The first three specimens referred to Brasilodon quadrangularis were found at the Linha São Luiz site, a quarry near the town of Faxinal do Soturno in the state of Rio Grande do Sul.

The rocks where Brasilodon was found belong to the upper part of the Candelária Sequence of the Santa Maria Supersequence, corresponding to the traditional Caturrita Formation, which has been dated to the early Norian age of the Late Triassic.

[1][2][3] The holotype (UFRGS-PV-0611-T) consists of a well-preserved skull retaining both the left and right upper postcanine teeth, but missing the lower jaw.

[1][2] The genus Brasilodon was named in a 2003 paper by José F. Bonaparte, Agustín G. Martinelli, Cesar L. Schultz and Rogerio Rubert.

The generic name Brasilodon is derived from the country of Brazil where it was found, and from the Greek word odon, meaning "tooth".

[4] In 2010 a third brasilodontid species, Minicynodon maieri, was named by Bonaparte et al., based on a single well-preserved skull from Faxinal do Soturno.

This species was differentiated from Brasilodon by the firm attachment of the bones of the skull roof, and from Brasilitherium by the lack of a cusp b in the lower postcanines.

[5] Later studies have cast doubt on the validity of Brasilitherium and Minicynodon, proposing instead that they, along with Brasilodon, merely represent individual variation within a single species.

[7] It exhibited many mammal-like features, including a well-developed secondary palate, symmetrical tooth development, and a more derived ear anatomy than in earlier cynodonts.

[4] The front part of the roof of the mouth consisted of a well-developed secondary palate, formed by the maxillae and the palatine bones, which extended about as far back as the last postcanine.

The roots of the postcanines were not fully divided as they are in modern mammals, but they had a noticeable constriction in the middle, giving them an 8-shaped cross-section.

The shape of the base of the neural spine (a pointed extension on the top surface of the vertebra) indicates that it was elongated anteroposteriorly (in a front-to-back direction).

On the front surface of the humerus, there was a wide bicipital groove, bordered by the deltopectoral and teres crests, similar to that of many other Mesozoic cynodonts.

Conversely, there was no ectepicondylar foramen; this hole was found in most cynodonts more basal than Brasilodon, but missing in tritylodontids and most mammaliaforms.

The condyles were separated by a narrow groove, and lacked the trochlear (pulley-like) shape seen in many crown-group mammals, like therians or the stem-monotreme Kryoryctes.

The head of the radius (where it articulated with the humerus) was approximately circular, with a cup-shaped depression in the middle surrounded by a bulbous rim.

The distal end was somewhat curved posteromedially, which would have allowed the bone to cross over the front of the ulna, as in tritylodontids, Morganucodon and opossums.

The head was angled around 60 degrees medially (to the right) compared to the longitudinal axis of the femur, resembling the condition in multituberculates and spalacotheriids.

On the back side of the femur, between the greater and lesser trochanters, there was a deep and narrow depression called the intertrochanteric fossa.

There was a relatively shallow, triangular depression located distally to the intertrochanteric crest; this probably served as an attachment point for the hip adductor muscles.

There was a well-developed tuber calcis on the back end of the bone; this feature is found in most eucynodonts, but is missing in more basal taxa like Thrinaxodon.

[13] However, Protheriodon has more recently been found to be an early-diverging probainognathian unrelated to brasilodontids,[14] while Panchetocynodon is otherwise treated as an incertae sedis taxon, whose relationships to other taxa are unclear, due to its incompleteness.

The cladogram below is adapted from a 2019 analysis by Wallace et al.:[16] Probainognathus Prozostrodon Therioherpeton Pachygenelus Riograndia Pseudotherium Oligokyphus Kayentatherium Bienotherium Tritylodon Botucaraitherium Brasilitherium Brasilodon Sinoconodon Morganucodon Mammalia Features of the postcranium indicate that Brasilodon was a generalised animal capable of diverse modes of locomotion, including digging and climbing.

Evidence for scansorial (climbing) abilities includes the hemispherical humeral and femoral heads, which would have allowed a wide range of rotation of the shoulder and hip joints, the well-developed ectepicondylar crest, the hemispherical capitulum and nearly circular radial head, which would have conferred high mobility to the elbow, and the small anconeal process of the ulna.

Other specimens have been found at the Sesmaria do Pinhal locality in the municipality of Candelária; both of these locations lie within the Brazilian part of the Paraná Basin.

[18] The rocks where Brasilodon was found belong to the upper part of the Candelária Sequence, which corresponds to a biostratigraphic unit known as the Riograndia Assemblage Zone.

The Riograndia AZ has been dated to the early Norian age of the Late Triassic epoch,[3] around 225.42 million years ago.

[19] In addition to Brasilodon, cynodonts are represented by the tritheledontids Irajatherium and Riograndia, the basal mammaliamorph Botucaraitherium, and indeterminate traversodontids.

Other animals include the dicynodont Jachaleria, the procolophonid Soturnia, the lepidosauromorphs Cargninia, Clevosaurus and Lanceirosphenodon, and the avemetatarsalians Faxinalipterus, Guaibasaurus, Macrocollum, Maehary,[3] Sacisaurus and Unaysaurus.

[18] The location where these fossils were found is a fluvial system, characterized by large quantities of fine sandstone forming sandy beds, resulting from sedimentation in the basin during peak flow events.