Eomesodon

Eomesodon (Greek for "dawn Mesodon", Mesodon being a now-disused pycnodont genus) is an extinct genus of prehistoric marine pycnodont fish.^[1][2]

Eomesodon Temporal range: Early Jurassic PreꞒ Ꞓ O S D C P T J K Pg N ↓ Potential Late Triassic, Middle Jurassic, and Early Cretaceous records
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	†Pycnodontiformes
Genus:	†Eomesodon Woodward, 1918
Type species
†Pycnodus liassicus Egerton, 1854
Other species
?See text

It contains only a single definitive species, E. liassicus (Egerton, 1854) from the Early Jurassic (Hettangian to Sinemurian) of England (Lower Lias), France, and Belgium (Marnes de Jamoigne Formation). The specimen from England is known from a nearly complete skeleton.^[2][3] E. liassicus is the only known species of pycnodont known from the earliest Jurassic Europe following the Triassic-Jurassic extinction event, and the group does not see further diversification in Europe until the Toarcian.^[4]

In addition to E. liassicus, several other disputed species are known from earlier (Late Triassic) and much later (up to the earliest Cretaceous). However, the status of these species and their placement within Eomesodon is disputed, and later studies refer to them as "Eomesodon". If the Triassic species actually did belong to this genus, then Eomesodon would be the only pycnodont known from both sides of the Triassic-Jurassic boundary.

The following disputed species are known:^[5]

• "E." barnesi (Woodward, 1906) - latest Jurassic (Tithonian)/earliest Cretaceous (Berriasian) of England (Purbeck Group). Nearly complete specimen known.
• "E." depressus Woodward, 1916 - Tithonian/Berriasian of England (Purbeck Group)

• "E." hoeferi (Gorjanovic-Kramberger, 1905) - Late Triassic (middle Norian) of Austria (Seefelder Formation). Many small, complete specimens known.^[6][7]
• "E." granulatus (Münster, 1846) - Oxfordian (Corallian Group) to Kimmeridgian of England and potentially France
• "E." rugulosus (Agassiz, 1839) - middle Jurassic (Bathonian) of England (Taynton Limestone Formation) and France (Great Oolite Group)

Some studies have found it to be potentially related to the Triassic genus Brembodus, while others have found it to be more basal.^[8]

See also

• Paleontology portal
• Fish portal

• Prehistoric fish
• List of prehistoric bony fish