, but markedly in the Ornithocheiroidea, where all taxa show some sort of crest on the skull. The loss of teeth, previously assumed to have occurred independently in several lineages, seems to be a general trend among dsungaripteroids. Several nodes recovered by this analysis are supported by very few characters, a result at least partially attributable to the limited available information from several taxa due to poor preservation and/or preparation.

Abstract Archosauromorphs radiated into numerous trophic niches during the Mesozoic, many of which were accommodated by particular suites of cranial adaptations and feeding behaviours. The mandibular symphysis, the joint linking the mandibles, is a poorly understood craniomandibular joint that may offer significant insight into skull function and feeding ecology. Using comparative data from extant amniotes, we investigated the skeletal anatomy and osteological correlates of relevant soft tissues in a survey of archosauromorph mandibular symphyses. Characters were identified and their evolution mapped using a current phylogeny of archosauriforms with the addition of non-archosauriform archosauromorphs. Extinct taxa with the simple Class I condition (e.g. proterochampsids, ‘rauisuchians’), rugose Class II (aetosaurs, protosuchians, silesaurids) and interdigitating Class III symphyses (e.g. phytosaurs, crocodyliforms) and finally fused Class IV (avians) build the joints in expected ways, although they differ in the contributions of bony elements and Meckel’s cartilage. Optimization of the different classes of symphyses across archosauromorph clades indicates that major iterative transitions from plesiomorphic Class I to derived, rigid Class II–IV symphyses occurred along the lines to phytosaurs, aetosaurs, a subset of poposauroids, crocodyliformes, pterosaurs and birds. These transitions in symphyseal morphology also appear to track changes in dentition and potentially diet.

Abstract Although primarily a pre-eminent palaeoichthyologist, Arthur Smith Woodward’s research and publications ranged across all major tetrapod groups: nevertheless, his contributions in this area have generally been overshadowed by involvement in the ‘Piltdown Man’ affair. Smith Woodward published on fossil amphibians, every major group of reptiles and on mammals. Most of the new taxa he named remain valid, a testament to his wide knowledge and understanding of fossil vertebrates beyond his principal speciality, although some of these have now been extensively revised. He travelled widely in Europe and the Americas, resulting in some of the earliest work on Gondwanan Cretaceous reptiles. Several of his taxa revealed the existence of previously unknown groups (e.g. notosuchian crocodiles) or provided important character data that have fuelled various phylogenetic debates (e.g. snake and tyrannosauroid origins). His influence extended beyond his own scientific efforts to incorporate his role as a senior administrator, supporting the acquisition of significant reptile specimens for the collection, and as an educator, producing articles for museum visitors and the general public.