Caelestiventus

Caelestiventus (/səˌlɛstɪˈvɛntəs/ sə-LES-tih-VEN-təs, meaning "heavenly wind") is a pterosaur genus from the Late Triassic (Norian or Rhaetian) found in western North America.[1] The type species, Caelestiventus hanseni, honors Robin Hansen, the Bureau of Land Management geologist (BLM), who facilitated access to the excavation site.

Caelestiventus is important because it is the sole example of a desert-dwelling non-pterodactyloid pterosaur and is 65 million years older than other known desert-dwelling pterosaurs. Additionally, it shows that even the earliest pterosaurs were morphologically and ecologically diverse and that the Dimorphodontidae originated in the Triassic Period.[1]

Caelestiventus
Temporal range: Norian, 208 Ma
Caelestiventus skull
3D printed skull reconstruction; the dip in the forehead is perhaps too pronounced
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Order: Pterosauria
Family: Dimorphodontidae
Genus: Caelestiventus
Britt et al., 2018
Type species
Caelestiventus hanseni
Britt et al., 2018

Description

Caelestiventus NT
Restoration

Most Triassic pterosaurs are small.[2][3][4] Caelestiventus, however, is one of, if not the largest known Triassic pterosaurs, with a wingspan of at least 1.5 metres (4 ft 11 in) and a skull 17.8 cm (7.0 in) long (based on a complete mandible).This is also based on the only known Specimen, which has not yet reached full maturity. So it would have been slightly larger.[1] Unlike most Triassic pterosaurs which are severely deformed by crushing, the bones of Caelestiventus are three-dimensional and uncrushed.[1] This preservation provides insights into the delicate structures of skull bones, including pneumatic features such as foramina/fossae and internal chambers.

Caelestiventus is known from a single individual (BYU 20707, in the Museum of Paleontology at Brigham Young University) that preserves much of the skull (skull cap, sides of the face, and a complete lower jaw (mandible) along with a single non-skull bone – the last finger bone at the end of the elongated fourth finger (manual digit IV 4) that supported the tip of the wing.[1]

Skull

Most of the skull is known. The laterally narrow and vertically deep skull is similar to that of Dimorphodon, with an enormous external naris (nostril) being the largest skull opening, and a large antorbital fenestra. Unlike most pterosaurs, the margin of the antorbital fenestra bears a remnant of an antorbital fossa.[1]

The skull roof has a median ridge as well as large ridges along the medial borders of the upper temporal fenestra that mark attachments for the muscle that closed the mandible. A prominent hood at the back of the skull, the nuchal crest, marks the attachment of large neck muscles. Sizeable pneumatic openings on the skull top lead into small pneumatic chambers in the skull roof. The uncrushed skull cap permitted the first endocranial reconstruction in a Triassic pterosaur and shows the brain had large cerebral lobes, from which the optic lobes bulge, and small olfactory lobes.[1]

The lower portion of the front of the mandible has a keel.[1] There are large pneumatic openings in the posterior mandible and the whole of the mandible is hollow and was likely air-filled (pneumatic).

Caelestiventus is heterodont, with three different tooth shapes - long fang-like spikes, large "leaf-shaped" blades, and tiny blades.[1] There are two long, spike teeth near the front of each side of the lower jaws that were likely opposed by similar teeth at the tip of the skull snout (premaxilla). In the lower jaws, behind the fangs, is a tooth gap (diastema) which is followed by 38 tiny teeth on each side of the lower jaw (mandibular ramus). Each upper jaw bone (maxilla) is armed with twelve large, blade-like, triangular teeth. Both sides of the maxillary teeth are strengthened by a central ridge and these teeth terminate in two tips (bicuspid).

Discovery

Caelestiventus was recovered from the Saints & Sinners Quarry of northeastern Utah. The site was discovered in 2007 by Dan Chure and George Engelmann while working on the geology and paleontology of the fossilized dunes of the Nugget Sandstone.[5] In 2015, the find of a pterosaur skeleton was reported in the scientific literature.[6][7]

Classification

Phylogenetic analyses show Caelestiventus as the sister taxon to Dimorphodon macronyx in the family Dimorphodontidae, which was defined by Britt and colleagues as the most inclusive clade containing of Caelestiventus hanseni and Dimorphodon macronyx, the only two genera recovered as dimorphodontids in their analyses. They also found that the purported Dimorphodon species 'D.' weintraubi is the sister taxon to Anurognathidae, and thus was outside of Dimorphodontidae as defined by Britt and colleagues.[1]

Pterosauria

Austriadraco dallavecchiai

Arcticodactylus cromptonellus

Preondactylus buffarinii

Austriadactylus cristatus

Peteinosaurus zambellii

Macronychoptera
Dimorphodontidae

Dimorphodon macronyx

Caelestiventus hanseni

Lonchognatha
Eudimorphodontidae

Eudimorphodon ranzii

Carniadactylus rosenfeldi

Caviramus schesaplanensis

Raeticodactylus filisurensis

Novialoidea

Campylognathoides

Caelidracones
Anurognathidae

"Dimorphodon" weintraubi

Batrachognathus volans

Anurognathus ammoni

Dendrorhynchoides

Jeholopterus ningchengensis

Rhamphorhynchidae

Dorygnathus banthensis

Rhamphorhynchus muensteri

Scaphognathus crassirostris

Sordes pilosus

Monofenestrata

Darwinopterus

Pterodactylus antiquus

Pteranodon longiceps

Anhanguera

Paleoecology

Pterosaurs ranged from the Late Triassic to the end of the Cretaceous. The earliest known pterosaurs are from the late Triassic Period and provide insights into the origin and diversification of the group.[3] Triassic pterosaurs, however, are rare. In 2014, just twenty-seven specimens were reported to be known, many consisting of a single bone.[2][4] All but one, Arcticodactylus, come from the Alps.[2][3][4]

In addition to Caelestiventus, the Saints & Sinners Quarry has produced a diverse vertebrate fauna including two sphenosuchian genera, two sphenodontian genera, a drepanosaurid, a procolophonid and two theropod dinosaurs – a coelophysoid and a medium-sized genus represented only by teeth.[5] No invertebrates are known from the site. Plants from the quarry consist of Bennettitalean fronds.[1]

References

  1. ^ a b c d e f g h i j k Britt, B. B.; Dalla Vecchia, F. M.; Chure, D. J.; Engelmann, G. F.; Whiting, M. F.; Scheetz, R. D. (2018). "Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years". Nature Ecology & Evolution. 2 (9): 1386–1392. doi:10.1038/s41559-018-0627-y. ISSN 2397-334X. PMID 30104753.
  2. ^ a b c Dalla Vecchia, F. M. (2014). Gli pterosauri triassici. Memorie del Museo Friulano di Storia Naturale. 54. Udine: Museo Friulano di Storia Natural. ISBN 9788888192543.
  3. ^ a b c Dalla Vecchia, F. M. (2013). "Triassic pterosaurs". In Nesbitt, S. J.; Desojo, J. B.; Irmis, R. B. (eds.). Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin. Geological Society, London, Special Publications. 379. pp. 119–155. doi:10.1144/SP379.14.
  4. ^ a b c Kellner, A. W. A. (2015). "Comments on Triassic pterosaurs with discussion about ontogeny and description of new taxa". Anais da Academia Brasileira de Ciências. 87 (2): 669–689. doi:10.1590/0001-3765201520150307. ISSN 0001-3765. PMID 26131631.
  5. ^ a b Britt, B. B.; Chure, D. J.; Engelmann, G. F.; Shumway, J. D. (2016). "Rise of the erg—Paleontology and paleoenvironments of the Triassic-Jurassic transition in Northeastern Utah". Geology of the Intermountain West. 3: 1–32. doi:10.31711/giw.v3i0.5. ISSN 2380-7601.
  6. ^ Britt, B.B., Chure, D.J., Engelmann, G.F., Dalla Vecchia, F., Scheetz, R., Meek, S., Thelin, C., and Chambers, M., 2015, "A new, large, non-pterodactyloid pterosaur from a Late Triassic interdunal desert environment within the eolian Nugget Sandstone of northeastern Utah, USA, indicates early pterosaurs were ecologically diverse and geographically widespread", Journal of Vertebrate Paleontology, Program with Abstracts, p. 97
  7. ^ Britt, B.B., Dalla Vecchia, F.M., Chure, D.J., Engelmann, G.F., Chambers, M.A, Thelin, C., Scheetz, R., 2015, "New Triassic pterosaur from interdunal desert deposits of the Nugget Sandstone NE Utah, USA", Flugsaurier 2015, 5th International Symposium on Pterosaurs, Portsmouth, England, Program with Abstracts, p. 17–18
Anchisauria

The Anchisauria were a clade of sauropodomorph dinosaurs that lived during the Late Triassic and Early Jurassic. The name Anchisauria was first used by Galton and Upchurch in the second edition of The Dinosauria. Galton and Upchurch assigned two families of dinosaurs to the Anchisauria: the Anchisauridae and the Melanorosauridae. The more common prosauropods Plateosaurus and Massospondylus were placed in the sister clade Plateosauria.

However, recent research indicates that Anchisaurus is closer to sauropods than traditional prosauropods; thus, Anchisauria would also include Sauropoda.The following cladogram simplified after an analysis presented by Blair McPhee and colleagues in 2014.

Averostra

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.

Avetheropoda

Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.

Cerapoda

Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.

Dimorphodontia

Dimorphodontia is a group of early "rhamphorhynchoid" pterosaurs named after Dimorphodon, that lived in the Late Triassic to Early Jurassic.

A family, Dimorphodontidae, was named in 1870 by Harry Govier Seeley (as "Dimorphodontae") with Dimorphodon as the only known member. In 2003 David Unwin defined a clade Dimorphodontidae, as the group consisting of the last common ancestor of Dimorphodon macronyx and Peteinosaurus zambellii, and all its descendants. However, later studies found that Dimorphodon may not be closely related to Peteinosaurus, so this definition of Dimorphodontidae would therefore be superfluous. In 2014, Brian Andres and colleagues defined another clade, Dimorphodontia, as a replacement. Dimorphodontia would include all pterosaurs more closely related to Dimorphodon than to Pterodactylus. According to the analysis published by Andres et al., Dimorphodontia is also a small group, including only Dimorphodon and Parapsicephalus.In 2018, a close relative of Dimorphodon was described from the Late Triassic of North America by Britt and colleagues, and was named Caelestiventus. This discovery expanded the geographic, temporal and also the ecological range of dimorphodontians, as it was discovered in the Late Triassic Nugget Sandstone in Utah, which was a desert at the time. Britt and colleagues also redefined Dimorphodontidae as the least inclusive clade containing Dimorphodon macronyx and Caelestiventus hanseni.

Dinosauriformes

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.

Haya griva

Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.

Jeholosauridae

Jeholosaurids were herbivorous neornithischian dinosaurs from the Cretaceous Period (Aptian - Santonian, with a possible Campanian record) of Asia. The family was first proposed by Han et al. in 2012. The jeholosaurids were defined as those ornithischians more closely related to Jeholosaurus shangyuanensis than to Hypsilophodon foxii, Iguanodon bernissartensis, Protoceratops andrewsi, Pachycephalosaurus wyomingensis, or Thescelosaurus neglectus. The Jeholosauridae includes the type genus Jeholosaurus and Yueosaurus.

Jingshanosaurus

Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.

Melanorosauridae

The Melanorosauridae were a family of sauropodomorph dinosaurs which lived during the Late Triassic and Early Jurassic. The name Melanorosauridae was first coined by Friedrich von Huene in 1929. Huene assigned several families of dinosaurs to the infraorder "Prosauropoda": the Anchisauridae, the Plateosauridae, the Thecodontosauridae, and the Melanorosauridae. Since then, these families have undergone numerous revisions. Galton and Upchurch (2004) considered Camelotia, Lessemsaurus, and Melanorosaurus members of the family Melanorosauridae. A more recent study by Yates (2007) indicates that the melanorosaurids were instead early sauropods.

Neotheropoda

Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra.

Nugget Sandstone

The Nugget Sandstone is a Late Triassic geologic formation that outcrops in Utah, western United States. Fossil theropod tracks have been reported from the formation.

Orionides

Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.

Orodrominae

Orodrominae is a subfamily of parksosaurid dinosaurs from the Cretaceous of North America and Asia.

Plateosauridae

Plateosauridae is a family of plateosaurian sauropodomorphs from the Late Triassic of Europe. Although several dinosaurs have been classified as plateosaurids over the years, the family Plateosauridae is now restricted to Plateosaurus. In another study, Yates (2003) sunk Sellosaurus into Plateosaurus (as P. gracilis).

Raeticodactylidae

Raeticodactylidae is a family of eudimorphodontoid eopterosaurian pterosaurs that lived in Switzerland during the Late Triassic. The family includes Caviramus, and the type genus Raeticodactylus, which are both known from the Kössen Formation, around 205 mya. Raeticodactylidae was first used in 2014 by Andres et al., as a group of all pterosaurs closer to Raeticodactylus than Eudimorphodon. The following phylogenetic analysis follows the topology of Andres et al. (2014).

Riojasauridae

Riojasauridae is a family of sauropod-like dinosaurs from the Upper Triassic. It is known primarily from the genera Riojasaurus and Eucnemesaurus. Sites containing Riojasauridae include the Lower Elliot Formation of Orange Free State, South Africa (where fossils of Eucnemesaurus have been found), and Ischigualasto, in La Rioja Province, Argentina ( where fossils of Riojasaurus have been recovered).

Xixiposaurus

Xixiposaurus is a genus of prosauropod dinosaur which existed in what is now Lower Lufeng Formation, China during the lower Jurassic period. It was first named by Sekiya Toru in 2010 and the type species is Xixiposaurus suni.

Yueosaurus

Yueosaurus is an extinct genus of basal ornithopod dinosaur known from Zhejiang Province, China.

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