Jurassic Age!! 9.14cm Polished Ammonite Cross-section Fossil from Madagascar (160 million years)

SPECIES

Phylloceratida - Ptychophylloceras

This is a beautiful polished Jurassic aged ammonite cross-section fossil collected in the Tulear Province of Madagascar. Most of the cut and polished ammonites that you see from Madagascar are Cretaceous in age, but these with orange/yellow/pink coloration are Late Jurassic (Oxfordian Stage) in age, nearly 50 million years older. There are a number of species/genus of Phylloceratida ammonites from this location which look very similar, this one appears to be Ptychophylloceras.

The previously hollow chambers of the ammonite were replaced with a beautiful agate during the fossilization process. Some of these chambers are still partially hollow and lines with druzy crystals. The ammonite was cut in half and polished revealing the inner chamber structure of this ancient marine animal.

Ammonites were sea creatures (more specifically, molluscs) that look similar to today's squid and octopus. They had eyes, spiral shells and tenticles. The oldest ammonite fossils that we have are 240 million years old. The most recent ones are 65 million years old, suggesting that this was the period when they became extinct. Their fossils were found in many different countries. Ammonites are known for their beauty; their suture points create beautiful patterns. Ammonite females are believed to be larger than the males. It is also thought that ammonites had ten arms to grasp small prey such as fish. The largest ammonites that were ever found measure around 180cm.

Ammonites had a strong existence; they survived most major extinction events. With every extinction event, there were some ammonite species that came extinct and those that survived. The last ammonites got extinct in the same extinction event as the dinosaurs, approximately 65 million years ago. Some of the ammonite fossils have been found with triangular holes in them, believed that these were puncture holes created by mosasaurs (large marine reptiles that existed at that time).

History indicates that humans have always been fascinated by ammonites. In our times, the different species of ammonites that are found in the rocks, were and still are, a key to biostratigraphy (the study of different layers of rock and their age estimation). And definitely they are still much appreciated for their spectacular and beautiful features.