Hybodus was a once wildly successful prehistoric shark that became extinct hundreds of millions of years after it first evolved. The genus first appeared in the Late Permian, then went extinct in the Early-Mid Cretaceous - from 260-90 Million Years Ago (and it may have lived beyond that, possibly dying out entirely in the K-T Extinction 65.5 Million Years Ago, though as yet 90 Million Years Ago is the date of the last known specimens) It was about 2.5 metres long, making it a modest shark in size. This shark had a unique set of dorsal fin spines, but their purpose is unclear. It is speculated, that as giant marine reptiles terrorised the marine ecosystems throughout almost all of the time Hybodus existed, these may have actually been defensive counter measures against predation. The idea, is that if say a large Pliosaur such as Liopleurodon attacked Hybodus and actually managed to catch the nifty shark, then even though the chances of survival would always be slim what with the devastating array of interlocking teeth clamping down with great force, there could be the chance that if simply swallowed whole, the backwards pointing spines would spear the roof of the mouth of the attacker. Regurgitation would perhaps be the salvation of the Hybodus victim, though of course the shark would be injured, at least it would be alive.Cruel Sea. It was drawn by the smell of blood to an Ophthalmosaurus in labour. It also hunted a male Ophthalmosaurus pup. When the pup needed to go up to breathe, it just escaped the shark, before hiding once again in the coral.
SpecialsHybodus appeared again in Sea Monsters. It was seen alongside Liopleurodon, feeding on Leedsichthys, in The Second Most Dangerous Sea. It wasn't dangerous due to the shark though - the main hazard was Liopleurodon. Unlike in Walking with Dinosaurs, the species is identified by Nigel Marven in the episode.
- In Nigel's timeline, the Hybodus on the Jurassic line doesn't have its original version, but its version on the timeline resembles Physogaleus (you can see that it doesn't have horns and a large dorsal fin) however this may be a female which may resemble modern sharks.