Plate Nº 60 · recorded October 10, 2026
Biology & EvolutionReported finding
Half-meter Jurassic predator rewrites mammal feeding origins
Researchers describe Megacauda sungei, a 165-million-year-old half-meter aquatic predator from the Jurassic. It is the largest known mammaliaform of its era and shows the earliest soft palate.
By Priya Raman3 min read597 words
In brief
- Megacauda sungei measured 0.5 m (1.6 ft) long and weighed about 2 kg (4.4 lb).
- The fossil dates to 165 million years ago and was found in Xiayingzi, Inner Mongolia, China.
- It is the largest mammaliaform species found from the Jurassic Period.
- The specimen represents the earliest known evidence of an aquatic lifestyle in mammals.
- It preserves the earliest known soft palate, the tissue that separates mouth from throat in mammals.
A 165-million-year-old aquatic predator measuring only 0.5 meters (1.6 feet) from nose to tail is the largest mammaliaform—an extinct relative of modern mammals—ever found from the Jurassic Period, researchers report in Nature.
The new species, named Megacauda sungei, weighed roughly 2 kilograms (4.4 pounds) and hunted in water 165 million years ago. Its fossil, recovered from Xiayingzi in Inner Mongolia, China, belongs to the docodonts, an extinct mammaliaform group that thrived during the Mesozoic Era (roughly 230 to 66 million years ago).
The team includes Dr. Zhe-Xi Luo of the University of Chicago, Dr. Thomas Martin of the University of Bonn, and Dr. Chang-Fu Zhou of Shandong University. The species name "sungei" honors Sun Ge, honorary director of the Paleontological Museum of Liaoning. "Megacauda" translates as "large tail."
What did the predator look like?
At first glance, the furry animal resembles an otter, beaver, or platypus. It had a flattened tail and other features suited to swimming. Three-dimensional reconstructions from CT scans—computed tomography, which builds 3D images from X-rays—show the creature paddled with its front legs, moved its tail in a wavelike motion, and steered with its hind legs.
"It is the earliest evidence of an aquatic lifestyle in mammals," Martin said.
The teeth offered additional surprises. The specialized canines had three roots, an unusual feature visible in detailed scans. The cusps, the pointed bumps on the chewing surface, curved backward, helping the predator grip slippery prey.
Why does the soft palate matter?
The most striking find is a piece of soft anatomy: a soft palate. This flexible tissue separates the mouth from the throat, allowing an animal to swallow and breathe at the same time.
Most animals lack this structure. Crocodiles, for example, must raise their heads and use jerky movements so food slides down their throats with the help of gravity, Martin explained. Mammals can swallow against gravity—people can drink from a straw while hanging upside down, breathing through the nose the entire time.
The soft palate is essential for suckling milk safely. Without it, liquid could enter the nasal passages. This adaptation allowed mammals to feed their young on nutrient-rich milk, fueling rapid brain growth.
"It was this adaptation that made brain development, eventually leading to humans, possible," Martin said.
What does this change about mammal evolution?
The find pushes back the origin of the mammalian soft palate by tens of millions of years. It appeared in Megacauda sungei well before modern mammals emerged, suggesting the feeding mechanism evolved earlier than the fossil record previously showed.
Docodonts occupied a striking range of habitats. Other finds show the group lived in trees, underground in mole-like burrows, and in water, as Megacauda sungei did. Martin said the diversity shows how widespread docodonts were across the Northern Hemisphere at an early stage.
How did the fossil reach the lab?
The Paleontological Museum of Liaoning in Shenyang acquired the specimen years ago, together with other finds from Inner Mongolia. It took years of joint examination by the three researchers before the unique nature of the animal became clear. Martin called the description "the result of a long period of teamwork."
What are the limitations?
The analysis rests on a single fossil. Soft-tissue structures like the palate rarely preserve, so the identification relies on CT imaging and comparisons with living mammals. Further finds could clarify whether other docodonts shared the same feeding mechanism and how widely this adaptation spread.
The study appears in Nature. DOI: 10.1038/s41586-026-11107-0.
via Phys.org Biology (Source)
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Senior reporter covering industry trends and analytics at SciBeat.
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