Fossil Finder Database 2022
Apiocrinites is one of the more unusual and distinctive crinoids from the Jurassic Coast. Unlike the Lower Jurassic Pentacrinites which has a star-shaped cross section, Apiocrinites is composed of a series of round disks that swell in size to form the calyx, the structure that houses the main body. The individual, scattered disks are more…
This crinoid, Marsupites, has a relatively large, bulbous body (the calyx) which might have been partly buried when the creature was alive, increasing its fossilisation chances. The long arms (not preserved here) extended into the water. Some sea cucumbers, another type of echinoderm, live in a very similar way today on the sandy sea bed of…
Often, the delicate test (shell) of the sea urchin is crushed, but some like this are beautifully preserved. You can clearly see the ‘knobbles’ where the spines were attached to the test, and the rows of tiny holes where flexible ‘tubed feet’ extended out.
Ammonite zones Many ammonite species evolved rapidly but only survived for about 250,000 years before evolving into something different. So rock layers can be dated based on the appearance and disappearance of different ammonites. These time periods are known as ammonite zones. This fossil, Quenstedoceras lamberti, defines the Lamberti Zone at the very top of the…
The specimen that defines a species This is a really significant specimen as it is a ‘holotype’, meaning it defines the species Reineckia duplex. If anyone wants to identify a similar find, they would need to come back to this specimen in order to make comparisons. The fossil is also unusual in that the mouth…
One weird specimen! This is one of the most extraordinary ammonites. It is clearly an ammonite because the broken edge on the left, next to the label, shows the chamber wall complete with folds that form the suture line. Ammonites from the Lower Chalk did all sorts of strange things, some are partially uncoiled and…
Ammonites with uneven coils like these are called heteromorph ammonites. Uncoiled Cretaceous ammonite shells have similar shapes to belemnite guards (the back of the shell). However, belemnite guards were inside the animals, whereas ammonite shells enclosed the animals’ bodies.
Uneven coils Ammonites with uneven coils like these are called heteromorph ammonites. The shells of this ammonite were coiled tightly when it was young and wider as it got older. Why? No-one is really sure but this must have had a profound impact on how the animal lived. It is thought that Scaphites probably floated in the…
This belemnite, Belemntella mucronata, is from chalk, the very highest and youngest rocks in the Jurassic Coast World Heritage Site. This specimen is not identified to species level, but geologists can sub-divide the rocks into fine time zones defined by the presence of certain fossils because the animals evolved or changed through time. Ammonites are the…