Zhuchengtyrannus is here!

Zhuchengtyrannus life reconstruction by Bob Nicholls

So, as probably everyone knows by now, I have a new paper out and this is the first dinosaur I have named (as a first author) so welcome please, Zhuchengtyrannus magnus. This is a very large tyrannosaurine theropod that is comparable in size to that legendary source of all dinosaur comparisons: Tyrannosaurus rex. Yep, Zhuchengtyrannus, (or ZT as I’ve been informally calling it) is a big guy with a skull over a metre in length, in the 10 metre range for total length and thus also probably around 6 tons or so.

Obviously this is a big deal for me so there’s lots more to come on this over the next few posts and so don’t panic if this first introduction doesn’t give you all the details you were hoping for. Despite the apparent paucity of the available material (as will become clear) there is a lot that can be said about this and other things that are mentioned in the paper.

First off is that name. Those who are long time readers will know I’m not at all fond of ‘place-name-saurus’ type names but some of us are born with bad names for dinosaurs, some achieve bad dinosaur names, and (in this case) some have bad names thrust upon them! Anyway, if you’ve not guessed the genus name Zhuchengtyrannus simple means ‘tyrannosaur from Zhucheng’ and the species ‘magnus’ refers to the large size. Zhucheng, if you don’t know, is a small town in eastern China and has recently achieved fame for the huge amount of dinosaur fossils that have been found there and this is the latest of a number of new taxa. It’s can be pronounced as either ‘Zoo-cheng-tie-rannus’, or with more of a ‘Joo’ for the first syllable. The latter being closer to the formal Chinese pronunciation of the name, the former a less formal anglicised one.

Locality map for Zhuchengtyrannus. From Hone et al., in press

On that note, while 2010 was celebrated as the year of ceratopsians by many, it should not be overlooked the huge number of tyrannosaurs that have cropped up in the last year or so. Teratophoneus, Raptorex, Xiongguanlong, Sinotyrannus, Bistahieversor and others have all come through recently which adds massively to the number of tyrannosaurs of various ranks in the literature. That’s quite an increase for a clade known from only about 15 species or so as little as 3 years ago and now you can rack up two more. Yes, two.

Zhuchengtyrannus maxilla (bone above, cast below). From Hone et al., in press

As for Zhuchengtyrannus itself, I’m a few paragraphs in and have yet to talk about the thing yet. It is, sadly, represented by a less than complete specimen – we have a near complete maxilla (above) and a dentary (below), both with most of the teeth intact. The maxilla is one of the main bones of the face that makes up most of the side of the snout and holds most of the teeth for the upper jaws, while the dentary is the main part of the lower jaw that again, holds the teeth. That’s not much, but happily (as I’ll be covering in a later post) tyrannosaur maxillae are full of important taxonomic characters and as a result we are quite happy with this being diagnostic as a new genus and species. While that’s not much the material we do have is in great condition (well, more on that too). As noted it is a big one and comparisons to the maxillae and dentaries of other tyrannosaurs show that it’s bigger than anything out there except Tyrannosaurs and Tarbosaurus and it’s comparable in size to both of them. Obviously there’s just one specimen here and there are bigger specimens of Tyrannosaurs at least, but this is right in the mix. There’s nothing really odd or unusual about ZT so we it is ‘basically’ just another giant tyrannosaurine in the mould of these two more famous giants.

Zhuchengtyrannus dentary. From Hone et al., in press

But it’s not the only one. While we don’t describe it or figure it, we do mention in the paper that ZT is one of, what we think, are two new tyrannosaurs at the site. In addition to the elements of Zhuchengtyrannus, there are a variety of teeth and postcranial elements including vertebrae, femora and various metatarsals. Significantly there are also another maxilla and another dentary, neither of which match ZT or those of other tyrannosaurs meaning there are probably two taxa here. However, it also complicates that postscranial material – with these pieces being isolated and there being two genera present, it’s not possible to assign them to one or the other reliably at the moment. Thus there quite probably is a lot more of Zhuchengtyrannus already in our possession, but we can’t prove it, limiting us (for now) to just the skull pieces that were found together.

Between these new taxa and others recently described Asia now seriously rivals north America in the tyrannosauroid diversity stakes. While that’s perhaps not a big surprise in the basal tyrannosauroid stakes which already had a strong Asian base and were not that big in the Americas, that the tyrannosaurids and tyrannosaurines are catching up in diversity is rather more notable. No longer is Tarbosaurus the only Cretaceous giant tyrannosaurine in Asia, so once more I must ask you to please welcome Zhuchnegtyrannus to the world and do come back, there’s lots more to say.

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Hone, D.W.E., Wang, K., Sullivan, C., Zhao, X., Chen, S., Li, D., Ji, S., Ji, Q. & Xu, X. 2011. A new, large tyrannosaurine theropod from the Upper Cretaceous of China. Cretaceous Research, in press.

DOI: 10.1016/j.cretres.2011.03.005

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And of course, my thanks to Bob Nicholls of Paleocreations for the magnificent artwork. And thanks to those bloggers who have held off on their own posts on this before I was ready, it’s very much appreciated. I should also make a final extra point that once again a journal has stuck up an uncorrected proof of a paper – I can see already that a rather critical part of one table has been cut off and there are a couple of errors that need fixing which is why I don’t like these things.