Re: Paronychodon teeth are NOT homalocephalid fangs - killing an internet rumor

["franklin e. bliss" <frank@blissnet.com>]

At my Hell Creek localities, I have slightly more paronychodon teeth  
than Pachychephalosaur teeth coming from the microsites. (Neither are  
common.)   I do find some obvious Pachycephalosaur material (a very  
nice skull cap and several squamosal spines).  I would expect many  
more Pachycephalosaur teeth than I actually find here. While not very  
large, their distinctive patterning makes them easy to spot.

Frank (Rooster) Bliss
MS Biostratigraphy
Weston, Wyoming
www.wyomingdinosaurs.com
On Jul 27, 2007, at 5:57 PM, Michael Mortimer wrote:

> While researching Paronychodon for my website, I came across a  
> rumor started on the DML by Olshevsky, and decided I might as well  
> kill it on the DML as well.
>
> An odd possibility was suggested by Olshevsky (DML, 1997), that  
> some Paronychodon specimens, including the holotype, may be  
> anterior dentary fangs of "homalocephalid" pachycephalosaurs (cf.  
> Goyocephale) . However, the dentary fangs of Goyocephale are  
> serrated distally, polygonal in section, have a bulbous root, and  
> seem to only possess one lingual ridge. Premaxillary teeth of  
> Goyocephale are somewhat similar to type B teeth of Paronychodon,  
> but lack ridges, are much less labiolingually compressed, and have  
> distal serrations apically. Stegoceras teeth are even less similar,  
> being serrated both mesially and distally with no ridges. The  
> supposed Middle Jurassic pachycephalosaur Ferganocephale has  
> vertical enamel ridges on the base of one side and lacks  
> serrations, but is otherwise highly distinct, being unrecurved,  
> short and uncompressed labiolingually, with a prominent cingulum.  
> The ridges radiate from the base instead of the apex and the entire  
> tooth shape is distinctively ornithischian. Besides the anatomical  
> differences, stratigraphically Paronychodon and "homalocephalids"  
> are also mismatched, with the latter only known from the Campanian- 
> Maastrichtian of Mongolia and perhaps China. The utter lack of  
> "homalocephalids" in well sampled strata like the Dinosaur Park  
> Formation is particularily telling. Also notable is that each  
> "homalocephalid" only had eight fang-like teeth, but had around  
> sixty-six leaf-shaped teeth. So we would expect more  
> pachycephalosaur teeth by a factor of 8:1 or so, but Baszio (1997)  
> showed this is not the case. For instance, he recorded 12  
> Paronychodon teeth from the Dinosaur Park Formation, and only 16  
> pachycephalosaur teeth. Similarly, Baszio recorded 84 Paronychodon  
> teeth from the Milk River Formation, but only 16 pachycephalosaur  
> teeth. Finally, Zinke and Rauhut (1994) described paronychodontid  
> teeth within a theropod dentary fragment, though these differ from  
> Paronychodon in some details.
>
> References- Zinke and Rauhut, 1994. Small theropods (Dinosauria,  
> Saurischia) from the Upper Jurassic and Lower Cretaceous of the  
> Iberian Peninsula. Berliner geowiss. Abh.. E 13, 163-177.
> http://dml.cmnh.org/1997Dec/msg00058.html
> Baszio, 1997. Investigations on Canadian dinosaurs: systematic  
> palaeontology of isolated dinosaur teeth from the Latest Cretaceous  
> of south Alberta, Canada. Courier Forschungsinstitut Senckenberg.  
> 196, 33-77.
>
> Mickey Mortimer
> http://home.myuw.net/eoraptor/Home.html