Semi-Aquatic Jurassic Mammal Discovered: Meet Megacauda Sungei
- Researchers in China have discovered a 160-million-year-old fossil of a semi-aquatic, mammal-like creature named Megacauda sungei, offering new evidence about early mammalian evolution during the Middle Jurassic period.
- Paleontologists detailed the find in a new study published in the journal Nature, placing Megacauda sungei within the extinct docodont branch of mammaliaformes, cnews.fr reported.
- The excavation team recovered the remarkably complete fossil from a rock layer rich in prehistoric remains.
Researchers in China have discovered a 160-million-year-old fossil of a semi-aquatic, mammal-like creature named Megacauda sungei, offering new evidence about early mammalian evolution during the Middle Jurassic period. The specimen, unearthed in 2015 within the Haifanggou Formation in southeastern Inner Mongolia, weighs between one and two kilograms and bridges the evolutionary gap between land animals and water-dwelling mammals.
Paleontologists detailed the find in a new study published in the journal Nature, placing Megacauda sungei within the extinct docodont branch of mammaliaformes, cnews.fr reported. The animal displays a hybrid body plan featuring a duck-billed platypus-like frame, an otter-like tail, and a canine-like head. Zhe-Xi Luo, a paleontologist at the University of Chicago and lead author of the study, noted that the creature stands out as the largest known mammaliaforme from the Jurassic.
Fossil Discovery in Inner Mongolia
The excavation team recovered the remarkably complete fossil from a rock layer rich in prehistoric remains. Luo expressed relief that the vast majority of the skeleton's bones were preserved intact. She highlighted specialized traits including foot and ankle structures, pelvic design, broadened ribs, webbed feet, a flattened tail, and exceptionally thick fur.
Despite those shared traits, significant physiological differences separate the two species. While modern platypuses possess a fossil record stretching back only about 3.8 million years, the newly analyzed Jurassic predator diverged sharply in its dental weaponry. Luo explained that unlike the platypus, Megacauda featured powerful canines and sharp teeth built for a carnivorous diet in aquatic environments.
Evolutionary Signatures in Soft Tissue
Beyond its swimming adaptations, the fossil preserves soft tissues around the throat region that shed light on fundamental mammalian behaviors. Researchers found that the throat anatomy was structured for nursing during early developmental stages before transitioning to adult food swallowing. Those anatomical markers mirror traits observed in living mammals today.
The mammaliaformes semi-aquatiques ne sont pas rares dans le monde actuel : Il existe aujourd’hui 140 espèces de mammifères qui vivent au bord des cours d’eau et dépendent de ces milieux.
Zhe-Xi Luo
Luo emphasized that swimming capabilities emerged much earlier in mammalian lineage history than previously understood, noting that roughly 140 modern mammal species depend on waterfront habitats. Hand suggested that future analyses examining the internal microstructure of the fossil’s limb bones will help quantify how much time the creature split between aquatic foraging and terrestrial life.