Kaprosuchus: Beast of the Week

This week we shall be looking at a totally unique crocodilian.  Enter Kaprosuchus saharicus!

Kaprosuchus was a prehistoric crocodilian, related to today's alligators and crocodiles, that lived in what is now Niger, Africa, during the Cretaceous period, about 95 million years ago.  Sadly it is only known from one skull, and therefore size estimates for its entire snout-to-tail length vary from anywhere between ten to twenty feet depending on who you ask.  I suppose it depends on how proportionally this beast's head was.  When alive, Kaprosuchus almost certainly ate meat, judging by its teeth, which were enormous and sharp.  Four of these teeth that grew from the lower jaw were so long, in fact, that when Kaprosuchus' mouth was closed, would have stuck out above the top of the snout.  This is how Kaprosuchus earned its genus name, which translates to "boar crocodile" because of the tusk-like appearance of these teeth. 

Life reconstruction of a Kaprosuchus with her nest, by Christopher DiPiazza.  Sadly no fossil eggs or nests from this creature have been found yet.

Kaprosuchus became very popular in the grand scheme of things after it was discovered and published.  A few toy companies made figures of it, it was featured on an episode of the BBC show, Primeval, it even appeared in several electronic games, including the latest Jurassic World game.  When a new fossil creature is discovered, this rarely happens.  It is hard to carve out a niche in popular culture next to Tyrannosaurus, Triceratops, and Velociraptor.  Kaprosuchus was able to do this because it just looks so different.  Not only that but its unique look is also intimidating.  This crocodile has four pairs of super long teeth that extend beyond the snout when the mouth was closed!  How could you not showcase that? 

But what were the teeth actually for?  What is interesting is that Kaprosuchus' teeth were actually pretty different from those of other crocodilians not just in length, but in structure, too.  Kaprosuchus' teeth, especially the longest ones had an edge to them, like blades.  This means that they would have been better at cutting meat, rather than grabbing and holding onto prey, like the teeth are in most of its relatives, which are more cone-shaped, with a round cross-section.  At the same time, however, Kaprosuchus'skull still shows us that it still could have delivered a devastating bite, since the bones surrounding the nostril hole were fused together, forming a structure that could handle pressure better. Kaprosuchus' jaws show us that it could have opened its mouth extremely wide in life, even ensuring that those long teeth totally clear each other, to not get in the way when biting things.  In addition to weapons, I have to wonder if the extremely long teeth on this beast could also have been used for display within the species.  Sadly we only have one skull so far, but I can't help but wonder if the teeth were different sizes in males and females.  Modern male crocodilians are typically larger than the females.  Perhaps Kaprosuchus was similar in a way?  We may never know. 

Kaprosuchus skull.  Note how four (almost five) pairs of teeth extend past the snout when the jaws are closed.  Photo by Carol Abraczinskas originally used for Sereno PC, Larsson HCE (2009)

Kaprosuchus also had eye sockets that were close together, but faced more forward and outward than what we see in modern crocodilians, who's eye sockets face above the skull, so the animal can see while mostly submerged in water.  This has led many to speculate that Kaprosuchus spend more time on land than what we typically see in other crocodilians from that time.  However, the eyes were at about the same level, if not a bit higher than where the nostrils were.  Also, the nostril hole does face upward, like in aquatic crocodilians.  I have heard some who defend the terrestrial hypothesis say that this was an adaptation that left the front of the snout solid to be used as a ramming weapon, but again, modern crocodilians ram too while still being mostly aquatic.  Kaprosuchus may have spent more time out of the water than say a modern alligator or crocodile, but personally, I am not completely sold on the fully terrestrial idea for this animal.  Maybe one day if someone discovers the body of this beast, the placement and length of the legs will tell us more clues as to how it lived!

That is all for this week.  As always feel free to comment below or on the facebook page!

References

Sereno, Paul; Larsson, Hans; Larsson, Paul Sereno, Hans (2009). "Cretaceous Crocodyliforms from the Sahara". ZooKeys. 28: 1–143.