A Triassic World in Red Sandstone
The Talampaya Formation is a layer of pink and reddish sandstone that forms cliffs up to 200 meters high. Part of the Ischigualasto-Villa Unión Basin, these sedimentary rocks were deposited during the Triassic Period, from approximately 245 to 208 million years ago. The entire basin provides one of the most complete continental fossil records from this time anywhere on Earth, which is why Talampaya National Park is a UNESCO World Heritage Site.
The striking red color of the rock comes from hematite, an iron oxide mineral. During the Triassic, this area was a vast, volcanically active floodplain with high-energy braided rivers. The climate was temperate to warm with high humidity, and the landscape experienced seasonal monsoons that caused flash floods. These conditions were ideal for burying and preserving the remains of animals and plants. The layers of the Talampaya Formation, which reach a general thickness of 260 meters, capture an environment evolving from alluvial fans to river systems and eventually to ephemeral lakes as conditions became more arid.
The Dawn of the Dinosaurs
The fossils preserved here document an important moment in Earth's history. The sediments were deposited after the Permian-Triassic extinction event, which occurred around 252 million years ago and eliminated most life on the planet. The Talampaya Formation, along with the other five formations in the basin, contains fossils that show the recovery and diversification of vertebrates.
While no complete dinosaur skeletons have been found in the Talampaya Formation itself, it contains the fossilized footprints of tetrapods. These tracks, known as ichnofossils, are assigned to the genus Chirotherium and were likely made by early archosaurs, the group that includes crocodiles, dinosaurs, and their ancestors.. Fossils of Lagosuchus talampayensis, a small dinosauromorph considered a very close relative to the first dinosaurs, were discovered in the greater park area. The surrounding formations in the basin contain some of the earliest dinosaurs ever found, such as Eoraptor and Herrerasaurus, as well as a wide variety of mammal-like reptiles called therapsids. These finds collectively show the transition from a world dominated by mammalian ancestors to the beginning of the Age of Dinosaurs.