Turanosuchus aralensis, Halliday & Andrade & Benton & Efimov, 2015
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publication ID |
https://doi.org/ 10.4202/app.2013.0018 |
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persistent identifier |
https://treatment.plazi.org/id/039287C3-3E56-FFE6-FCC3-FDB48B6B5D90 |
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treatment provided by |
Felipe |
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scientific name |
Turanosuchus aralensis |
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Family? Goniopholididae Cope, 1875 Gen. et sp. indet.
Figs. 11 View Fig , 12 View Fig .
1988 Turanosuchus aralensis sp. nov.; Efimov 1988: 55, fig. 9 [nomen dubium].
Material.— PIN 2229-501–510. Isolated fragments of bone, including a mandible fragment (PIN 2229-501) and a putative dentary element (PIN 2229-506). The specimen described as holotype of T. aralensis is PIN 2229-507, a mandibular symphyseal region approximately 10 cm long and 5 cm wide ( Fig. 11 View Fig ). It lacks a portion of the tooth row on the right-hand side, and is damaged by erosion. The symphysis itself extends along the whole length of the specimen, implying that the whole animal was of a similar size to Kansajsuchus . PIN 2229 was found on Tyul’kili Hill, an “isolated hill about 80 km north of Dzhusaly” ( Averianov and Sues 2009: 553) in the north-eastern Aral Sea region, Kazakhstan. The beds of Tyul’kili are part of the Upper Cretaceous (Santonian) Zhirkindek Formation, a unit consisting primarily of sandstone, interspersed with grey and yellow clays. The Tyul’kili beds are 45 m thick; the material was discovered 18 m above the base ( Kordikova et al. 2001) in a “gravelly sandstone”.
Description.— General features: The scrappy nature of PIN 2229 ( Figs. 11 View Fig , 12 View Fig ) means that no diagnostic features can be interpreted about the general shape of the skull. Based on the length and flatness of the mandibular symphyseal region, the skull was probably extremely long-snouted, unlike European goniopholidids, but like Sunosuchus thailandicus .
Maxilla: The maxilla is poorly preserved in part in PIN 2229-502 ( Fig. 12C View Fig ). It is rather flat, and the medial suture with the nasal bones can be seen, indicating that the snout was extremely narrow. Ornamentation is not very clear, but it appears to show the same sort of pitted pattern as in oth- er goniopholidids. The maxillary teeth are circular in cross section and sit in individual alveoli. There is also some festooning, as in both Sunosuchus and Kansajsuchus , where the larger alveoli are present at expansions in both the lateral and ventral directions.
Nasals: The nasal bones are thin, meeting the maxilla extensively with a concave border. The nasal passage is also preserved in part, though it is highly damaged.
A canine alveolus
Dentary: The mandibular symphysis is extended at least as far as the seventh mandibular tooth ( Fig. 11 View Fig ). The first and second mandibular teeth are present on the converging edges of the mandible, after which the tooth rows become parallel with the third tooth. The symphysis has a clear groove running down the midline, as the fusion of the bones is weak. The whole symphysis is only 15 mm deep, and it is very compressed dorsoventrally compared to other mandibular symphyseal regions such as that of Sunosuchus . There are remnants of a pitted ornamentation on the underside of the symphysis.
A second part of the dentary, PIN 2229-506, has also been assigned to T. aralensis ( Fig. 12A View Fig ). It is, however, far deeper, though the teeth are approximately the same size. It is almost certainly not from the same individual, and probably represents an unknown neosuchian crocodylomorph.
Splenial: The splenial is present as a thin wedge at the rear of the mandibular symphysis, but little more can be said because of its incompleteness.
Angular: In PIN 2229-501, the angular of the left mandible is preserved ( Fig. 12D View Fig ). It strongly resembles the mandible of Kansajsuchus in both the honeycomb-pitted ornamentation, and the shape and size of the foramina situated in the internal groove. The whole fragment is over 20 cm in length.
Osteoderms: The available dermal osteoderms are also ornamented with pits ( Fig. 12B View Fig ). They possess anteroposterior keels, and have an area of unornamented bone that is overlapped by the neighbouring scute on the anterior edge.
Comparisons.—The material attributed to Turanosuchus aralensis is so incomplete that there are no diagnostic characters. Coding for cladistic analysis results in a highly unstable position, being unresolved across many eusuchian lineages. PIN 2229 is certainly crocodylomorph, and most likely neosuchian, but beyond that it is impossible to place phylogenetically. For these reasons, Turanosuchus aralensis is here considered a nomen dubium.
Remarks.— Turanosuchus aralensis was originally assigned to Kansajsuchus borealis ( Efimov 1988a) , before Efimov (1988b) decided that the two species could not be combined within a single genus. Turanosuchus is a monospecific genus, it has been found at only one site in Kazakhstan, and the holotype comprises only the mandibular symphyseal region. In his monograph on crocodiles and champsosaurs of Mongolia and Central Asia, Efimov (1988b) admits that “the phylogenetic position of Turanosuchus may cause some debate”. We propose that the material attributed to T. aralensis is non-diagnostic, and as such the genus be reduced to a nomen dubium. A description of those few fragments formerly attributed to the genus is presented here.
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