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Dinosaurs The History of Paleontology

Why are Paleontologists Obsessed with Spinosaurus?

Instead of an in-depth analysis of the latest paper about Spinosaurus, it’s time to examine why this dinosaur is such a controversial subject for paleontologists.

252 days. That’s how long it had been since the last controversial Spinosaurus paper was published.

Then, on November 30th, peace time was over. Simply titled “Spinosaurus is not an aquatic dinosaur,” the newest paper constructed models of Spinosaurus utilizing CT technology to test whether it was a fully aquatic dinosaur. The new study, authored by Paul Sereno, refutes the notion of a fully aquatic Spinosaurus, claiming that their models show Spinosaurus was incapable of diving and postulate that new fossils of Spinosaurus have been found inland[i].

Normally, I would launch into a detailed examination of the study. But this study just didn’t interest me like previous ones. Similar methodology has been used to try and disprove the aquatic theory before (Henderson 2018[ii]), so the study’s conclusions weren’t anything new. Additionally, some aspects of the study were problematic, most notably its approach to determining whether these new Spinosaurus fossils were inland. Even though Spinosaurus lived during the Cenomanian age of the Cretaceous, between 100-93 million years ago, positional geography in the study is based on maps from the Albian (110 million years ago). It goes without saying that a lot can change in 15 million years, making this aspect of the study disputable.

I digress. Instead of the usual analysis, I wanted to talk about why Spinosaurus has become paleontology’s greatest controversy of the 2020’s. To examine the recent history of Spinosaurus, it needs to be asked: why are paleontologists are so obsessed with Spinosaurus?

There are a few reasons. Let’s start with its enigmatic history.

Spinosaurus was discovered in 1912 by German paleontologist Ernst Stromer in the Bahariya Formation of Egypt. The holotype specimen consisted of two lower jaw bones, about a dozen vertebrae with massive neural spines, and a handful of ribs. While some photos of the holotype have survived, the bones themselves were destroyed in an allied bombing raid of spring 1944, making them impossible to study.

Illustrations from Stromer’s 1915 publication of Spinosaurus. ©Ernst Stromer & The Carnegie Museum of Natural History

For the next 70 years, fossils of Spinosaurus were scarce. No specimens were found between Stromer’s expeditions and the 1980’s, and while a handful of specimens were found in the 1990’s and 2000’s, they mostly consisted of incomplete jaw bones. Without much fossil material, Spinosaurus became something of a cryptid species; paleontologists knew it was large, had massive spines, and was probably a piscivore, but not much else. This absence of material generated abundant interest in an already weird dinosaur, making the discovery of a new specimen in 2014 even more celebrated.

Which brings us to the second reason paleontologists are so fascinated by Spinosaurus: it is like no other animal in our planet’s history. The 2014 specimen, named FSAC-KK 11888, provided a greater glimpse at Spinosaurus than any other specimen. Initial digs discovered cranial elements and neural spines, but also found proportionally short hindlimbs that seemed ill equipped to hunt on land. Instead, Spinosaurus was proposed to be a quadruped that spend most of its life in the water. This is where the notion of a fully aquatic Spinosaurus began, but far from where it ended.

FSAC-KK 11888. Bones in red published in 2014, while those in green published in 2020. ©Nizar Ibrahim

Fast forward to spring 2020, where the fully aquatic hypothesis reached its apex. Further excavations on the site where FSAC-KK 11888 was discovered unveiled the presence of a massive, paddle-like tail. This tail was perceived to have been like that of a crocodile, enabling Spinosaurus to dive beneath the surface as a pursuit predator[iii]. Further studies on Spinosaurus tooth localities and bone density added support for this theory, painting a picture of a very unique dinosaur.

Put it all together and you have a carnivorous dinosaur larger than Tyrannosaurus, had a sail that reached nearly two meters tall at its apex, and lived exclusively in water. Depending on who you ask, some will even claim that it had webbed feet, though there is currently no evidence to support this. Such a dinosaur makes for a fascinating subject, but it also has generated plenty of controversy.

Diving Spinosaurus. ©Ole Zant (@TheBioBob)

While paleontologists agree that Spinosaurus spent some time in the water, the extent of this lifestyle is hotly debated. Some evidence, such as conical teeth and the presence of sawfish teeth embedded in its jaw, indicate that it lived in water to some extent. However, other traits – namely the massive, cumbersome sail – have led paleontologists to dispute the notion that it was an efficient, deep-water swimmer. Instead, they propose that it was a surface-level predator that hunted more like a heron than a dolphin.

This debate has seeped its way into paleontological literature and culture, heightening the infamy of Spinosaurus. Following every major update to the fully aquatic hypothesis, rebuttals have been published that frame it as a semi-aquatic predator. Sereno’s latest study fulfills this step in the seemingly never-ending cycle, probably meaning that more evidence of fully aquatic behaviours is soon to come. Just look at Twitter following the release of a new Spinosaurus paper, and you’ll be quick to find an uproar of paleonerds (like me) reacting to the news.

A less aquatic Spinosaurus. ©Mark Witton

But is there really a debate? Most paleontologists seem to side with the semi-aquatic proposal, with only Ibrahim and a select few leaning towards the fully aquatic side. In fact, the legions of paleonerds on Twitter react with exasperation more than anything else, perhaps even frustration with the constant vacillation.

If this is the case, then why does it seem to be a massive debate? Part of the reason may have to do with media coverage. Ibrahim, the most prominent figure in the fully aquatic hypothesis, is a frequent collaborator with National Geographic. Every time he publishes research it ends up on Nat Geo, which shines a spotlight on the fully aquatic hypothesis. In fact, other media sources like Smithsonian have picked up on the popularity of the debate too, keeping new updates on both sides relevant in the media.

I am part of this coverage. Including this article, I have written about Spinosaurus on six different occasions (and to be perfectly transparent, shifted my views on it once or twice). Every time I have written about it has been a joy, as it allows me to reflect on how this enigma of paleontology metamorphoses into something new every few months.

The last thing to consider is that we shouldn’t strictly adhere to preconceived and popular notions when considering Spinosaurus. Relying on comparisons to other animals to make approximations, as was done in Sereno’s latest study, is probably unreliable given… Spinosaurus’ unique condition. There are many features and adaptations of extinct animals that are impossible to discover in the fossil record, meaning it’s entirely possible that Spinosaurus had some unique mechanisms that allowed it to live in water.

That’s not to say Spinosaurus was fully aquatic. But instead of looking at it with a black and white lens, perhaps we should examine it as a spectrum. Perhaps it spent time on the shores to lay its eggs and forayed to open seas sporadically. Maybe it didn’t. In my opinion, paleontologists – including paleonerds such as myself – should stop trying to make it fit a specific role and instead embrace its status as a prehistoric Rorschach test. Everyone can see something different, and that should make it all the more special.  

Thank you for reading! If you liked today’s article and would like to know more about Spinosaurus, I suggest you read the last time that I wrote about it and what its bones can tell us here at Max’s Blogosaurus!

I do not take credit for any images found in this article. All images belong to their respective artists.

Header image courtesy of The_Nutkase, found here

Works Cited:


[i] Sereno, Paul C, et al. “Spinosaurus Is Not an Aquatic Dinosaur.” ELife, vol. 11, 2022, https://doi.org/10.7554/elife.80092.  

[ii] Henderson, Donald M. “A Buoyancy, Balance and Stability Challenge to the Hypothesis of a Semi-Aquatic Spinosaurus Stromer, 1915 (Dinosauria: Theropoda).” PeerJ, vol. 6, 2018, https://doi.org/10.7717/peerj.5409.

[iii] Ibrahim, Nizar, et al. “Tail-Propelled Aquatic Locomotion in a Theropod Dinosaur.” Nature, vol. 581, no. 7806, 2020, pp. 67–70., https://doi.org/10.1038/s41586-020-2190-3.

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