A Jurassic mammaliaform swimmer and transformation of the mammalian pharynx.

A Jurassic mammaliaform reveals early evolution of mammalian feeding and swimming adaptations, with evidence of therian-like soft tissues and a semiaquatic lifestyle.

• Why it matters: Understanding the origins of mammalian feeding behaviors and ecological diversity is crucial for tracing mammal evolution, especially during the Mesozoic era when dinosaurs dominated.
• What they did: The study examined a well-preserved Middle Jurassic mammaliaform fossil from China, analyzing its skull, teeth, and hindlimb features, including rare soft-tissue evidence, to infer its ecology and anatomy.
• The result: Findings show that critical soft-tissue structures for swallowing and suckling evolved before modern mammals, and the species was likely semiaquatic, expanding knowledge of early mammal diversity and ecological roles.