Type Geologic formation | Country Argentina | |
Region La Rioja Province, Argentina | ||
The Chañares Formation is geologic formation located in La Rioja Provence, Argentina.
It was originally thought to be formed during the Ladinian age of the Middle Triassic epoch, in the Triassic Period of the Mesozoic Era; Marsicano et al. (2016) dated it to early Carnian (236–234 Ma), Late Triassic.
Fossils
Some localities are well known for their abundance of tetrapod fossils. Theraspids include the kannemeyeriid Dinodontosaurus, and cynodonts such as Probainognathus and Massetognathus, the latter being the most abundant tetrapod taxon in the formation. Other notable tetrapods present from the formation are the archosaurs. Ornithodirans include Lewisuchus, Lagerpeton, Marasuchus, and Pseudolagosuchus. Other archosaurs include Gracilisuchus and Luperosuchus. Three proterochampsids are known from the formation, Tropidosuchus, Chanaresuchus, and Gualosuchus. They are very similar in appearance, but differ in size and cranial proportions.