Phaedrolosaurus

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Phaedrolosaurus
Temporal range: Early Cretaceous, ~130–120 Ma
Only known tooth of Phaedrolosaurus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Coelurosauria
Genus: †Phaedrolosaurus
Dong, 1973
Type species
†Phaedrolosaurus ilikensis
Dong, 1973

Phaedrolosaurus (meaning "elated lizard") is a dubious genus of dromaeosaurid coelurosaurian theropod dinosaur, based on an isolated and non-diagnostic tooth from the Early Cretaceous Lianmuqin Formation of Wuerho, in the autonomous region of Xinjiang, China.

Discovery and naming

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In 1963, a team of local geologists were exploring an area near the town of Wuerho, located within the Junggar Basin of northern Uyghurstan. Within this area are the rocks of the Lianmuqin Formation, which is the uppermost formation of the Tugulu Group. Here, they stumbled upon fossils belonging to several dinosaur species. The type locality where the fossils were found is classified as “IVPP site 64043”, which is regarded as being deposited by a river delta on the shore of a lake.[1] The entirety of the Lianmuqin Formation’s strata within this area measures 405 meters thick, and the fossil horizon found within the locality designated “IVPP site 64043” was uncovered within the lower section of the formation.[2] In 1964, paleontologists visited the site, excavated the fossils, and brought them to the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) for study.[3]

One of the fossils which was recovered at the locality was a single tooth, dating back to the Early Cretaceous, possibly during the Valanginian-Albian stages.[4] The tooth, IVPP V 4024-1, was in 1973 described and named by Dong Zhiming as a new genus and species. The type species is Phaedrolosaurus ilikensis. Dong stated the thirty-one millimetre long tooth was like those of Deinonychus, albeit thicker, shorter, and more solid. He regarded the new genus as a possible dromaeosaurid.[5]

As part of the type material of this genus Dong described several skeletal elements from other sites, among them a partial, articulated right leg.[5] Because this latter limb material showed autapomorphies, distinctive characteristics, and there was no reason to connect it to the non-diagnostic tooth, Oliver Rauhut and Xu Xing in 2005 gave this material its own name, Xinjiangovenator parvus. It was noted that while Dong gave a general description of the tooth, he did not list any characters which distinguished this tooth from any other theropod dinosaur teeth. Therefore, the article argued, Phaedrolosaurus ought to be regarded as a nomen dubium.[3] Although, In 1990, British paleontologist David Norman stated that Phaedrolosaurus was a nomen dubium but didn’t provide further information.[6] Because Dong had not designated a holotype among the several specimens in 1973 assigned to Phaedrolosaurus, in 1977 Hans-Dieter Sues had made the tooth the lectotype.[7]

Description

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Phaedrolosaurus was likely a small-medium sized theropod, probably around 3-4 meters (9.8-13 ft), and similar to that of a dromaeosaur, which was also first interpreted by Dong. It would've been quite agile and relatively bulky, capable of running at high speeds and probably also having feathers. From the shape of its teeth, it's possible that the skull of Phaedrolosaurus was rather more strongly-built and broad and not as streamlined as the many other members of the Coelurosauria. Because of the tooth's similarity to those of other dromaeosaurs, Phaedrolosaurus would've likely been similar in size and appearance to other dromaeosaurs.[5]

Classification

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Dong Zhiming had originally described Phaedrolosaurus as a possible dromaeosaurid, based on the robustly-built tooth, which bore a resemblance to other dromaeosaurs, such as Deinonychus.[5] In 1977, Hans Dieter-Sues had classified it as an indeterminate member of the Dromaeosauridae. Sues was also the first to regard Phaedrolosaurus as a doubtful name, as the species is based off very limited material. In the years that followed, Phaedrolosaurus was placed as an indeterminate coelurosaurian by many others. However, based on the descriptions provided of the lectotype tooth's structure and appearance, Phaedrolosaurus was most likely a dromaeosaurid.[4]

Etymology

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The type and only species is Phaedrolosaurus ilikensis. The generic name, "Phaedrolosaurus" is derived from the Greek φαιδρός, phaidros, "elated", referring to the supposed agile and energetic lifestyle of the animal. The specific name, "ilikensis," refers to the Ilike Formation.

References

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  1. ^ Xing, Lida; Lockley, Martin G.; Li, Zhongdong; Klein, Hendrik; Chen, Shaojie; Persons IV, W. Scott; Wang, Miaoyan (2020-06-10). "Large scale dinoturbation in braided stream deposits: evidence from the Cretaceous Tugulu Group of the Hami area, Eastern Xinjiang, China". Biosis:Biological Systems: 72–84. doi:10.37819/biosis.001.02.0054. ISSN 2707-9783.
  2. ^ Xing, Lida; Lockley, Martin G.; Jia, Chengkai; Klein, Hendrik; Niu, Kecheng; Zhang, Lijun; Qi, Liqi; Chou, Chunyong; Romilio, Anthony; Wang, Donghao; Zhang, Yu; Persons, W Scott; Wang, Miaoyan (2021-05-28). "Lower cretaceous avian-dominated, theropod, thyreophoran, pterosaur and turtle track assemblages from the Tugulu Group, Xinjiang, China: ichnotaxonomy and palaeoecology". PeerJ. 9: e11476. doi:10.7717/peerj.11476. ISSN 2167-8359. PMC 8166242. PMID 34123592.
  3. ^ a b Rauhut, O.W.M., and Xu, X. (2005). The small theropod dinosaurs Tugulusaurus and Phaedrolosaurus from the Early Cretaceous of Xinjiang, China. Journal of Vertebrate Paleontology 25(1):107-118
  4. ^ a b Oliver W. M. Rauhut and Xing Xu (2005) "The Small Theropod Dinosaurs Tugulusaurus and Phaedrolosaurus from the Early Cretaceous of Xinjiang, China".
  5. ^ a b c d Z.-M. Dong. (1973). [Dinosaurs from Wuerho]. Memoirs of the Institute of Vertebrate Paleontology and Paleoanthropology, Academic Sinica 11:45-52. [Chinese]
  6. ^ Norell, Mark (1991-06-07). "The Taxa of Dinosaurs: The Dinosauria . David B. Weishampel, Peter Dodson, and Halszka Osmólska, Eds. University of California Press, Berkeley, CA, 1990. xvi, 733 pp., illus. $85". Science. 252 (5011): 1437. doi:10.1126/science.252.5011.1437-a. ISSN 0036-8075.
  7. ^ Sues, H.-D., 1977, "The skull of Velociraptor mongoliensis, a small Cretaceous theropod dinosaur from Mongolia", Paläontologische Zeitschrift, 51: 173-184