| Zhuchengtyrannus | |
|---|---|
 | |
| Reconstructed skeleton, with missing bones cast fromTyrannosaurus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Tyrannosauridae |
| Subfamily: | †Tyrannosaurinae |
| Tribe: | †Tyrannosaurini |
| Genus: | †Zhuchengtyrannus Hone et al.,2011 |
| Type species | |
| †Zhuchengtyrannus magnus Hone et al., 2011 | |
| Synonyms | |
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Zhuchengtyrannus (meaning "Zhucheng tyrant") is agenus oftyrannosauridtheropoddinosaur known from theCampanian stage of theLate Cretaceous ofShandong Province,China. It belongs to thesubfamily Tyrannosaurinae, and contains a single species,Zhuchengtyrannus magnus.
Zhuchengtyrannus was first described and named by David W. E. Hone, Kebai Wang, Corwin Sullivan, Xijin Zhao, Shuqing Chen, Dunjin Li, Shuan Ji, Qiang Ji and Xing Xu in2011 and thetype species isZhuchengtyrannus magnus. The generic name is derived from the wordZhucheng, which refers to the type locality, andtyrant in reference to its phylogenetic position as a tyrannosaurid. Thespecific namemagnus meaning "great" inLatin refers to the relatively large size ofZhuchengtyrannus.[1]
Zhuchengtyrannus is known solely from theholotype ZCDM V0031, a nearly complete rightmaxilla and associated leftdentary (lower jaw, both with teeth) discovered around 2010 with theSinankylosaurus holotype,[2] and is currently housed at theZhucheng Dinosaur Museum. Casts of the holotype, IVPP FV 1794, are held at theInstitute of Vertebrate Paleontology and Paleoanthropology. ZCDM V0031 was collected in the Hongtuya Formation[3] from theWangshi Group at Zangjiazhuang quarry,Zhucheng City, dating to theCampanian stage, at least 73.5 million years ago. A second tyrannosaurid dentary (ZCDM V0030) and maxilla (ZCDM V0032) have also been collected at Zangjiazhuang quarry. Even though they were not associated with one another, both specimens are different from other tyrannosaurids, includingZhuchengtyrannus, implying the existence of at least one additional tyrannosaurid from the quarry. Apart from the tyrannosaurid material, specimens ofSinoceratops,hadrosaurids (probablyShantungosaurus) andankylosaurs such asSinankylosaurus were recovered from it.[1]Zhuchengtyrannus was found in an area that was a floodplain in the Cretaceous period and contains one of the highest concentrations of dinosaur bones in the world.[4]
Zhuchengtyrannus was a large carnivorous theropod, and the holotype has been estimated to have been "similar in size and gross morphology toTarbosaurus",[1] which is about 10 metres (33 ft) in body length and 5 metric tons (5.5 short tons) in body mass.[5][6][7] The holotype dentary was significantly smaller than the corresponding bones of one of the largestTyrannosaurus specimens ("Sue").[8]
Zhuchengtyrannus can be distinguished from all other tyrannosaurines by a singleautapomorphy, the presence of a horizontal shelf on the lateral surface of the base of the ascending process of themaxilla, and a rounded notch in the anterior margin of the maxillaryfenestra.Zhuchengtyrannus also possesses a ventral margin of the antorbital fenestra that lies well above that of the ventral rim of the antorbital fossa. Additionally, the total length of the maxillary fenestra is more than half the distance between the anterior margins of the antorbital fossa and fenestra. Unlike the contemporaneousTarbosaurus,Zhuchengtyrannus lacks a subcutaneous flange on the posterodorsal part of thejugal ramus of the maxilla, and a ventrally convex palatal shelf that covers the bulges of the roots of the rear teeth in medial view.[1]
It is possible that several isolated teeth from one of the Zhucheng dinosaur quarries, previously given the nameTyrannosaurus zhuchengensis, belong to this or a related species. TheT. zhuchengensis teeth are characterized by serrations that extend all the way to the base of the tooth crown, a feature not seen in any other tyrannosaurine species. All known teeth ofZhuchengtyrannus are too poorly preserved in this area to compare withT. zhuchengensis, but further finds may clarify their relationship.[1]
Aphylogenetic analysis published with the description of the tyrannosaurineLythronax in the journalPLOS One by Loewen et al. 2013, recoveredZhuchengtyrannus as thesister taxon ofTarbosaurus. It also suggests thatZhuchengtyrannus and other currently known Asian tyrannosaurids were part of an evolutionary radiation descending from the same North American stem that later gave rise toTyrannosaurus, recovered as their closest known relative. Below are the results obtained in their phylogenetic analysis:[9]
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More recent study by Voris et al in 2020 recoveredZuchengtyrannus as the sister taxon to a clade containing theMaastrichtian generaTyrannosaurus andTarbosaurus,[10] see this phylogeny below.
Winter 2011 Appendix
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