period: Middle Jurassic – Bathonian (166.1-168.3 million years ago)
excavation site: Gnaszyn near Częstochowa (Kraków-Częstochowa Upland)
Ammonites are extinct organisms which belong to the most evolved group of mollusca – cephalopods. Ammonitida, to which Procerites belong, emerged at the turn of the Triassic and Jurassic periods. They used to live in loamy sediments, away from the marine coast. Ore-bearing loams containing iron, in clay pit of Gnaszyn brickfield, are abundant in fossils of this kind. The smallest ammonites measured about 1 cm, but the diameter of the largest specimens was up to 2 metres wide (the biggest specimen found in Poland measures 1.5 m). They became extinct due to the same reasons as dinosaurs – as a result of catastrophic environmental changes probably triggered by the hit of meteorite at the end of the Cretaceous.
The piece comes from the collection of Geological Museum of the National Geological Institute – National Research Institute.