Re: Abelisaur & Titanosaur migratory routes

["Nicholas J. Pharris" <pharrinj@PLU.edu>]

On Mon, 22 Jan 1996, John Schneiderman wrote:

> The route illustrated (p.15, fig.3): South America to North America 
> (western half) to Asia via. Beringia to India and finally India to 
> eastern Africa to France.

Is it just me, or does this seem a little bass-ackwards?

> 
> This doesn't seem right...
> 1) No Abelisaur or Titanosaurs have been found in the northern parts of 
> North America and Asia with any certainity.
> 2) Assumption made that Abelisaurs & Titanosaurs originated in South 
> America.

!

> 
> Alternative view...
> 1) Titanosaurs originiated in Africa (lastest Jurassic or early Cretaceous) 
> and radiated to Europe, South America, and India via Madagascar.  The 
> titanosaur (Alamosaurus) invaded western North America (as far north as 
> Utah) via South America.
> 2) Abelisaurs originated in Europe and radiated to Africa then to South 
> America and India.

1) Sounds good:  Titanosaurs appear to be represented in Late Jurassic 
Africa (but nowhere else at the time) by the early genera _Janenschia_ 
and _Malawisaurus_.  I like the South American origin for _Alamosaurus_, too.

2) Alternatively, abelisaurs might have originated in Africa as well 
(inhabited by their Late Jurassic relative _Elaphrosaurus_) and taken the 
same migration routes as the titanosaurs.


..snip...

> ---John Schneiderman (dino@revelation.unomaha.edu)
> 
> 


I had a question or two of my own:

Was Africa indeed split into two continents (west and the rest) in the 
Cretaceous, as I have seen illustrated on maps?

This could explain the absence of abelisaurs from the western portion, 
which came to be dominated by eustreptospondyls and baryonychids, and 
their presence in India and South America, which would have been 
connected to the mainland.

I suppose the only way to confirm this would be to find abelisaurs in 
Cretaceous sub-Saharan Africa.  Anyone up for an expedition?...

BTW, the type braincase of Indosuchus raptorius appears to have been 
referred to the Abelisauridae, but what of the rest?  As Paul (1988) 
notes, some of it might just be tyrannosaurid.  Apparently there are some 
D-sectioned premaxillary teeth known, indicating the presence of an 
arctomet, at least.

Nick Pharris
Pacific Lutheran University
Tacoma, WA 98447
(206)535-8204
PharriNJ@PLU.edu

"If you can't convince them, confuse them." -- Harry S. Truman