78-668: Tapejaroidea (or tapejaroids ) is a group of pterosaurs belonging to the clade Ornithocheiroidea . Tapejaroids lived from the Early to Late Cretaceous periods, with one possible member, Tendaguripterus , extending the fossil range to the Late Jurassic period. Tapejaroidea contains two groups, the Dsungaripteridae and the Azhdarchoidea , which in turn includes the azhdarchids , the group that contains some of
156-566: A crest consisting primarily of bone; the crest had a large component of soft tissue in other members of the group. Martill and Naish considered Tapejaridae a paraphyletic (unnatural) group in 2006, and found Tupuxuara (which included Thalassodromeus in their analysis) to be the sister taxon to the family Azhdarchidae . This clade ( Tupuxuara and Azhdarchidae) had been named Neoazhdarchia by palaeontologist David Unwin in 2003, an arrangement Martill and Naish concurred with. According to Martill, features uniting members of Neoazhdarchia included
234-420: A crest, and wind and water could also have helped cool pterosaurs in high-temperature maritime settings. In 2013, Witton agreed that the substantially larger crests of adult thalassodromids indicated that they were more important for behavioural activities than for physiology. He found the idea that the crests were used for thermoregulation problematic, since they did not grow regularly with body size; they grew at
312-457: A different manner of feeding than azhdarchids, which had longer, stiffer necks. He suggested that thalassodromids may have had more generalised feeding habits, and azhdarchids may have been more restricted; Thalassodromeus may have been better at handling relatively large, struggling prey than its relative, Tupuxuara , which had a more lightly built skull. Witton stressed that more studies of functional morphology would have to be done to illuminate
390-406: A fast pace in near-adults, quicker than what would be predicted for the growth of a thermoregulatory structure. According to Witton, the large, highly vascular wing membranes of pterosaurs would provide the surface area needed for thermoregulation, meaning the crests were not needed for that function. He concluded that the crest's blood-vessel patterns did not differ much from those seen on bones under
468-452: A feature also shared with Thalassodromeus . Unlike skimmers and other pterosaurs, the palatine bones of Thalassodromeus were concave, which the writers suggested could have helped it momentarily store food. Like skimmers, Thalassodromeus also appears to have had powerful neck muscles, large jaw muscles, and an upper jaw tip well-irrigated by blood (features which Kellner and Campos interpreted as adaptations for skimming). They concluded that
546-436: A large team of colleagues immediately rejected the pterosaurian identification of the T. sebesensis fossil, instead arguing that it was a misidentified part of a plastron (lower shell) of the prehistoric turtle Kallokibotion bajazidi (named in 1923). The idea that the fragment belonged to a turtle had been considered and rejected by Grellet-Tinnera and Codrea in their original description. Grellet-Tinnera and Codrea denied
624-516: A new species, T. sebesensis , based on what they interpreted as part of a cranial crest in a concretion found near the Sebeș River in Romania. The authors said that this would extend the range in time and space for the genus Thalassodromeus considerably, creating a 42-million-year gap between the older South American species and the younger European species. Palaeontologist Gareth J. Dyke and
702-408: A sharp margin. Near the front end of the symphysis, the edges which formed the margins became broader towards the front of the shelf until they met and fused. The upper and lower surfaces of the jaw at the front of the shelf were keeled (the upper keel more robust and starting before the lower), which gave the symphysis a blade-like shape. The lower keel became deeper towards the front of the jaw, giving
780-412: A system of channels of varying size and thickness, probably the impressions of extensive blood vessels. A small, 46 mm (1.8 in) opening was present above the orbit (eye socket), piercing the basal part of the crest; such a feature is unknown in other pterosaurs, and does not appear to be due to damage. The margins of the opening are smooth, and the inner border has fenestration connecting it to
858-400: A valid genus. Another species ( T. sebesensis ) was described in 2015 based on a supposed crest fragment, but this was later shown to be part of a turtle shell. Thalassodromeus had one of the largest known skulls among pterosaurs, around 1.42 m (4 ft 8 in) long, with one of the proportionally largest cranial crests of any vertebrate . Though only the skull is known, the animal
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#1732800905287936-625: Is a genus of pterosaur that lived in what is now Brazil during the Early Cretaceous period , about a hundred million years ago. The original skull, discovered in 1983 in the Araripe Basin of northeastern Brazil, was collected in several pieces. In 2002, the skull was made the holotype specimen of Thalassodromeus sethi by palaeontologists Alexander Kellner and Diogenes de Almeida Campos. The generic name means "sea runner" (in reference to its supposed mode of feeding), and
1014-422: Is a group of pterosaurs within the extinct suborder Pterodactyloidea . They were typically large pterosaurs that lived from the Early to Late Cretaceous periods ( Valanginian to Maastrichtian stages), with fossil remains found all over the world except Antarctica . Ornithocheiroids were the most advanced group of pterosaurs, as the group includes the clade Azhdarchoidea , of which its members lived until
1092-438: Is estimated to have had a wingspan of 4.2 to 4.5 m (14 to 15 ft). The crest was lightly built and ran from the tip of the upper jaw to beyond the back of the skull, ending in a unique V-shaped notch. The jaws were toothless, and had sharp upper and lower edges. Its skull had large nasoantorbital fenestrae (opening that combined the antorbital fenestra in front of the eye with the bony nostril), and part of its palate
1170-538: Is one of the most contentious issues regarding their group. Kellner and Campos originally assigned Thalassodromeus to the family Tapejaridae , based on its large crest and large nasoantorbital fenestra. Within this clade, they found that it differed from the short-faced genus Tapejara but shared a keel on the palate with Tupuxuara . Kellner elaborated on the relationships within Tapejaridae in 2004, and pointed out that Thalassodromeus and Tupuxuara also shared
1248-527: Is shown below: Banguela oberlii Dsungaripterus weii Noripterus complicidens Chaoyangopterus zhangi Shenzhoupterus chaoyangensis Quetzalcoatlus sp. [REDACTED] Azhdarcho lancicollis Zhejiangopterus linhaiensis Tupuxuara leonardii [REDACTED] Thalassodromeus sethi Tupandactylus imperator [REDACTED] Tapejara wellnhoferi Sinopterus dongi Eopteranodon lii Huaxiapterus corollatus Huaxiapterus benxiensis More recently,
1326-630: The Thalassodromeus model was destroyed during the experiment, due to the high and unstable forces exerted on it while skimming at high speed, casting further doubt on this feeding method. The authors used the jaw tip of T. oberlii to model the performance of Thalassodromeus , since it was assigned to T. sethi at the time. Unwin and Martill suggested in 2007 that thalassodromids may have foraged similarly to storks , as had been suggested for azhdarchids. Witton said in 2013 that although skim-feeding had been suggested for many pterosaur groups,
1404-417: The articular bone of the lower jaw. The front of the premaxillae had sharp upper and lower edges, unique to this species. As in related genera, the nasoantorbital fenestra was comparatively large; it was 650 mm (26 in) long and 200 mm (7.9 in) high, which was 71 percent of the skull length (excluding the crest). The lacrimal bone , which separated the orbit from the nasoantorbital fenestra,
1482-549: The holotype specimen . The generic name is derived from the Ancient Greek words θάλασσα , thálassa , '"sea"' and δρομεύς , dromeús , '"runner"', meaning "sea runner" in reference to the animal's supposed skim-feeding behaviour. The specific name refers to the Egyptian god Seth . The specimen was not fully prepared at the time of this preliminary description. The original describers chose
1560-443: The mandible is missing, but its front surface indicates that it might have been turned slightly upwards as in T. oberlii (the possible second species of Thalassodromeus , or possibly a different genus ( Banguela ) which is known only from a jaw tip). The symphyseal shelf, the upper surface of the symphysis, extended for 170 mm (6.7 in) and had a flat surface. Seen from above, the side edges of this area were tall and formed
1638-428: The specific name refers to the Egyptian god Seth due to its crest being supposedly reminiscent of Seth's crown. Other scholars have pointed out that the crest was instead similar to the crown of Amon . A jaw tip was assigned to T. sethi in 2005, became the basis of the new genus Banguela in 2015, and assigned back to Thalassodromeus as the species T. oberlii in 2018, though other researchers consider it
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#17328009052871716-447: The (presumably) non-skimming Tupuxuara and towing them along a water-filled trough at varying speeds. The researchers found that skimming used more energy for skimmers than previously thought, and would have been impossible for a pterosaur weighing more than 1 kg (2.2 lb) due to the metabolic power required. They found that even smaller pterosaurs, like Rhamphorhynchus , were not adapted for skimming. The aluminium rigging of
1794-900: The Dsungaripteridae and the Azhdarchoidea. Dsungaripterus weii Noripterus parvus Azhdarcho lancicollis Quetzalcoatlus sp. [REDACTED] Zhejiangopterus linhaiensis Chaoyangopterus zhangi Jidapterus edentus Shenzhoupterus chaoyangensis Keresdrakon vilsoni Thalassodromeus sethi Tupuxuara leonardii [REDACTED] Caupedactylus ybaka Aymberedactylus cearensis Eopteranodon lii "Huaxiapterus" benxiensis "Huaxiapterus" corollatus Sinopterus dongi Europejara olcadesorum Caiuajara dobruskii Tapejara wellnhoferi Tupandactylus imperator [REDACTED] In 2021, Pêgas et al. named and officially registered two new clades: Azhdarchomorpha ,
1872-571: The Maastrichtian stage of the Late Cretaceous, around 66 million years ago. Notable pterosaurs from this group include the pteranodontians Pteranodon and Nyctosaurus , the ornithocheirid Ornithocheirus , the anhanguerid Tropeognathus , as well as the azhdarchids Hatzegopteryx and Quetzalcoatlus . The name Ornithocheiroidea was originally defined as an apomorphy -based taxon by Christopher Bennett in 1994. It
1950-400: The animal to dissipate excess metabolic heat through convection), while heat transfer was controlled by – and depended on – the network of blood vessels. The ability to control its body temperature would have aided Thalassodromeus during intense activity (such as hunting), and they suggested that, when in flight, heat would have been dispelled more effectively if
2028-458: The beaks of birds, which are used for transporting nutrients to the bone and soft tissues rather than for thermoregulation. Witton noted that although bird beaks lose heat quickly, that is not what they were developed for; the crests of pterosaurs might also have had an effect on thermoregulation, without this being their primary function. Pêgas and colleagues noted that sexual dimorphism in crest size and shape has been proposed for some pterosaurs;
2106-410: The bills of toucans (the largest of any modern birds) grow drastically out of proportion to body size and function as thermoregulatory structures, as well as facilitating feeding and social behaviour. Pêgas and colleagues found the vascular structure of toucan bills comparable to that in the crest of T. sethi , concluding that the crest also had multiple functions. Kellner and Campos originally found
2184-422: The bony part of their crests beginning at the front of the skull and continuing further back than in other pterosaurs. The interrelationship of these clades within the larger clade Azhdarchoidea remained disputed, and the clade containing Thalassodromeus and Tupuxuara had received different names from different researchers (Thalassodrominae and Tupuxuaridae). Palaeontologist Mark Witton attempted to resolve
2262-554: The clade part of Neoazhdarchia. A 2011 analysis by palaeontologist Felipe Pinheiro and colleagues upheld the grouping of the clades Tapejarinae and Thalassodrominae in the family Tapejaridae, joined by the Chaoyangopterinae . A 2014 study by palaeontologist Brian Andres and colleagues instead found thalassodromines to group with dsungaripterids, forming the clade Dsungaripteromorpha within Neoazhdarchia (defined as
2340-406: The contact between the premaxillae and the frontoparietal part, and became gradually thinner toward the top and back (except for the lower part behind the occiput, where it had a thick base). Despite its size, the crest was lightly built and essentially hollow; some areas indicate signs of skeletal pneumatisation and a well-developed trabecular system uniting the bones. The crest's surface had
2418-486: The crest shape seen in the T. sethi holotype may correlate with one sex and may have been the result of sexual selection . They suggested that both sexes could have had similar crests due to mutual sexual selection, but interpretation of exaggerated features was challenging due to the small sample size ; more T. sethi specimens would have to be found to evaluate these theories. They did not think that thermoregulation correlated with crest growth relative to body size, since
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2496-423: The crest were aligned with the wind, while the head was intentionally moved to the sides. Kellner and Campos posited that the crest could have had additional functions, such as display ; aided by colour, it could have been used in species recognition , and could also have been a sexually dimorphic feature (differing according to sex), as has been proposed for Pteranodon . In 2006, Martill and Naish found that
2574-400: The crests of Tupuxuara and its relatives developed by the premaxillary portion of the crests growing backwards over the skull-roof (as indicated by the well-defined suture between the premaxilla and the underlying bones). The hind margin of the premaxillary part of this specimen's crest had only reached above the hind margin of the nasoantorbital fenestra, indicating that it was not an adult at
2652-1706: The definition of Kellner (2003) to avoid confusion with similarly-defined groups, like Pteranodontoidea . Below is a cladogram showing the results of a phylogenetic analysis presented by Longrich and colleagues in 2018. They found Ornithocheiroidea to consist of the clades Pteranodontoidea and Azhdarchoidea , as well as the genus Piksi . Haopterus gracilis Piksi barbarulna Tethydraco regalis Pteranodon longiceps [REDACTED] Pteranodon sternbergi Alamodactylus byrdi Volgadraco bogolubovi Cretornis hlavaci Alcione elainus Simurghia robusta Muzquizopteryx coahuilensis Barbaridactylus grandis Nyctosaurus lamegoi Nyctosaurus nanus Nyctosaurus gracilis [REDACTED] Hongshanopterus lacustris Lonchodraco giganteus Lonchodectes compressirostris Boreopterus cuiae Zhenyuanopterus longirostris Nurhachius ignaciobritoi Liaoxipterus brachyognathus Istiodactylus sinensis Istiodactylus latidens Aetodactylus halli Cimoliopterus dunni Cimoliopterus cuvieri Guidraco Ludodactylus [REDACTED] Cearadactylus Brasileodactylus Anhangueridae [REDACTED] Ornithocheiridae Bennettazhia oregonensis Tapejara wellnhoferi Europejara olcadesorum Vectidraco daisymorrisae Caiuajara dobruskii Tupandactylus navigans Tupandactylus imperator [REDACTED] Bakonydraco galaczi [REDACTED] "Huaxiapterus" benxiensis "Huaxiapterus" corollatus Eopteranodon lii Huaxiapterus jii Thalassodromeus sethi Thalassodromeus
2730-413: The extent of this is unknown. The upper jaw of T. sethi was primarily composed of premaxillae and maxillae ; the suture which formed the border between these bones is not visible. As in all members of its clade, the jaws were edentulous (toothless). The rostrum (snout) was 650 mm (26 in) long from the tip of the premaxilla to the joint where the quadrate bone of the skull connected with
2808-411: The front part of a mandible collected from the same formation to T. sethi in 2005. They concluded that although the two specimens differed in several details, the differences were not significant enough to base a new species on the mandible, and that the new specimen filled in the gap of Kellner and Campos' T. sethi skull reconstruction. Palaeontologists Jaime A. Headden and Herbert B. N. Campos coined
2886-534: The genus name implies, Thalassodromeus was originally proposed to have fed like a modern skimmer bird , by skimming over the water's surface and dipping its lower jaws to catch prey. This idea was later criticised for lack of evidence; Thalassodromeus has since been found to have had strong jaw musculature, and may have been able to kill and eat relatively large prey on the ground. The limb proportions of related species indicate that it may have adapted to fly in inland settings, and would have been efficient at moving on
2964-467: The ground. Thalassodromeus is known from the Romualdo Formation , where it coexisted with many other types of pterosaurs, dinosaurs and other animals. The first known specimen of this pterosaur (an extinct order of flying reptiles) was collected in 1983 near the town of Santana do Cariri in the Araripe Basin of northeastern Brazil. Found in outcrops of the Romualdo Formation , it
3042-558: The idea was criticised in recent years; pterosaurs lacked virtually all adaptations for skim-feeding, making it unlikely that they fed this way. Thalassodromeus (unlike skimmers) did not have a particularly wide or robust skull or especially large jaw-muscle attachment sites, and its mandible was comparatively short and stubby. Witton agreed with Unwin and Martill that thalassodromids, with their equal limb proportions and elongated jaws, were suited to roaming terrestrially and feeding opportunistically; their shorter, more flexible necks indicated
3120-453: The impression that the jaw deflected downwards; it was actually straight, except for the (perhaps) upturned tip. The mandibular fossae (depressions) at the back of the upper jaw were deeper and broader than usual in pterodactyloids, creating large surfaces for the lower jaw to articulate with. The possible species T. oberlii differed from T. sethi and other relatives by the upper surface of its mandibular symphysis being slightly shorter than
3198-441: The inner structure of the crest. The back of the crest ended in a prominent V-shaped notch, a unique feature of this species. Although other parts of the crest have V-shaped breaks, the V shape at the end does not appear to have been due to breakage; the margins of the bone can be seen there, still encased by matrix . The crest probably had a keratinous (horny) covering and may have been extended by soft tissue in some areas, but
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3276-433: The jaw while skimming. In 2007, biophysicist Stuart Humphries and colleagues questioned whether any pterosaurs would have commonly fed by skimming and said that such conclusions had been based on anatomical comparisons rather than biomechanical data. The drag experienced by bird bills and pterosaur jaws was hydrodynamically and aerodynamically tested by creating model bills of the black skimmer , Thalassodromeus , and
3354-593: The jaws of Thalassodromeus similar to those of modern skimmers – three bird species in the genus Rhynchops – with their sideways-compressed jaws, blade-like beak, and protruding lower jaw (resembling scissors in side view). They argued that Thalassodromeus would have fed in a similar way, as implied by the genus name; skimmers skim over the surface of water, dipping their lower jaw to catch fish and crustaceans. Kellner and Campos listed additional skull features of skimmers which are adaptations for skim feeding, including enlarged palatine bones,
3432-491: The largest flying animals. The group was named by Brazilian paleontologist Alexander Wilhelm Armin Kellner in 1996. Tapejaroidea was named by paleontologist Alexander Kellner from Brazil in 1996, and in 2003 it was given a phylogenetic definition by Kellner himself as the most recent common ancestor of Dsungaripterus , Tapejara and Quetzalcoatlus , and all their descendants. Tapejaroidea, in Kellner's 2003 study,
3510-414: The long wing-finger). The hindlimbs were eighty percent that of the forelimb length, a unique ratio among pterodactyloids (short-tailed pterosaurs). As a pterosaur, Thalassodromeus was covered with hair-like pycnofibres and had extensive wing membranes (which were extended by the wing finger). The skull of T. sethi had a streamlined profile, especially from the tip of the snout to the front edge of
3588-428: The lower surface, and was further distinguished from T. sethi by the upper edge of the symphysis being much sharper than the lower. The two species shared features such as the compression of the symphysis sideways and from top to bottom, the sharp keel at the upper front of the symphysis, and the small groove running along the upper surface of the shelf. The classification of Thalassodromeus and its closest relatives
3666-522: The mandible) are pushed slightly inward. The skull was first reported in a 1984 Italian book, and preliminarily described and figured in 1990 by palaeontologists Alexander Kellner and Diogenes de Almeida Campos. Although the pieces of skull had been divided between museums in South and North America, they were assembled before 2002. In 2002, Kellner and Campos described and named the new genus and species Thalassodromeus sethi , skull DGM 1476-R being
3744-738: The most inclusive clade containing Dsungaripterus weii but not Quetzalcoatlus northropi ). Azhdarchidae Thalassodromeus sethi Tupuxuara deliradamus Tupuxuara leonardii Jidapterus Shenzhoupterus Chaoyangopterus Sinopterus Huaxiapterus Tapejara Tupandactylus Cladogram based on Andres and colleagues, 2014: Chaoyangopteridae Azhdarchidae Dsungaripterus weii Domeykodactylus ceciliae Noripterus parvus Noripterus complicidens Thalassodromeus sethi Tupuxuara longicristatus Tupuxuara leonardii Pêgas and colleagues kept Tapejarinae and Thalassodrominae as part of Tapejaridae in 2018, but acknowledged that
3822-445: The most inclusive clade containing Azhdarcho but not Tapejara or Thalassodromeus , and Alanqidae , containing Alanqa but not Chaoyangopterus or Azhdarcho . Their phylogeny is shown below: Dsungaripterus Noripterus Tupuxuara Thalassodromeus oberlii Thalassodromeus sethi Aymberedactylus Caupedactylus Bakonydraco Ornithocheiroidea Ornithocheiroidea (or ornithocheiroids )
3900-460: The name sethi because the crest of this pterosaur was supposedly reminiscent of the crown worn by Seth, but the palaeontologists André Jacques Veldmeijer, Marco Signore, and Hanneke J. M. Meijer pointed out in 2005 that the crown (with its two tall plumes) was typically worn by the god Amon (or Amon-Ra) and his manifestations – not by Seth. In 2006, palaeontologists David M. Martill and Darren Naish suggested that Thalassodromeus
3978-407: The naming issue in 2009, noting that the name "Tupuxuaridae" (first used in the vernacular form "tupuxuarids" by palaeontologist Lü Junchang and colleagues in 2006) had never been validly established and Thalassodrominae should be the proper name (although it was bestowed a year later). Witton further converted the subfamily name Thalassodrominae into the family name Thalassodromidae, and considered
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#17328009052874056-472: The nasoantorbital fenestra (opening which combined the antorbital fenestra in front of the eye with the bony nostril). The most conspicuous feature of the skull was the large crest, which ran along the upper edge from the tip of the snout and beyond the occiput at the back of the skull, almost doubling the length and height of the skull. With the exception of the pterosaur Tupandactylus imperator (whose crest consisted mainly of soft tissue), T. sethi had
4134-476: The nasoantorbital fenestra, and therefore very low on the skull. Although the bones bordering the lower temporal fenestra (an opening behind the orbit) were incomplete, it appears to have been elongated and slit-like (as in Tupuxuara and Tapejara ). The palatal area at the tip of T. sethi ' s snout was a sharp ridge, similar to the keel seen on the upper surface of the mandibular symphysis where
4212-474: The new binomial Banguela oberlii , based on their reinterpretation of the jaw tip as belonging to a toothless member of the family Dsungaripteridae , in 2015. The generic name is Portuguese for "toothless" and the specific name honours private collector Urs Oberli, who had donated the specimen to the Naturmuseum St. Gallen (where it is catalogued as NMSG SAO 25109). Headden and Campos interpreted
4290-433: The original definition of Tapejaroidea has been used in a number of phylogenetic analyses conducted in 2019 and 2020, meaning that Tapejaroidea and Pteranodontoidea were once again recovered as the sister taxa and within the larger Ornithocheiroidea. The cladogram below represents the phylogenetic analysis conducted by Kellner and colleagues in 2019, where they recovered Tapejaroidea as the more inclusive group containing both
4368-496: The presence of a notarium (fused vertebrae in the shoulder region), the loss of contact between the first and third metacarpals (bones in the hand), and very long snouts (more than 88% of the skull length). Kellner and Campos defended the validity of Tapejaridae in 2007, dividing it into two clades: Tapejarinae and Thalassodrominae, the latter containing Thalassodromeus (the type genus ) and Tupuxuara . They distinguished thalassodromines by their high nasoantorbital fenestrae and
4446-532: The proportionally largest cranial crest of any known vertebrate (75 percent of the skull's side surface). The crest was mainly formed by the premaxillae (the frontmost snout bones), frontal bones , parietal bones , and part of the supraoccipital bone. The premaxillae formed most of the crest, extending to its back, and contacted the frontoparietal part of the crest by a straight suture (a distinct feature of this species ). The crest varied from 1 to 10.5 mm (0.039 to 0.413 in) in thickness; it thickened at
4524-572: The pterosaur with jaws most similar to those of Thalassodromeus was the smaller Rhamphorhynchus , although they believed that it would have had limited skimming ability. In 2004, palaeontologist Sankar Chatterjee and engineer R. Jack Templin said that smaller pterosaurs may have been able to skim-feed. They doubted that this was possible for larger ones, due to their lesser manoeuvrability and flying capability while resisting water. Chatterjee and Templin noted that skimmers have blunter beaks than pterosaurs like Thalassodromeus , to direct water from
4602-441: The role of the crest was relevant only after maturity (when the structure was fully grown). They deemed the thermoregulation hypothesis an unlikely explanation for the blood-vessel channels on the crest, which they found consistent with nourishment for growing tissue (such as the keratin in bird beaks). Hone, Naish, and Cuthill suggested that the wing membranes and air-sac system would have been more effective at controlling heat than
4680-442: The scissor-like bill and thin crest almost made other modes of capturing prey – such as swooping down toward water and plunging into it – impossible. Conceding the difficulty of reconstructing Thalassodromeus ' s fishing method, they envisioned it with a less-mobile neck than skimmers; with the crest impeding its head from submersion it would glide, flapping its wings only occasionally. They found that
4758-417: The subject and speculated that Thalassodromeus might have been a raptorial predator, using its jaws to subdue prey with strong bites; its concave palate could help it swallow large prey. Pêgas and Kellner presented a reconstruction of the mandibular muscles of T. sethi at a conference in 2015. They found that its well-developed jaw muscles differed from those of the possible dip-feeder Anhanguera and
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#17328009052874836-404: The subject was still controversial. Possible functions for Thalassodromeus ' s cranial crest were proposed by Kellner and Campos in 2002. They suggested that the network of blood vessels on its large surface was consistent with use for thermoregulation , which had also been suggested for the crests of some dinosaurs . Kellner and Campos thought that the crest was used for cooling (enabling
4914-411: The symphyseal shelf at the front end of the lower jaw, and they would have tightly interlocked when the jaws were closed. The palatal ridge ended in a strongly concave area unique to this species. The postpalatine fenestrae (openings behind the palatine bone) were oval and very small, differing from those of related species. The ectopterygoid (bone on the side of the palate) had large, plate-like sides, and
4992-442: The terrestrially stalking azhdarchids, indicating that T. sethi had a strong bite force . In 2018, Pêgas and colleagues agreed that Thalassodromeus ' blade-like, robust jaws indicated that it could have used them to strike and kill prey, but they thought that biomechanical work was needed to substantiate the idea. They found (unlike Witton) that Thalassodromeus had a reinforced jaw joint and robust jaw muscles, but more work
5070-465: The theory that the lower jaw of T. sethi was downturned, and reinterpreted the frontmost piece of the lower jaw to have connected directly with the subsequent piece (with no gap). In 2020, palaeontlogist James McPhee and colleagues considered Banguela a valid genus, and instead classified it as a member Chaoyangopteridae , and did not find a dsunagripterid identity well-supported. In 2015 palaeontologists Gerald Grellet Tinner and Vlad A. Codrea named
5148-823: The time of death. This suggests that the development of the crest happened late in the growth of an individual, was probably related to sexual display , and the sexual maturity of a given specimen could be assessed by the size and disposition of the crest. The T. sethi holotype, with its hypertrophied (enlarged) premaxillary crest, would thereby represent an old adult individual (and the mature stage of Tupuxuara , according to their interpretation). Kellner and Campos found Martill and Naish's discussion of cranial crest development interesting, although they found their proposed model speculative. Palaeontologists David W. E. Hone, Naish, and Innes C. Cuthill reiterated Martill and Naish's growth hypothesis in 2012; since pterosaurs were probably precocial and able to fly shortly after hatching,
5226-441: The tip of T. sethi 's lower jaw as downturned; this and other features distinguished it from Banguela . In their 2018 re-description of the further-prepared T. sethi holotype skull, palaeontologists Rodrigo V. Pêgas, Fabiana R. Costa, and Kellner assigned B. oberlii back to Thalassodromeus while recognising it as a distinct species, and thereby created the new combination T. oberlii . Pêgas and colleagues also rejected
5304-422: The turtle identity suggested by Dyke and colleagues, noting that those researchers had not directly examined the fossil. The holotype (and only known skull) of Thalassodromeus sethi is one of the largest pterosaur skulls ever discovered. The entire skull is estimated to have been 1.42 m (4 ft 8 in) long; the bones were fused together, indicating adulthood. Based on related pterosaurs, its wingspan
5382-448: The two halves of the lower jaw connected. Small slit-like foramina (openings) on the lower side edges of the ridge indicate that it had a horny covering in life, similar to Tupandactylus . The lower edge of the area was somewhat curved, which probably created a small gap when the jaws were closed. Further back, immediately in front of the nasoantorbital fenestra, the palatal ridge became a strong, blunt, convex keel. This convexity fit into
5460-437: Was 4.2 to 4.5 m (14 to 15 ft), making Thalassodromeus the largest known member of its clade , Thalassodromidae . Of similar proportions, its skull was more heavily built than that of its relative Tupuxuara . Although the postcranial skeleton of Thalassodromeus is unknown, relatives had unusually short and blocky neck vertebrae, with well-developed front and hind-limbs that were almost equal in length (excluding
5538-466: Was a junior synonym of the related genus Tupuxuara , which was named by Kellner and Campos in 1988 based on fossils from the same formation. In the view of Martill and Naish, the differences between these genera (including two species of Tupuxuara , T. longicristatus and T. leonardii ) were due to ontogeny (changes during growth) and compression of the fossils; Thalassodromeus was simply an older, larger, and better-preserved individual. This idea
5616-494: Was collected over a long period in several pieces. The specimen (catalogued as DGM 1476-R at the Museu de Ciências da Terra ) was preserved in a calcareous nodule , and consists of an almost-complete, three-dimensional skull (pterosaur bones are often flattened compression fossils ), missing two segments of the bottom of the skull and mandible and the front of the lower jaw. The left jugal region and right mandibular ramus (half of
5694-755: Was concave. The lower jaw was blade-like, and may have turned slightly upwards. The closest relative of Thalassodromeus was Tupuxuara ; both are grouped in a clade that has been placed within either Tapejaridae (as the subfamily Thalassodrominae ) or within Neoazhdarchia (as the family Thalassodromidae). Several theories have been suggested to explain the function of Thalassodromeus ' s crest, including thermoregulation and display , but it likely had more than one function. The crests of thalassodromids appear to have developed late in growth (probably correlated with sexual maturity ) and they may have been sexually dimorphic (differing according to sex). As
5772-503: Was given a relationship-based definition in 2003 by Alexander Kellner, who defined it as the least inclusive clade containing Anhanguera blittersdorffi , Pteranodon longiceps , Dsungaripterus weii , and Quetzalcoatlus northropi . Later that year, David Unwin suggested a more restrictive definition, in which the clade only contains Pteranodon longiceps , Istiodactylus latidens , and their descentants. Brian Andres (2008, 2010, 2014) in his analyses, defined Ornithocheiroidea using
5850-504: Was recovered as the sister taxon of the Pteranodontoidea , both within the group Ornithocheiroidea , and consisting of the groups Dsungaripteridae and Azhdarchoidea . However, in a phylogenetic analysis made by Jaime Headden and Hebert Bruno Nascimento Campos in 2014, Tapejaroidea was recovered within the Azhdarchoidea, as a clade comprising the families Tapejaridae and Thalassodromidae . The cladogram of their analysis
5928-516: Was rejected by Kellner and Campos in 2007, who pointed out these species had differences in features other than their crests. They also noted that one specimen of Tupuxuara had a larger skull than Thalassodromeus (measured from the tip of the premaxilla to the back of the squamosal bone ), despite Martill and Naish's contention that the latter was an older individual. Kellner and Campos' view has since been accepted by other researchers, including Martill and Naish. Veldmeijer and colleagues assigned
6006-414: Was vertically elongated and higher than the upper surface of the orbit (in contrast to the condition seen in pterodactyloids with smaller nasoantorbital fenestrae). The orbit was slender and compressed from front to back compared to Tupuxuara and tapejarids , but similar to some of them in being more than half the height of the nasoantorbital fenestra. The orbit was positioned lower than the upper margin of
6084-422: Was well-developed compared to related species. The supraoccipital bone, which formed the hindmost base of the cranial crest, had muscle scars at its upper end (probably corresponding to the attachment of neck muscles). Although the lower jaw of T. sethi is incomplete, its total length is estimated at 670 mm (26 in) – 47 percent of which was occupied by the mandibular symphysis. The tip of
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