Capitanian in the context of Emeishan Traps

The Capitanian mass extinction, also known as the end-Guadalupian, Guadalupian-Lopingian, or pre-Lopingian extinction began around 262 million years ago with its most intense pulse peaking at 259 million years ago, marking the end of the Capitanian stage and Guadalupian (Middle Permian) epoch of the Permian. Historically conflated with the better-known Permian–Triassic extinction, it was only recognised as a distinct event in 1994. Despite this, the mass extinction is believed to be the third-largest of the Phanerozoic in terms of the percentage of genera (33-35%) and species (60-63%) lost after the end-Permian and Late Ordovician mass extinction, while being the fifth worst in terms of ecological severity. The global nature of the Capitanian mass extinction has been called into question by some palaeontologists as a result of some analyses finding it to have affected only low-latitude taxa in the Northern Hemisphere.

Varanopidae is an extinct family of amniotes known from the Late Carboniferous to Middle Permian that resembled monitor lizards (with the name of the group deriving from the monitor lizard genus Varanus) and may have filled a similar niche. Typically, they are considered to be relatively basal synapsids (and thus more closely related to mammals than to reptiles), although some studies from the late 2010s recovered them being taxonomically closer to diapsid reptiles, recent studies from the early 2020s support their traditional placement as synapsids on the basis of high degree of bone labyrinth ossification, maxillary canal morphology and phylogenetic analyses. A varanopid from the late Middle Permian Pristerognathus Assemblage Zone (Capitanian) is the youngest known varanopid and the last member of the "pelycosaur" group of synapsids. Thus, Varanopidae vanishes from the fossil record at the same time as dinocephalians, plausibly as a result of a major mass extinction event that has been called the "Dinocephalian extinction event".