Fossil Finder Database 2022
Cut and polished ammonite Several stages of crystallisation preserved this ammonite shell. Pyrite (fool’s gold) crystallised and replaced the shell and chamber walls, then, calcite crystals grew within the centre of each chamber. The iron pyrites form because, at times, the sea bed became poisonous and stagnant. Without the presence of oxygen, iron and sulphur…
The largest ammonite in our collection! This specimen is identified as Glaucolithies, but most people know the giant ammonites from Portland as Titanites. What’s the difference? They both have different shell profiles and ribbing. It’s hard to imagine such a huge ammonite scooting around in the sea.
Spines and ribs This is probably the most distinctive of the often highly-eccentric ammonites from the Lower Chalk. The image is two views of the same ammonite, showing how the ribs extend right across the keel (the edge of the ammonite). There are several similar forms of ammonite in the Lower Chalk and they can…
Not what it appears to be This is an ammonite, not a snail! Ammonites from the Lower Chalk are very distinctive and evolved into a range of bizarre forms. In this case, rather than developing as a flat spiral like nearly all other ammonites, it coiled into a spire, like a snail. It is thought…
Spot the difference! The identification of ammonites requires a very detailed study of their shape and form. This species, Androgynoceras wrighti, is subtly different from the much more common Androgynoceras lataecosta (also pictured). On A. wrighti there are double tubercles or spines along each rib, whereas the ribbing of A. lataecosta is smooth and even. If you find an…
Not what it appears to be Despite its appearance, this is an ammonite not a snail. Look very closely at the small break in the shell and you’ll see the suture line, made where the internal chambered shell meets the outside of the shell. Ammonites from the Lower Chalk are very distinctive and developed into…
The ancestral ammonite This humble crushed ammonite, Psiloceras is the oldest ammonite, regarded as the common ancestor to the ammonites found in the Jurassic and Cretaceous rocks of the Jurassic Coast. It is also a survivor from an older type of ammonite (‘ammonoid’ to be more precise) known as a Ceratite and these lived during…
A living fossil Unlike ammonites, nautili did not become extinct at the end of the Cretaceous period. Studying modern nautili helps us to understand ammonites. They move using water jet propulsion, and regulate their buoyancy with gas and water in their shell chambers.
A rare treasure This tiny specimen is extremely rare. It’s the top jaw and skull of a flying reptile, Dimorphodon, one of only four known specimens. They’ve been found no-where else except Lyme Regis. Mary Anning found a near-complete specimen in 1828 and at the time it was the first UK discovery of a flying…