Re: Ceratops (was RE Glishades ericksoni, ...)

["heby\@libero\.it" <heby@libero.it>]

> >...Ceratops montanus posseses postorbital horncores procurved, which is an 
> >apomorphic trait shared only with derived chasmosaurines, Albertaceratops 
> >and MOR 692. Basal chasmosaurines (Chasmosaurus spp. Agujaceratops), 
> >centrosaurines (the forthcoming >WahWeap Taxon plus some other undescribed 
> >stuff), and basal ceratopsomorphs (Zuniceratops, Turanoceratops) have 
> >recurved postorbital horncores. 
> 
> No. Aside from the fact that orientation of horncores is a trait strongly 
> ontogenetically controlled,  Albertaceratops & MOR 692 both have procurving 
> brow horns, 


Mh. I don't understand your point here. Ceratops, as Albertaceratops and MOR 
692 show the 'adult' (or near-adult) condition. This could be very helpful if 
we're trying to understand if this taxon (even if it's only a nomen dubium) 
it's within the clade Triceratops+Centrosaurus.
As I've stated below, this condition is absent in more basal ceratopsomorphs.

> as do (I believe) some horncores from the Zuniceratops bonebed.
> 

In no specimen that I'm aware of. The largest horcores (MSM 2102 and MSM 2103) 
in the BB are still caudally recurved, suggesting that the procurved condition 
was acquired only by (adult) derived chasmosaurines (and homoplastically shared 
with some centrosaurines). At least, this is at present the most parsimonious 
explanation.

> The only reason I don't say fully ontogenetically controlled is that 
> some taxa like Chasmosaurus may have posteriorly recurved brow horns as 
> adults via paedomorhosis, and noone has yet tested the hypothesis of maturity 
> in these Chasmosaurus specimens.

 Agree. Clearly we need more data on the ontogenetic state of many 
ceratopsids(especially the basal ones).

Best,
Lukas