Evolution: An ancient platypus-like relative of mammals (Nature)
8 October 2026
The fossil of an early relative of mammals that shares some adaptions seen in the modern platypus, from the Jurassic period of China, is described in this week’s Nature. The remains, which include an exceptionally well-preserved throat, shed light on the evolutionary origins of suckling and swallowing and increase the known diversity of mammal-like creatures from the Jurassic.
The specialised pharynx in the throat of mammals helps them to suckle milk as infants, and to swallow food and liquid as adults. When this feature evolved has been unclear, as it is uncommon for such soft tissue to fossilize. Yukun Li, Zhe-Xi Luo and colleagues describe the discovery of a docodont, a member of the Mammaliaformes clade (which includes extinct relatives of mammals, and living mammals), with a rare example of preserved delicate throat tissue. The newly described animal, named Megacauda, lived around 168–163 million years ago in what is now Inner Mongolia, China; it had a wide, flattened tail, short hindlegs with relatively long feet, and distinctive teeth capable of shearing action. These features indicate that this creature was a predatory animal with a semiaquatic lifestyle. The authors suggest that Megacauda may have sheltered in burrows on land, and foraged in the water for fish, salamanders and invertebrates.
Analysis of the specimen’s throat region suggests that the apparatus needed for suckling milk and swallowing had already evolved in the early relatives of modern mammals by the Middle Jurassic (around 174 to 164 million years ago). At around 1–2 kg, and about the size of a modern platypus, Megacauda is also the largest of all known Jurassic mammaliaforms. Its discovery adds to the growing body of evidence that these early mammal-like animals, which lived alongside the dinosaurs, occupied and exploited a diverse range of niches.
- Article
- Published: 07 October 2026
Li, Y., Li, P., Neander, A.I. et al. A Jurassic mammaliaform swimmer and transformation of the mammalian pharynx. Nature (2026). https://doi.org/10.1038/s41586-026-11107-0
Research Briefing: An early predecessor to mammals could swim, suckle and swallow
https://www.nature.com/articles/d41586-026-03069-0
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