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Paleontology

Two pre-mammals in southern Brazil

Artist rendering and partial lower jaw of a Bonacynodon schultzi cynodont, an insectivore that lived over 230 million years ago

Jorge Blanco | PLOS Artist rendering and partial lower jaw of a Bonacynodon schultzi cynodont, an insectivore that lived over 230 million years agoJorge Blanco | PLOS

Found in the state of Rio Grande do Sul, two new species of cynodonts, a vast group of animals that includes the ancestors of mammals, were described in the science journal PLOS ONE on October 5, 2016. Measuring from 15 to 30 centimeters, both are small cynodonts that resemble rats or wild squirrels. Paleontologists at the Federal University of Rio Grande do Sul (UFRGS) and the Porto Alegre campus of the Federal Institute of Education, Science and Technology of Rio Grande do Sul named the species and analyzed the fossils, which were recovered from early Late Triassic rocks formed 237 to 235 million years ago. Bonacynodon schultzi was described on the basis of skulls and jaws that were found in the municipality of Candelária, Rio Grande do Sul, in 1946 but have only now been studied. The name of the new genus pays tribute to Argentinean paleontologist José Bonaparte, while the species name honors César Schultz, paleontologist at UFRGS. Description of the second new species, Santacruzgnathus abdalai, was based on a jaw with dentition that was discovered in the municipality of Santa Cruz do Sul; its name is a tribute to Fernando Abdala, another Argentinean paleontologist and an expert in South American and African cynodonts. “The new fossils help provide a more thorough understanding of the evolution of the pre-mammal forms that gave rise to mammals,” says Agustín Martinelli, doctoral candidate at UFRGS and principal author of the article.

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