Since January 2025, this incredible ichthyosaur has been on display in the Charmouth Heritage Coast Centre for all to discover the story of its unique and special preservation. Not only is this ichthyosaur preserved in astonishing detail and in 3D, but palaeontologists can piece together what happened to it after death.
Named “Gonzo”, this fossil was found by local collector Chris Moore in February, 2024. Chris has loaned Gonzo to the Centre after spending over 600 hours preparing it with Alex Moore. During this time they’ve revealed some amazing features of this specimen.
Float and Bloat
Following Gonzo’s death, approximately 195 million years ago in the Jurassic, it experienced what is known as “float and bloat”. In marine animals gases produced by decay can cause animals to float in the water column for some time after death. This floating carcass provided an open invitation to various scavengers swimming in the Jurassic seas.
New Toothy Scavengers
During preparation, Chris noticed several teeth around Gonzo’s body. These teeth weren’t from an ichthyosaur, but a small shark. They have likely become lodged in its body as the shark was feeding. Sharks shed their teeth throughout life, continually replacing them with new ones.
Close inspection of the shark teeth reveal them to be from a new species of hexanchiform (six-gilled shark), also known as a cow shark. This find is the earliest known evidence of this kind of shark in the fossil record.
Tiny Giants
Elsewhere on the body, like around the left paddle, Chris found numerous small crustaceans known as ostracods, which can still be found in today’s oceans. These ostracods are thought to be scavengers, feeding upon the floating body. Chris thinks they’re also possibly feeding upon the internal organs of the ichthyosaur too, it may require CT scanning to completely reveal these fossils.
Most species are very small creatures, only measuring about 1 millimetre, but the ones on Gonzo are giants measuring over 1 centimetre.
Plummeting Headfirst
Eventually, the gases keeping Gonzo afloat escaped the body, causing it to sink. Ichthyosaurs have a very streamlined body which means that when they die, they very often nosedive to the seafloor. The broken snout of Gonzo show it likely did the same, crashing into the soupy sediments below. This provided the ideal conditions to preserve the buried front-half of the ichthyosaur, even allowing it to be preserved 3-dimensionally with skin and musculature. These kinds of soft tissue are extremely rare in the fossil record and are scientifically important.
The exposed back-half of Gonzo wasn’t buried in the sediments, exposed to the currents and scavengers on the sea floor. As such, it hasn’t been preserved like the rest of the animal. Only a few vertebrae were left, scattered around the rest of the creature.