''Eocasea'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

caseid Caseidae are an Extinction, extinct Family (biology), family of Basal (phylogenetics), basal synapsids that lived from the Late Carboniferous to Middle Permian between about 300 and 265 million years ago. Fossils of these animals come from the so ...

synapsid Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...

s from the

Late Pennsylvanian The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, in the ICS geologic timescale, the younger of two subperiods (or upper of two subsystems) of the Carboniferous Period. It lasted from roughly . As with most oth ...

of Kansas. It is known from a single

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, ''Eocasea martini''.

Description

''Eocasea'' is the oldest and most basal member of Caseidae, lacking many of the specialized anatomical features that characterize later members of the group. Caseids are notable for being one of the first groups of

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct theraps ...

s to evolve

herbivory A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

; large-bodied taxa such as ''

Casea ''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 ...

'' and ''

Cotylorhynchus ''Cotylorhynchus'' is an Extinction, extinct genus of herbivorous Caseidae, caseid synapsids that lived during the late Cisuralian, Lower Permian (Kungurian) and possibly the early Guadalupian, Middle Permian (Roadian) in what is now Texas and Ok ...

'' have barrel-shaped rib cages and leaf-shaped, serrated teeth that are clear adaptations for breaking down plant

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

. ''Eocasea'' differs from these taxa in having a narrow rib cage, simple cone-shaped teeth, and a much smaller body size. All of these are

plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and ...

features for synapsids, meaning that ''Eocasea'' inherited a carnivorous lifestyle from similarly small-bodied carnivorous ancestors of synapsids. As the earliest known caseid, ''Eocasea'' represents one of the first transitions from carnivory to herbivory in tetrapods.

References

{{Taxonbar, from=Q16394898 Caseasaurs Prehistoric synapsid genera Carboniferous synapsids of North America Fossil taxa described in 2014 Carboniferous synapsids Paleontology in Kansas