The fossil-bearing locality of Polazzo is a Lagerstätte dating to the Santonian (Late Cretaceous), about 85 million years ago.

The site B (a site A excavated earlier occurs NNE), excavated every year since1996 (with a stop of one year for bureaucratical reasons), is situated on the SSE edge of the village of Polazzo. It consists of an outcrop of stratified limestone of limited extension belonging to the “calcari di Aurisina”. The strike is 290°, the average dip is 24°. From a lithological and sedimentological point of view, it is made mainly of thinly-laminated limestone, usually of a light colour (grey or greenish), with a tabular geometry and sets that were disturbed post-deposition by tectonics. Micro-breccia levels are also present. The kind of fossils preserved and their state of conservation indicate the presence of an environment favourable to the fossilization of organic remains that are usually destroyed by the taphonomic processes.

The excavated area covers about 50 square meters and its stratigraphic section is about 1 m thick. The section was divided into six main intervals (beds), and further divided into sub-intervals. The finds from the excavation total 1075 (in 2004). They comprise mainly skeletal remains of neopterygian bony fish mostly incomplete but very well preserved, and rarer plant remains (conifers). Among the Neopterygians, the Teleosts are dominant. Of particular importance are the specimens of the alepisauriform Rhynchodercetis (two specimens preserve their prey within their rib-cage), Beryciformes (basal Perciformes, of particular evolutionary interest), pycnodontiformes (basal Neopterygians), and several small teleosts possibly related to Cypriniformes. The tooth of a diapsid reptile, perhaps a small crocodyliform, was also found. All the specimens recovered are housed in the Museum in Via Valentinis, 134 at Monfalcone (Gorizia).