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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
feathers.

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
birds?

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
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
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