Description
- Sutured Ammonites
- Species: Mix of Desmoceras sp and Cleoiceros sp
- Age: Cretaceous, 100 Million Years Old
- Source: Madagascar
- Size: Approx 30-50mm
- Quality will vary, one supplied, not exact one pictured.
Ammonites are probably the most recognisable fossils, known by many they are usually one of the first acquired when starting a collection due to their availability. Their familiar spiral shape shell is incredibly iconic and whilst it appears similar to a snail shell, these animals were not that closely related to snails. They were marine animals, present between 240 – 65 million years ago, that had a coiled segmented shell similar to what we see in the present day nautilus. Ammonites are molluscs that are most closely related to living Cephalopods, i.e. octopus, squid, and cuttlefish.
Madagascar is well known as a source for beautifully preserved ammonite fossils, the majority of which date back to the Cretaceous period. These marine cephalopods swam in the ancient Tethys Ocean, where they varied in size from a coin up to the size of a dustbin lid. Madagascan ammonites are highly sought after by paleontologists and fossil collectors due to their vibrant colouration and stunning patterns, as well as the way in which they are processed and polished.
These Sutured Ammonites are carefully polished in order to make the intricate ‘shell lines’ more visible; the correct name for these lines is sutures. These complex patterns of lines on the shell mark the intersection of the septa and the shell wall. They helped ammonites survive at deeper pressures by spreading water pressure across the shell’s surface, making each chamber stronger without increasing the weight of the shell. Suture patterns became more complex over time, from simple weaving lines in the earliest species to complex patterns in those found in the Triassic and Cretaceous. This increase in suture complexity over time has been used to classify and date ammonites and the rocks they were found in.
