Jurassic fossil reveals ancient origins of how mammals drink milk
Researchers have discovered a 165-million-year-old fossil named Megacauda sungei in Inner Mongolia. The findings suggest that the anatomical structures necessary for mammalian suckling and breastfeeding evolved much earlier than previously thought.
Why it matters
This discovery provides critical insight into the evolutionary timeline of mammals and the development of key biological traits that define the class.
edited by Sadie Harley , reviewed by Robert Egan
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Add to Preferred Sources Skeletal photograph and reconstruction of the mammaliaform M. sungei gen. et sp. nov. (Docodonta). Credit: Nature (2026). DOI: 10.1038/s41586-026-11107-0 An international team of researchers has uncovered new evidence illuminating the evolutionary origins of one of the defining features of mammals: the ability to suckle and consume milk during infancy. Their findings, published in Nature , suggest that key anatomical structures required for mammalian suckling, swallowing and breastfeeding behaviors evolved nearly 165 million years ago, long before the appearance of modern mammals.
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