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RE: Edmontosaurus (male?) had fleshy cock's comb crest (free pdf)



I'm gonna be a bit of a downer on this and suggest that what we're seeing isn't 
the full picture. It's a tantalizing glimpse, but not a complete perspective. 
The authors do look into argument that counters their claim, but I do not think 
they do a full job, possibly due to limitations, or because they are trying to 
merely present argument FOR, without being super thorough. If they did, if they 
followed every line of reasoning and applied deductive logic to everything, 
they might not come to any conclusion about much of anything, so this is fine. 
That said:

After a quick browse of the paper: 

1) there is no reason to 
assume the structure's shape represents the total structural shape in 
life, as we may be missing margins and surface detail; 

2) the structure appears to be as broad the squamosals, so if 
aligned to the cranial mid-line, it would be as broad, if not broader 
than the skull itself and not a purely mid-line feature inset from the 
margins; 

3) if it were mid-line and not so broad, it would be displaced 
to one side, which casts doubt on the structure's authenticity as a 
natural, undisplaced feature of integument; 

4) despite argument 
otherwise, the lateral surface of the "crest" feature lacks clear 
elements of skin structure that one expects from a negative mould, as 
seen in the neck integument further caudal to the preserved skull 
region, and thus suggests that the element really isn't preserved of the 
surface integument directly; 

5) there is no reason to assume this structure was NOT part of a
 larger whole, but disassociated from that through taphonomic processes -- 
though the authors do attempt to resolve this complaint in specific, it is 
merely to address that this is not the case, and move on. 

I think this last point is most relevant, and preserves Bell et al.'s 
argument whilst also taking into account that their interpretation is 
wrong. In other words, the structure appears to be a mould of the 
integument at the back of the skull, and laying on one's side would 
cause the stru

shape. I quite imagine instead that this indicates a more continuous 
skull-neck integumentary "frill" rather than a limited "cocks-comb."

(Reposted and modified from a Facebook comment.)

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


----------------------------------------
> Date: Thu, 12 Dec 2013 09:13:40 -0800
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: Edmontosaurus (male?) had fleshy cock's comb crest (free pdf)
>
> From: Ben Creisler
> bcreisler@gmail.com
>
> A new online paper with free pdf:
>
>
> Phil R. Bell, Federico Fanti, Philip J. Currie & Victoria M. Arbour (2013)
> A Mummified Duck-Billed Dinosaur with a Soft-Tissue Cock’s Comb.
> Current Biology (advance online publication)
> doi: 10.1016/j.cub.2013.11.008
> http://www.cell.com/current-biology/abstract/S0960-9822(13)01394-8
> Click on "pdf" to open and save.
>
>
> Among living vertebrates, soft tissues are responsible for labile
> appendages (combs, wattles, proboscides) that are critical for
> activities ranging from locomotion to sexual display. However, soft
> tissues rarely fossilize, and such soft-tissue appendages are unknown
> for many extinct taxa, including dinosaurs. Here we report a
> remarkable “mummified” specimen of the hadrosaurid dinosaur
> Edmontosaurus regalis from the latest Cretaceous Wapiti Formation,
> Alberta, Canada, that preserves a three-dimensional cranial crest (or
> “comb”) composed entirely of soft tissue. Previously, crest function
> has centered on the hypertrophied nasal passages of lambeosaurine
> hadrosaurids, which acted as resonance chambers during vocalization.
> The fleshy comb in Edmontosaurus n
> explanation most likely related to either social signaling or sexual
> selection [ 5, 6 and 7]. This discovery provides the first view of
> bizarre, soft-tissue signaling structures in a dinosaur and provides
> additional evidence for social behavior. Crest evolution within
> Hadrosaurinae apparently culminated in the secondary loss of the bony
> crest at the terminal Cretaceous; however, the new specimen indicates
> that cranial ornamentation was in fact not lost but substituted in
> Edmontosaurus by a fleshy display structure. It also implies that
> visual display played a key role in the evolution of hadrosaurine
> crests and raises the possibility of similar soft-tissue structures
> among other dinosaurs.
>
>
> HIGHLIGHTS
>
> A soft-tissue cranial crest is described for the hadrosaurid
> Edmontosaurus regalis.
>
> The crest, analogous to a cock’s comb, was likely a sexual display structure.
>
> Fleshy combs replaced bony crests in some hadrosaurids at the end of
> the Cretaceous.