International team describes Megacauda sungei from Inner Mongolia and presents early evidence of aquatic mammal life
Paleontologists described a new docodont species from fossils found in present‑day Inner Mongolia, dated to about 165 million years ago. The animal appears to have led a semi‑aquatic lifestyle and may have been the largest known mammal of the Jurassic.
An international team of paleontologists has described an animal previously unknown to science, named Megacauda sungei, based on fossils discovered in what is now Inner Mongolia in China. The fossils date to roughly 165 million years ago, according to a study published in the journal Nature.
The creature belongs to the extinct group known as docodonts, considered among the closest relatives of early mammals. The researchers' description indicates that Megacauda sungei followed a semi‑aquatic lifestyle and may be the largest known mammal from the Jurassic period.
Morphologically, the researchers described the animal as a visual mix of a beaver, an otter and a water shrew, with short fur and a flattened tail. It apparently swam using its forelimbs while using its hindlimbs for steering.
The team estimated the discovered individual weighed at least 2.5 kg, a large mass compared with many small Jurassic animals that did not exceed a few grams. The researchers describe this animal as a powerful predator that might qualify as a "superpredator" by the relative standards of that era.
Analyses revealed evidence of a soft palate in the animal, a structure that helps both breathing and suckling. This feature was previously thought to have appeared later in mammal evolution, making its presence in Megacauda noteworthy.
Thomas Martin, professor of paleontology at the University of Bonn and a co‑author of the study, noted that these findings represent the earliest evidence of an aquatic lifestyle among mammals, in his words.
