Aetosaurs

Aetosaurs are an extinct group of heavily armored, herbivorous archosauriform reptiles that lived during the Triassic period. They are known for their distinctive dorsal armor and broad, stocky bodies. They occupied terrestrial habitats alongside early dinosaurs and other archosauriforms.

Taxonomy and relationships: Aetosaurs belong to the clade Aetosauria within Suchia, a subgroup of Archosauriformes. They are more closely related to phytosaurs and crocodile-line archosaurs than to dinosaurs, representing an early diversification of armored pseudosuchians.

Anatomy: The most distinctive feature is the extensive osteoderm armor that forms a protective dorsal shield, often with paramedian rows of plates and sometimes tall lateral spines. The skull is typically elongate with a beak-like snout, and the teeth are leaf-shaped, indicating a diet of tough plant material.

Ecology and diet: Most evidence points to herbivory or omnivory. Their heavy armor suggests defense against predators, while their limb proportions imply a slow, deliberate gait. Wear patterns on dentition and jaw mechanics support processing of fibrous vegetation rather than active predation.

Distribution and diversity: Fossils of aetosaurs have been found in several regions, including North America, Europe, Africa, and South America. Notable genera include Aetosaurus (Germany), Desmatosuchus (North America), Typothorax (North America), and Stagonolepis (Europe).

Fossil record and significance: Aetosaurs are among the better-known Triassic armored reptiles. Their distinctive armor and body plan provide important clues about Triassic ecosystems, predator–prey dynamics, and the early evolution of archosauriforms.