Casea is a genus of herbivorous caseid synapsids that lived during the late Lower Permian (Kungurian) in what is now Texas, United States.

The genus is only represented by its type species, Casea broilii, named by Samuel Wendell Williston in 1910.

The first six teeth of the upper and lower jaws are very strong, conical, almost circular at their base, but more rounded at the apex, and somewhat compressed medio-laterally.

Those of the upper jaws are vertical, while the first six teeth of the mandible are directed outward and forward at an angle of forty degrees or more.

However, more careful preparation of the maxillary teeth of the specimen FMNH UC 1011 revealed the presence of tricuspid crowns.

[7] An incomplete skeleton of Casea broilii (FMNH UR 2514), from the type locality and only described in 2014, shows an astragalus still articulated with the tibia.

[7] All Casea broilii specimens come from a single fossiliferous pocket known as Cacops bone bed, located in Baylor County, Texas.

[10][8] This locality, discovered and excavated by Paul Miller in 1909 and 1910, is no longer accessible today because it was submerged in the 1920s after the construction of the Lake Kemp dam.

[10][8][7] Ammonoids faunas found in marine strata present at the base and top of the Clear Fork Group indicate that the three formations (Arroyo, Vale, and Choza) that compose it represent a relatively short geological duration corresponding to part of the Kungurian.

[14] The Casea specimens were in association with very numerous specimens of the armoured and entirely terrestrial amphibian Cacops (more than 50 individuals are listed including ten skulls, hence the name of the bone bed), a dozen skeletons of the Varanopidae Varanops, and fragments of Seymouria and Captorhinus.

In 1954, Everett C. Olson reported two new species found in the Clear Fork Group in Texas, Casea nicholsi and C.

[15] In 1974, Denise Sigoneau-Russell and Donald E. Russell established the species Casea rutena for a specimen from southern France.

[18] Eothyris parkeyi Oedaleops campi Oromycter dolesorum Casea broilii Trichasaurus texensis “Casea” rutena Ennatosaurus tecton Angelosaurus romeri Cotylorhynchus romeri Cotylorhynchus hancocki Cotylorhynchus bransoni A study published in 2015 by Romano & Nicosia, and including almost all the Caseidae (with the exception of Alierasaurus ronchii from Sardinia, considered too fragmentary), shows a similar position for Casea broilii.

[20] The locomotion of Casea involves a three-vertebra sacrum in early synapsids and no apparent link to body size.

LeBlanc and Reisz argue that this sacral anatomy was related to more efficient terrestrial locomotion than to increased weight bearing.

[7] Selective pressures for weight-bearing or more efficient locomotory styles and increasingly terrestrial lifestyles may have promoted the repeated acquisition of three sacral vertebrae in Synapsida.