Azhdarchidae

Abstract: Immature specimens of the Late Cretaceous pterosaur Pteranodon were identified using three size-independent criteria: (1) fusion of various cranial and postcranial elements; (2) degree of epiphyseal ossification; and (3) bone grain or degree of ossification of limb-bone shafts. Immature individuals make up 15% of available specimens of Pteranodon and do not differ significantly in size from mature individuals. This and the extensive fusion of the mature skeleton suggest that Pteranodon had determinate growth. The bone of limb-bone shafts of immature individuals is fibro-lamellar bone, which suggests that they grew rapidly to adult size. The size-independent criteria can also be used to identify immature and mature individuals of other pterosaur taxa, and other large pterodactyloids also probably exhibited rapid determinate growth.

Abstract: Two newly discovered fossil pterosaurs from the Liaoning deposits in northeastern China add yet more known species to an already diverse population of flying reptiles. Living about 225 million years ago in the Cretaceous period, they belong to groups previously found only in Europe. An interesting aspect of the Liaoning deposits is the co-occurrence of pterosaurs and birds. The indications are that birds outnumbered pterosaurs in diversity and quantity. And that birds were confined to inland regions while pterosaurs dominated nearer the coast. New specimens and an analysis of the Jehol pterosaur faunae of northeastern China show an unexpected diversity of flying reptile groups in terrestrial Cretaceous ecosystems1,2,3,4. Here we report two new pterosaurs that are referred to European groups previously unknown in deposits of northeastern China. Feilongus youngi, from the Yixian Formation1,3, is closely related to the Gallodactylidae5,6 and is distinguished by the presence of two independent sagittal crests and a protruding upper jaw. Nurhachius ignaciobritoi, from the Jiufotang Formation2,3, has teeth formed by labiolingually compressed triangular crowns, only previously reported in Istiodactylus latidens7 from England. With these new discoveries, the Jehol pterosaurs show a wide range of groups including both primitive and derived forms that are not matched by any other deposit in the world. The discoveries also document the turnover of pterosaur faunae, with the primitive Anurognathidae and early archaeopterodactyloids being replaced by derived pterodactyloids. Furthermore, these deposits offer an opportunity to examine the interaction and competition between birds and pterosaurs—it indicates that the avian fauna during the Lower Cretaceous (and possibly most of the Mesozoic) dominated terrestrial, inland regions, whereas pterosaurs were more abundant in coastal areas.

Abstract: In this article we describe a new and exceptionally well-preserved pterodactyloid pterosaur,Sinopterus dongi gen. et sp. nov. from the Jiufotang Formation in western Liaoning Province of northeast China. The new species is referred to the family Tapejaridae, representing its first record outside Brazil. It also represents the earliest occurrence as well as the most complete skeleton of the family. Some revisions are made about the family according to the morphological observations of the postcranial bones ofSinopterus. Two pterosaur assemblages appear to have existed in the Jehol Group, represented by the lower Yixian Formation and upper Jiufotang Formation, respectively. The lower pterosaur assemblage shows some resemblance to that of the Late Jurassic in Solnhofen (Tithonian) by sharing members of the Pterodactylidae and Anurognathidae. The upper one shows more resemblance to that of the Early Cretaceous Santana Formation (Aptian/Albian) by comprising only pterodactyloids such as the Tapejaridae. The age of the Yixian Formation is younger than that of the Solnhofen lithographic limestone, and the age of the Jiufotang Formation (Aptian) is slightly older than the Santana Formation.