Thoughts on Aegyptosaurus

Ah Aegyptosaurus. We all know that Ernst Stromer described this for a set of appendicular and axial elements from the Cenomanian epoch of Egypt’s Baharya Oasis. And of course, along with Spinosaurus and Carcharodontosaurus, the remains were obliterated by RAF bombing on April 24/25 1944 (damn Brits…), and the only known specimen of Aegyptosaurus was forever condemned to the history books.

Aegyptosaurus-019

Fossil material of Aegyptosaurus (Stromer, 1932a).


 

Or so it would seem. Fortunately, through communication with several members of the Paleo community, I managed to get my hands on the original description paper. So (naturally) I’ve spent a lot of time looking at the fossil material as figured by Stromer.

So what can we see? Well the middle caudals are procoelous, which means that this is at least beyond Malawisaurus in derivedness (one day will be a post on the different types of articulations in vertebrae). Interestingly, the femur of Aegyptosaurus is very similar to the femora of both Lognkosauria and Euhelopodidae (two unrelated groups who developed VERY similar femoral morphs so much so that sometimes it’s hard to tell which belongs to which (cough Ruyangosaurus cough). Which means that either the femur and caudals are from different genera, or (more likely) that Aegyptosaurus is a Lognkosaurian of sorts. Don’t believe me, check it out below.

Titanosaur Femora

Comparison of various Somphospondyl femora, modified by Paleo King. Note how similar the femora of Ruyangosaurus, Malawisaurus, and Daxiatitan are to Aegyptosaurus. Same massive lateral tuberosity and all.


 

Personally I fully expect this to be a Lognkosaur. Same femur morphology and procoelous middle caudals (as in Mendozasaurus, Futalognkosaurus, and Dreadnoughtus). However, due to the humerus morphology (the proximal humeral head is nowhere near as ridiculously expanded transversely as in Notocolossus, and is still even less so than that of Dreadnoughtus) Aegyptosaurus may be a much more basal Lognkosaur, perhaps intermediate between Malawisaurus and Mendozasaurus.

Notocolossus-003

Notocolossus humerus, along with the pubis and pes. Note how massive the humeral head is compared to Aegyptosaurus.


 

Of particular interest to note is that Aegyptosaurus actually has been included in a phylogenetic analysis before. This is Curry-Rogers (2005). When it was released it was the definitive analysis on Titanosaurs. And even now, 11 years later, it still holds up quite well, despite many former characters no longer being accurate enough, and some of the character codings are wrong (seriously, Argentinosaurus as an Opisthocoelicaudiine?! That makes about as much sense as Huabeisaurus as a Nemegtosaurid). In the only MPT Aegyptosaurus was included in, it was found within a large polytomy of essentially every non-Saltasauroid Titanosaur with the exception of Malawisaurus, Paralititan, and the (definitely not a Titanosaur) Phuwiangosaurus, though this polytomy also includes the oddly out of place Alamosaurus, Aeolosaurus, and Agustinia (which may not even be a Titanosaur!).

One more thing: Lapparent (1960) referred a caudal sequence to Aegyptosaurus, based on “a short, compact vertebral centrum that is flattened laterally and not dorsoventrally; they are strongly procoelous. These characters indicate the family Titanosauridae…leads me to refer these elements to Aegyptosaurus baharijensis.” Now I don’t have the figures in my copy of Lapparent, 1960 (hint hint), but these caudals MAY be referrable to Aegyptosaurus. However in recent years another new Titanosaur emerged, Paralititan stromeri (Smith, et al 2001), and this genus also features procoelous caudals (no middle caudals are known, but the anterior caudals are). As well, the Continental Intercalaire formation from which these caudals were described is from the Albian epoch from Algeria, while both Aegyptosaurus and Paralititan are from the Cenomanian in Egypt. Do I think these caudals belong to Aegyptosaurus or Paralititan? No, but they may be from a close relative of either Lognkosauria or Argyrosauridae (maybe even Euhelopodids, which are also known for procoelous caudals).

So to conclude, Aegyptosaurus  was a potential Lognkosaur which was likely a valid genus, and coexisted alongside the much larger Paralititan. Feel free to leave any comments below if I missed something (or if someone has a copy of Lapparent 1960 with figures).

References


Advertisements

4 thoughts on “Thoughts on Aegyptosaurus”

  1. I’m not very good with anatomy, but the femur looks at least superficially like Argyrosaurus to me. Is placement in Argyrosauridae a possibility?

    Like

    1. It’s possible, as Argyrosaurids seem to be sister taxon to Lognkosauria. However those femurs are no longer considered to belong to Argyrosaurus, so they could potentially be Lognkosauria femurs.

      Like

  2. It may be of note that Aegyptosaurus was also included in Klein et al (2012), based on Curry-Rogers, and it was resolved as more derived that Antarctosauridae (Antarctosaurus, Isisaurus and Argentinosaurus) but basal to Nemegtosauridae and Saltasauridae.

    Klein, N.; Sander, P. M.; Stein, K.; Le Loeuff, J.; Carballido, J. L.; Buffetaut, E. (2012). Farke, Andrew A, ed. “Modified Laminar Bone in Ampelosaurus atacis and Other Titanosaurs (Sauropoda): Implications for Life History and Physiology”. PLoS ONE. 7 (5): e36907. doi:10.1371/journal.pone.0036907. PMC 3353997free to read. PMID 22615842.

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s