Pterosaur Stance and Gait and the Interpretation of Trackways

The tracks ascribed to pterosaurs from the Late Jurassic limestones at Crayssac, France, must be pterosaurian because the manus prints are so far outside those of the pes, the pes print is four times longer than wide, and the manus prints appear to preserve distinct traces of a posteromedially directed wing-finger. These tracks are different in important ways from previously described Pteraichnus trackways, which have been variably considered pterosaurian, crocodilian, or indeterminate. No Pteraichnus (sensu stricto: those not from Crayssac) tracks have diagnostic features of pterosaurs and in none can a complete phalangeal or digital formula be reconstructed; however, all published Pteraichnidae tracks fulfill the criteria of poor preservation, and some have some diagnostic features of crocodile tracks. Reconstructions of pterosaurs walking in pteraichnid tracks do not fit those tracks well, but crocodiles do. In contrast, the Crayssac tracks demonstrate the erect stance and parasagittal gait previously reconstructed for pterosaurs. They also demonstrate that the footfall pattern was not as in typical reptiles (LH-RF-RH-LF), but that the manus must have been raised before the next forward step of the ipselateral foot (LH-LF-RH-RF), suggesting that the quadrupedal pattern was secondary. The metatarsus in pterosaurs was set low at the beginning of a stride, as it is in crocodilians and basal dinosaurs. The diagnosis of the Ichnofamily Pteraichnidae comprises features of possible crocodilian trackmakers, but not of possible pterosaurian trackmakers. Trackways considered for attribution to pterosaurs should show (1) manus prints up to three interpedal widths from midline of body, and always lateral to pes prints, (2) pes prints four times longer than wide at the metatarso-phalangeal joint, and (3) penultimate phalanges longest among those of the pes.     

A new scaphognathid pterosaur from western Liaoning,China

A partial skeleton of a new pterosaur, Jianchangnathus robustus gen. et sp. nov. from western Liaoning, China, is described. The specimen (IVPP V16866) was collected near Linglongta, Jianchang County, whose deposits have a disputed age that range from Middle Jurassic to Early Cretaceous. The new species shares several features with the non-pterodactyloid Scaphognathus from the Late Jurassic deposits of southern Germany, such as a deep anterior end of the lower jaw, a piriform lower temporal fenestra with the ventral margin broader than the dorsal one and the interalveolar spacing of the maxillary teeth about three alveolar spaces, allowing its allocation to the Scaphognathidae. The main diagnostic features of J. robustus include the large maxillary process of the jugal, the convex alveolar margin of the lower jaw and the procumbent disposition of the first three pairs of dentary teeth. The new Chinese taxon also differs from Fenghuangopterus lii, which comes from the same deposit and is here regarded as Scaphognathidae incertae sedis, mainly by the lower number of teeth and several proportions of the wing elements. The discovery of J. robustus demonstrates a larger diversity in the pterosaur fauna of the Linglongta region so far dominated by the non-pterodactyloid clade Wukongopteridae.     

On a 19th Century Pterodactylus (Pterosauria) specimen held in the Natural History Museum of La Rochelle,France

A new specimen of the pterosaur Pterodactylus, purchased in the second half of the 19th Century by the Natural History Museum of La Rochelle and still held in that institution, is described. This previously unreported and almost complete specimen is one of the very few original pterosaur fossils from Solnhofen present in the French historical palaeontological collections. It corresponds to a large adult individual displaying some interesting anatomical details as well as a possible healed fracture of the tibia.     

A NEW AZHDARCHOID PTEROSAUR FROM THE CRATO FORMATION (LOWER CRETACEOUS,APTIAN?) OF BRAZIL

Abstract: A partial pterosaur skull from the Nova Olinda Member of the Crato Formation (Lower Cretaceous, Aptian?) represents a new edentulous pterodactyloid, Lacusovagus magnificens gen. et sp. nov. The absence of teeth and a large nasoantorbital fenestra suggest assignment to Azhdarchoidea, and the combination of a particularly short, crestless and shallow rostrum and laterally flared jaw margins distinguish it from other azhdarchoid taxa. The position of the new form within Azhdarchoidea is problematic: Lacusovagus is distinguished from Tapejaridae in its straight, as opposed to ventrally displaced, jaw tip and absence of a premaxillary crest; from thalassodromids by the absence of a premaxillary crest; and from Azhdarchidae by the short length of the rostrum and shallow posterodorsal extension of the premaxilla. Lacusovagus shares a shallow, crestless rostrum and a slender posterodorsal premaxillary extension with Jiufotang Formation azhdarchoids such as Chaoyangopterus and Jidapterus. The position of these genera within Azhdarchoidea is controversial, but the suite of plesiomorphic and derived azhdarchoid characters in each suggests a placement between Tapejaridae and Neoazhdarchia. Further research is required, however, to determine the relationships of these genera both to each other and to other azhdarchoids. The new taxon elevates the faunal similarity found between the roughly contemporaneous Jiufotang and Crato formations and continues the pattern of Crato Formation azhdarchoids being much larger than those from the Jehol Group. It also has jaws at least 67 and 55 per cent longer, respectively, than those of the largest azhdarchoids and ornithocheirids from the Crato pterosaur assemblage, making Lacusovagus the largest pterosaur known from this unit.     

First record of a pterosaur landing trackway

The terrestrial progression of pterosaurs, the flying reptiles of the Mesozoic Era, has been debated for over two centuries. The recent discovery of quadrupedal pterodactyloid pterosaur tracks from Late Jurassic sediments near Crayssac, France, shows that the hindlimbs moved parasagittally, as in mammals, birds and other dinosaurs, and the hypertrophied forelimbs could make tracks both close to the body wall and far outside it. Their manus tracks are unique in form, position and kinematics, which would be expected because the forelimbs were used for flight. Here, we report the first record of a pterosaur landing track, which differs substantially from typical walking trackways. The individual landed on both hind feet in parallel fashion, dragged its toes slightly as it left the track, landed again almost immediately and placed the hindfeet parallel again, then placed its forelimbs on the ground, took another short step with both hindlimbs and adjusted its forelimbs, and then began to walk off normally. The trackway shows that pterosaurs stalled to land, a reflection of their highly developed capacity for flight control and manoeuverability.     

Palaeohistology of the bones of pterosaurs (Reptilia: Archosauria): anatomy, ontogeny, and biomechanical implications

Thin sections from long bones of specimens representing pterosaurs ranging from the Early Jurassic to the latest Cretaceous provide a profile of bone histology across a range of sizes, skeletal elements, growth stages, and phylogenetic positions. Most pterosaur bone is fibro-lamellar, organized in an unusual way that suggests high growth rates through ontogeny. Fibro-lamellar deposits are finished by a relatively abrupt deceleration or cessation of growth represented by lamellar, poorly vascularized subperiosteal bone in what appear to be adults. Pterosaurs had the thinnest bone walls of any tetrapods; they complemented high rates of periosteal deposition with almost equally high rates of endosteal erosion. Pterosaurs show a great variety of histologic features that include articular calcified cartilage, sub-chondral bone plates, trabecular bone struts and related internal supports, and secondary deposition and remodeling of bone. They remodeled their bones internally by (1) depositing endosteal bone coatings on the inner cortex and over struts of pre-existing internal bone, (2) secondarily filling bone spaces, and (3) Haversian reworking. The construction of these struts reflects both developmental patterns of bone construction and biomechanical function. Alternating plywood-like layers of bone, heretofore undescribed in tetrapods, provided strength, as did the obliquely oriented system of reticular blood vessels in the bones. The distribution and ontogenetic features of pterosaur bone tissues, when combined with other evidence, suggest generally high growth rates, high metabolic levels, altricial birth, and extended parental care.     

Do different disparity proxies converge on a common signal? Insights from the cranial morphometrics and evolutionary history of Pterosauria (Diapsida: Archosauria)

Disparity, or morphological diversity, is often quantified by evolutionary biologists investigating the macroevolutionary history of clades over geological timescales. Disparity is typically quantified using proxies for morphology, such as measurements, discrete anatomical characters, or geometric morphometrics. If different proxies produce differing results, then the accurate quantification of disparity in deep time may be problematic. However, despite this, few studies have attempted to examine disparity of a single clade using multiple morphological proxies. Here, as a case study for this question, we examine the disparity of the volant Mesozoic fossil reptile clade Pterosauria, an intensively studied group that achieved substantial morphological, ecological and taxonomic diversity during their 145+ million-year evolutionary history. We characterize broadscale patterns of cranial morphological disparity for pterosaurs for the first time using landmark-based geometric morphometrics and make comparisons to calculations of pterosaur disparity based on alternative metrics. Landmark-based disparity calculations suggest that monofenestratan pterosaurs were more diverse cranially than basal non-monofenestratan pterosaurs (at least when the aberrant anurognathids are excluded), and that peak cranial disparity may have occurred in the Early Cretaceous, relatively late in pterosaur evolution. Significantly, our cranial disparity results are broadly congruent with those based on whole skeleton discrete character and limb proportion data sets, indicating that these divergent approaches document a consistent pattern of pterosaur morphological evolution. Therefore, pterosaurs provide an exemplar case demonstrating that different proxies for morphological form can converge on the same disparity signal, which is encouraging because often only one such proxy is available for extinct clades represented by fossils. Furthermore, mapping phylogeny into cranial morphospace demonstrates that pterosaur cranial morphology is significantly correlated with, and potentially constrained by, phylogenetic relationships.     

The true world's first sculptures of antediluvian animals, which never were…

In 1852, the French state commissioned the artists Frémiet and Jacquemart to execute bronzes of a plesiosaur and a pterodactyl for the Jardin des Plantes in Paris. The orders were cancelled before the sculptures could be realized, largely because of petty jealousies among the professors of the Muséum national d’Histoire naturelle, who maintained that the long-extinct animals were too poorly understood for accurate reconstructions. In this way an important opportunity to educate and inspire the French public about the life of the past was lost.     

A possible pterosaur manus track from the Late Cretaceous of Alberta

An isolated track from the latest Campanian–Maastrichtian Wapiti Formation (Alberta) is tentatively identified as a pterosaur manus print. The basic digital formula (digit I < digit II < digit III) is consistent with the plesiomorphic condition in pterosaurs. The track measures 25.5 cm in length, making it the largest putative pterosaur manus print (estimated wingspan 7.7 m) from North America. Although precise chronostratigraphic data are lacking, sedimentary evidence indicates the track comes from a mid‐ to late Campanian fluvial deposits that accumulated approximately 400 km from the closest shoreline within a high‐latitude (65°N) setting.