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



Denver,

"The neurocentral fusion is not addressed in the vertebral descriptions"

This because the JVP editor obliged me to shorten the text of the article. It was an unnecessary precisation. However, I will discuss about the neurocentral fusion in the papers dealing with the detailed description of the vertebral column.

", and is not confirmed histologically."

Usually, you just look at the presence of absence of the suture. It's enough and you do not need to cut and destroy unique specimens to confirm the obvious. You do not seem to have experience of the real problems that a paleontologist must face in the real world.

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.

Read the skull description carefully. And then compare it with that of the other hadrosauroids.

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.

Are you saying that the subadults of Maiasaura, Brachylophosaurus or Corythosaurus show such a mosaic of basal and derived characters?

The larger specimens of Tethyshadros could just be older individuals or just larger individuals because of intraspecific adult-size variability. Can you disprove this? Can you exclude sexual dimorphism in this taxon? Can you do this in absence of indisputable evidence of osteological immaturity and juvenile features?

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.

Crazy man. Nice? Do you think you can cut the "Gioconda" at Louvre just to confirm that the colors are not synthetic? FIRST - No museum in the world would allow something like this. However, the specimen is not "in the world", it is in Italy where the fossils are State property. Therefore, things are even worse for the poor paleontologist. No chance to obtain the permission to do such a thing from the Ministry in Rome. It easier for you to obtain the permission to cut the leg of the bed of the USA President in Washinghton D.C. I hope it is clear what I mean. SECOND - In order to detect the ontogenic status of a single individual, you need an ontogenic series (i.e., a lot of well-preserved limbs of different sizes to section). Sorry, we do not have that ontogenic series for Tethyshadros. THIRD - You do not know if the bone has the kind of preservation that allows the identification of the histological features. Maybe I am not so stupid as you seem to think. Maybe I decided not to cut that precious bone because it is obvious that it could not give us much information. FOURTH - It is not necessary to cut the bone to take an histological sample. A microsample taken drilling the bone could be enough in a well-preserved bone. However, I do not have the instruments to do it here. Searching for a permission from the State do do the drill and searching for the instrument would take several months and economic resources that I did not have. I will try this in the future, if I will be authorized, but I am pessimistic about the possibility to obtain clear indications about the ontogenic status of the holotype.

Fabio

----- 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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