We all know and love the new Spinosaurus aegyptiacus reconstruction right? "Disenchanting" is how Douglas Henderson described it on facebook. And it does fall a little bit shy of the impressive dual land/water arch predator it has so often been posited to be, especially since a little movie came out (JP3 duh) and our friend the Spino terrorized everything from T-rex to estranged parents. Truth be told it looks a little clunky, a little too front heavy to work right - at least the way we expect theropods to work since GSP started drawing them as svelte athletes rip roaring across the page. So, yeah I do want to comment on the new Spino reconstruction and yeah there are a lot of people - very knowledgeable ones at that - that would definitely disapprove of what I am going to do before publication of the new material. But I will argue that my interpretation on what was going on with Spino is in fact presaged by what we already know from other members of spinosauridae and yes, as suggested by the title, I think Bakker got the jump on all of us by suggesting way back when that Spinosaurus was a lot more aquatic than generally portrayed. But I will offer my little Antediluvian Salad spin on Spinosaurus and hopefully you find it interesting. And leave a comment.
|Moss Landing/Elkhorn Slough US Army Corps. public domain
Large tetrapods that do not use this technique in deep mud risk getting mired. For large bipeds the risks are even more extreme as all of the weight is concentrated on just one limb when pushing off. As the picture above attests a very large American crocodile has some advantages over a bipedal hominid in deep mud (he survived btw). Whether you are a trained soldier or a simply like to take the Spartan Challenge one is quick to see the benefits of getting down into the mud to get through it. It might seem counter intuitive at first but just ask this guy.
Now following this line of thought of how to traverse muddy areas as a large tetrapods let us revisit Spinosaurus aegyptiacus - especially with respect to the new reconstruction c/o Paul Sereno.
Seen in this manner the long low torso, short legs, short but powerful forearms, and downward sloping neck shared by all spinosauridae now start to make sense. Chasing after stuff on terra firma these animals were not. But if you were in the water, or a hapless dinosaur mired in the mud, spino could get the jump on you.
Below is a depiction I did of Spino with just the body showing and not obscured in the mud. It is a little difficult to draw as such and work kinematically where everything goes. But I think such a style of movement is a fair compromise considering what we know from these critters anatomically and ecologically.
As for how they moved in the water I think more or less like a hippo but bipedal running underwater. Not tail driven.
|Subadult Spino. wiki. legs were likely shorter. Creative Commons Funkmonk
|Baronyx walkerii. CC Funkmonk. Note heavy, but short forearms
Above is a skeletal by blogger/artist/researcher Jaime A. Headden. You will notice that of the material we have, the lower legs are missing. Never the less, as in this skeletal, they are usually rendered fairly long and gracile. But they may have been quite a bit stumpier.
|Suchomimus tenerensis. CC AStrangerintheAlps
|Suchomimus tenerensis CC Belinda Hankins Miller
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