Anabisetia

Anabisetia is a genus of extinct, small, early mammal-like reptiles that lived during the Late Triassic period, approximately 220 to 200 million years ago. Fossils of Anabisetia have been discovered primarily in South America, particularly in Argentina, where they were found in sedimentary rock layers from the Chañares Formation. This genus belongs to the group known as cynodonts, which are considered transitional forms between reptiles and mammals due to their unique anatomical features.

Anabisetia is notable for its relatively advanced mammalian traits, such as a secondary palate that allowed it to breathe while chewing, a more complex jaw structure, and a more upright posture compared to earlier reptilian ancestors. These adaptations suggest it may have had a more active lifestyle, possibly feeding on insects or small vertebrates. Its skull was elongated, and its teeth were differentiated into incisors, canines, and molars, resembling the dental arrangement seen in modern mammals.

The genus was first described in 1998 by paleontologists Ricardo Martínez and Fernando Novas, who named it after the indigenous Argentine term *Anabisetia*, meaning "ancient hunter," reflecting its predatory or omnivorous nature. Fossil remains of Anabisetia include partial skulls and postcranial bones, providing insights into its size, estimated to be around 30 to 50 centimeters in length. Its discovery contributes to the understanding of mammalian evolution, particularly the transition from reptilian ancestors to the first true mammals.

Anabisetia is often studied alongside other Late Triassic cynodonts, such as *Prohalleosaurus* and *Thrinaxodon*, to compare anatomical variations and evolutionary trends during this critical period. Its fossil record remains limited, but ongoing research continues to refine knowledge of its biology and ecological role in its environment.