Studying ancient mammals helps scientists understand how life evolved and adapted over millions of years, writes Interesting Engineering.

One such mystery surrounded Mixodectes pungens, a small mammal from the early Paleocene, which lived in western North America around 62 million years ago.

A recent study analyzing the most complete skeleton ever found of Mixodectes has finally provided crucial insights into its size, lifestyle, diet, and evolutionary relationships.

The findings of this study were published in the journal Scientific Reports.

According to the study, Mixodectes was an arboreal (tree-dwelling) mammal that primarily ate leaves.

It weighed about 3 pounds (1.3 kg) and had limb and claw structures that suggest it could cling to tree trunks and branches.

The animal’s molar teeth featured crests that helped break down tough plant materials, confirming its leaf-based diet.

While it was omnivorous, leaves comprised most of its food intake.

The study, co-authored by Yale University anthropologist Eric Sargis, reveals that Mixodectes was closely related to primates and colugos (also known as flying lemurs from Southeast Asia).

Both primates and colugos belong to a mammal group called Euarchonta. This connection means Mixodectes is a distant but relatively close evolutionary cousin of humans.

“A 62-million-year-old skeleton of this quality and completeness offers novel insights into mixodectids, including a much clearer picture of their evolutionary relationships,” said Sargis. “Our findings show that they are close relatives of primates and colugos, making them fairly close relatives of humans.”

Mixodectes was considered a large tree-dwelling mammal in North America during the early Paleocene.

Its skeleton was found alongside Torrejonia wilsoni, another early primate relative.

However, Torrejonia was smaller and primarily ate fruit, while Mixodectes thrived on leaves. These differences suggest that mixodectids occupied a distinct ecological niche at the time, separate from other arboreal mammals.