This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The "top predator" from the Jurassic is relatively small: Megacauda sungei measures just half a meter (1.6 feet) from its nose to the tip of its tail. The furry ancestor of today's mammals hunted its prey in water 165 million years ago.
The cusps of its teeth were also curved backward to enable it to catch its slippery prey. However, the true evolutionary revolution is its soft palate, which separates the oral cavity from the pharynx while also enabling swallowing and breathing. This is an important requirement for suckling, which provides a survival advantage.
The findings by researchers from the universities of Shenyang, Chicago and Bonn are now being published in the journal Nature. Many animal species do not have a soft palate and have only a simple hyoid bone apparatus without a swallowing mechanism. Crocodiles, for instance, raise their heads and use jerky movements to make their unchewed prey slide down their throats.
"This is achieved with the aid of gravity," explains paleontologist Dr. Thomas Martin from the University of Bonn. In contrast, mammals, with their complex hyoid structure in the pharynx, are even able to swallow against gravity: As a result, we humans can drink upside down through a straw while breathing.
This ability is a key adaptation that allows mammals to feed on nutrient-rich milk and swallow it safely without it entering their noses. "It was this adaptation that made brain development, eventually leading to humans, possible," stresses Martin. "The soft palate and the shaping of the oral cavity and pharynx are directly linked to the evolution of mammals." This new development was already apparent in Megacauda sungei long before the emergence of modern mammals.
At first glance, the short-coated animal with a flattened tail resembles an otter, beaver or platypus. Like these descendants, the predator from the Jurassic was a good swimmer: Three-dimensional reconstructions from computed tomography images of the fossil suggest that, 165 million years ago, the animal paddled with its front legs and moved its tail in a wavelike motion, using its hind legs to steer. "It is the earliest evidence of an aquatic lifestyle in mammals," says the paleontologist from the University of Bonn.
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