Monday 12/7/21 - Palaeontology's History of Spinosaurus
Spinosaurus over the decades, Mario Lanzas
In a strange twist of fate, being very deeply obsessed with Dinosaurs as an adult means that it's a lot harder to choose a favourite Dinosaur. I have a few I hold higher than most species, and one of those is Spinosaurus.
Spinosaurus is a very unique animal, even among Dinosauria. It was thought to be the largest meat-eating dinosaur, and also the most aquatically adapted dinosaur. Despite being such a mainstream dinosaur, Spinosaurus is only known from a handful of specimens, and none of them have been close to 100% complete. This has meant that every time we find new remains, we often find something we never knew about the dinosaur before.
In today's article, I'm gonna go over a brief history of Spinosaurus discoveries and how we thought it looked at the time.
Although there are many intricate unique parts to its anatomy, the first and most striking thing about it is the tall neural spines on its back, and this became its namesake, Spinosaurus. In 1912, the first remains of Spinosaurus were discovered in the Bahariya formation, Egypt, and named by Ernst Stromer in 1915.
The full species name was Spinosaurus aegyptiacus, meaning Egyptian Spine Lizard. This specimen became the Holotype, which means this specimen is what all future specimens would refer to when deciding if remains belong to Spinosaurus aegyptiacus.
Original Skeletal remains, as reconstructed by Stromer. The bones actually found highlighted in black.
Since the Holotype lacked the top of the skull, Spinosaurus was originally reconstructed with a more typical therapod head, and also more upright, as was standard with meat eating dinosaur reconstructions at that time.
Stromer's Spinosaurus skeleton was destroyed during a bombing raid in WW2 that destroyed part of Berlin Museum, so modern Palaeontological techniques cannot be used to uncover more information about that particular set of remains.
1998 - New Century Spinosaurus
Some very fragmentary remains of Spinosaurus was found over the 20th Century, but nothing substantial enough to inform palaeontologists about more of Spinosaurus's anatomy, until 1998.
Although these remains were still very incomplete compare to many other popular dinosaurs, we now had part of the upper jaw. Scientists could now group Spinosaurus with other similar crocodile headed dinosaurs, especially Baryonyx, described in 1986. This new Spinosaurus was tentatively given its own species, S. marrocanus, but most scientists do not consider the species valid, and lump it together with S. aegyptiacus.
Left: Upper jawbone of Spinosaurus described by Taquet, and Russell.
Right: Skeletal remains of Baryonyx (top) Suchomimus (middle), 1998 Spinosaurus (bottom)
Since 1998's Spinosaurus was just a sized-up Baryonyx with a large dorsal sail, it became a very exciting dinosaur. Spinosaurus was now taller, heavier and longer than Tyrannosaurus rex. This popularity peaked with Jurassic Park 3, which was based on this reconstruction.
Below: Jurassic Park 3 Spinosaurus, NikoRex (DeviantArt)
2014 - The Aquatic Neotype
In 2014, a new skeleton of Spinosaurus was found in Morocco, and it was the most complete skeleton yet. Not only did we have almost a complete skull, but we had a full neck, several neural spines, and LIMBS! The completeness of this specimen has made it the Neotype (the new Holotype which we compare Spinosaurus remains to).
2014 reconstruction of Spinosaurus, actual bones in red
Ibrahim et al's description of Spinosaurus aegypticus revolutionised how we reconstructed Spinosaurus. The legs recovered from this specimen revealed that they were way... smaller than what we'd expect of a dinosaur it's size. Based on the maths of trying to balance Spinosaurus, reconstructions of the 2014 specimen had concluded that Spinosaurus was too front-heavy to be bipedal on land.
Facultative Quadrupedal Spinosaurus, Davide Bonadonna
Thus began the new age of the river monster Spinosaurus, who spent a lot of time in the water and knuckle-walked on all fours while on land.
You may have noticed in all the skeletal remains diagrams I've posted so far, the tail has never been anywhere near complete. That changed in 2020, when Ibrahim and company returned to the site of the 2014 discovery and found more bones, this time of a truly unique tail seen nowhere else in the dinosaur clade.
2020 Spinosaurus, remains found in red, green, and yellow, bones never found previously in green.
This new tail discover all but confirms an aquatic lifestyle for Spinosaurus, as this new tail also had taller spines that would have supported a Newt or Crocodile-like tail paddle in life.
Also for the knuckle-walk haters, this tail would've overbalanced Spinosaurus wayyyy in the other direction. Spinosaurus was not only definitely bipedal again, but it probably walked more upright that any other of its close relatives, or most therapods in general.
2020 Spinosaurus, Mark Witton.
As of writing, no more major overhauls in what we know of Spinosaurus's anatomy have been proposed. But there are new possibilities just waiting to be discovered.
To put it in perspective for a second, there have been about 50 partial to full skeletons described of Tyrannosaurus rex, so our understanding of what that dinosaur looks like is pretty set in stone. There have been less than 10 partial remains described of Spinosaurus, maybe 2 of them are complete enough to give a good picture of the full animal, and the Holotype was destroyed by bombs.
Part of why Spinosaurus is among my favourite dinosaurs is because how unique it is. Part of it is that new stuff about the animal is being found all the time.
Hope you enjoyed the read. If there's anything you wanna correct me on, feel free. I'm not a palaeontologist, just a dinosaur enthusiast, so there's bound to be stuff I got wrong. If you wanna suggest another article topic on dinosaurs, my asks and inbox are open.
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