Sharks have been around for a long time – about 420 million years, in fact. Today, we have around 470 species of shark roaming the waters, but there used to be many, many more and some of them were bizarre, astonishing or downright weird.
Might as well start off with the “daddy” of all extinct shark species. When he’s not talked about in documentaries, he’s featured in B-grade horror movies. Why? Because he’s the biggest shark that ever lived. In terms of appearance, he is considered to be somewhat similar to the Great White, although the two are not related. In terms of size, though, he even makes the massive whale shark appear tiny in comparison. There is still ongoing debate regarding how big Megalodon actually was, although current estimates place him at around 50 ft (16 m) in length and 60 metric tons in weight. Megalodon went extinct around 2 million years ago (despite what Discovery thinks).
Cladoselache was one of the earliest species of shark that appeared in the Devonian period somewhere between 380 and 420 million years ago. With that in mind, it really didn’t look like our idea of a modern shark, especially the head which was more reminiscent of an eel. Despite this, Cladoselache was an agile and efficient predator, although its relatively small size of 4 ft (1.2 m) meant that he wasn’t an apex predator. Despite being such an ancient species, we have been able to learn a lot about Cladoselache and ancient sharks as a whole thanks to some incredibly well-preserved fossils that even contained trace amounts of tissue, muscle and organs.
We have in our heads an image of sharks as always being ferocious, large predators, but not all species were like that. In fact, Falcatus was very, very tiny – about 10 inches (25 cm) in length. Even so, its size is not its most distinguishing feature, but rather a fin spine located on top of its head and curved in front. This unique look is also what earned Falcatus its nickname – the unicorn shark. It lived sometime in the Carboniferous period which came right after the end of the Devonian about 360 million years ago.
Stethacanthus was a shark that lived around the same time as Falcatus during the early Carboniferous period. Also like Falcatus, it wasn’t a very large shark as it grew to about 7 feet (2 m) in length. It had a unique and very prominent feature which still ranks him as one of the most bizarre species of shark that ever existed – it had a dorsal fin shaped like an anvil (some would say an ironing board). The top of the anvil was covered in small spikes which were also displayed prominently on the shark’s head. This bizarre appearance was unique to the males as the females had a much more traditional appearance.
Edestus is a genus of shark that is comprised out of several species about which we know very little. The only remains we have ever found were their teeth but, in a way, this is a good thing as the teeth are what make these species unique. Like some other entries on this list, Edestus had very bizarrely shaped teeth that grew in curved brackets. Unlike modern sharks, they didn’t have multiple rows of teeth that were constantly changing, but rather one single row. It was also active during the Carboniferous period around 300 million years ago. The largest species of this shark named Edestus giganteus has been identified from a single set of teeth and is comparable in size to the great white.
Right off the top, let’s specify that we know very little about Listracanthus other than the fact that it had some remarkable scales which were more like spines in appearance – they were several inches long and had smaller secondary spines coming out of the sides. In that sense, they looked more like feathers than actual scales. Although we have discovered the scales and know that Listracanthus was active during the Carboniferous period and disappeared sometime during the late Triassic, we don’t really know anything else about the species. We don’t know how big it was or even if the spines covered its entire body. The illustration makes it out to be somewhat similar to the modern frill shark.
Another shark with a very bizarre look, Scapanorhynchus is characterized by a very long and flat snout. It lived during the Cretaceous period between 140 and 66 million years ago and its distinct look made it very similar to the modern goblin shark. In fact, the similarity was strong enough to make certain experts consider whether the two species are related or distinct genera. There is also quite a size difference to take into account – while the goblin shark reaches about 10 ft (3 m) in length, average estimates of Scapanorhynchus didn’t get longer than 25 inches (65 cm).
We have quite a fascination with massive sharks like the great white and Megalodon. This makes it all the more surprising that Otodus isn’t more well-known. It lived around 60 to 45 million years ago during the Paleocene and Eocene epochs. Fossil evidence suggests that the Carcharocles genus might have evolved from Otodus (and this includes Megalodon). In terms of size, Otodus was huge, but not quite matching Megalodon – somewhere between 30 ft (9 m) to 40 ft (12 m). It still would have been much larger than the great white and similar in size to the whale shark.
Xenacanthus was one of the most successful species of shark. It stuck around for about 150 million years between the Devonian and Triassic periods and was found throughout most of the world’s oceans. Despite this, it wasn’t very big – about 40 inches (1 m) in length and, more importantly, it hardly looked like a shark. Xenacanthus’ morphology is much more similar to that of an eel than a shark. It had a long, thin body and a dorsal fin that ran down the length of it and eventually joined with another fin underneath the body. It also had a long, sharp spine rising from its head which lead experts to suggest that it might have been venomous, similar to a stingray.
Helicoprion is, arguably, the most well-known and definitely the most bizarre member of the extinct Agassizodontidae shark family. All of the members were characterized by very weird teeth, usually in the form of a whorl. Helicoprion had a tooth whorl in the form of a spiral, but only on its lower jaw. There is still plenty of ongoing debate regarding the exact position of the tooth whorl. It used to be that the whorl was placed right at the tip of the mouth, but now experts suggest that it was actually located inside the mouth towards the end of the jaw. Despite its bizarre look, Helicoprion was a highly successful predator. It appeared about 310 million years ago during the Carboniferous period and lasted for roughly 60 million years, even surviving the Permian-Triassic extinction event (The Great Dying).