Placerias

Placerias is an extinct genus of large, herbivorous dicynodont therapsids from Late Triassic North America, known especially from fossils in Arizona.

Dicynodontia: Dicynodonts were herbivorous therapsids, many with two prominent tusks and beaked mouths. Placerias belongs to this diverse group of tusked, plant-eating therapsids.
Petrified Forest National Park: Petrified Forest National Park in Arizona preserves fossil-rich deposits of the Late Triassic Chinle Formation. Its deposits include the region and strata associated with Placerias fossils.
Dicynodont beak: A dicynodont beak is a keratin-covered jaw structure used to crop or bite vegetation. Placerias used a beak-like front jaw to crop plant material.
End-Triassic extinction: The End-Triassic extinction was a major loss of biodiversity around 201 million years ago, at the Triassic–Jurassic boundary. Placerias disappeared before this boundary, amid broader Late Triassic faunal changes.
Therapsida: Therapsids are a major group of synapsids that includes mammals and their extinct relatives. Placerias was a non-mammalian therapsid within this evolutionary lineage.
Chinle Formation: The Chinle Formation is a sequence of Late Triassic sedimentary rocks exposed across the southwestern United States. Chinle strata preserve Placerias and many other components of its ecosystem.
Dicynodont tusks: Dicynodont tusks are enlarged upper canines that project from the jaws in many members of the group. Placerias had prominent tusks, the feature behind the name dicynodont.
Triassic–Jurassic extinction event: The Triassic–Jurassic extinction event was a global biodiversity crisis at the end of the Triassic Period. Its timing helps frame the turnover that followed Placerias's last known appearances.
Late Triassic: The Late Triassic was the final epoch of the Triassic Period, lasting about 237 to 201 million years ago. Placerias lived during this interval, when ecosystems were changing before the end-Triassic extinction.
Postosuchus: Postosuchus is an extinct genus of large predatory pseudosuchian archosaurs from the Late Triassic of North America. This predator shared the Late Triassic North American ecosystems where Placerias lived.

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