Resumo em Inglês:

Abstract A “comb-dentition”, characterized by long, needle-like, and closely-spaced teeth, is found in the ctenochasmatid pterosaurs as an adaptation for filter-feeding. However, little is known about their tooth replacement pattern, hindering our understanding of the development of the filter-feeding apparatus of the clade. Here, we describe the tooth replacement of the pterosaur Forfexopterus from the Jehol Biota based on high-resolution X-ray Computed Tomography (CT) reconstruction. As in the ornithocheirid Coloborhynchus, the tooth germs are relatively medially positioned along the middle line; the replacement teeth erupt at the posteromedial side of the functional tooth; no more than one replacement tooth present in each alveolus. The replacement teeth are less than half of the length of the full-grown tooth, and alternatively positioned along the tooth row. The alternatively-positioned young and mature functional teeth are dominant and abrased, maintaining the active tooth-tooth occlusion of the filter-feeding apparatus. Reconstruction of Zahnreihen shows an average Z-spacing of 2.02, comparable to that of the simple alternate replacement (Z-spacing = 2) between odd- and even-numbered tooth positions in reptiles. Based on comparisons with Balaenognathus, Ctenochasma, and Pterodaustro, the tooth replacement pattern appears to be varied in ctenochasmatids, and needs to be further studied in the future.

Resumo em Inglês:

Abstract Pterosaur remains are rare from the lowermost Cretaceous, hampering our understanding of the taxonomic and morphological diversities of pterosaurs during this period. The Lower Cretaceous Tugulu Group in Wuerho, China is renowned for hosting the Wuerho Pterosaurian Fauna (WPF), which has so far yielded numerous fossil remains of two dsungaripterid pterosaurs, Dsungaripterus weii and Noripterus complicidens. Here we report a partial ornithocheiromorph humerus from the WPF, representing a deeply divergent clade from Dsungaripteridae. The scarcity of ornithocheiromorphs from the WPF might be interpreted by niche partitioning with dsungaripterids. Meanwhile, we also report a U-Pb zircon age of 134.27 ± 0.36 Ma dated by LA-ICP-MS for the tuffaceous layer at the uppermost part of the Shengjinkou Formation, confirming the Valanginian age of the WPF presented by a previous study. The Wuerho region is one of the few localities producing abundant pterosaur fossils and the only one with an earliest Cretaceous age. The new finding here also suggests that Ornithocheiromorpha had rapidly diversified and achieved a global distribution during the earliest Cretaceous, presumably through a series of modifications on the locomotor apparatus including the warped deltopectoral crest of the humerus, which might substantially improve their flight efficiency.

Resumo em Inglês:

Abstract Powered flight has evolved separately in three tetrapod clades: pterosaurs, birds (avian dinosaurs), and bats. To meet the challenges of powered flight, tetrapods acquired structural, mechanical, and physiological adaptations. Circumferential vascular canals, forming laminar bone, have been proposed to be an adaptation linked to withstanding torsional loading during flight in birds. However, whether laminarity serves as an indicator of biomechanical torsion in pterosaurs, remains to be elucidated. Through a comparative statistical approach, we investigate the association between cortical bone laminarity and skeletal stress in pterosaur flight. For the first time, the presence of laminarity in pterosaur bones was analyzed to observe torsion in bones associated with flight, using thirty-five thin sections of the tapejarid Caiuajara dobruskii, Anhangueridae, and Dsungaripteroidea pterosaurs. We conclude that adaptive relationships arise between bone microstructure and biomechanical function, with forelimb elements (humerus, ulna, and wing phalanges) exhibiting higher laminarity rates compared to hindlimb bones. Additionally, the results provide insights into the possible flight style of these pterosaurs through comparison with bird groups. The presence of laminarity in pterosaurs and birds, but not in bats, highlights that this feature, once considered exclusive to birds, may have convergently evolved in pterosaurs and birds.

Resumo em Inglês:

Abstract The Wukongopteridae is an important pterosaur clade from the Yanliao Biota, combining features of basal and derived pterosaurs. So far, the Wukongopteridae consists of five species divided into three genera: Wukongopterus lii, Darwinopterus modularis, Darwinopterus linglongtaensis, Darwinopterus robustodens, and Kunpengopterus sinensis. Here we report a new species, Darwinopterus camposi sp. nov., based on an almost complete skeleton (IVPP V 17957). The new species is referred to Darwinopterus due to the presence of an elongated posterior region of the skull and the bony premaxillary crest that starts about the anterior margin of the nasoantorbital fenestra. It differs from all other wukongopterids by having the dorsal margin of the premaxillary crest straight, without an extensive dorsal projection and presenting a smooth lateral surface. Furthermore, D. camposi sp. nov. has eighteen and fourteen teeth on each side of the upper and lower jaws, respectively, and the fourth phalanx of the wing finger shorter than the first. IVPP V 17957 shows some fused postcranial bones, like the extensor tendon process to the first wing finger phalanx, but also has unfused premaxilla and frontal, which provides further information about wukongopterid ontogeny.

Resumo em Inglês:

Abstract Pterosaurs, remarkable for their extensive evolutionary history and role as the first vertebrates to achieve active flight, have long intrigued paleontologists and the public alike. Spanning over 150 million years and vanishing at the end of the Mesozoic Era, pterosaurs represent a major evolutionary radiation within terrestrial ecosystems. Despite their prominence, the origins of pterosaurs have remained a complex puzzle in paleontology for over 200 years. We present a comprehensive catalog of pterosaur precursors specimens from the Upper Triassic of the Candelária Sequence within the Santa Maria Supersequence in southern Brazil and discuss their significance for understanding pterosauromorph radiation and the origins of Pterosauria. Additionally, we carried out a phylogenetic analysis to investigate the hypothesis that lagerpetids are closely related to pterosaurs, incorporating new data into the most comprehensive dataset of Triassic dinosauromorphs. Our results support the hypothesis that lagerpetids are pterosauromorphs, offering new insights into the evolutionary relationships between non-pterosaur pterosauromorphs and their better known volant relatives. This study highlights the importance of detailed anatomical and phylogenetic analyses in resolving the complex origins of pterosaurs and underscores the value of the Triassic fossil record in understanding the early evolution of pterosauromorphs.

Resumo em Inglês:

Abstract Herbstosaurus pigmaeus Casamiquela, 1975 is a Late Jurassic pterosaur from northwestern Patagonia. It is based on the natural moulds and a few bony patches of the sacrum, prepubis, ilium, and both femora of a small-sized specimen. The phylogenetic relationships of this species have been a matter of debate, having been originally interpreted as a theropod dinosaur and subsequently as a pterosaur, either as an indeterminate pterodactyloid or a probable dsungaripteroid. However, a detailed and updated reassessment of its anatomy was still lacking. Here, we redescribe and compare the holotype and only known specimen of Herbstosaurus pigmaeus. We agree with previous authors in that the specimen is diagnostic to the species level and provide an emended diagnosis, including two autapomorphies. Quantitative phylogenetic analyses consistently find Herbstosaurus pigmaeus as deeply nested within the Pterodactyloidea and as a member of the Dsungaripteroidea. The dsungaripteroid affinities of Herbstosaurus pigmaeus are weak, based solely on femoral character-states, but is the most parsimonious hypothesis with the evidence at hand. The recognition of Herbstosaurus pigmaeus as a deeply nested pterodactyloid expands the taxonomic diversity of the pterosaur record of southwestern Gondwana during the Late Jurassic.

Resumo em Inglês:

Abstract The osteological variations present in the cervical vertebrae of pterosaurs represent changes in the soft tissues of the neck and reflect their function. Here, we infer the presence, volume, and capacity of the cervical musculature of pterosaurs. We performed our analyses on three-dimensionally preserved cervical series of Anhanguera sp. (AMNH 22555), Anhanguera piscator (NSM-PV 19892), Azhdarcho lancicollis (ZIN PH and CCMGE, several specimens), and Rhamphorhynchus muensteri (MGUH 1891.738), the last three of which were digitally modeled for muscle reconstruction. We identified osteological correlates from structures observed in extant archosaur vertebrae and skulls and supported by Extant Phylogenetic Bracket (EPB) criteria. We estimated the muscular capacity using the “Maximal Force Production” formula. According to our analyses, at least thirteen muscles were present in the neck of pterosaurs, only one of which does not correspond to an EPB level I inference. The muscles that performed skull and neck pitching were more robust and stronger to execute the movements. Muscles that showed extremely low potential had a more cervical stabilization function. Specializations we identified in the muscles are compatible with the foraging habits previously inferred for these pterosaurs, namely surface fishing by Rhamphorhynchus and Anhanguera and capture of small terrestrial prey by Azhdarcho.

Resumo em Inglês:

Abstract Saratovia glickmani, gen. et sp. nov., is described based on a dentary symphysis fragment from the Upper Cretaceous (upper Cenomanian) Melovatka Formation at Saratov, Russia. This specimen was found by L.S. Glickman in late 1940s and was referred previously to Ornithocheirus, Anhanguera, or Coloborhynchus. S. glickmani is attributed to Targaryendraconia because of strongly scalloped and subparallel lateral margins of dentary symphysis, which is transversely narrow, with the interalveolar width subequal to the alveolar width. It differs from all known targaryendraconians by having a dentary crest. The new taxon differs from all toothed pterodactyloids by lack of median groove on dentary symphysis. Instead, it has a raised flat platform pierced by numerous relatively large nutrient foramina, which are connected by short canals with a median canal within this platform. S. glickmani is one of the latest toothed pterosaurs known in the fossil record.

Resumo em Inglês:

Abstract We describe here the first record of pterosaur fossil tracks from the Lower Cretaceous of Brazil, based on new records from the Botucatu Formation (Paraná Basin). These rocks comprise a desert region of dunes and interdunes from which several tetrapod tracks/trackways are known, including tridactyl dinosaurs, lizards and small mammals; giving some clues about the inhabitants of this ancient desert. The new findings were recovered from the well-known Ouro ichnosite (Araraquara Municipality, São Paulo State), and are represented by isolated and well-preserved tridactyl tracks, with left manus (LPP-IC-0232) being digitigrade and the left pes (LPP-IC-0233) being plantigrade. The manus imprint is asymmetrical with a long impression of digit III pointing backwards; these features distinguish this track from tridactyl dinosaurs, resembling a rhombic track morphology, diagnostic of <italic>Pteraichnus</italic>. Furthermore, in the pes imprint, the metatarsal region is about four times longer than the digital region. Three short, anteriorly directed digit impressions are present, in addition to the midfoot arch (pedal isthmus) on the medial edge of track, which are also features of <italic>Pteraichnus</italic>. This is the first occurrence of pterosaur tracks in Brazil, classified as <italic>Pteraichnus</italic> isp., increasing the ichnological diversity of the Botucatu Formation and also of the Brazilian geopaleontological heritage.

Resumo em Inglês:

Abstract The wing membrane of pterosaurs is the earliest innovation in the evolution of vertebrate powered flight and led to pterosaurs dominating the Mesozoic skies. Most studies of pterosaur flight focus on the main wing surface, the brachiopatagium, whereas the small but aerodynamically potentially important tail membrane, the uropatagium, is comparatively understudied. This review presents the current knowledge of the shape, extent, structure and function of the uropatagium that lies between the legs in pterosaurs, based on the available fossil evidence. Both direct evidence from soft tissue preservation and indirect evidence from osteological and ichnological data, suggest variation in the uropatagium among taxa, although evolutionary trends can still be outlined. While early branching pterosaurs had a proportionally large, confluent uropatagium integrated to varying extent with the tail and attached to the elongate fifth toe, pterodactyloid pterosaurs had a greatly reduced and split uropatagium spanning a much smaller triangular area between the knee joint and the base of the tail. The uropatagium was an important component of flight in early pterosaurs and its modification and reduction in derived forms is part of a major transition with the origins of the pterodactyloids and their changing flight and walking apparatus.

Resumo em Inglês:

Abstract The Araripe Basin in northeastern Brazil is a key site for Cretaceous pterosaur fossils from Gondwanan deposits. Most discoveries are concentrated in its northern portion, particularly in Ceará state, within the Crato and Romualdo formations. In contrast, records from the southern part of the basin, especially in Piauí and Pernambuco, remain scarce. This study reports the first pterosaur fossils from the Romualdo Formation in Piauí, represented by two three-dimensionally preserved, incomplete wing phalanges: LPP Pt-002 and LPP Pt-005. Osteohistological analysis of LPP Pt-002 reveals a cortex composed of parallel-fibered bone, with endosteal lamellae and an external fundamental system (EFS), indicating skeletal maturity. In contrast, LPP Pt-005 displays a cortex of woven bone and circumferential lamellae, with a highly vascularized matrix and no evidence of EFS or endosteal lamellae, suggesting a post-juvenile stage. These differences indicate that the specimens represent distinct individuals. Although the reasons for the lower abundance of pterosaur remains in the southern Araripe Basin are unclear, these findings expand the known geographic range of Pterosauria within the basin and underscore the importance of further paleontological exploration in underrepresented regions to better understand pterosaur diversity and distribution during the Cretaceous.

Resumo em Inglês:

Abstract The record of pterosaur fossils in Brazil is significant, however, it remains limited to a few sedimentary basins from the Cretaceous period. This study describes an isolated pterosaur tooth assigned to Ornithocheiriformes, collected from the Quiricó Formation, São Francisco Basin, Early Cretaceous (Aptian), of Minas Gerais State. The tooth was found in association with fossil plants and articulate gonorynchiform fishes. The tooth has a narrow elliptical cross-section, with marked mesial and distal carinae bearing no denticles. In lateral view, the tooth is triangular, being slightly curved lingually. The enamel is thin with no striations. These features, coupled with the Lower Cretaceous age of the deposits it was found, suggest the tooth belongs to an ornithocheiriform pterosaur. This finding represents the first report of pterosaur material from the São Francisco Basin and fills a geographical gap when previous records of ornithocheiriforms in Brazil are considered (Araripe, Bauru, Grajaú, and Recôncavo basins), suggesting a broader distribution of these flying archosaurs in Brazil. Also, this new ornithocheiriform record in the São Francisco Basin strengthen the similarity of its vertebrate fauna to the vertebrates found in Kem Kem Beds in Morocco.

Resumo em Inglês:

Abstract The Early Cretaceous pterosaur Sinopterus atavismus, from Northeast China, belongs to the Tapejaridae. The furrowed structure of its wing phalanges is relatively primitive, possibly indicative of atavism. New information of Sinopterus atavismus is therefore of great interest in studies of evolution among Tapejaridae, especially for interpreting some anatomical features of the holotype. In this paper, the distribution patterns and characteristics of chemical elements in the holotype specimen were analyzed by non-destructive micro-X-ray fluorescence (micro-XRF). The chemical mapping results show that the element Ca was significantly associated with pterosaur bones, showing residual traces of the left lower part of the humerus; Sr replaced Ca and the distribution was uniform, suggesting that phosphate recrystallization occurred in the specimen; Fe is concentrated in the soft tissue parts of the pterosaur fossil, which may be related to pyritization, and Mn appears as the alteration phase of the original iron-rich phase. The elemental migration and sedimentary environment of the fossil require further study. The XRF elemental imaging study of Sinopterus atavismus is helpful for explorations of the development and evolution of Tapejaridae, and also provides more chemical information on the taphonomy of the Jehol Biota.

Resumo em Inglês:

Abstract More than fifty years after the first discoveries of pterosaurs in the Araripe Basin, this sedimentary unit remains one of the most informative windows into the diversity and biology of these fantastic flying reptiles. With dozens of proposed species from two different Lagerstätten, the exceptional preservation of Araripe fossils offers a detailed view of the anatomy, function, and ecology of Cretaceous pterosaurs. These fossils reveal complex faunal assemblages populated by these animals, providing rare snapshots of ancient ecosystems. Today, Araripe pterosaur diversity appears to have reached a plateau, with fewer new taxa and more specimens assigned to known species. This situation calls for a comprehensive reassessment of Araripe pterosaur diversity. Here, we present an in-depth, richly illustrated taxonomic review of all taxa proposed for the basin, along with a synthesis of available paleobiological data. This work aims to establish a solid foundation for future research and proposes guidelines for advancing our understanding of Araripe pterosaurs, especially from biostratigraphic and paleoecological perspectives—areas severely affected by the ongoing threat of illegal collecting and fossil trade.

Resumo em Inglês:

Abstract Tupandactylus imperator, a striking tapejarid pterosaur from the Lower Cretaceous (Aptian) Crato Formation (Araripe Basin), is renowned for its extraordinary cranial crest, one of the proportionally largest among pterosaurs and, indeed, also among all living and extinct vertebrates. This species is known from six specimens, showing different degrees of completeness. Here we describe a new material (MN 7852-V) that represents the most complete skull and articulated lower jaw of Tupandactylus imperator to date, presenting an exceptionally well-preserved cranial crest composed of bone and extensive soft-tissue. Uniquely, the soft-tissue portion of the crest has a sinuous dorsoposterior margin, contrasting with previously reconstructions that suggested a convex or concave profile. The new specimen also shows several new anatomical features such as a free descending process of the nasal and several unfused elements of the lower jaw. It further displays a well-developed dentary crest and a pronounced retroarticular process, differing from previous interpretations. The specimen also displays plant material in direct contact with the mandible, which may be taphonomic or could tentatively be seen as an indication of a herbivorous feeding habit for this species.

Resumo em Inglês:

Abstract The fossil remains of Thanatosdrakon from the Plottier Formation (PS-3 quarry, Mendoza, Argentina) offer a unique opportunity to investigate the preservation of pterosaurs in fluvial environments. The objective of this study is to reconstruct the taphonomic history of the holotype (UNCUYO-LD 307) and paratype (UNCUYO-LD 350). Detailed stratigraphic analysis together with taphonomic attributes allowed defining that the specimens were preserved with a variable drainage floodplain taphonomic mode (VDF-BA). Distinct taphonomic submodes were defined for each specimen, reflecting differences in biostratinomic and fosildiagenetic processes. The holotype, which was discovered in reddish pelites interpreted as floodplain deposits, exhibits associated skeletal elements suggesting rapid burial. In contrast, the paratype, composed of only one humerus, exhibits evidence of prolonged subaerial exposure, which is evidence that it was exposed to different paleoenvironmental conditions. These findings underscore the variable preservation pathways within the same depositional setting and highlight the influence of both rapid burial and prolonged exposure on the fragile skeletons of large pterosaurs. The taphonomic submodes that have been defined contribute valuable insights into the taphonomic biases that have shaped the pterosaur fossil record in the Cretaceous Patagonian basins.

Resumo em Inglês:

Abstract The Pterosauria comprises the Mesozoic flying reptiles whose unique anatomy imposes some challenging constraints to be surpassed when it comes to biomechanical studies, besides having left no modern descendants. Thus, trying to understand its motion dynamics is quite challenging and much relies on technological devices. Here a review on the literature encompassing pterosaur locomotion and general biomechanics is provided. The number of articles per year have increased continuously since 90’s. “Evolution” and “Flight” were the most frequent words and usually cited together in scientific production, and the trend topics of the XXI century. Flight was also the trending topic before 2001 and played an important role as expected for volant reptiles. It also suggests that further scientific studies are needed to better understand other biological issues regarding land locomotion, musculoskeletal system, mechanostat, density and properties, neuromechanical aspects, and biomimetics. An increasing integration between paleontology and fields such as engineering, physics, and computational sciences is anticipated—particularly through the use of modeling, 3D simulations, and computer graphics software. This interdisciplinary approach is expected to advance our understanding of the movement dynamics of these flying reptiles, while also enabling the application of their biological principles in the development of bioinspired engineering technologies.

Resumo em Inglês:

Abstract We describe a large, three-dimensionally preserved pterosaur humerus from Bone Cabin Quarry in the Upper Jurassic Morrison Formation; one of the largest Jurassic pterosaur humeri on record. The tongue-shaped, relatively unconstricted deltopectoral crest suggests it belongs to a member of the clade Scaphognathinae, though humeri of scaphognathines remain poorly described in the literature. Bone Cabin Quarry has also produced the holotype rostrum of a scaphognathine pterosaur, Harpactognathus gentryii, which possesses a similar estimated wingspan of over two meters, so we tentatively refer the Bone Cabin Quarry humerus to this species. The three-dimensional preservation seen is very rare for “rhamphorhynchoid” elements, preserving features typically obscured or obliterated in other specimens. As a result, this humerus reveals potentially useful characters for rhamphorhynchids, particularly scaphognathines. This specimen is noteworthy for its prominent condyles and expanded distal end, which may have implications for functional morphology. The distal encd of the humerus bears a pneumatic foramen, representing the first known occurrence of pneumatization in the appendicular skeleton of non-monofenestratan pterosaurs. This pneumatization may be a function of size and convergent with pterodactyloids, but because most humeri lack well-preserved and visible distal ends, pneumatization in other known taxa of non-pterodactyloid pterosaurs cannot be explicitly ruled out.

Resumo em Inglês:

Abstract Pterosaurs had a unique morphology among flying vertebrates, and therefore, a direct comparison with living vertebrates regarding their terrestrial locomotion is impossible. In this study, we used the athletic capability indexes to infer aspects of the terrestrial proficiency of pterosaurs. We estimated the body mass, bending strength, and stylopodial axial strength indexes of 25 specimens of non-pterodactyloid and pterodactyloid pterosaurs. We used linear regression models to investigate the relationships between the indexes of athletic capability and the two stylopodia, and the indexes of athletic capability and the body mass of pterosaurs. We also compared the values of the index with those of other extinct and living animals. The results show higher values of the indexes of athletic capability for the humerus than the femur, indicating a higher relative strength of the forelimbs compared to the hindlimbs for bending and axial compression forces. We also detected a negative relationship between both indexes of athletic capability and body mass. Comparing the pterosaur athletic capability with other quadruped vertebrates indicates they had a good proficiency for terrestrial locomotion, even for plesiomorphic forms previously thought to have limited terrestrial locomotion. Even so, pteranodontoids are found to exhibit lower femoral ACI if compared to similar-sized pterodactyloids, notably azhdarchoids and dsungaripterids.