Pycnodus

{{Short description|Extinct genus of fishes}}

{{Automatic taxobox

| image = Pycnodus platessus.jpg

| image_caption = Pycnodus apodus (=P. platessus)

| fossil_range = {{Fossil range|Ypresian|earliest=Kimmeridgian}}

Teeth assigned to Pycnodus date back to Kimmeridgian, see text

| taxon = Pycnodus

| authority = Agassiz, 1833

| type_species = Pycnodus apodus

| type_species_authority = Volta, 1796

| synonyms = Coryphaena apoda Volta, 1796

Zeus platessus Blainville, 1818

Pycnodus platessus Agassiz, 1833

Pycnodus gibbus Heckel, 1856

}}

Pycnodus (from {{langx|el|πυκνός}} {{Transliteration|el|puknós}}, 'dense' and {{langx|el|ὀδούς}} {{Transliteration|el|odoús}} 'tooth') is an extinct genus of ray-finned fish from the Eocene period.{{Cite journal |last=Poyato-Ariza |first=Francisco José |date=2013-02-01 |title=Sylvienodus, a new replacement genus for the Cretaceous pycnodontiform fish "Pycnodus" laveirensis |url=https://www.sciencedirect.com/science/article/pii/S1631068313000183 |journal=Comptes Rendus Palevol |language=en |volume=12 |issue=2 |pages=91–100 |doi=10.1016/j.crpv.2013.01.001 |bibcode=2013CRPal..12...91P |issn=1631-0683|url-access=subscription }} It is a wastebasket taxon, although many fossils from the Jurassic or Cretaceous are assigned to this genus, only the Eocene species, P. apodus is valid.{{Cite journal |last1=Cawley |first1=John Joseph |last2=Marramà |first2=Giuseppe |last3=Carnevale |first3=Giorgio |last4=Kriwet |first4=Jürgen |date=2018-05-18 |title=A quantitative approach to determine the taxonomic identity and ontogeny of the pycnodontiform fish Pycnodus (Neopterygii, Actinopterygii) from the Eocene of Bolca Lagerstätte, Italy |journal=PeerJ |language=en |volume=6 |pages=e4809 |doi=10.7717/peerj.4809 |pmid=29796348 |s2cid=43924767 |issn=2167-8359|pmc=5961631 |doi-access=free }} As its name suggests, it is the type genus of Pycnodontiformes.

File:Pycnodus bernardi.jpg bernardi, one example of pycnodont that was once assigned as Pycnodus{{Cite journal |last=Ebert |first=Martin |date=2013 |title=The Pycnodontidae (Actinopterygii) in the late Jurassic: 1) The genus Proscinetes GISTEL, 1848 in the Solnhofen Archipelago (Germany) and Cerin (France) |url=https://www.researchgate.net/publication/272886291 |journal=}}]]

The known whole fossils of Pycnodus are up to {{convert|30.6|cm|in|sigfig=1}} 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.

Valid species of Pycnodus is only known from Monte Bolca Lagerstätte in Italy, however fossils that were assigned to Pycnodus have been found in present-day India, North Africa, Belgium, England, regions corresponding with the Tethys Ocean.{{Cite journal|url=http://www.geosocindia.org/index.php/jgsi/article/view/68397|title=Pycnodus lametae (Pycnodontidae), a Holostean Fish from Freshwater Upper Cretaceous Lameta Formation of Maharashtra|journal=Geological Society of India|date=May 1996|volume=47|issue=5|pages=593–598|last1=Mohabey|first1=D. M.|last2=Udhoji|first2=S. G.}} 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.{{cite journal |last1=Voss |first1=Manja |last2=Antar |first2=Mohammed Sameh M. |last3=Zalmout |first3=Iyad S. |last4=Gingerich |first4=Philip D. |title=Stomach contents of the archaeocete Basilosaurus isis: Apex predator in oceans of the late Eocene |journal=PLOS ONE |volume=14 |issue=1 |page=e0209021 |year=2019 |doi=10.1371/journal.pone.0209021|pmc=6326415 |pmid=30625131 |bibcode=2019PLoSO..1409021V |doi-access=free }}