Percomorpha

Percomorpha is a large clade of ray-finned fish with more than 17 000 known species that includes the tuna, seahorses, gobies, cichlids, flatfish, wrasse, perches, anglerfish, and pufferfish.

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 ca. 66 Ma 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.

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: