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Giant azhdarchid pterosaurs from the terminal Cretaceous of Transylvania (western Romania)
Abstract and Figures
Pterosaur remains from the Late Cretaceous of the Hateg Basin of western Romania were reported by Nopcsa as early as 1899. Recent discoveries from the Late Maastrichtian Densuş-Ciula Formation include the giant azhdarchid Hatzegopteryx thambema, the holotype of which, consisting of skull elements and a humerus from the Vǎlioara locality, is described in detail. A very large femur from the same formation at Tuştea is also described. The systematic position of Hatzegopteryx is discussed. The wing span of H. thambema is estimated to be close to that of Quetzalcoatlus northropi (≥ 12 m), but its skull is especially robust and may have been remarkably long (≥ 2.5 m). The skull bones of H. thambema consist of a very thin outer cortex enclosing an inner meshwork of extremely thin trabeculae surrounding very numerous small alveoli, an unusual structure reminiscent of expanded polystyrene. This peculiar structure, combining strength with lightness, can probably be considered as an adaptation to flight in a very large animal, through reduction of skull weight.
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... Femora are reported in the azhdarchid species Q. lawsoni, cf. A. philadelphiae (BSPG 1966 XXV 506) (Martill and Moser, 2017), cf. H. thambema (FGGUB R.1625) (Buffetaut et al., 2003), Z. linhaiensis (Cai Andres and Langston-Morphology and taxonomy of Quetzalcoatlus and Wei, 1994), C. boreas (Hone et al., 2019), A. lancicollis (Nesov, 1984); and the putative azhdarchid specimens MCNA number unknown (Averianov, 2014), NJSM 18772 (Parris et al., 2004), TMM 41839-3.1 and 3.2, TMP 1991.36.616 and 92.83.6 (Godfrey and Currie, 2005, and ZIN PH 82/44 (Averianov, 2014). ...
... 4d), A. lancicollis (Averianov, 2010:309), and at least the distal half of Pteranodon and YPM VPPU 021821 (Bennett, 2001a:103-104). A jagged ridge on the medial surface of the proximal shaft that curves distoposterolaterally is identified here as the adductor ridge (small depression with rugose surface of Kellner and Tomida, 2000, well-marked oblique ridge of Buffetaut et al., 2003, and low and blunt ridge of Frey et al., 2011) for the insertion of M. adductor femoris (Bennett, 2001a:103, fig. 107B). ...
... The left jugal of TMM 41961-1.1 is the most completely preserved, but the main body of its right jugal has been largely destroyed. A jugal is also reported in the azhdarchid species H. thambema (Buffetaut et al., 2003), Z. linhaiensis (Cai and Wei, 1994), and A. bostobensis (CCMGE 41/11915) (Averianov, 2004). ...
Quetzalcoatlus is the largest flying organism ever known and one of the most familiar pterosaurs to the public. Despite a half century of interest, it remains very incompletely described. This shortfall is addressed here through a full morphological description of Quetzalcoatlus and the other pterosaur material of Big Bend National Park, Texas. The first reported material was described and named Quetzalcoatlus northropi by Douglas Lawson in 1975, but in two separate publications. A ruling by the International Commission of Zoological Nomenclature was required for the name to be made available. Review of the pterosaur fauna of the Park recovers three valid species of azhdarchid pterosaurs in the latest Cretaceous Period Javelina and Black Peaks formations. The size and occurrence of these species are correlated with depositional environment. The holotype of the giant Quetzalcoatlus northropi and six other giant specimens referred to it occur in stream-channel deposits, including the youngest reported pterosaur. The vast majority of specimens (200+) are from large pterosaurs found in the abandoned channel-lake deposits at Pterodactyl Ridge; they form a diagnosable natural group erected as the new species Quetzalcoatlus lawsoni. A moderate-sized partial skull and cervical series also found in the abandoned channel-lake deposits at Pterodactyl Ridge, but lower in the section, is distinct from both species and is erected as Wellnhopterus brevirostris, gen. et sp. nov. Overbank flood-plain facies preserve another eleven specimens of extreme size variation, including small azhdarchids. The Big Bend pterosaur fauna provides the greatest known sample of azhdarchid pterosaurs and three-dimensional pterosaur morphology.
... Il nuovo millennio ha visto la scoperta di nuovi azhdarchidi. Hatzegopteryx thambema (Fig. 22) fu il primo a ricevere un nome nel XXI secolo (Buffetaut et al., 2002;Buffetaut et al., 2003). Rappresentato da molteplici elementi frammentari di cranio e arti, questo pterosauro dal Maastrichtiano della Romania, sembra essere il più grande mai conosciuto. ...
... Queste forme giganti sono sfortunatamente rappresentate da poco materiale fossile. Inizialmente, quando vi erano poche conoscenze in merito, fu stimata un'apertura alare tra 11 e 21 m (Lawson, 1975a), ma con una comprensione maggiore degli azhdarchidi le misure furono riviste in 10.5 m per Quetzalcoatlus northropi (Langston, 1981), 12 m per Hatzegopteryx (Buffetaut et al., 2003) e tra 11-13 m per Arambourgiania . Più Zhejiangopterus la parte posteriore è esente da creste, Queztalcoatlus sp. ...
... Dai resti fossili è possibile stimare una larghezza della mandibola di almeno 0.5 m, quindi può essere stiamata una varizione in lunghezza di mascella e mandibola tra 2.5 m, come in Bakonydraco, e 5 m, come in Qetzalcoatlus sp. La seconda ipotesi è ritenuta da molti, con cognizione di causa, abbastanza fantasiosa anche per uno pterosauro (Buffetaut et al., 2003). Ma l'ipotesi più conservativa rimane comunque sorprendente, dato che con i 2.5 m di fauci e almeno 0.5 m di parte posteriore del cranio la lunghezza totale raggiungerebbe almeno 3 m. ...
A new and articulated specimen of a pterosaur wing including upper arm, forearm, parts of the carpus and metacarpus, and a wing phalanx from Maastrichtian phosphatic deposits of Morocco are assigned to Tethydraco cf. regalis Longrich et al., 2018.
The specimen comes from the village of Ouled Abdoun, close to the Oued Zem basin and its phosphatic mines (Morocco). The fossil is part of the collection of the Université Hassan II of Casablanca (ID Number FSAC CP 251).
In the first part, the thesis presents a synthetic introduction about the morphology, anatomy, physiology and evolution of pterosaurs in order to offer a comprehensive framework on this fascinating group of extinct flying tetrapods.
The main goal of this work is the taxonomic identification of the specimen, principally by morphological and morphometric/statistic analysis, based on the comparison with the most similar pterosaurs of the same epoch.
Aspect of the humerus morphology and dimensional ratios of the wing elements suggest that T. cf. regalis is an azhdarchid rather than pteranodontid, as originally proposed. A high abundance of azhdarchid remains in the open marine setting of the Moroccan phosphates casts doubt on suggestions that Azhdarchidae were largely terrestrial pterosaurs.
... Pteranodon, arguably the most famous pterosaur, is estimated to have had a wingspan of 6-7 m (Table 1) (8,9). The azhdarchids are one of the most successful Cretaceous pterosaur groups and include several large species with wingspans of approximately 9-11 m ( Table 1) (10)(11)(12)(13). Although their huge sizes have been led debate about whether they were flightless (14)(15)(16), Quetzalcoatlus northorpi, an azhdarchid species, is often regarded as one of the largest flying animals in history (16). ...
... A low sinking speed and a narrow circle radius are advantageous during the ascent phase of thermal soaring, whereas a high glide ratio and flight speed are advantageous during the glide phase, the benefits of which are not simultaneously satisfied. Natural (10) California condor (10) Argentavis magnificens (11) kori bustard (10) white stork (13) ASK 14 (motor glider) (28) Quetzalcoatlus (10) Pteranodon (36.7 kg) (13) Pteranodon (18.6 kg) (12) magnificent frigatebird (16) Pelagornis sandersi (40.1 kg) (16)(17) Pelagornis sandersi (21.8 kg) (16)(17) brown pelican (14) kori bustard selection has favored bird species that prioritize performance in the ascent phase; thermal soaring species have a smaller wing loading relative to their size than other species (45). This aids in achieving a slower sinking speed and tighter circle radius, as they must use weak updrafts at low altitudes after landing on the ground for foraging and/or flying in poor updraft conditions due to unexpected weather changes. ...
The largest extinct volant birds (Pelagornis sandersi and Argentavis magnificens) and pterosaurs (Pteranodon and Quetzalcoatlus) are thought to have used wind-dependent soaring flight, similar to modern large birds. There are two types of soaring: thermal soaring, used by condors and frigatebirds, which involves the use of updrafts to ascend and then glide horizontally; and dynamic soaring, used by albatrosses, which involves the use of wind speed differences with height above the sea surface. Previous studies have suggested that Pelagornis sandersi used dynamic soaring, while Argentavis magnificens and Quetzalcoatlus used thermal soaring. For Pteranodon, there is debate over whether they used dynamic or thermal soaring. However, the performance and wind speed requirements of dynamic and thermal soaring for these species have not yet been quantified comprehensively. We quantified these values using aerodynamic models and compared them with that of extant birds. For dynamic soaring, we quantified maximum travel speeds and maximum upwind speeds. For thermal soaring, we quantified the animal's sinking speed circling at a given radius and how far it could glide losing a given height. Our results confirmed those from previous studies that Argentavis magnificens and Pteranodon used thermal soaring. Conversely, the results for Pelagornis sandersi and Quetzalcoatlus were contrary to those from previous studies. Pelagornis sandersi used thermal soaring, and Quetzalcoatlus had a poor ability both in dynamic and thermal soaring. Our results demonstrate the need for comprehensive assessments of performance and required wind conditions when estimating soaring styles of extinct flying species.
... Pterosaurs, a clade of volant archosaurs, evolved in the Late Triassic, and diversified in the Jurassic and Cretaceous (Wellnhofer, 1991;Unwin, 2005;Witton, 2013). They include the largest flying animals to have ever lived, some with wingspans exceeding 10 m (e.g., Lawson, 1975;Frey and Martill, 1996;Buffetaut et al., 2003). Pterosaurs were incredibly diverse both taxonomically and morphologically. ...
... In Volgadraco bogolubovi, only the diaphysis of the femur is preserved, and it is a large, hollow, thin-walled bone, with a bowed shaft (Averianov et al. 2008). Hatzegopteryx has a slightly bowed femur with a thin wall, the fourth trochanter lacks a marked tuberosity, and a small knob is located close to the proximal ridge, perhaps corresponding to the internal trochanter (Buffetaut et al. 2003). A curved femur is recognized also in the azhdarchoids Shenzhoupterus (Lü et al. 2008) and Huaxiapterus, where the femoral head is distinct and set on a narrow neck, angled from the shaft (Lü and Yuan 2005;Lü et al. 2006). ...
The pterosaur fossil record in Portugal is scarce, comprising mainly isolated teeth and rare postcranial material. Here,
we describe a well-preserved right proximal femur of a pterodactyloid pterosaur from the Kimmeridgian, Upper Jurassic
Praia da Amoreira–Porto Novo Formation of Peniche, Portugal. It is noteworthy for its relatively large size, compared to
other Jurassic pterosaurs. It shows affinities with dsungaripteroids based on a combination of features including the bowing
of the shaft, the mushroom-like cap of the femoral head, and the distinctly elevated greater trochanter. The femur has
a relatively thinner bone wall compared to dsungaripterids, and is more similar to basal dsungaripteroids. A histological
analysis of the bone cortex shows it had reached skeletal maturity. The preserved last growth period indicates fast, uninterrupted
growth continued until the final asymptotic size was reached, a growth pattern which could best be compared
to pterodactyloid femora from the Early Cretaceous. The specimen is the second confirmed report of a dsungaripteroid
from the Jurassic, and it is the first record of this group from the Iberian Peninsula.
... Most azhdarchids were smaller but still relatively large (~3e6 m in wingspan), such as the roughly Vultur-sized Zhejiangopterus linhaiensis, with 2.9 m in wingspan and~9 kg in body mass (see Witton, 2008a). Most records of azhdarchids come from the Northern Hemisphere (Lawson, 1975;Nesov, 1984;Wellnhofer, 1991;Cai and Wei, 1994;Kellner and Langston, 1996;Buffetaut et al., 1996Buffetaut et al., , 2002Buffetaut et al., , 2003Pereda-Suberbiola et al., 2003;Averianov, 2010;Holgado et al., 2011;Vremir et al., 2013). This includes, especially, Laurasian lands (including North America, Europe and Asia), as well as Northern Gondwana, particularly the Arabic Peninsula (Arambourg, 1959;Frey and Martill, 1996;Martill and Moser, 2017) and Northern Africa (Pereda-Suberbiola et al., 2003;Ibrahim et al., 2020). ...
Aerotitan sudamericanus, from the Upper Cretaceous of the Neuquén Basin (Patagonia, Argentina), is known from a partial jaw fragment which has been interpreted as either an azhdarchid upper jaw, azhdarchid lower jaw, or thalassodromine upper jaw (as the sister-group of Alanqa). Here, we compare it in detail to upper and lower jaws of taxa belonging to all azhdarchoid lineages. It possesses a lateral angle (angle of divergence between occlusal and apex margins in lateral view) that is too low for an upper jaw of any azhdarchoid group. It further differs from thalassodromine upper jaws in exhibiting a convex occlusal margin (in lateral view), a sulcate occlusal surface, and lacking a sagittal crest. Furthermore, Aerotitan differs from Alanqa in 5 aspects: (1) occlusal margin shape in lateral view (convex in Aerotitan, straight in Alanqa), (2) median dentary eminence shape (slender in Aerotitan, posteriorly expanded in Alanqa), (3) median dentary eminence position (anterior in Aerotitan, close to the posterior end of the symphysis in Alanqa), (4) tomial edges shape (thick and blunt in Aerotitan, thin and sharp in Alanqa), and (5) occlusal surface anterior to the median eminence (cross-section concave in Aerotitan, slightly convex in Alanqa). We also conclude that the holotype of A. sudamericanus is a match for an azhdarchid lower jaw, being extremely similar to that of Mistralazhdarcho. When scored as a lower jaw in our phylogenetic analysis, it is recovered as a close relative of Mistralazhdarcho, in a polytomy that also includes Arambourgiania. In contrast, Alanqa is recovered as the sister-group of Keresdrakon, both located at the base of a broader clade of long-snouted azhdarchoids that also includes chaoyangopterids and azhdarchids, to the exclusion of tapejarines and thalassodromines.
... Pteranodon, presumably the most famous pterosaur, is estimated to have had a wingspan of 6 m (Table 1) (5). The azhdarchids are one of the most successful Cretaceous pterosaur groups and include several large species with wingspans of approximately 10 m (Table 1) (6)(7)(8)(9). Quetzalcoatlus northorpi, an azhdarchid species, is regarded as one of the largest flying animals in history. The icons indicate dynamic soarer, thermal soarer, and poor soarer and summarize the main results of this study. ...
The largest extinct volant birds ( Pelagornis sandersi and Argentavis magnificens ) and pterosaurs ( Pteranodon and Quetzalcoatlus ) are thought to have used wind-dependent soaring flight, similar to modern large birds. There are two types of soaring: thermal soaring, used by condors and frigatebirds, which involves the use of updrafts over the land or the sea to ascend and then glide horizontally; and dynamic soaring, used by albatrosses, which involves the use of wind speed differences with height above the sea surface. Previous studies have suggested that Pelagornis sandersi used dynamic soaring, while Argenthavis magnificens, Pteranodon , and Quetzalcoatlus used thermal soaring. However, the performance and wind speed requirements of dynamic and thermal soaring for these species have not yet been quantified comprehensively. We quantified these values using aerodynamic models and compared them with that of extant birds. For dynamic soaring, we quantified maximum flight speeds and maximum upwind flight speeds. For thermal soaring, we quantified the animal’s sinking speed circling at a given radius and how far it could glide losing a given height. Our results confirmed those from previous studies that Pteranodon and Argentavis magnificens used thermal soaring. Conversely, the results for Pelagornis sandersi and Quetzalcoatlus were contrary to those from previous studies. Pelagornis sandersi used thermal soaring, and Quetzalcoatlus had a poor ability both in dynamic and thermal soaring. Our results demonstrate the need for comprehensive assessments of performance and required wind conditions when estimating soaring styles of extinct flying species.
The Maastrichtian Javelina Formation of southwestern Texas comprises a thick sequence of stream channel and floodplain deposits accumulated in a broad southeast-trending valley, several hundred kilometers inland from the Late Cretaceous shoreline. Three pterosaur species are found here. Remains of Quetzalcoatlus lawsoni, sp. nov., are concentrated in deposits of shallow alkaline lakes that developed in abandoned reaches of stream channels. Areas surrounding the lakes were vegetated with fan palms, and the higher floodplain supported a subtropical forest dominated by the dicot tree Javelinoxylon and araucariacean conifers. The shallow lakes were inhabited by a diverse invertebrate fauna of arthropods, gastropods, and bivalves, a likely food source for the slender-beaked Quetzalcoatlus lawsoni, sp. nov., which may have had a lifestyle similar to modern large gregarious wading birds. In contrast, remains of the giant Q. northropi are rare and found instead only in stream channel facies. It may have had a more solitary lifestyle and preferred riparian habitats. The warm, dry, subtropical but nonseasonal conditions of the region may represent a preferred climatic regime for azhdarchid pterosaurs generally.
Azhdarchid pterosaurs, the largest flying vertebrates, remain poorly understood,
with fundamental aspects of their palaeobiology unknown. X-ray computed tomography
reveals a complex internal micro-architecture for three-dimensionally
preserved, hyper-elongate cervical vertebrae of the Cretaceous azhdarchid
pterosaur, Alanqa sp. Incorporation of the neural canal within the body of the
vertebra and elongation of the centrumresult in a ‘‘tubewithin a tube’’ supported
by helically distributed trabeculae. Linear elastic static analysis and linearized
buckling analysis, accompanied with a finite element model, reveal that as few
as 50 trabeculae increase thebuckling loadby up to 90%, implying that a vertebra
without the trabeculae is more prone to elastic instability due to axial loads. Subsuming
the neural tube into the centrum tube adds considerable stiffness to the
cervical series, permitting the uptake of heavy prey itemswithout risking damage
to the cervical series, while at the same time allowing considerable skeletal mass
reduction.
The Haţeg region of Transylvania-Romania, known as the "Haţeg Country", due to its specific character as a region wholly encircled by mountains, has been renowned for over a century for its palaeontological geosites from which dinosaur bones of several species, dinosaur eggs and hatchlings, were unearthed along with numerous other taxa representative of all the major vertebrate groups: fishes, amphibians, reptiles, birds and mammals. The region illustrates the phenomenon of "insular dwarfism", linked to the lengthy persistence of animals in isolated habitats. Palaeontological research in the region took place across two periods, separated by a 50-year gap in which no systematic studies were carried out. The first, closely associated with Franz Nopcsa, spanned between 1897 and 1929; the second period, begun in 1977, continues to this day. The main achievements of these two periods are briefly presented. After 1990, the region also became a center for geoconservation, incorporating a complex activity of research, protection and valorisation of existing dinosaur sites, under the tutelage of geologists from the University of Bucharest. These efforts led to UNESCO recognizing the region as the "Haţeg Country Dinosaurs Geopark" in 2005. Afterwards, it became a leading centre for geoeducation and geotourism in Romania. Here, we discuss the roles played in this achievement by enduring scientific research in the fields of geology and palaeontology across the region, the efforts for the geoconservation of the fossiliferous sites and not least local authorities' involvement and cooperation.
The holotype and only specimen of Ornithodesmus cluniculus, a sacrum from the late Wealden (=Barremian) of the Isle of Wight, is redescribed and is shown not to be pterodactyloid as previously described. Comparison with sacral vertebrae of pterodactyloids and of advanced theropod dinosaurs shows it to resemble most closely those of the small theropod Saurornithoides. Because O. cluniculus is the type species of Ornithodesmus, the genus is transferred to the Theropoda. It is assigned to the Troodontidae with uncertainty, because of the limited nature of the holotype. Ornithodesmus cluniculus cannot be diagnosed with the Troodontidae and is the nomen vanum within the family. If it is a troodontid, it represents the first record of a troodontid from the Wealden of Europe, and also the earliest record of this family. The undoubted pterodactyloid material from the Barremian of the Isle of Wight, "Ornithodesmus' latidens, requires a new generic name. -Authors
The morphology of jaws, neck, notarium, ribs, sacrum, pectoral girdle, wing and hind limbs of the type genus of azhdarchids are described and analyzed. Diagnosis of the family and genera Tepuxuara, Bennettazhia gen. nov., Azhdarcho, Bogolubovia, Quetzalcoatlus and Arambourgiania are given. -English summary
The first occurrence of a pterosaur fossil from the Early Cretaceous of Peru is reported. The specimen consists of a nearly complete right humerus of a pteranodontid pterosaur preserved in three dimensions, presumably in a concretion. The Pteranodontidae is rediagnosed, and included genera and materials are listed. The Nyctosauridae and Dsungaripteridae are also diagnosed on the basis of postcranial characters, and the relationships of those three taxa plus the Azhdarchidae are discussed. The species Santanadactylus spixi Wellnhofer (1985) is reassigned to the Dsungaripteridae. -Author
The skeletal proportions and size distribution of the Late Cretaceous pterosaur Pteranodon are described. The functional morphology of flight is discussed and it is argued that the patagium attached to the femora which enabled the hindlimb to assist in flapping and control of the patagium. Movements of the wing provided yaw control so that the skull and cranial crest need not be interpreted as a forward rudder. Terrestrial locomotion is discussed, and it is argued that Pteranodon and other large pterodactyloids must have been bipedal. The functional morphology of the jaws and feeding are discussed, and it is argued that Pteranodon could swim and fed while swimming on the water rather than dipping food while in flight. The function of postcranial pneumaticity is also discussed.