Fossils of Earliest Arboreal and Subterranean Mammals Discovered

Posted on February 13, 2015

Scientists have discovered fossils of the earliest known arboreal and subterranean mammals. The mammals, discovered in China, lived over 160 million years ago. The tree dwelling Agilodocodo ate tree sap while Docofossor likely dug tunnels with its shovel-like fingers.

The discoveries were made by researchers from the University of Chicago and Beijing Museum of Natural History. The find suggests there was a wide range in diversity among mammals even during the Jurassic period.

Zhe-Xi Luo, PhD, professor of organismal biology and anatomy at the University of Chicago, says in a statement, "We consistently find with every new fossil that the earliest mammals were just as diverse in both feeding and locomotor adaptations as modern mammals. The groundwork for mammalian success today appears to have been laid long ago."

The photograph below shows the fossil specimens of Docofossor (left) and Agilodocodon (right).

Agilodocodon scansorius is thought to be arboreal because its finger and limb bone dimensions are similar to that of modern tree-dwelling species. It had curved horny claws on its hands and feed. It also had flexible elbows and wrist and ankle joints.

The researchers say Docofossor brachydactylus had shovel-like fingers for digging and short and wide upper molars that are found in creatures that forage underground. The reduced bone segments in the fingers of Docofossor is similar to that of modern African golden moles.

Luo says, "We believe the shortened digits of Docofossor, which is a dead ringer for modern golden moles, could very well have been caused by BMP and GDF. We can now provide fossil evidence that gene patterning that causes variation in modern mammalian skeletal development also operated in basal mammals all the way back in the Jurassic."

Take a look:

Research papers on the ancient mammals can be found here and here in the journal, Science.

ANIMALS