Although dinosaurs are very popular, the contemporary Mesozoic crocodilians and
their relatives, the crocodylomorphs, remain obscure to the general public.
Despite their former diversity in both size and shapes, the few relatively mainstream species,
such as Deinosuchus, were more or less simply larger versions of today’s crocodilians.
This sole exception to this is the bizarre Kaprosuchus saharicus. Its
name means “Saharan Boar Crocodile”, which is in reference to its massive, almost tusk-like
teeth. This striking appearance has inspired the Boar Croc’s inclusion in various media,
such as the video game ARK: Survival Evolved as well as a shockingly inaccurate portrayal
in the series Primeval. Kaprosuchus is often depicted as a terrestrial animal.
While there were a number of fully terrestrial crocodylomorphs throughout prehistory,
whether or not Kaprosuchus was among their number is still under debate. Despite its fame,
very little is known about Kaprosuchus. Only a single skull has been found and remarkably
little research relating to it has been conducted since the initial description in 2009. The skull
was found in the Echkar Formation in Niger, which was formed between 100 to 95 million years ago.
This means Kaprosuchus lived at roughly the same time as the famous dinosaurs Carcharodontosaurus
and Spinosaurus. Kaprosuchus was originally estimated to have been six meters long. More
recent estimates of its size based on its close relative Mahajangasuchus suggest a more modest
length closer to three meters, which is still impressive for a non-dinosaur at the time.
Kaprosuchus had powerful jaws and its skull was reinforced to withstand the power created by its
own devasting bite. Its skull was long, wide, and flat, much like those of today’s crocodilians.
The Boar Croc had a total of three pairs of very large teeth, with the pair on the bottom being
responsible for its boar-like appearance. Compared to crocodilian teeth, these were not only larger
but straighter and sharper. Kaprosuchus also had smaller teeth, a few of which were still
noticeably larger than the rest. One pair even looked like a second, smaller set of tusks. All
of the teeth are compressed on one side, with the smooth side facing where the tongue would have
been. Although Kaprosuchus’s teeth are its most famous feature, they are far from its only strange
trait. Its skull also has a pair of horn-like structures, which are formed from its squamosal
and parietal bones. Some modern crocodiles also have smaller horns formed from the squamosal bone,
which the extinct crocodile Voay robustus took too an extreme. Unlike these species, the Boar
Croc’s horns face the front rather than the side. In life they may have been covered in keratin,
making them even larger. While Kaprosuchus’s snout is long and flat like most crocodilians,
the end of its snout is elevated. The bone is also heavily vascularized and has a wrinkled texture.
All of these traits suggest that Kaprosuchus’s snout ended in a keratin shield. In the paper
it was named in, it was hypothesized that the Boar Croc used this keratin shield to ram into its prey
to stun them. Another possible use of this armored snout was as a weapon in contests between rivals.
It may have instead been used to support some sort of display structure to attract mates,
perhaps in conjunction with its horns. While Kaprosuchus is only known from its skull, during
the initial description, the authors, including the famous paleontologist Dr. Paul Sereno,
considered it to have been a terrestrial animal. Ever since, this has been the most common way
it has been portrayed. The evidence cited for a land-bound Boar Croc includes its orbits.
Crocodilian eyes are positioned so that they can see their prey while keeping most of their bodies
underwater. Kaprosuchus’s eyes were instead directed more towards the side, which would
have made it difficult to both keep a low profile and to see prey approaching from the shore. Its
horns would have also poked out of the water. In contrast, the horns of Voay faced the sides,
making them less noticeable than Kaprosuchus’s horns, and even it is also suspected to have spent
a lot more time on land than most crocodilians due to its robust limbs. The elevated snout
would have also risked giving the Boar Croc away in the water. Of course, today’s male gharials
have nasal bosses on the same part of their snouts which are even more noticeable, but they primary
hunt fish rather than ambushing terrestrial prey. Additionally, assuming it was a tool for hunting,
the Boar Croc’s ram-like snout would have been a lot more effective on land than in the water.
Finally, Kaprosuchus has been argued to have been primarily terrestrial because its teeth,
large and small, differ substantially from the subconical teeth of crocodilians.
However, as some of the art in this video implies, there are also arguments in favor of an amphibious
Kaprosuchus. Despite the differences between the skulls of modern crocodilians and the Boar Croc,
they still had many features in common. Like crocodilians and most other semi-aquatic
crocodylomorphs, Kaprosuchus’s skull is flat, which would have reduced the drag it produced
while in the water. In contrast, the skulls of most land crocs were generally deep.
If the Boar Croc wasn’t aquatic, it seems it at least had a recent ancestor who was. Also
unlike most terrestrial crocodylomorphs but like crocodilians, Kaprosuchus’s nostrils were on the
top of it snout. Modern crocodilians use their similar nostrils to breath
while keeping most of their bodies submerged. On the other hand, it has been argued that
Kaprosuchus’s crocodile-like nostrils were instead a consequence of it evolving
its ram-like snout. Furthermore, while Kaprosuchus’s teeth are different from those
of amphibious crocodiles, they are also different from the teeth of most predatory land crocs.
Their teeth were usually ziphodont, meaning they were laterally compressed, recurved, and serrated.
Therefore, the Boar Croc’s teeth lack an apparent ecological equivalent. Due
to the mixed signals present in its skull, Kaprosuchus may have been semi-terrestrial,
spending more time on land than most crocodilians but still spending a substantial amount of time in
the water. Another possibility is that Kaprosuchus did spend most of its time in the water but,
unlike most other semi-aquatic crocodylomorphs, it didn’t live as a crocodile analogue.
Until a postcranial Kaprosuchus skeleton is found, how much time the Boar Croc spent on land
remains speculation. When Kaprosuchus was first found, it was thought to be a member of Neosuchia.
This is the same branch of Crocodylomorpha as crocodilians. Like them,
most other neosuchians were amphibious, although some neosuchians like the planocraniids did revert
to a fully terrestrial existence. While this would still seemingly make an amphibious Boar Croc
the default assumption, Kaprosuchus is now placed as part of the clade Notosuchia. Most notosuchians
were fully terrestrial, which would seemingly make a terrestrial Kaprosuchus the default assumption.
However, Kaprosuchus’s closet relative was Mahajangasuchus, who was ironically semi-aquatic,
if still more competent on land than crocodilians. Furthermore, they belonged to a clade within
Notosuchia which included other species who had also become semi-aquatic independently
of the neosuchians. On the other hand, the relationships within this branch are poorly
resolved, and some of them, like Uberabasuchus, were fully terrestrial. Even Mahajangasuchus
lived sixty-six million years ago in Madagascar, about thirty million years after Kaprosuchus.
For context, in the same span of time the tyrannosauroids evolved from small predators
to the gigantic Tyrannosaurus rex. Therefore, the Boar Croc still lacks any particularly close
relatives, which makes this perplexing crocodylomorph all the more mysterious. Overall,
whether it spent more time on land or in the water, Kaprosuchus was one of the strangest
reptiles to ever evolve. Not only were its teeth unlike anything else in Crocodylomorpha,
but it also had horns and possibly even an armored snout reinforced for ramming.
Hopefully, a complete skeleton of the Boar Croc will be discovered
soon so many of the mysteries surrounding it can be solved. Thank you for watching.
I hope you learned something interesting. If you enjoyed this video, please remember to hit the
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