Agudotherium gassenae: Fossils of New Cynodont Species Found in Brazil

Tuesday, December 8, 2020

Life reconstruction of Agudotherium gassenae. Image credit: Márcio L. Castro.

A new genus and species of probainognathian cynodont that roamed our planet during the Triassic period has been identified from two fossilized specimens found in southern Brazil.

The new cynodont species lived approximately 218 million years ago (Late Triassic period).

The animal, scientifically named Agudotherium gassenae, was a type of non-mammaliaform probainognathian.

Probainognathia is a group of cynodonts that originated during the early Middle Triassic and includes the crown group, Mammalia,” Dr. Micheli Stefanello of the Universidade Federal de Santa Maria and her colleagues wrote in their paper.

“The non-mammaliaform probainognathians have a rich fossil record, and are abundant and diverse in the Triassic fauna from the supercontinent Gondwana.”

“The South American record, so far known only from Brazil and Argentina, consists of about 20 species from Middle and Upper Triassic strata, most of them based upon relatively well-preserved specimens.”

“The diversity and morphological disparity of Middle-Late Triassic South American probainognathian cynodonts are remarkable,” they added.

“They form the primary basis for understanding the evolutionary transformations underlying the origin of the Mammaliaformes, a group including mammals and their closest extinct relatives.”

The paleontologists examined two specimens of Agudotherium gassenae: a left lower jaw with the canine and postcanine teeth and a right lower jaw with incisors, canine and postcanines.

The fossils were collected at the Niemeyer Site in the municipality of Agudo in the Brazilian state of Rio Grande do Sul.

Agudotherium gassenae is based on a unique combination of features not present in other cynodonts, such as a robust dentary, with the dorsoventrally deep dentary body and a rectilinear ventral margin,” the researchers wrote.

Agudotherium gassenae was about 30 cm (11.8 inches) long and most likely had a carnivorous/insectivorous diet, consuming small invertebrates such as insects, worms, and small vertebrates.

“The new species contributes to our knowledge of the evolutionary radiation of small prozostrodonts that occurred in western Gondwana during the Late Triassic and led to the emergence of several important cynodont groups, including Mammaliaformes,” the scientists concluded.

paper describing the discovery was published in October 2020 in the Journal of Vertebrate Paleontology.


Micheli Stefanello et al. 2020. A New Prozostrodontian Cynodont (Eucynodontia, Probainognathia) from the Upper Triassic of Southern Brazil. Journal of Vertebrate Paleontology 40 (3): e1782415; doi: 10.1080/02724634.2020.1782415