Chile unveils 74‑million‑year‑old mammal fossil, reshaping mammal evolution
New Discovery Reveals the Smallest Mammal of Patagonia
Scientists have identified a tiny, mouse‑sized mammal that lived alongside dinosaurs in present‑day southern Chile. The fossil, named Yeutherium pressor, came from the Upper Cretaceous period, about 74 million years ago.
Key Facts About Yeutherium pressor
- Weight: 30–40 grams (≈1 ounce)
- Size: Smallest mammal found in South America during the Gondwana era
- Teeth: One small jaw fragment with a molar, plus the crown and roots of two other molars
- Location: Rio de las Las Chinas Valley, Magallanes region (≈3 000 km south of Santiago)
- Publication: Proceedings of the Royal Society B (March 2025)
What Makes This Species Unique?
The fossil suggests that Yeutherium pressor was a mammal that must have reproduced like a platypus or kept its young in a pouch (similar to kangaroos or opossums). Despite its rodent‑shaped appearance, it was a true mammal.
Its teeth indicate a diet of hard vegetables, showing it had a specialized feeding strategy during the dinosaur era.
Extinction and Historical Context
Like the dinosaurs it shared the continent with, Yeutherium pressor abruptly went extinct at the end of the Cretaceous period, about 66 million years ago.
Conclusion
The discovery of Yeutherium pressor provides new insight into the early mammalian fauna of Patagonia and the evolutionary history of mammals during the age of dinosaurs.
