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Re: why isn't Tethyshadros insularis just a juvenile?



Okay, so I see that in the "description" paragraph: "Fusion of vertebral centra 
and neural arches, the presence of barely visible sutures between many skull 
elements, the degree of ossification, the skull elongation and the relative 
size of the orbit do not support a juvenile status for the holotype". So I 
should have spotted that, my bad. The neurocentral fusion is not addressed in 
the vertebral descriptions, and is not confirmed histologically.

Scanning the skull descriptions, some sutures are partially obliterated 
(premax-nasal is given as an example, but this area is only partly preserved in 
the holotype), but others are described as still open.

Given the larger body size of some referred specimens, isn't it possible that 
some or many of the mosaic basal and derived characters present in the holotype 
are there not because of a truly basal phylogenetic position, but because of a 
non-mature status for the holotype specimen? Even a half to 75% grown 
non-mature specimen might still exhibit basal characters forcing it into a more 
basal phylogenetic position.

I'm not saying the specimen is not an adult, it just would have been nice to 
have had a limb bone histologically sectioned to confirm a mature status is all.

 ----------------------------------
Denver Fowler
df9465@yahoo.co.uk
http://www.denverfowler..com
-----------------------------------



----- Original Message ----
From: Fabio Dalla Vecchia <fabdalla@tin.it>
To: df9465@yahoo.co.uk
Cc: dinosaur@usc.edu
Sent: Mon, 14 December, 2009 12:44:15
Subject: Re: why isn't Tethyshadros insularis just a juvenile?

Read the paper..

----- Original Message ----- From: "Denver Fowler" <df9465@yahoo.co.uk>
To: "DML" <dinosaur@usc.edu>
Sent: Monday, December 14, 2009 8:24 PM
Subject: why isn't Tethyshadros insularis just a juvenile?


> Although the various specimens "lack evidence of osteological immaturity 
> suggestive of a juvenile condition" (in the paleobiogeography section), I 
> don't see where this is addressed elsewhere in the paper.
> 
> There is no histological 
tion of neural arch fusion stated (although this is not entirely reliable as a 
maturity indicator anyway). Sacral count seems low for a hadrosauroid 
(consistent with juve status), and the skull seems unfused. Hence a 
non-juvenile status cannot be supported from the evidence presented.
> 
> A "mixture of derived... and primitive characters" is often a good indication 
> of non-maturity in dinosaurs (as Padian said in his ?2007 or 2008? SVP talk). 
> If indeed the specimen is a dwarf, then this may explain juvenile characters, 
> but a dwarf adult should show an EFS and the paper does not address this.
> 
> Maybe this is addressed in the follow-up description of the postcrania.
> 
> ----------------------------------
> Denver Fowler
> df9465@yahoo.co.uk
> http://www.denverfowler.com
> -----------------------------------
> 
> 
> 
> ----- Original Message ----
> From: "heby@libero.it" <heby@libero.it>
> To: dinosaur@usc.edu
> Sent: Mon, 14 December, 2009 5:17:32
> Subject: R: The new dinosaur Tethyshadros insularis
> 
> 
> Here's some info:
> 
> http://news.discovery.com/dinosaurs/meet-antonio--a-new-
> italian-dinosaur.html
> 
> 
> 
> Cheers,
> 
> Lukas Panzarin
> 
> 
> 
> 
> 


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