Raptor Red and Heyday Of The Giants

[Tim Williams <twilliams_alpha@hotmail.com>]

Thomas R. Holtz, Jr. wrote:

> Here's a blast from the past (nearly 10 years old) in the archives:
> http://dml.cmnh.org/1995Sep/msg00258.html

To quote from the piece: "Curiously out of place are the unnamed diplodocid 
(at least Bakker now
recognizes that they did make it into the Cretaceous),"

I metion this not to make HP Holtz look foolish (I swear!), but this line 
got me thinking.  I don't think there are any Cretaceous diplodocoids from 
North America.  AFAIK, the only sauropods from this time and place are all 
titanosauriforms.  The alleged diplodocid from the Early Cretaceous of North 
America may be based on neck vertebrae that were provisionally referred to 
_Barosaurus_, but are now assigned to _Sauroposeidon_.

Which leads me to...

Mickey Mortimer wrote:

> Bruhathkayosaurus is Maastrichtian.  Then there's the huge 
> Kimmeridgian-Tithonian Morrison diplodocids, and the large Early Jurassic 
> Moroccan femur and footprints...

_Sauroposeidon_ is another huge mid-Cretaceous sauropods; and it had a close 
relative across the Pond, known from a single neck vertebra 
("Angloposeidon", from the Isle of Wight).

To emphasize Mickey's point, really big sauropods appear to have existed 
from the mid-Jurassic onwards.  The Morrison Formation does appear to have 
had more than its fair share - although the size estimates for some of these 
sauropods have been significantly downsized since their original 
descriptions (e.g., "Ultrasaurus", _Seismosaurus_).  _Amphicoelias 
fragillimus_ may have been enormous; but it's based on a single dorsal 
vertebra that is now lost.

Also, don't forget that diplodocids might have been very long, but they were 
also very lightly built.  A large portion of the length was made up of the 
very long neck and the even longer whiplash tail.  The heaviest (most 
massive) dinosaurs were the titanosauriforms, including brachiosaurids.  
Although huge brachiosaurids and titanosaurians are known from the Early 
Cretaceous, some impressively-sized titanosaurians are also known from the 
Late Cretaceous, including _Pelligrinisaurus_ and "_Antarctosaurus_" 
_giganteus_.

David Marjanovic wrote:

> The footprints from Morocco called *Breviparopus* are Middle Jurassic, 
> aren't they?

Yep, the ichnotaxon _Breviparopus taghbaloutensis_ comes from the Middle 
Jurassic (Bathonian) of the High Atlas Mountains.

A 2.36m long sauropod femur has been described from the Middle Jurassic of 
Morocco (Charroud and Fedan, 1992).  In their description of _Atlasaurus_ 
(also from the Middle Jurassic of Morocco), Monbaron et al. (1999)  mention 
this huge femur and suggest that it may belong to the same sauropod that 
produced the _Breviparopus_ footprints.

> The Cenomanian may well have been an interesting time for sauropods, but 
> without a better Albian and Turonian record it's difficult to make 
> comparisons.

True.  The Aptian/Albian does appear to have been produced some very large 
sauropods (e.g., _Sauroposeidon_, "Hughenden sauropod"), but most are very 
poorly known.

Tim