Percomorpha


Percomorpha is an extremely large and diverse clade of ray-finned fish. With more than 17,000 known species known from both marine and freshwater ecosystems, it is the most speciose clade of extant vertebrates.

Evolution

Percomorpha are the most diverse group of teleost fish today. Teleosts, and percomorphs in particular, thrived during the Cenozoic era. Fossil evidence shows that there was a major increase in size and abundance of teleosts immediately after the mass extinction event at the Cretaceous-Paleogene boundary ago. The oldest known percomorph fossils are of the early tetraodontiforms Protriacanthus and Cretatriacanthidae from the Santonian to Campanian of Italy and Slovenia. A higher diversity of early percomorphs is also known from the Campanian of Nardò, Italy, and these also show some level of diversification into modern orders, with representatives of the Syngnathiformes and Tetraodontiformes known. Possibly the oldest percomorph is Plectocretacicus from the Cenomanian of Lebanon, which may be a stem-tetraodontiform; however, some morphological analyses indicate that it shows similarities with non-percomorph groups.
File:Evolution of ray-finned fish.png|500px|thumb|left|Evolution of ray-finned fishes, Actinopterygii, from the Devonian to the present as a spindle diagram. The width of the spindles are proportional to the number of families as a rough estimate of diversity. The diagram is based on Benton, M. J. Vertebrate Palaeontology, Blackwell, 3rd edition, Fig 7.13 on page 185.

Taxonomy

Many of the orders placed in Percomorpha today were originally placed in an expanded Perciformes, hence many sources often referring to that order as the most diverse vertebrate clade. However, more recent studies have found such a placement to be paraphyletic, and many have thus been moved to their orders within Percomorpha.
The Percomorpha are an extremely diverse group with at least 22 orders according to Eschmeyer's Catalog of Fishes. Other authorities find a different number of orders depending on the classification used.
The following taxonomy is based on Eschmeyer's Catalog of Fishes, with additional suborders based on other studies:

External relationships

The two cladograms below are based on Betancur-R et al., 2017. Percomorphs are a clade of teleost fishes. The first cladogram shows the interrelationships of percomorphs with other living groups of teleosts.

Internal relationships

The following cladogram shows the evolutionary relationships of the various groups of extant percomorph fishes: