Phosphatodraco
| Phosphatodraco | |
|---|---|
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| Assigned C5 cervical (neck) vertebra in multiple views
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | †Pterosauria |
| Suborder: | †Pterodactyloidea |
| Family: | †Azhdarchidae |
| Subfamily: | † Quetzalcoatlinae
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| Genus: | †Phosphatodraco Pereda-Suberbiola et al., 2003 |
| Type species | |
| †Phosphatodraco mauritanicus Pereda-Suberbiola et al., 2003
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Phosphatodraco is a
Due to the fragmentary nature of the holotype cervical vertebrae, there has been controversy over their order. The describers considered them as cervicals (abbreviated as C) C5–C9 in the series, the first preserved vertebra (C5) being broken in two, but others consider them C3–C8, C3 and C4 being two different vertebrae. The interpretation followed has consequences for how Phosphatodraco is distinguished from other azhdarchids and how large it is thought to have been; the describers considered it to have had a wingspan of 5 m (16 ft); the alternate interpretation would lead to a 4 m (13 ft) wingspan. The complete neck may have been 865 mm (2 ft 10 in) long. Phosphatodraco is mainly distinguished by its C8 (or C7) vertebra being very elongated, 50% longer than the C5, and in having a prominent
The closest relatives of Phosphatodraco appear to have been
Discovery
During the late 1990s, remains of
The pterosaur material, catalogued as specimen OCP DEK/GE 111, consists of five disarticulated but closely associated cervical (neck) vertebrae and an indeterminate bone, most likely belonging to a single individual. The vertebrae are crushed and damaged, and the surface of the bone is missing in some areas, with some infilling of phosphate sediments, and the fossils have therefore not been removed from the matrix. The block containing the bones is 98 cm (39 in) long and 34 cm (13 in) wide. During mechanical preparation of the specimen fossil remains of other animals were also found in association, including of several types of fish and mosasaurs.[1]
The specimen was made the holotype of the new genus and species Phosphatodraco mauritanicus by paleontologist Xabier Pereda-Suberbiola and colleagues in 2003. The genus name derives from the words phosphate and the Latin draco, meaning "dragon from the phosphates", and the specific name refers to the region of Mauretania where the fossils were found.[1] The describers gave the etymology of Mauretania as Latin for North Africa; other sources specify it as an area stretching from Algeria to Morocco.[1][3][4] Phosphatodraco was the first Late Cretaceous pterosaur known from North Africa (and thus the first known member of the family Azhdarchidae of this age from the region), and only the second pterosaur genus described from Morocco (the first being Siroccopteryx). At the time it was described, it was one of the only known azhdarchids preserving a relatively complete neck (the others being Zhejiangopterus and Quetzalcoatlus[5]), and was one of the last known pterosaurs.[1] Complete neck vertebral series are rare for azhdarchids, but such vertebrae are some of the most commonly found and best known remains of the group.[6]
In 2018 paleontologist Nicholas R. Longrich and colleagues reported pterosaur fossils collected from "couche III" in cooperation with the
In 2020 paleontologists Claudio Labita and David M. Martill described an articulated (where the bones are connected as in life) pterosaur wing from "couche III" (specimen FSAC CP 251, bought from
Interpretations of cervical (neck) vertebra order
Pereda-Suberbiola and colleagues originally interpreted the five preserved cervical vertebrae of Phosphatodraco as cervicals C5–C9. The frontmost preserved vertebra they interpreted as C5 consisted of two fragments; they found it unlikely that these belonged to two different vertebrae, since they lay in continuity with no sediment in between, and overlapped each other in some areas. They considered the sideways expansion at the front of this vertebra to be due to crushing, and pointed out that such preservation where fragile, yet well-preserved bones are associated with damaged material of the same individual is known from other vertebrate fossils in the same level. They identified the frontmost vertebra as a C5 because this is usually the longest cervical vertebra in pterosaurs, their length decreasing hindward.[1]
In 2007 paleontologist
Subsequent articles from 2011 and 2015 with Kellner among the co-authorship have concurred with Kellner's interpretation.[12][13] Paleontologist Alexander Averianov disagreed with Kellner's reinterpretation of the cervical vertebrae in 2014, and considered the original description accurate.[14] A 2015 article by paleontologist Mátyás Vremir and colleagues called the issue "controversial" and considered the specimen too crushed for proper comparison,[15] and Martill and Markus Moser concurred with this in 2018.[16] Paleontologists Darren Naish and Mark P. Witton (the co-authors of Vremir's article) followed Kellner's interpretation in 2017.[1][17] Paleontologist Rodrigo V. Pêgas and colleagues also followed Kellner's order in 2021.[18] Though the palaeontologist Alexandru A. Solomon and colleagues noted the suggested change in interpretation of the holotype order in 2019, they stated that even if the reinterpretation was correct, the specimen was too damaged for comparison with the single known cervical vertebra of their new genus Albadraco.[19]
Description
In their 2003 description, Pereda-Suberbiola and colleagues estimated Phosphatodraco to have had a wingspan close to 5 m (16 ft), based on comparison with other azhdarchids with preserved cervical vertebrae, and referred to it as a "large azhdarchid pterosaur". This is larger than azhdarchids such as Zhejiangopterus and Montanazhdarcho, and comparable to the smaller species of Quetzalcoatlus, Q. lawsoni; the larger Q. northropi is thought to have reached 10–11 metres (33–36 ft), thereby being the largest known flying animal.[1][20] Witton grouped Phosphatodraco with "midsized" azhdarchids based on this size estimate in 2013.[21] In 2010, Kellner suggested this size estimate too large, based on his reinterpretation of the neck vertebra order.[10] Naish and Witton, who followed Kellner's interpretation, listed a neck-length of 865 mm (2 ft 10 in) for Phosphatodraco in 2017, and a wingspan of 4 m (13 ft).[17]
There were two main types of azhdarchid skulls; very long, low skulls that were up to ten times longer than wide, and some that were much shorter than that, closer to those of other pterosaurs. Some had crests and some did not. Azhdarchids had necks that were proportionally longer than those of other pterosaurs, and their
Cervical vertebrae
The suite of features that distinguish a taxon from other related taxa is called a diagnosis, and in the case of Phosphatodraco, these features are all found in the cervical vertebrae. Since Pereda-Suberbiola and colleagues considered the preserved vertebrae to be C5–C9 of the series in their description, that is the diagnosis and description followed here.
The five preserved cervical vertebrae have hollow centra and their
The C6 (Kellner's C5
The following C7 vertebra (Kellner's C6
The next to last vertebra is C8 (Kellner's C7
The last vertebra is the C9 according to Pereda-Suberbiola and colleagues (Kellner's C8,
Pereda-Suberbiola and colleagues found that the frontmost preserved cervical vertebrae of Phosphatodraco (their C5–C7) were similar in form to those of the mid-series cervical vertebrae of other long-necked
Classification
In their 2003 description Pereda-Suberbiola and colleagues considered Phosphatodraco a member of Azhdarchidae based on features such as its mid-series cervical vertebrae being elongated, with low
Longrich and colleagues performed a
In 2021 paleontologist Brian Andres and colleagues also found Phosphatodraco and Aralazhdarcho to be sister taxa, supported by the reduction of pneumatic foramina on the side of the neural canal. This clade was recovered as part of the azhdarchid subclade Quetzalcoatlinae. The
Azhdarchiformes
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Paleobiology
Feeding and ecological niche
In 2008 Witton and Naish pointed out that although azhdarchids have historically been considered to have been
Witton and Naish instead stated that azhdarchids probably inhabited inland environments, based on the taphonomic contexts their fossils have been found in (more than half the fossils surveyed were from for example
Witton elaborated in a 2013 book that the proportions of azhdarchids would have been consistent with them striding through vegetated areas with their long limbs, and their downturned skull and jaws reaching the ground. Their long, stiffened necks would be an advantage as it would help lowering and raising the head and give it a vantage point when searching for prey, and enable them to grab small animals and fruit.[24] In their 2021 study that reinterpreted Tethydraco as an azhdarchid, and possibly the same as Phosphatodraco, Labita and Martill noted that azhdarchids might have been less terrestrial than suggested by Witton and Naish, since the Moroccan fossils were from marine strata, as was Arambourgiania from the phosphates of Jordan. They noted that no azhdarchids had been found in truly terrestrial strata, and proposed they could instead have been associated with aquatic environments, such as rivers, lakes, marine and off-shore settings.[7]
Pterosaurs are generally thought to have gone gradually
Locomotion
Witton summarized ideas about azhdarchid flight abilities in 2013, and noted they had generally been considered adapted for soaring, although some have found it possible their musculature allowed flapping flight like in swans and geese. Their short and potentially broad wings may have been suited for flying in terrestrial environments, as this is similar to some large, terrestrially soaring birds. Albatross-like soaring has also been suggested, but Witton thought this unlikely due to the supposed terrestrial bias of their fossils and adaptations for foraging on the ground. Studies of azhdarchid flight abilities indicate they would have been able to fly for long and probably fast (especially if they had an adequate amount of fat and muscle as nourishment), so that geographical barriers would not present obstacles.[25]
Azhdarchids are also the only group of pterosaurs to which trackways have been assigned, such as Haenamichnus from Korea, which matches this group in shape, age, and size. One long trackway of this kind shows that azhdarchids walked with their limbs held directly underneath their body, and along with the morphology of their feet indicates they were more proficient on the ground than other pterosaurs. According to Witton, their proportions indicate they were not good swimmers on the other hand, and though they could probably launch from water, they were not as good at this as some other pterosaur groups.[25]
Paleoenvironment
Phosphatodraco is known from the "couche III" phosphatic unit of the Ouled Abdoun Basin in Morocco, which was deposited during the late Maastrichtian age of the Late Cretaceous period, which ended 66 million years ago. The phosphatic series is condensed and the Maastrichtian part is only 3–5 cm (1.2–2.0 in) thick. From the bottom to the top, "couche III" consists of thin phosphatic levels and
The phosphatic matrix of the original Phosphatodraco specimen is gray and mottled with orange, and contained fossils including of the fish
See also
References
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- ^ PMID 29534059.
- ISBN 978-0-8108-7919-5.
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- ^ PMID 18509539.
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- ^ PMID 21152777.
- ^ Wellnhofer 1991, pp. 50–52.
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- ^ PMID 28133577.
- ^ S2CID 238725853.
- S2CID 213808137.
- S2CID 245125409.
- ^ a b Witton 2013, pp. 249–255.
- ^ Witton 2013, pp. 51–52.
- S2CID 245078533.
- ^ Witton 2013, pp. 257–258.
- ^ a b Witton 2013, pp. 255–257.
- ^ .
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Bibliography
- Wellnhofer, P. (1991). The Illustrated Encyclopedia of Pterosaurs. Crescent Books. ISBN 978-0-517-03701-0.
- Witton, M. P. (2013). Pterosaurs: Natural History, Evolution, Anatomy (1st ed.). Princeton University Press. ISBN 978-0-691-15061-1.
