Stegosaurian remains from Lower Cretaceous of Argentina (free pdf)

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper:

Free pdf:

Facundo Javier Riguetti, Sebastián Apesteguía, Juan Ignacio Canale & Pablo Ariel Gallina (2026)
New thyreophoran remains with stegosaurian affinities from the Lower Cretaceous of Argentina
Nuevos restos fósiles con afinidades estegosaurianas del Cretácico Inferior de Argentina
Publicación Electrónica de la Asociación Paleontológica Argentina 26(1): 56-79
DOI: https://doi.org/10.5710/PEAPA.25.11.2025.551
https://peapaleontologica.org.ar/index.php/peapa/article/view/551

Free pdf:
https://peapaleontologica.org.ar/index.php/peapa/article/view/551/936


South American Mesozoic vertebrate fossils are key in contrasting the classic North American and European views of clades evolution. During the last decades, several relevant findings of stegosaurian remains from Argentina show a greater diversity than previously thought. These include the early stegosaur Isaberrysaura from Los Molles Formation (Middle Jurassic) and indeterminate stegosaurian remains from the Cañadón Calcáreo (Upper Jurassic) and the La Amarga (Lower Cretaceous) formations, all from the Argentinian Patagonia. In addition to these scarce records, new remains from the Berriasian–Valanginian Bajada Colorada Formation of Neuquén Province (Argentina) are presented here. These consist of sacral vertebrae, dorsal ribs and several osteoderm types, including stegosaurian-like spines. The shape analysis of the sacral vertebrae, anatomic features (e.g., sacral vertebrae and ribs dorsoventrally compressed, and dorsal ribs with T-shaped proximal transversal section), and the morphologic disparity of the osteoderms, support an assignation to Thyreophora with affinities to Stegosauria. The finding of these remains in Bajada Colorada reinforces the presence of stegosaurs in Argentinian Patagonia during the Lower Cretaceous. Our explorations and research in Bajada Colorada also support that the historical absence of stegosaurian remains in Southern continents was an effect of searching and/or preservational biases, as other authors proposed. These new stegosaurian remains also support the presence of a transitional fauna in Bajada Colorada including both Jurassic and Cretaceous components.

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