Pycnodontiformes is an extinct order of bony fish. The group evolved during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America.
The pycnodontiforms were small to middle-sized fish, with laterally-compressed body and almost circular outline.
Pycnodontiform fishes lived mostly in shallow-water seas. They had special jaws with round and flattened teeth, well adapted to crush food items. One study links the dentine tubules in pycnodont teeth to comparable structures in the dermal denticles of early Paleozoic fish. Some species lived in rivers and possibly fed on molluscs and crustaceans.
Acrotemnus is an extinct genus of prehistoric ray-finned fish that lived during the Late Cretaceous epoch.Anomoeodus
Anomoeodus is an extinct genus of prehistoric ray-finned fish from the Albian to Maastrichtian of France, Belgium, the Netherlands, Egypt, Uzbekistan and the United States.Coccodontidae
Coccodontidae is a family of extinct pycnodontid fish that lived during the lower Cenomanian. The various genera had massive, curved spines.
The family is composed of five genera, the type genus, Coccodus, Paracoccodus which was split off from Coccodus, the newly described Corusichthys, the sexually dimorphic Hensodon, and Trewavasia. Ichthyoceros was, at one time, placed in Coccodontidae, but then was moved with Trewavasia in "Trewavasiidae," and then, in 2014, was placed in the related pycnodontid family Gladiopycnodontidae, while Trewavasia was returned to Coccodontidae.Coccodontidae, together with Gladiopycnodontidae and the superficially shrimpfish-like Gebrayelichthyidae, make up the pycnodontid superfamily Coccodontoidea.Coccodus
Coccodus is an extinct genus of extinct pycnodontid fish that lived during the lower Cenomanian. The various species had a pair of massive, curved spines emanating from the lower sides of the head, and one curved spine on the top of its head. Unlike most pycnodontids (which tend to have short, marine butterflyfish-like bodies), Coccodus species had a comparatively long body, giving the living animals a superficial resemblance to a scaly chimaera.
Coccodus is closely related to the similarly spined genera Trewavasia, Corusichthys, Paracoccodus, and Hensodon, which also lived during the Cenomanian of Lebanon.Corusichthys
Corusichthys megacephalus is an extinct pycnodontid that lived during the lower Cenomanian of what is now Lebanon. C. megacephalus is known from a 34 mm long fossil. It had plates arranged like a helmet around its head, and had a massive, triangular spine on its dorsal side. C. megacephalus is closely related the genera Trewavasia and Hensodon, as well as Coccodus.Eomesodon
Eomesodon is an extinct genus of prehistoric ray-finned fish. It lived during the Late Triassic and Jurassic.Grypodon
Grypodon is an extinct genus of prehistoric ray-finned fish that lived during the Late Cretaceous epoch.Gyrodus
Gyrodus is an extinct genus of pycnodontiform ray-finned fish that lived from the late Triassic (Rhaetian) to the middle Cretaceous (Cenomanian).Gyronchus
Gyronchus is an extinct genus of prehistoric ray-finned fish from the Jurassic.Ichthyoceros
Ichthyoceros spinosus is an extinct pycnodontid that lived during the lower Cenomanian of what is now Lebanon. I. spinosus had a triple, forward-pointing horn-like spine between its eyes, very similar to the single spine of Trewavasia, and a massive, multipointed spine emanating from the back of its head. It was originally placed in the family Coccodontidae, but then was transferred to "Trewavasiidae" with Trewavasia. Recently, it has been placed in Gladiopycnodontidae due to recent anatomical similarities with the various genera within that family, including Gladiopycnodus.Micropycnodon
Micropycnodon is an extinct genus of prehistoric ray-finned fish that lived during the Santonian.Nursallia
Nursallia is an extinct genus of pycnodontid ray-finned fishes, ranging from the Late Cretaceous period until its extinction during the Eocene.Polazzodus
Polazzodus is an extinct pycnodontid from the late Cretaceous (early Santonian) of the Polazzo locality of northeastern Italy. The paleoenvironment of Polazzo was a large marine carbonate platform and shallow internal lagoons formed from rudist reefs. P. coronatus is known from a large number of 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 and Tergestrinia, though its body shape is more oval than these genera.Proscinetes
Proscinetes is an extinct genus of prehistoric ray-finned fish from the Jurassic.Pycnodontidae
Pycnodontidae is an extinct family of ray-finned fishes, ranging from the Triassic period until the Eocene.Pycnodus
Pycnodus (from Greek for crowded teeth) 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 fossils of Pycnodus are around 12 centimetres (5 in) long, and have a superficial resemblance to angelfish or butterflyfish. The animals, as typical of all other pycnodontids, had many knob-like teeth, forming pavements in the jaws with which to break and crush hard food substances, probably mollusks and echinoderms. These teeth are the most common form of fossil.
Pycnodus fossils have been found in present-day India, Northern Africa, Belgium, England, and Italy, regions corresponding with the Tethys Ocean. A specimen of the prehistoric whale, Basilosaurus isis, was found in the Eocene-aged Wadi El Hitan with stomach contents of its last meals, including a large specimen of the species P. mokattamensis along with skeletons of a smaller whale called Dorudon.Stephanodus
Stephanodus is a genus of fossil fish that lived in the Mesozoic era. It was described by Zittel in 1883.Tibetodus
Tibetodus is an extinct genus of prehistoric ray-finned fish that lived during the Late Jurassic epoch.Trewavasia
Trewavasia carinata is an extinct pycnodontid that lived during the lower Cenomanian of what is now Lebanon. It had a large, forward-pointing horn-like spine between its eyes, and a massive stump-like spine emanating from the back of its head. T. carinata is closely related the genera Corusichthys and Hensodon, as well as Coccodus.