RE: Dino/bird amphibians & Carcharocles [Carcharodon] megalodon

[Tim Williams <twilliams_alpha@hotmail.com>]

Jaime A. Headden wrote:

>   To my knowledge, the only Mesozoic amphibious dinosaurs are
> hesperornithiforms, such as *Hesperornis,* *Baptornis,* *Pseudhesperornis,*

You're staying up too late Jaime.  :-)  I think you mean _Parahesperornis_ 
rather than _Pseudhesperornis_ .  This may be a case of crossed neurons: 
there is a _Hesperosuchus_ and a _Pseudhesperosuchus_.

> and
> so forth; there may be a few other taxa there, and the most basal hespers 
> are
> apparently flight-capable and thus probably not amphibious.

I've heard about these flight-capable hesperornithiforms before.  Are these 
the ones that are known from fragmentary material in Russia?

Jura wrote:

> Anyway, there's an in depth discussion on the various aspects of 
> _C.megalodon_ including the infamous "Carcharodon/Carcharocles" debate,

In brief, the crux of the issue is whether the modern great white shark 
(_Carcharodon carcharias_) is more closely related to the modern mako sharks 
(_Isurus_ spp.) or to the extinct 'mega-toothed' sharks like _Carcharodon 
megalodon_.  Those researchers who believe that _C. carcharias_ is closer to 
_Isurus_ advocate putting _C. megalodon_ in a separate genus, named 
_Carcharocles_.  However, it's my understanding that most fossil shark 
researchers favor the other view: that the modern great white is closer to 
_C. megalodon_ (and other 'mega-toothed' sharks), and _Carcharocles_ is 
therefore a junior synonym of _Carcharodon_.  Nevertheless, _Carcharocles_ 
is a great name.

Cheers

Tim