10. ANOMALOCARIS (~ 525 Ma)
This one metre long invertebrate surely deserves to be included on the list, being one of the first complex oceanic predators to ever have existed. Anomalocaris stalked the Cambrian oceans, viewing the world with a deadly new evolutionary innovation - eyes. Complex eyes allowed this creature to storm its way to the top of the food chain, and with powerful appendages covered in spines it had no trouble devouring prey with tough carapaces. Whilst Anomalocaris is dwarfed by the other contenders on this list, it was still over 10 times larger than any other animal of its time.

9. KRONOSAURUS (125-99 Ma)
Kronosaurus, a Cretaceous mosasaur, is named after the Greek titan, Cronus. Its name is well deserved as this ancient beast was a remarkably powerful being. Kronosaurus could reach up to 10 metres long and had a mouth full of sharp, conical teeth. Unlike most other mosasaurs its tail was relatively short, however, evidence shows that Kronosaurus has immensely powerful fins and a pectoral girdle making it an impressive swimmer and hunter.

8. HELICOPRION (290-250 Ma)
Helicoprion has astounded scientists since its discovery over 100 years ago. It is iconic for its bizarre spiral of teeth, there are still debates on where exactly these teeth where on the shark with proposals stating they were inside the mouth, on the tip of the tail, the dorsal fin or hanging under the jaw. The most commonly accepted location of the teeth is inside the lower jaw enabling Helicoprion to cleanly slice its prey into pieces.

7. XIPHACTINUS (~110-70 Ma)
Xiphactinus was an extraordinary fish that lived during the Cretaceous. It was an esteemed predator that could reach an incredible 6 metres in length and specimens are renowned for their stunning preservation. One such example was 4 metres long and found with another exceptionally well preserved fish just short of 2 metres inside it implying that this particular Xiphactinus individual died shortly after its last feast. Xiphactinus had immensely sharp, slim teeth and an unmistakable underbite which was a possible aid when snaring creatures from below.

6. TYLOSAURUS (86-75 Ma)
Tylosaurus is considered a mosasaur and was a vivacious predator all be it smaller than its relative Mosasaurus. Tylosaurus could reach up to 15 metres in length and was one of the apex predators of its day. Fossilised stomach contents of Tylosaurus contain fish, sharks, turtles and other marine reptiles. Despite having an impressive set of teeth, the frontal areas of the jaws exhibit a large reduction in tooth size as well as a more heavily reinforced snout in comparison to other mosasaurs suggesting that Tylosaurus may have rammed into victims with immense force damaging prey internally.

5. MOSASAURUS (70-66 Ma)
The mosasaurs ruled the Cretaceous oceans and Mosasaurus was no exception. It could reach up to 17 metres long, longer than most other mosasaurs. Mosasaurus had a strong jaw packed with numerous conical teeth, bite marks of which have been found in huge prehistoric turtles and ammonites suggesting that Mosasaurus was a formidable hunter capable of catching large prey. Mosasaurus was a profound swimmer with strong paddle-like limbs and a huge tail capable of rapidly accelerating the animal when required.

4. DUNKLEOSTEUS (382-358 Ma)
Dunkleosteus terrorised the oceans around 370 million years ago and was part of a dynasty known as the placoderm fish (meaning armoured). Dunkleosteus could reach a whopping 6-10 metres in length and probably weighed over a ton. The skull was made up of huge, solid bony plates giving unrivalled protection allowing them to dominate the oceans. Placoderm fish were some of the first organisms to have a mobile jaw, as can be seen in Dunkleosteus’ impressive shearing plates which were used to slice cleanly through prey. Despite an revolutionary jaw, Dunkleosteus could not chew and several fossilised regurgitated remains of its meals have been found that the giant fish simply could not stomach.  

3. DAKOSAURUS (157-137 Ma)
Dakosaurus was the largest of a group of marine reptiles that were distant relatives of crocodiles. Dakosaurus could reach up to 5 metres long and had a streamlined body with large paddle-like fins and a long muscular tail implying that is was a very efficient swimmer. The diet of Dakosaurus consisted mostly of fish. The teeth of Dakosaurus are lateromedially compressed and serrated which is a similar morphology to modern killer whales indicating that Dakosaurus was an apex predator of the Jurassic oceans. Skull fenestrae provides evidence that Dakosaurus had very large adductor muscles (which are responsible for the jaw closing) and so it was certainly capable of a forceful bite.

2. LIOPLEURODON (160-155 Ma)
Liopleurodon stormed the Jurassic oceans, its huge 7 metre long frame effortlessly cruised through the water. The skull itself could reach a massive 1.5 metres long with a jaw that was packed with teeth up to 10cm long and was capable of an immense bone-crushing force. Liopleurodon was a remarkable hunter with the ability to swim with its nostrils open and so could use its powerful sense of smell to track prey from afar, much like sharks do. Liopleurodon most likely had good camouflage such as a lighter underside and a darker topside so it would blend in with the water to prey above and below.  

1. MEGALODON (~16-2.6 Ma)
Megalodon rightfully deserves the top position of the greatest prehistoric ocean predators, ruling the seas for an incredible 14 million years. Megalodon has been estimated to reach up to 18 metres in length and weighing over 40 tonnes. Megalodon is known for its huge 6 inch teeth which were serrated on both sides for an efficient slicing action. Fossils of Megalodon’s prey have also been found, the shark appeared to have adapted its hunting tactics for different sized prey; for smaller prey they would just use their bone crushing bite to pulverise internal organs, but for larger prey they would bite or rip flippers off of creatures to immobilise them and then go in for the kill.
The exact bite force of Megalodon has been estimated at around 110,000 N which was more than enough to shatter even the most robust bones. The hunting methods of Megalodon will unfortunately remain a mystery but it was been hypothesised that they swam at great depths and used short bursts of speed to swim up and tear into their preys vulnerable underbelly.
Sharks have existed for over 420 million years and still continue to be some of the most successful predators alive, Megalodon is a perfect example of how deadly they can be.

The Helicoprion was a prehistoric genus of shark with an utterly terrifying lower jaw, which displayed a “wheel” of teeth that could apparently spin and pulverize it’s prey completely. Fossils show that they grew to up to 7 meters in length and were one of the deep sea’s most ferocious predators. Some marine biologists have made the far-fetched claim that a species of Helicoprion may still exist, and is lurking on the ocean floor somewhere, just waiting for it’s next victim.


“Spiral saw”
Early Permian-Early Triassic, 290-250 million years ago

This ancient shark relative went extinct in the early Triassic, just as dinosaurs were rising to prominence. As with many cartilaginous fish, most of their bodies didn’t fossilize, but they did leave behind their trademark “tooth whorls.” Helicoprion has been reconstructed in several… “inventive” ways over the years, but now I’m assaulted by visions of all the horrific ways a buzzsaw-jawed shark could eviscerate me and I’m super regretful that I made fun of it and oh my god you guys oh god.

ixa193  asked:

Has there been any "discourse" on the identification of Eugenodonts? Because, I mean- they just look so impractical.

Before we talk about Eugeneodontida as a whole, let’s talk about their most famous member.

In 1899, the above fossil was discovered in the Ural Mountains of Russia, depicting a spiral-shaped whorl of teeth resembling a circular saw.  The teeth resembled those of a shark, but paleontologists were uncertain of how this tooth-whorl would operate, or how it would fit into the animal’s anatomy.  They named it Helicoprion (”spiral saw”), and began working on a century-long puzzle as to its true shape.

Hypotheses as to the animal’s true nature included:

  • The animal had an extended lower jaw shaped like a pizza cutter, used to “saw” flesh off of much larger prey.
  • The animal’s lower jaw was a coiled-up tentacle-like structure, capable of lashing out at prey like a whip.
  • The “saw” was located in the back of the animal’s throat.
  • The “teeth” were actually defensive spines located on one of the animal’s fins. 
  • The animal was actually more ray-like than shark-like, with a spiral-shaped tooth-lined throat used to grind up small prey.

It wasn’t until the discovery of a more completely preserved specimen of one of Helicoprion’s relatives that the true nature of the animal was revealed.  The “tooth-whorl” was actually a preserved growth ring; the large, exterior teeth would gradually be worn down and replaced by the smaller, still-growing inner teeth.  The top of this ring protruded at the front of the lower jaw.

The purpose of the “tooth-whorl” is still not entirely known.  It’s possible that it was used to snag soft-bodied animals, like jellyfish or cephalopods.  It might also have been used to slice small bits of flesh off of larger, slow-moving prey.

Helicoprion belonged to an order of cartilaginous fish called Eugeneodontida.  While originally thought of as sharks, more recent anatomical discoveries place them closer to Chimeridae, commonly known as chimeras, rabbitfish, or ratfish, a more obscure family of cartilaginous fish.

The eugeneodonts had a near-global distribution from the Early Carboniferous to the Late Triassic periods, with fossils known from Russia, Greenland, China, and the Americas.  They were united by the presence of “tooth-whorls”, but these whorls looked quite different from species to species.  

Parahelicoprion had sharp-edged, protruding teeth that may have been used to wound fast-moving prey.

Sarcoprion had a row of teeth on its snout running parallel to its tooth-whorl, said to have been used to snatch up small prey and grind them to death - something that strikes me as needlessly sensationalist.  I personally believe that it “ratcheted” small animals into its mouth with a series of rapid jaw movements, like the modern Nemichthydae.

One of the largest eugeneodonts was the Late Carboniferous species Edestus, which grew to the same size as a modern great white shark.  It lacked a tooth-whorl, instead possessing twin rows of teeth that have drawn frequent comparisons to pinking shears.  Like Helicoprion, only its teeth have been found, so much of its appearance is unknown; the shark-like reconstruction above is highly speculative.

The eugeneodonts are believed to have been the dominant marine predators during the Early Triassic, until the rise and diversification of the ichthyosaurs drove them to extinction.  Their living relatives have a worldwide distribution, including the deep-sea abyss, but have never been as well-known or popular as the other members of the class Chondrichthyes - the sharks, rays, skates, and sawfish.

Helicoprion and Nautiliods (WIP)

Layout and lighting for a piece I’m working on. Helicoprion was a prehistoric shark genus that existed from the late Carboniferous period (around 310 million years ago) and became extinct in the Late Triassic period (around 250 million years ago). They possessed a lower ’whorled-jaw’. It is believed that the odd jaw structure helped the shark remove the fleshy parts of the nautiliod from it’s shell.

External image

This is a fossil of the teeth located inside the Helicoprion’s ‘whorled-jaw’. The skeletons of sharks are made from cartilage, a substance that usually doesn’t survive the fossilization process. The shark’s teeth are often the only part preserved.

still messing around in my new sketchbook.  i realize that i never draw any monsters with their eyes closed, and i’ve found out why, they look so gosh darn happy when they’re closed.  what a jubilant shark fellow.  i’m guessing this is the type of creature that laughs at everything.

kinda based this guy’s bottom jaw off of one of the Helicoprion renditions that i think looks wonderfully goofy.
I might experimenting painting over this later.