Overview
- The paper published in Nature on Wednesday names Megacauda sungei from Ningcheng, Inner Mongolia, as a roughly 40–52 cm, about 1–2 kg docodont and reports it as the largest known member of the group.
- The skeleton preserves a broad, flattened tail, paddle-capable hind limbs and distinctive H-shaped tail vertebrae that the authors interpret as adaptations for swimming and a semiaquatic lifestyle.
- Tiny, delicate throat elements including an ossified hyoid and a therian-like pharyngeal vault were resolved by high-resolution CT scans and X-ray imaging and are presented as early evidence for mammal-like swallowing, lapping, and possibly suckling behaviors.
- Researchers also report small vertebrate bones in the gut region that point to a faunivorous diet, and they compare Megacauda to earlier finds such as Castorocauda and Microdocodon to show repeated semiaquatic ecomorphs among docodonts.
- The discovery was enabled by CT and X-ray fluorescence imaging but the authors and outside commentators say bone microstructure studies and biomechanical tests are needed to confirm the degree of aquatic locomotion and the functional role of the throat bones, a step that could reshape how scientists view early mammaliaform ecology and feeding evolution.