Hubbry Logo
AzhdarchoideaAzhdarchoideaMain
Open search
Azhdarchoidea
Community hub
Azhdarchoidea
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Azhdarchoidea
Azhdarchoidea
Azhdarchoidea
View on Wikipedia
from Wikipedia

Azhdarchoids
Temporal range:
Early - Late Cretaceous, 143–66 Ma Possible Late Jurassic record[1]
Four azhdarchoids (clockwise from top left): Quetzalcoatlus, Tapejara, Tupuxuara, and Meilifeilong
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: †Pterosauria
Suborder: †Pterodactyloidea
Superfamily: †Ornithocheiroidea
Clade: †Azhdarchoidea
Unwin, 1995
Subgroups

Azhdarchoidea (/æʒdɑːrˈkɔɪdɪːə/, meaning "azhdarchid-like forms") is a group of pterosaurs within the suborder Pterodactyloidea. Pterosaurs belonging to this group lived throughout the Early and Late Cretaceous periods, with one tentative member, Tendaguripterus, that lived in the Late Jurassic period. Remains of this group have been found in the Americas, Africa, and Eurasia, suggesting that they probably had a global distribution.

Azhdarchoids are generally distinguished from other pterodactyloids by their relatively low arm-to-leg-length ratio, suggesting that they were more proficient in moving on the ground than pterosaurs like Pteranodon or Anhanguera (which had very long arms relative to the length of their legs). This has led some researchers to suggest that many azhdarchoids, such as the azhdarchids and dsungaripterids, may have been primarily terrestrial, while retaining the ability to fly when necessary.[2]

Classification

[edit]

Azhdarchoidea was named by paleontologist David Unwin in 1995.[3] He later gave the clade a phylogenetic definition in 2003. He defined the group as the most recent common ancestor of Quetzalcoatlus and Tapejara, and all its descendants.[4]

Relationships

[edit]

Azhdarchoidea is generally considered as one of three major clades of pterodactyloids. The other two major groups are Archaeopterodactyloidea and Pteranodontoidea. In some older classification schemes, azhdarchoids were considered to be closely related to ctenochasmatoids like Pterodactylus and Ctenochasma. However, most researchers no longer consider this arrangement to be very likely. Instead, azhdarchoids are grouped as close relatives of pteranodontoids under the clade Ornithocheiroidea, which would comprise the bulk of pterodactyloid diversity.

A simplified cladogram illustrating the relationships between azhdarchoids and other pterosaurs based on the analysis of Brian Andres, James Clark, and Xu Xing in 2014 is shown below.[5]

Monofenestrata

Taxonomy

[edit]
Kariridraco, a member of the disputed family Thalassodromidae

Azhdarchoidea is generally believed to be composed of several principle families: Azhdarchidae, Chaoyangopteridae, Tapejaridae, Thalassodromidae, and potentially Dsungaripteridae, although Thalassodromidae of these is considered to be a lineage tapejarids by some researchers. However, the interrelationships of these groups is not confidently understood. The azhdarchids and chaoyangopterids are generally considered to be one another's closest relatives, but the affinities of tapejarids, thalassodromids, and dsungaripterids are controversial.[6] Some researchers also consider an additional grouping, Alanqidae, composed of taxa formerly considered azhdarchids.[7]

There are several competing views of azhdarchoid relationships. An early study presented by paleontologist Felipe Pinheiro and colleagues in 2011 considered the tapejarids to be a monophyletic clade including the thalassodromines and the chaoyangopterids (therein called "chaoyangopterines").[8] Other earlier studies, such as that of paleontologists Darren Naish & David Martill in 2006, and that of Lü Junchang and colleagues in 2008, considered the traditional "tapejarids" to be a paraphyletic grade of primitive azhdarchoids, with true tapejarids more basal, and the thalassodromines (alternatively called thalassodromids) and chaoyangopterids being successively more closely related to azhdarchids.[9][10]

Life reconstructions of Hatzegopteryx (top) and Arambourgiania (bottom), giant members of the family Azhdarchidae

Generally speaking, in the modern scientific literature, there are two major competing hypotheses regarding the classification of azhdarchoids. The first of these is based on the work of Brian Andres and colleagues, who have published multiple papers on the taxa Kryptodrakon, Elanodactylus, and Quetzalcoatlus among others, in which they examined the phylogenetic relationships of these groups.[5][11] Andres and colleagues have generally suggested that Dsungaripteridae and Thalassodromidae are closely related and that they form a clade (Dsungaripteromorpha) which is more closely related to Azhdarchidae than Tapejaridae.[5] This result has been corroborated by some other authors.[12] A simplified version of Andres and colleagues' phylogeny is shown below.[5]

Ornithocheiroidea

Pteranodontoidea

Azhdarchoidea

Tapejaridae

Neoazhdarchia
Tapejarids, one of the prominent azhdarchoid families. Sinopterus (left) and Huaxiadraco (right) are pictured

The second hypothesis of azhdarchoid relationships is that Dsungaripteridae is the sister taxon of Azhdarchoidea within the larger clade Tapejaroidea. This hypothesis has been published on by R. Pêgas and colleagues in their extensive studies of pterosaurs like Sinopterus, Thalassodromeus, and Aerotitan.[7][13][14][15] This hypothesis has also received support from other authors.[16][17] A simplified version of their phylogeny is shown below.[7]

Ornithocheiroidea

In 2025, Henry N. Thomas and Skye N. McDavid performed an extensive revision of pterosaur phylogenetics with a focus on Azhdarchomorpha. Their results align with a previous analysis by Pêgas et al., (2024)[15] finding Tapejaroidea to be monophyletic containing Dsungaripteromorpha and Azhdarchoidea, as well as Tapejaromorpha and Azhdarchomorpha being sister taxa within Azhdarchoidea.[18] A simplified version of their results is shown below.

Ornithocheiroidea

Subclades

[edit]

A wide variety of subclades have been defined within Azhdarchoidea in the last 15 years. Many of these have contradictory or overlapping definitions, and so whether or not these clades represent true monophyletic groups remains hotly debated. Some of the uncertainty regards the position of Thalassodromidae, which may be closely related to either Tapejaridae or Dsungaripteridae. Another source of uncertainty is the affinities of the dsungaripterids themselves. This problematic group has been found to be closely related to Ornithocheiromorpha,[19] just outside of Azhdarchoidea,[20][16][17][21] or within Azhdarchoidea.[5][22]

Name Named by Definition Notes
Azhdarchiformes Andres, 2021[23] Most-inclusive clade containing Quetzalcoatlus, but not Chaoyangopterus
Azhdarchomorpha Pêgas et al., 2021[7] Most-inclusive clade containing Azhdarcho, but not Tapejara or Thalassodromeus May be synonymous with Neopterodactyloidea if Thalassodromeus is a member of Tapejaridae
Concilazhia Thomas & McDavid, 2025[18] Least-inclusive clade containing Azhdarcho, Chaoyangopterus, and Alanqa Similar definition to 'Neopterodactyloidea' but uses Azhdarcho as an internal specifier rather than Quetzalcoatlus
Dsungaripteromorpha Andres et al., 2014[5] Most-inclusive clade containing Dsungaripterus but not Quetzalcoatlus May be synonymous with Dsungaripteridae if Dsungaripteridae is outside of Azhdarchoidea
Neoazhdarchia Unwin, 2003[4] Least-inclusive clade containing both Azhdarcho and Tupuxuara May be synonymous with Azhdarchoidea if Tupuxuara belongs to Tapejaridae; has alternately been used interchangeably with Azhdarchomorpha [6]
Neopterodactyloidea Andres et al., 2014[5] Least inclusive clade containing both Azhdarcho and Chaoyangopterus May be used interchangeably with Azhdarchomorpha if Chaoyangopterus is its most basal member; however, under the PhyloCode, this clade is improperly named, as it is derived from Pterodactylus despite not including the genus in the clade
Tapejariformes Pêgas et al., 2024[15] The clade characterized by a downturned rostrum synapomorphic with that of Tapejara May be synonymous with Tapejaridae if Caupedactylus is a tapejarid
Tapejaroidea Kellner, 1996[24] Least-inclusive clade containing Quetzalcoatlus, Tapejara, and Dsungaripterus May be synonymous with Azhdarchoidea if Dsungaripterus is more closely related to Quetzalcoatlus than either are to Tapejara; alternatively used for a clade containing Tapejaridae and Thalassodromidae[25]
Tapejaromorpha Andres et al., 2014[5] Most inclusive clade containing Tapejara but not Azhdarcho

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Azhdarchoidea

View on Grokipedia
from Grokipedia
Azhdarchoidea is a clade of pterodactyloid pterosaurs defined as the minimum inclusive group containing Tapejara wellnhoferi and Quetzalcoatlus northropi. This superfamily, nested within the larger group Pterodactyloidea, comprises a diverse assemblage of edentulous (toothless) flying reptiles distinguished by elongated cervical vertebrae with reduced neural spines, robust skulls often featuring prominent crests, and adaptations suggesting a primarily terrestrial lifestyle involving stalking and probing for prey. Subgroups include Tapejaromorpha (encompassing tapejarids and thalassodromids with elaborate cranial structures) and Azhdarchomorpha (including chaoyangopterids and azhdarchids, the latter known for extreme size and long, stiff necks). Azhdarchoidea originated in the ( stage) and flourished through the ( to ), with fossils documented across all continents, from and to , , and . Wingspans varied widely, from small-bodied taxa like Vectidraco daisymorrisae (~0.75 m) to gigantic forms such as Quetzalcoatlus northropi and Hatzegopteryx thambema (10–11 m), making azhdarchids the largest known flying vertebrates. Recent discoveries, including new azhdarchid species from Mongolia and North America in 2025, highlight ongoing revelations about their diversity and evolutionary radiation toward the end of the Mesozoic.

Morphology

Cranial features

Azhdarchoid skulls are notably elongated and lightweight, featuring extensive pneumaticity that reduces mass while maintaining structural integrity for aerial efficiency. A defining characteristic is the expansive , which often comprises more than 50% of the total length. This fenestra, combining the antorbital and nasal openings, dominates the lateral profile and contributes to the kinematic flexibility of the rostrum. The rostra of azhdarchoids are edentulous, with sharp, elongated tips adapted for grasping small prey or probing substrates. Crest morphology varies distinctly within the : tapejarids, such as , exhibit downturned, blade-like crests formed by upward-projecting premaxillae, while azhdarchids like Quetzalcoatlus northropi display straight, robust snouts lacking such pronounced ventral curvature. These crests, formed by extensions of the premaxillae and nasals, likely functioned as display structures for intraspecific signaling rather than aerodynamic aids. Posterior cranial elements show further specializations, including reduced or absent supratemporal fenestrae, as observed in , which minimizes weight at the skull's rear. The is elongated, articulating with the via two rounded condyles, and is firmly fused to surrounding cranial elements for enhanced stability during terrestrial foraging. Skull sizes range widely, from about 20-30 cm in smaller forms like Azhdarcho lancicollis to over 1 m (estimated up to 2.5 m) in giants such as , reflecting diverse body plans within the group. This lightweight cranial design is complemented by elongated , aiding balance during head movements.

Postcranial features

Azhdarchoids possessed notably long and flexible necks, formed by typically nine elongated that contributed to their overall lightweight build. These vertebrae featured procoelous —convex anteriorly and concave posteriorly—with extensive pneumatic invasion that hollowed the for substantial weight reduction while maintaining structural integrity. The were cylindrical and hyperelongated, particularly in mid-series elements, allowing a high degree of dorsoventral flexibility despite the neck's length. The further reflected adaptations for reduced mass, with a short and reduced comprising approximately 14-20 caudal vertebrae, lacking the stiffening chevrons and elongated zygapophyses seen in more basal pterosaurs. The was robust, characterized by a reduced and short , with the fused to the at an acute angle to form a strong scapulocoracoid that supported powerful flight musculature. This fusion enhanced stability during wingbeats, complementing the lightweight cranium to facilitate balanced aerial maneuvers. Limb proportions emphasized terrestrial competence alongside flight capability, with a low humerus-to-femur length ratio often below 1 (e.g., 0.79 in Aurorazhdarcho primordius), indicating relatively robust hindlimbs suited for quadrupedal support. The forelimbs featured hyperelongated metacarpal IV, which extended well beyond the other metacarpals and anchored expansive membranes along the manual digits. The pelvic girdle exhibited broad ilia and that flared laterally, distributing body weight effectively across the hindlimbs during ground-based activities. Pneumaticity was pervasive throughout the postcranium, with extensive diverticula invading the vertebrae, ribs, and long bones to minimize skeletal mass. In large taxa, this resulted in exceptionally thin bone walls, often less than 1 mm thick in the diaphyses of limb elements, as evidenced by cortical thicknesses ranging from 0.82 to 1.25 mm in mid-sized azhdarchoids. Such features underscored the group's optimization for flight efficiency in giants exceeding 10-meter wingspans.

Systematics

Etymology and definition

Azhdarchoidea was coined by paleontologist David M. Unwin in 1995 as a within Pterodactyloidea, named after the Azhdarcho Nesov, 1984, combined with the Greek suffix -oidea, denoting a higher taxonomic grouping of related forms. The name reflects the group's foundational role in encompassing advanced, toothless pterosaurs characterized by distinctive cranial and postcranial features. Unwin provided a formal cladistic definition for Azhdarchoidea in his 2003 monograph on pterosaurs, describing it as the most inclusive containing Quetzalcoatlus northropi Lawson, 1975, and Kellner, 1989, but excluding longiceps Marsh, 1876. This definition emphasized shared derived traits among azhdarchoids, including highly elongated necks composed of up to 18 with reduced neural arches, and edentulous (toothless) jaws adapted for specialized feeding strategies. Initially, the group was conceptualized within broader classifications that allied it closely with Ornithocheiroidea, incorporating some early pterodactyloids based on preliminary phylogenetic analyses. Subsequent refinements in Unwin's work and later studies excluded certain basal pterodactyloid lineages, such as ctenochasmatids, to focus Azhdarchoidea on the derived, long-necked forms that dominated diversity.

Phylogenetic relationships

Azhdarchoidea represents one of the three primary clades within , alongside Archaeopterodactyloidea and Pteranodontoidea, and is nested within the broader group Ornithocheiroidea, which encompasses advanced pterodactyloids characterized by elongated skulls and reduced . This positioning reflects a derived evolutionary stage among pterosaurs, where azhdarchoids diverged during the , contributing to the diversification of toothless, long-necked forms that dominated late skies. Key synapomorphies defining Azhdarchoidea include the absence of a , marked by a rigid connection between the quadrate and pterygoid bones that eliminates streptostylic movement; notably elongated with reduced neural arches and spines, enabling a stiff yet flexible ; and a low brachial index (humerus length relative to radius-ulna length below 0.8), indicating relatively short upper arm bones compared to the for optimized flight efficiency in large-bodied taxa. These traits distinguish azhdarchoids from earlier pterodactyloids, supporting their to terrestrial and soaring flight. Phylogenetic debates surrounding Azhdarchoidea center on its internal structure and relationships to other ornithocheiroids. Andres et al. (2014) recovered Azhdarchoidea as sister to Pteranodontoidea within Ornithocheiroidea, emphasizing shared cranial elongation but questioning the monophyly of tapejarid-azhdarchid groupings based on limited character overlap. In contrast, Pêgas et al. (2021) advocated for a monophyletic Azhdarchoidea with Tapejaridae and Chaoyangopteridae as successive basal clades leading to , supported by matrix-based analyses incorporating jaw morphology and vertebral proportions from South American and Asian specimens. This view was reinforced by Pêgas et al. (2024), who integrated additional dental and postcranial data to affirm the clade's cohesion. Most recently, Thomas and McDavid (2025) revised these relationships in a comprehensive analysis of over 150 taxa, aligning closely with Pêgas et al. by upholding and positioning tapejarids basally, while incorporating micro-CT scan data from to resolve ambiguities in inferences and giant body size evolution. Evidence suggests possible Jurassic origins for Azhdarchoidea, with Tendaguripterus from the of potentially representing a stem-azhdarchoid, based on its elongate cervicals and edentulous that prefigure synapomorphies, though its exact placement remains tentative pending further material. Major phylogenetic topologies consistently depict Azhdarchoidea as comprising Tapejaridae (basal, crested forms like Tapejara), Thalassodromidae (slender-jawed taxa like ), Chaoyangopteridae (intermediate, with expanded crests like Chaoyangopterus), and (derived giants like ), forming a ladderized structure that highlights progressive increases in neck elongation and body size. This arrangement underscores the clade's role in the radiation of toothless pterosaurs during the .

Included taxa

Azhdarchoidea encompasses several major families of toothless pterodactyloid pterosaurs, primarily from the period, defined as the most inclusive clade containing Tapejara wellnhoferi Kellner, 1989, and northropi Lawson, 1975, excluding Pteranodon longiceps Marsh, 1876. This group includes approximately 20–25 named genera, of which around 10 are well-established based on relatively complete material, with the remainder known from fragmentary remains that sometimes lead to taxonomic disputes. Subclades within Azhdarchoidea include Azhdarchiformes, comprising tapejarids and their close relatives, and Neoazhdarchia, which unites chaoyangopterids and azhdarchids as sister groups characterized by elongated and necks adapted for terrestrial foraging. The family Tapejaridae, known from the Early to Late Cretaceous of , , and , features genera such as Tapejara (type locality: Santana Group, ; notable for prominent premaxillary crests and downturned rostra) and Tupandactylus (Santana Group, ; distinguished by elaborate, blade-like cranial crests extending backward from the skull). These taxa exhibit wingspans of 3–5 m and are recognized by their deep, rounded jaw tips suited for probing soft substrates. Other tapejarid genera include Caiuajara (Mara Rosa Formation, ; gregarious with fan-shaped crests) and Sinopterus (Jiufotang Formation, ; multiple species with varying crest morphologies). Thalassodromidae, a smaller Early Cretaceous family from Brazil's Araripe Basin, includes Thalassodromeus (Romualdo Formation; small-bodied with estimated 5 m wingspan and possible soft-tissue crests inferred from neural arch impressions) and Tupuxuara (Romualdo and Santana Formations; robust build with elongated metacarpals, though sometimes classified as tapejarid). These forms are characterized by slender snouts and reduced premaxillary crests compared to tapejarids. Chaoyangopteridae, from the Late Cretaceous of Asia (primarily China), comprises intermediate forms with highly elongated, scoop-like rostra; key genera are Chaoyangopterus (Jiufotang Formation; type locality near Chaoyang City, with wingspan ~3.5 m and parallel-sided jaws) and Jidapterus (same formation; smaller, with similar mandibular morphology). Shenzhoupterus (Jiufotang Formation) and the recently described Meilifeilong (also Jiufotang; best-preserved chaoyangopterid skeleton showing elongated cervical vertebrae) further exemplify this family's adaptations for skim-feeding or ground-level prey capture. Alanqa (Kem Kem Beds, Morocco) is sometimes considered a potential chaoyangopterid due to its edentulous, rod-like jaws, though its placement remains debated. Azhdarchidae represents the dominant family (Turonian–), widespread across all continents, with giants like Quetzalcoatlus (Javelina Formation, , ; wingspan up to 10–11 m, known from partial skeletons including wing elements) and Hatzegopteryx (Densuş-Ciula Formation, ; estimated 10–12 m wingspan, robust humerus indicating predatory capabilities). Other well-established genera include Azhdarcho (Bissekty Formation, ; type genus with slender neck vertebrae), Arambourgiania (Balqa Group, ; large cervical vertebra suggesting 10 m wingspan), and Zhejiangopterus (Tangwang Formation, China; multiple articulated skeletons showing gracile build). Additional taxa such as Phosphatodraco (Oulad Abdoun Basin, Morocco; cervicals from phosphate deposits), Aerotitan (Allen Formation, ; rostrum fragment), Bakonydraco (Csehbánya Formation, ; mandible), Volgadraco (Rybushka Formation, ; snout and cervicals), and Eurazhdarcho (Sebeş Formation, ; partial skeleton, possibly synonymous with Hatzegopteryx) highlight the family's global diversity and size range from 3–12 m wingspans. Recent additions include Cryodrakon (Dinosaur Park Formation, ; inferred from associated bones), Gobiazhdarcho tsogtbaatari and Tsogtopteryx mongoliensis (Bayanshiree Formation, ; 2025 discoveries with wingspans estimated at 3–4 m), and Infernodrakon hastacollis (Hell Creek Formation, , ; 2025 description based on cervical vertebra, indicating a large-bodied form), underscoring ongoing discoveries. Dsungaripteridae, including (Early Cretaceous of ; known for upturned rostral tips and small teeth, though edentulous in adults), is sometimes excluded from Azhdarchoidea due to phylogenetic analyses placing it outside the core clade, though early definitions included it as a basal member.

Evolutionary history

Origins and diversification

The origins of Azhdarchoidea are rooted in the , with the earliest definitive record provided by Aurorazhdarcho primordius from the Early Tithonian in (~152–150 Ma), based on fragmentary cranial material exhibiting azhdarchoid features like a low orbital position. A potentially earlier tentative record is the mandibular symphysis of Tendaguripterus recki from the Upper in , dated to around 152 Ma, which exhibits features consistent with early azhdarchoids such as a slender, toothless jaw, though its phylogenetic placement as a dsungaripteroid remains debated due to fragmentary material. Diversification accelerated in the , particularly during the Aptian-Albian stages (approximately 125–100 Ma), marking a shift from sparse Jurassic occurrences to more abundant fossils. Key discoveries have shaped understanding of azhdarchoid evolution. The genus Quetzalcoatlus was first described in 1975 from the Late Cretaceous Javelina Formation in Texas, USA, based on a distal tibia and partial wing elements, highlighting the group's potential for gigantism early in its recognition. In 1984, Azhdarcho lancicollis was named from cervical vertebrae and other bones collected from the Turonian Bissekty Formation in Uzbekistan, establishing the family Azhdarchidae. Tapejarids, a major subfamily, emerged from Brazilian Lagerstätten in the late 1980s and 1990s, with Tapejara wellnhoferi described in 1989 from the Aptian–Albian Santana Formation, revealing diverse cranial crests and edentulous jaws. Diversification patterns show an initial radiation in during the , with rich assemblages in (e.g., Araripe Basin) and , encompassing tapejarids and early azhdarchids adapted to coastal and lacustrine environments. This Gondwanan phase was followed by increasing Laurasian dominance in the mid-Cretaceous, as evidenced by European and Asian finds. Peak diversity occurred during the – (approximately 100–90 Ma), with over 15 genera documented across subfamilies like Tapejaridae, Chaoyangopteridae, and , reflecting adaptive radiations in terrestrial and nearshore habitats. A notable trend was the increase in body size, from small forms with 1–2 m wingspans in the (e.g., early tapejarids) to giants exceeding 10 m in later azhdarchids, possibly facilitated by anatomical innovations in flight and locomotion. Significant gaps persist in the fossil record, particularly for the , where Tendaguripterus and Aurorazhdarcho stand as isolated occurrences amid otherwise poor preservation. Recent discoveries, such as Meilifeilong youhao from the Jiufotang Formation in (dated 125–113 Ma), help fill Early Cretaceous voids by documenting a new chaoyangopterid with preserved soft tissues and a estimated at 3–4 m. Additionally, a 2025 report of a gigantic azhdarchid from early phosphate deposits in the Palmyrides of highlights ongoing revelations in understudied regions, extending known distribution. These finds underscore the need for further exploration in understudied regions to clarify early evolutionary dynamics.

Temporal range and extinction

Azhdarchoidea first appeared during the , with the earliest definitive records dating to the Early stage approximately 150 million years ago, based on fragmentary remains from the in . The group persisted throughout the , achieving its greatest diversity and prominence in the , before going at the end of the stage around 66 million years ago, coinciding precisely with the Cretaceous-Paleogene (K-Pg) boundary event driven by the Chicxulub asteroid impact. No azhdarchoid fossils have been documented from strata, confirming their complete at this boundary without evidence of post-Cretaceous survival. During the , azhdarchoids dominated pterosaur faunas, particularly in terrestrial environments, with several giant taxa exemplifying their radiation. Notable examples include Hatzegopteryx thambema from the Densuș-Ciula Formation in , dated to the late around 70-66 million years ago, and Arambourgiania philadelphiae from the Al Hisa Formation in , dated to the stage approximately 80 million years ago. Isolated azhdarchoid remains, such as cervical vertebrae, have also been reported from the in , representing -aged deposits and highlighting their presence in Gondwanan continental settings. The extinction of Azhdarchoidea aligned with the broader K-Pg mass extinction that eliminated non-avian dinosaurs and many other groups, likely due to the combined effects of the Chicxulub impact, including global wildfires, climate disruption, and habitat loss. Some analyses suggest a pre-boundary decline in pterosaur diversity, potentially exacerbated by niche competition with expanding avian lineages that overlapped in aerial and foraging roles. The youngest records include an azhdarchid cervical vertebra from the in , , and well-preserved specimens of from the in , both from the latest . Preservation biases significantly influence the perceived temporal distribution of azhdarchoids, with better representation in terrestrial and nearshore deposits compared to earlier marine or lagoonal settings, leading to an overestimation of their late dominance. Fragmentary remains dominate the record, and estimates indicate that up to 50% of azhdarchoid diversity remains undiscovered due to these taphonomic and sampling limitations. Recent 2025 analyses of latest azhdarchid material from the Palmyrides in reinforce the absence of survivors, attributing their terminal record firmly to the and underscoring the abrupt nature of their at the K-Pg boundary.

Paleobiology

Locomotion and habitat

Azhdarchoids exhibited efficient , primarily through a quadrupedal parasagittal supported by robust s and elongated forelimbs, enabling them to traverse firm substrates with minimal energy expenditure. Trackway evidence, such as the ichnogenus Haenamichnus from the Uhangri Formation in , reveals narrow-gauge pes and manus impressions consistent with this , suggesting knuckle-walking-like propulsion on the forelimbs similar to modern ground-hornbills (Bucorvus). A 2025 study of neoazhdarchian tracks from the Hwasun Seoyuri Tracksite further links these structures to azhdarchoids, indicating they were adept ground-dwellers capable of occasional bipedal rearing for or vigilance, facilitated by strong hindlimb musculature. In flight, azhdarchoids employed a quadrupedal launch mechanism, using all four limbs to generate from a standstill, which was particularly advantageous for their large sizes and reduced . Their wings featured high aspect ratios (approximately 8.1), optimized for over long distances rather than rapid flapping, akin to modern or albatrosses. Aerodynamic models estimate gliding speeds of 80–100 km/h under favorable wind conditions, allowing efficient travel across continental landscapes. Azhdarchoids primarily occupied coastal plains and inland basins, as inferred from their fossil record in fluvial and lacustrine deposits worldwide. Notable examples include the in , representing riverine floodplains, and the in , indicative of lake-margin environments. Their distribution spanned the , , and during the , though it was patchy with no confirmed records from or , reflecting preferences for warm, continental interiors over fully marine settings. Key adaptations underpinned these locomotor and habitat preferences, including low forelimb-to-hindlimb length ratios (around 1.13 in Quetzalcoatlus), which promoted stable, energy-efficient walking on land. Extensive skeletal pneumaticity, with air space proportions reaching 68–72% in vertebral bones, minimized body mass to support flight in giants exceeding 10 m wingspans despite their terrestrial lifestyle. Their neck flexibility further aided ground-level maneuvering during habitat exploration.

Diet and feeding ecology

Azhdarchoids are primarily inferred to have been terrestrial carnivores, preying upon or scavenging small vertebrates such as juvenile dinosaurs and mammals in environments. This dietary preference is supported by cranial and postcranial morphology, including elongated necks and robust skulls adapted for seizing and manipulating prey on the ground. Feeding strategies among azhdarchoids varied by subgroup, with many employing a "stork-like" probing technique using their long, pointed to detect and extract hidden prey from or carcasses. In tapejarids, the downturned, edentulous with rounded tips resemble those of modern parrots, supporting hypotheses of frugivory or omnivory focused on soft fruits and seeds, potentially supplemented by small invertebrates; recent fossil evidence from , including phytoliths in stomach contents, confirms plant consumption in this . Chaoyangopterids, with intermediate rostral morphologies between tapejarids and azhdarchids, likely pursued a mixed piscivorous and omnivorous strategy, targeting in shallow waters alongside terrestrial items, though direct evidence remains limited to anatomical inferences. Ecologically, azhdarchoids occupied apex terrestrial predator niches in floodplains, where their large size and mobility allowed competition with small theropod dinosaurs for vertebrate prey. Possible kleptoparasitic interactions, such as stealing prey from smaller predators, have been proposed based on their opportunistic scavenging habits, but lack confirmatory evidence. Early suggestions of filter-feeding, inspired by elongated , have been refuted by the absence of specialized dental or structures and incompatible mechanics. A 2023 macroevolutionary study revealed rapid dietary diversification within Azhdarchoidea during the , driven by elevated evolutionary rates in cranial structures that enabled shifts toward specialized feeding apparatuses, including herbivorous and durophagous adaptations amid expanding angiosperm habitats. This burst contributed to their ecological dominance before a decline, potentially exacerbated by competition with birds over similar terrestrial resources.

References

  1. https://pmc.ncbi.nlm.nih.gov/articles/PMC12447946/
  2. https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1801703
  3. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0058451
  4. https://www.tandfonline.com/doi/abs/10.1080/02724634.2024.2442476
  5. https://doi.org/10.1371/journal.pone.0002271
  6. https://www.researchgate.net/publication/235806554
  7. https://doi.org/10.1111/j.1475-4983.2008.00761.x
  8. https://doi.org/10.1007/s00015-011-0073-1
  9. https://doi.org/10.1371/journal.pone.0010875
  10. https://doi.org/10.1371/journal.pone.0058451
  11. https://doi.org/10.1098/rsos.160333
  12. https://zookeys.pensoft.net/articles.php?id=3978
  13. https://www.researchgate.net/publication/27246965_Pterosaurs_From_Deep_Time
  14. https://www.lyellcollection.org/doi/10.1144/gsl.sp.2003.217.01.11
  15. https://www.researchgate.net/publication/395580185_The_phylogeny_of_Azhdarchoidea_Pterosauria_and_the_rise_of_toothless_pterosaurs
  16. https://pubs.geoscienceworld.org/books/book/1594/chapter/107367091/on-the-phylogeny-and-evolutionary-history-of
  17. https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.21376
  18. https://www.sciencedirect.com/science/article/abs/pii/S0195667121002469
  19. https://palaeo-electronica.org/content/2025/5546-systematics-of-ornithocheiriform-pterosaurs
  20. https://tandf.figshare.com/articles/dataset/Enter_the_dragons_the_phylogeny_of_Azhdarchoidea_Pterosauria_Pterodactyloidea_and_the_evolution_of_giant_size_in_pterosaurs/30541081
  21. https://doi.org/10.3897/zookeys.432.7913
  22. https://pmc.ncbi.nlm.nih.gov/articles/PMC9922500/
  23. https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2442476
  24. https://sjg.springeropen.com/articles/10.1007/s00015-011-0073-1
  25. https://onlinelibrary.wiley.com/doi/abs/10.1002/mmng.1999.4860020109
  26. https://www.researchgate.net/publication/235806554_The_osteology_of_Azhdarcho_lancicollis_Nessov_1984_Pterosauria_Azhdarchidae_from_the_Late_Cretaceous_of_Uzbekistan
  27. https://www.researchgate.net/publication/225910777_On_the_osteology_of_Tapejara_wellnhoferi_KELLNER_1989_and_the_first_occurrence_of_a_multiple_specimen_assemblage_from_the_Santana_Formation_Araripe_Basin_NE-Brazil
  28. https://pmc.ncbi.nlm.nih.gov/articles/PMC2386974/
  29. https://www.nature.com/articles/s41598-023-48076-7
  30. https://ui.adsabs.harvard.edu/abs/2025SciNa.112...78A
  31. https://www.lyellcollection.org/doi/10.1144/SP544-2023-126
  32. https://pmc.ncbi.nlm.nih.gov/articles/PMC5849296/
  33. http://markwitton-com.blogspot.com/2017/01/new-paper-when-short-necked-giant.html
  34. https://doc.rero.ch/record/15687/files/PAL_E2073.pdf
  35. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0002271
  36. https://www.cell.com/current-biology/fulltext/S0960-9822(25)00446-4
  37. https://www.app.pan.pl/archive/published/app60/app000052013.pdf
  38. https://doi.org/10.4202/app.00005.2013
  39. https://www.researchgate.net/publication/49185735_Comparative_evidence_for_quadrupedal_launch_in_pterosaurs
  40. https://pmc.ncbi.nlm.nih.gov/articles/PMC2981443/
  41. https://bioone.org/journals/journal-of-vertebrate-paleontology/volume-41/issue-sp1/02724634.2021.1907587/Morphology-and-Taxonomy-of-iQuetzalcoatlus-i-Lawson-1975-Pterodactyloidea/10.1080/02724634.2021.1907587.short
  42. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0097159
  43. https://www.nature.com/articles/s41598-021-97856-6
  44. https://doi.org/10.1111/brv.12431
  45. https://doi.org/10.1371/journal.pone.0038900
  46. https://www.science.org/content/article/pterosaur-died-belly-full-plants-fossil-first
  47. https://doi.org/10.1016/j.cub.2023.01.007
Add your contribution
Related Hubs
User Avatar
No comments yet.