Saturday, October 4, 2014

Short legs are in?

Spinosaurus aegypticus discusses with a certain individual of Homo sapiens about movie star traits.

So, everyone that's been keeping up with the Spinosaurus stuff these past few weeks have probably seen this post by Mark Witton by now. In it, Ibrahim and co. consulted with Mark and checked over the proportions and scaling in his model, which Mark checked a few days prior and found similar results to Scott Hartman's own numbers. They found out that the big scaling gap between their model and Scott and Witton's models was actually due to some scaling issues in the latter two's models with vertebrae D8, and when compensating for this, the short limbs become perfectly apparent. Scott later confirmed to me on Facebook that he was able to replicate their corrections, and that he was going to be talking more with the authors about things.

So, what does this mean?

Spinosaurus' comically short legs are real.

And my thoughts?


Seriously though, I was skeptical about the rear legs being that short due to all the questions and criticism being brought up about it. After all, extraordinary claims require extraordinary evidence, and when the evidence didn't seem to hold up, people should show skepticism to the idea proposed. That's what being a scientist is all about. This time however, Ibrahim and co. managed to shine through and show that their short-legged model held up to the intense scrutiny. Really great job on their part answering our questions, and their openness and willingness to talk and discuss has been a great asset to solving these problems.

Now, however, we should get onto the important bits about what the new legs actually mean. Spinosaurus being Mr. Shortstuff hasn't been too popular with people that I know (particularly a friend of mine who's a big Spino Fan), as well as many typical members "JP3 Fanboy" community on the internet. I, however, fully embrace this new model for Spinosaurus, since unlike those people, I don't care what Spinosaurus as an animal looked like. However I do care about why it looks that way, and that's where the biological questions of this new model come in.

So, how's a short-legged Spinosaurus going to function? The biggest question I and many people have is how it's going to be moving around on land easily. Ibrahim and co.'s proposed quadrupedal model still doesn't hold up in my opinion (for the reasons brought up on Headden's post as well as elsewhere), but then how is it going to be moving around? A few people have brought up some ideas on Facebook and elsewhere, but the Pangolin method of locomotion proposed by Darren Naish sounds plausible. By hunching over and sticking its tail out strait back, it might've been able to waddle around on land like a pangolin with some success. Perhaps also like a pangolin, it could've used its forelimbs to right itself occasionally while walking on rough terrain, but nothing like constant quadrupedal movement.

Pangolin waddling along... Waddle, waddle...

Moreover, as many people who've read about this already know, tail length in dinosaurs is highly varied, even on the individual level, and it's likely that many dinosaurs may have under-sized and/or over-sized tail proportions. Spinosaurus' tail could've been a good 20% longer than Ibrahim and co. proposed for all we know, if not more. It is also important to remember that dinosaurs, and particularly theropods, had massive, thick tails which would've been effective counterbalances. With the apparent presence of an extremely well-developed caudofemoralis muscle suggested by Ibrahim and co. for paddling, the tail might be extremely bulky, and this could help balance out their Spinosaurus even more while walking.

Another interesting method of locomotion that was mentioned online a few times here-and-there was the possibility of a therizinosaur-like or cormorant-like walking. That is, with a near-vertical back. This I thought was an interesting idea for the terrestrial locomotion of this animal. Normal theropods are already capable of upright movement for short periods, and considering that we think Spinosaurus wasn't spending much time on land to begin with, this could be a possible form of movement.

Behold the Crococormorant! Art by yoult of Deviantart, and name proposed by ornithischophilia.
The posture also brings back images and ideas of retrotheropods from the early and mid-1900s. In fact, wait... Possible upright posture, short legs, strong arms, aquatic habits, the largest theropod, tall extensions on the Spinosaurus a real-life Godzilla?

I'll leave you all with a third and possibly my favorite proposed method of locomotion for Spinosaurus. Stay sharp everyone! Cheers!

Obviously this method of locomotion proposed by Osmatar perfectly explains all of the bizarre proportions to the new Spinosaurus