''Polazzodus'' is an extinct pycnodontid from the late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

(early

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. The ...

) of the Polazzo locality of northeastern

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

. The paleoenvironment of Polazzo was a large marine carbonate platform and shallow internal lagoons formed from rudist

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

s. ''P. coronatus'' is known from numerous specimens, many of which were very well-preserved. The new genus ''Polazzodus'' was erected based on a number of autapomorphies that distinguished it from similar pycnodontid fish. These include a second dorsal ridge scale (from which the Latin species name, ''coronatus'', is derived), presence of olfactory fenestra on premaxilla, posterodorsal process on cleithrum, and several others. The largest measured recovered specimen was 97 mm (3.8 in), and the smallest was 30 mm (1.2 in), which represented a subadult specimen. ''Polazzodus'', being a low-bodied pycnodont, is most similar morphologically to ''

Pycnodus ''Pycnodus'' (from el, πυκνός , 'dense' and el, ὀδούς 'tooth') is an extinct genus of ray-finned fish ranging from the Jurassic to Eocene periods. As its name suggests, it is the type genus of Pycnodontiformes. The known whole ...

'' and ''Tergestrinia'', though its body shape is more oval than these genera.

References

Pycnodontiformes genera Fossil taxa described in 2010 {{paleo-rayfinned-fish-stub