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Re: What is big, fluffy, and could tear you to shreds? Yutyrannus, the 9 m long feathered tyrannosauroid from China

Feathered Gorgosaurus chicks sculpted for me a few years ago by Sean Cooper, based on my sketches.




Spike Ekins.

----- Original Message ----- From: "Thomas R. Holtz, Jr." <tholtz@umd.edu>
To: <dinosaur@usc.edu>
Sent: Wednesday, April 04, 2012 7:04 PM
Subject: What is big, fluffy, and could tear you to shreds? Yutyrannus, the 9 m long feathered tyrannosauroid from China

[It's after 1300 Eastern, so the embargo is off... But Nature hasn't updated their site, so here it goes anyway]

Xu, X., K. Wang, K. Zhang, Q. Ma, L. Xing, C. Sullivan, D. Hu, S. Cheng, and S. Wang. 2012. A gigantic feathered dinosaur from the
Lower Cretaceous of China. Nature 484: 92-95.

Abstract: Numerous feathered dinosaur specimens have recently been recovered from the Middle-Upper Jurassic and Lower Cretaceous deposits of northeastern China, butmost of themrepresent small animals1. Here we report the discovery of a gigantic new basal tyrannosauroid, Yutyrannus huali gen. et sp. nov., based on three nearly complete skeletons representing two distinct ontogenetic stages from the Lower Cretaceous Yixian Formation of Liaoning Province, China. Y. huali sharessomefeatures, particularly of the cranium,with derived tyrannosauroids2,3, but is similar to other basal tyrannosauroids4-12 in possessing a three-fingered manus and a typical theropod pes. Morphometric analysis suggests that Y. huali differed from tyrannosaurids in its growth strategy13,14. Most significantly, Y. huali bears long filamentous feathers, thus providing direct evidence for the presence of extensively feathered
gigantic dinosaurs and offering new insights into early feather evolution.

Yutyrannus = feathered tyrant
Huali = beautiful

Three (yes, 3!) very complete articulated specimens!! Sadly (see below) Xu & co. did not excavate these themselves. If other material comes from this site of comparable size and quality, this is a world-class dinosaur site. BIG dinosaurs in a Yixian
lacustrine facies!!

Yutyrannus is a good-sized dinosaur (9 m, 1.4 t). Manus has three large clawed digits; pes is non-artcometatarsalian and limb
proportions fall among basal (non-arctomet) theropod curve.

Feathers are preserved in patches over most of the body. Individual elements up to 20 cm long: remind me of emu or cassowary

The authors make a big deal about the plumage being an adaptation to chilly Liaoning. Well, maybe. But because we do NOT have any other big tyrants preserved in lacustrine/lagoonal deposits with grain size small enough to preseve feathers, we cannot reject the possibility that even an 8 t T. rex was just as fuzzy. It is my interpretation that we are seeing taphonomical, not morphological,
differences here.

Are they really tyrannosauroids? Yes, this is a quite reasonable interpretation. However, if they are NOT tyrannosauroids they are almost certainly not crownward towards birds from Tyrannosauridae: if anything, they would be more basal.

The bad news: these were collected by private collectors who have not released the information (or at least not formaly) to the researchers, and as such we lack important issues of provenance. Xu et al. examined these carefully for signs of tampering, and they seem okay. The sediment and quality of preservation are consistent with the Yixian; however, the older (Late J/earliest K) Tuchengzi
Formation is also present in the region from which it was recovered.

Xu et al. are at work preparing a long monographic description, but that is probably years off.

So how are the BANDits going to deal with this? Will they call them frauds or collegen fibers, or is Tyrannosauroidea now part of

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661

Faculty Director, Science & Global Change Program, College Park Scholars
Fax: 301-314-9843

Mailing Address: Thomas R. Holtz, Jr.
Department of Geology
Building 237, Room 1117
University of Maryland
College Park, MD 20742 USA