A 165-million-year-old fossil of a mammal ancestor shows modern traits related to milk feeding.

What it means

A 165-million-year-old fossil from China, named *Megacauda sungei*, preserves a complete hyoid apparatus — the throat bones that support the tongue and larynx — showing that this Jurassic mammal ancestor could suckle and swallow milk like modern mammals. This pushes back the evolutionary origin of mammalian milk-feeding mechanisms by tens of millions of years, and the fossil also reveals a broad, swimming tail, indicating an aquatic or semi-aquatic lifestyle. The study, published in *Nature*, was led by researchers from the University of Chicago and Ohio University.

Accuracy & sourcesGrounded

The claim is solid, based on a peer-reviewed *Nature* paper with detailed fossil analysis. Multiple reputable outlets (Phys.org, NPR, ABC Australia, UChicago News) report consistent details, and the fossil itself is the primary source. The reporting sits close to the original study, accurately describing its key findings without sensationalism.

How new

Genuinely new: the study was published in October 2026, and this coverage appeared on October 10–11, 2026.

Go deeper

• Phys.org — first to publish