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Raptor Red and Heyday Of The Giants

Thomas R. Holtz, Jr. wrote:

Here's a blast from the past (nearly 10 years old) in the archives:

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.