Age constraints on the dispersal of dinosaurs in the Late Triassic from magnetochronology of the Los Colorados Formation (Argentina)

A new magnetochronological study of the Los Colorados Formation in Argentina's Ischigualasto-Talampaya Natural Parks reveals that dinosaur-bearing deposits span from 227 to 213 million years ago, confirming their Norian age and predating the Jurassic by over 11 million years. This finding demonstrates a diachronous rise of dinosaurs across the Americas, with North American records (Chinle Formation) appearing later in the Norian. The research suggests that early dinosaur faunas thrived in a temperate humid belt before broader dispersal, likely driven by climate shifts and reduced atmospheric CO₂ levels. The study employs magnetic polarity correlations to refine age constraints, providing critical insights into Late Triassic vertebrate evolution.

Kent, D. V., Santi Malnis, P., Colombi, C. E., Alcober, O. A., & Martínez, R. N. (2014). Age constraints on the dispersal of dinosaurs in the Late Triassic from magnetochronology of the Los Colorados Formation (Argentina). Proceedings of the National Academy of Sciences, 111(22), 7958–7963. https://doi.org/10.1073/pnas.1402369111