Discovery of Tiny Mammal Fossil from Dinosaur Era in Chilean Patagonia

Scientists have uncovered the fossil of a diminutive mouse-sized mammal that lived during the age of dinosaurs, in Chilean Patagonia.

Details of the Fossil and Its Significance

The species, named Yeutherium pressor, weighed between 30 and 40 grams (approximately one ounce) and lived during the Upper Cretaceous period, roughly 74 million years ago.

It represents the smallest mammal ever discovered in this part of South America, dating back to when the continent was part of the ancient landmass known as Gondwana.

Fossil Composition and Research Team

The fossil comprises:

• A small piece of jawbone
• One molar tooth
• The crown and roots of two additional molars

This was explained by Hans Puschel, who led the scientific team from the University of Chile and Chile’s Millennium Nucleus research centre focusing on early mammals.

The discovery was recently published in the British scientific journal Proceedings of the Royal Society B.

Location and Geological Context

Researchers found the fossil in the Río de las Chinas Valley, located in Chile’s Magallanes region, approximately 3,000 kilometres (1,864 miles) south of the capital, Santiago.

Biological Characteristics and Lifestyle

Although resembling a small rodent, Yeutherium pressor was a mammal that likely:

• Laid eggs, similar to the modern platypus
• Or carried its young in a pouch, like kangaroos or opossums

The shape of its teeth indicates it probably consumed relatively hard vegetation.

Extinction and Coexistence with Dinosaurs

Like the dinosaurs it lived alongside, this tiny mammal abruptly became extinct at the end of the Cretaceous period, around 66 million years ago.

Yeutherium pressor Key Facts