Triassic Parks

Triassic Parks

Once home to Triassic reptiles and Inca society, northern Argentina contains several important archeological sites.

During the Triassic period (252 to 200 million years ago), northern Argentina was teeming with crocodile- and mammal-like reptiles. The Ischigualasto and Talampaya parks in the region are known for having one of the most complete known fossil records of the Triassic period. The fossils have been key to understanding the origins and behaviors of mammals and dinosaurs.

On February 28, 2023, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this image of Talampaya and Ischigualasto parks. The two parks jointly cover 275,000 hectares east of the Andes.

The red-stained, fossil-rich Talampaya National Park is famous for its 600-feet (200-meter) tall red sandstone cliffs and 1,500 year-old petroglyphs. The red soils of Talampaya contrast with the white and multi-colored sediments of Ischigualasto Provincial Park. Ischigualasto’s sparsely vegetated landscape has been named Valle de la Luna (Valley of the Moon).

Just northeast of the parks is the city of La Rioja. It is the capital city of the La Rioja Province, which was conquered by the Inca in the late 15th century. In the late 16th century, the region was settled by Spaniards exploring for gold and silver.

During the Triassic, Talampaya National Park was a volcanically active floodplain covered with rivers. The Triassic was a time of transition from mammal-like reptiles to the age of dinosaurs, which didn’t happen until the Jurassic. Much of the fossil remains found in the Ischigualasto Formation were mammal-like reptiles such as dicynodonts and rhynchosaurs, although some were early dinosaurs. Dicynodonts were stocky like rhinos with tusks instead of horns and a turtle-like beak. Rhynchosaurs have been described as a “reptilian pig with a hammerhead, no visible ears, and a parrot-like beak.”

In Talampaya, near its border with the Ischigualasto park, fossils dating back 250 million years provided researchers with evidence of how dicynodonts and rhynchosaurs lived and behaved. Clusters of fossilized dung indicate that dicynodonts likely used communal latrines. Using communal latrines, which is a social behavior used by rhinos and elephants, was once thought to be restricted to mammals. According to the research team that made the discovery, this is the oldest known fossil record of this behavior.

NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Emily Cassidy.

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