Updated 6/9/2020.
Our understanding and depiction of dinosaurs changes over time. This is natural; as we gather more data, our pictures of these animals grow and shift. Where we once saw scales, we see feathers. Where long-standing groups of dinosaurs once stood solid, proposed reorganizations challenge our basic assumptions.
No exception to this rule is Spinosaurus aegyptiacus, a species of theropod dinosaur from Cretaceous North Africa. However, its history is a bit more turbulent than your average dinosaur species.
Where it was once imagined to look like this:
We now believe it looks closer to this:
In between these reconstructions, we see fluctuations in how Spinosaurus has been understood and depicted. From being shown as a megalosaur with a weird bottom jaw and dorsal sail to a bipedal, monstrous superpredator, and then to an avid swimmer, Spinosaurus has evolved dramatically in our cultural and paleontological imaginations. But why?
A Tough Dinosaur to Find
This “evolution” has has been a difficult journey; a century’s worth of digging for spinosaurids (members of the clade Spinosauridae: Suchomimus, Spinosaurus, Baryonyx, etc.) across the globe—especially in Africa—has proven challenging. As a result, we’ve been unable piece together these dinosaurs in great detail.
Even with renewed interest in spinosaurids over the last 30 years, coming across anything other than jaw fragments and teeth is rare. Considering Spinosaurus was piscivorous (a fish eater) and lived in close proximity to water, this seems odd. Aquatic environments typically offer better opportunities for entry into the fossil record, so the lack of more complete specimens remains an unclear puzzle.
Earliest Discoveries
That being said, records of Spinosaurus fossils go back to the mid-1800s. Sir Richard Owen, the English anatomist and paleontologist, described Spinosaurus teeth he’d obtained from fellow paleontologist Gideon Mantell in the 1840s. However, he’d concluded at the time the teeth were crocodilian and not from a dinosaur.
Material was also collected from Algeria at the turn of the 20th century. Explorer Fernand Foureau brought back (surprise!) a handful of teeth to France after his “scientific” mission from colonial Algeria to Lake Chad (Foureau was doing scientific work; the French troops accompanying him were playing violent colonial games with indigenous tribes, as well as Britain). One of Foureau’s contemporaries eventually assigned the teeth to Saurocephalus, an extinct Cretaceous fish. It was only when Ernst Stromer had actually described Spinosaurus that this assignment was revisited.
Ernst Stromer’s Spinosaurus
Born in 1870 to a well-established family of German aristocrats, paleontologist Ernst Freiherr Stromer von Reichenbach would become the first to officially find and describe Spinosaurus.
During his career, Stromer conducted regular fossil collecting expeditions in Egypt. His sammler (fossil collector) Richard Markgraf helped him collect for the Paläontologische Staatssammlung, the state fossil collection in Munich. However, the sammler was consumed with regular illness. Suffering from a particularly bad bout in 1910, he left Stromer to strike out on his own into the Bahariya Oasis. While searching the region alone for mammal fossils, Stromer stumbled upon much larger remains–remains he was not in any way equipped to dig out.
Markgraf recovered and eventually joined Stromer. Together, they excavated, packed up, and shipped these early finds back to Munich. Afterwards Markgraf stayed behind to continue working the site in Bahariya while Stromer returned to Germany. Among the fossils Markgraf gathered in that time was Spinosaurus, in 1912. The holotype specimen he sent back to Stromer consisted of a number of dorsal vertebrae, jaw fragments, and (you guessed it) teeth.
1915: The First Description
Grappling the first World War, Stromer was able to get the Spinosaurus specimens back to Munich to study. He very quickly understood the animal as unique among theropods, and stressed this in the description he published in 1915:
Certainly we are here dealing with a highly specialized form, as not only the body size but also the form of the upper edge of the dentary, the differentiation in tooth size and above all the size, orientation and form of the neural spines of the dorsal vertebrae prove.
Just from the limited remains he had, Stromer was able to clearly establish this animal was special. Unlike other theropods, it had:
- Elongated neural spines, the tallest of which stretched up to two meters
- A long, narrow snout
- Conical, nearly cylindrical teeth lacking serration
After evaluating these features of the holotype, Stromer erected Spinosaurus aegyptiacus (“Egyptian spine lizard”) as a new species. As well, he established the taxonomic clade Spinosauridae. His description was the first documentation of theropods with elongated, crocodile snouts; however, his reconstructions of Spinosaurus would complicate how these features were understood.
1936: Stromer Reconstructs Spinosaurus
Although Stromer understood the jaws of Spinosaurus were different than other theropods, he the jaw fragments he and Markgraf had collected were from Spinosaurus’ mandible; its maxilla (upper jaw) had not been found yet.
Stromer resolved this for his 1936 reconstruction of Spinosaurus (see above) by skewing conservative; he imagined the rest of the skull might be closer to the deep-snouted skulls of megalosaurs and allosaurs. However, he was a little more cavalier with its spines, suggesting the iconic dorsal sail we recognize today.
His reconstruction also showed Spinosaurus in a “kangaroo-like” stance, as was popularized for bipedal dinosaur depictions at the time. This depiction would become–due to tragic circumstances–the dominant Spinosaurus reference for several decades to come.
Lost to War
Stromer had the Spinosaurus holotype mounted at the Munich museum, along with other Bahariya specimens. Not long after publishing his reconstruction, World War II broke out, and Stromer did everything he could to ensure the safety of his discoveries. He repeatedly petitioned the collections manager of Paläontologische Staatssammlung, Karl Beurlen, to move his specimens out of the museum for safekeeping. However, due to his reputation for anti-Nazi views and Beurlen’s blind faith in Nazi propaganda, Stromer was unsuccessful.
Munich–a site for the production of high-performance fighting aircraft–was eventually targeted by the Allies. Between April 24 and 25 of 1944, bomb divisions of the Eighth Air Force raided and bombed the city. In the bombings, the Paläontologische Staatssammlung was severely damaged and the majority of Stromer’s Bahariya collection was destroyed–including the Spinosaurus holotype.
New Findings and Imaginings
After the war, only Stromer’s detailed illustrations and descriptions remained for paleontologists to study (photographs of the holotype existed but weren’t known until 1995). As a result, Spinosaurus remained dormant for several decades in the paleontological periphery. It wasn’t until the 1970s and 1980s that interest in this odd theropod would really pick back up.
Fragments of Spinosaurus in Morocco, Libya, and other North African localities began appearing in the 1970s. Around the same time, artists were starting to depict the dinosaur in children’s books. Two separate, popular reconstructions of Spinosaurus then began to appear—one bipedal, the other quadrupedal. The former would win out (for a short while) after the discovery of Baryonyx in 1986.
While it took over a decade to more firmly establish that both Spinosaurus and Baryonyx belonged to the same clade, understanding this relationship led to both a flood of new discoveries and filling the gaps in our knowledge of Spinosaurus. Phylogenetic studies and data collected from the photographs of Stromer’s holotype were key in closing these gaps. As a result, imaginations gravitated towards depicting Spinosaurus as a crocodile-like, bipedal theropod. However, the alternate depictions persisted—until 2001, that is.
A Jurassic Monster
At the start of the new millennium, filmmaker Joe Johnston had been handed the reins to one of the most iconic movie franchises of all time—Jurassic Park. After consulting with Jack Horner, the paleontologist who worked on the previous two Jurassic films, Johnston and his team concluded that for Jurassic Park III, a “replacement” for the iconic Tyrannosaurus rex was needed. The simplest solution they found was scaling up. Horner advised Johnston’s team to pick the massive Spinosaurus as its new, terrifying theropod.
While currently the largest carnivorous dinosaur known, evidence and research into Spinosaurus at the time was adding weight to ideas around its piscivorous lifestyle and potential non-competitiveness with other theropods. Despite this, the filmmakers decided to present it as a hyper-aggressive superpredator: a killing machine more monster than animal.
After Jurassic Park III’s release in 2001, this iteration of Spinosaurus caught on quickly. It saw itself replicated across all manner of popular media, and most alternate depictions disappeared from view. As a result, the idea of Spinosaurus as an obligate biped would remain the common understanding for almost a decade and a half.
The Life Semi-Aquatic with Spinosaurus
In 2008, while in Morocco, a graduate student by the name of Nizar Ibrahim (by his own account) was presented with a cardboard box of fossils by a nomad. Ibrahim took them and sent them to a university in Casablanca. A year later in Italy, he connected the nomad’s fossils with the Moroccan Spinosaurus remains colleagues at the Natural History Museum of Milan had showed him.
Ibrahim went back to Morocco and allegedly tracked down the nomad, getting him to reveal the fossils’ original location. Shortly thereafter, Ibrahim and a team of researchers were excavating in the hopes of finding more Spinosaurus material. They eventually succeeded, collecting partial remains–including those of a juvenile—from the Kem Kem Beds.
2014: The Semi-Aquatic Spinosaurus is Proposed
After years of study and reconstruction, Ibrahim and his team published their findings in 2014. Their evidence and conclusions were novel and groundbreaking, painting a picture of Spinosaurus in stark contrast to the “conventional” knowledge of the dinosaur. Through analysis of a composite reconstruction and the presence of “reduced hindlimbs,” the team argued Spinosaurus had adaptations for a primarily aquatic lifestyle, and when on land walked on all fours.
This argument has shifted our perception of Spinosaurus considerably, but the hypothesis is still up for debate. Experts like Gregory S. Paul have criticized the reconstruction, arguing the fossil materials composing it could have come from “sediments whose exact temporal correspondence is not certain.” Others, like scientist and skeletal reconstruction expert Scott Hartman, have expressed doubts about the scaling used to make the composite.
Additionally, criticisms over the proposed “novelty” of an aquatic Spinosaurus—as portrayed in the media that surrounded the paper’s release—were raised, as well as over how some of the specimens used were collected. Overall, the main concerns raised over Ibrahim et. al.’s work was while the team had done their best to reconstruct Spinosaurus with what they had to work with, what they built might be more Frankenstein than dinosaur.
2020: The New Spinosaurus Comes to Town
Since the 2014 study, additional work was done to understand how Spinosaurus lived and what it looked like. Some studies called into question the validity of all of Ibrahim et. al.’s material gathered from the Kem Kem Beds, arguing more than one spinosaurid taxa was present there; likewise, others took this new image of Spinosaurus to attempt explanations of features such as its iconic dorsal sail. As well, the presence of reduced hindlimbs on Spinosaurus and their explanation were still being debated.
However, some of these criticisms now appear moot. In April 2020, Ibrahim and his team released a groundbreaking new study on Spinosaurus–one that fundamentally changes our understanding of these insane theropods and their paleoecological function.
In the 2020 paper, Ibrahim et al. describe extensive new material from the Kem Kem Beds. Recovering 30 near-sequential tail vertebrae with elongated neural spines, the team matched this material with the Spinosaurus remains discovered and published in 2014. This effectively ended arguments made against the original specimen being piecemeal. But that’s only the beginning.
The long spines jutting from the top and bottom of the vertebrae give the tail an oar-like profile. Ibrahim’s team discovered this profile, along with other unique features of Spinosaurus’ tail, afforded a level of flexibility and undulation not seen in other theropods. Conducting comparative analysis to other theropods and extant animals that leverage their tails for propulsion, the team established that Spinosaurus‘ tail was more efficient and capable of generating thrust in aquatic environments. In other words, it seems like Spinosaurus might have been far more adapted for swimming than previously understood.
These new findings are indeed extraordinary. There are definitely still questions about the efficacy of this tail when attached to an animal that weighed over six tons, and, there’s still Don Henderson’s 2018 study on its stability in water with which to contend. Assertions over how much time these animals actually spent in the water are also being debated. But at this point, a lot of debate can be put to rest. Indeed, Spinosaurus was at least a semi-aquatic animal with incredibly unique adaptations for living in said environments.
What a Weird Dinosaur
No doubt one of the strangest and most controversial theropods in the fossil record, Spinosaurus has been propelled into the spotlight of our cultural and paleontological imaginations. Its history of discovery and depiction is incredibly captivating, and there are too many crazy stories about it to talk about in one blog post. From its life and extinction to discovery, annihilation, and metaphorical rebirth, Spinosaurus is—without a doubt—one of the most fascinating dinosaurs to have ever walked (and swam) the Earth.
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