Repenomamus, an extinct genus from the Cretaceous period, was a carnivorous mammal notable for its relatively large size, reaching up to 1 meter in length. It had robust jaws and teeth adapted for eating vertebrate prey, including juvenile dinosaurs, highlighting its role as a formidable predator.

Repenomamus is an extinct genus of mammal that lived during the Early Cretaceous period. Fossils have been primarily discovered in the Yixian Formation of Liaoning Province, northeastern China. This region is part of a lagerstätte known for its exceptionally well-preserved fossils, dating back approximately 125 million years.

During the Early Cretaceous period, the region that is now Liaoning Province had a temperate climate with distinct seasons. The environment was characterized by volcanic activity, which contributed to the preservation of fossils. The landscape included lakes, rivers, and lush forests, providing a diverse ecosystem.

Repenomamus occupied a unique ecological niche as one of the largest known Mesozoic mammals. It was carnivorous, with evidence suggesting it preyed on smaller vertebrates, including juvenile dinosaurs. This indicates that Repenomamus was an active predator, likely adapted to hunting and scavenging within its forested and aquatic habitat.