Fossil of 65-Million-Year Mammal Found in China, Offers Clues About Mammal Ancestors

A well preserved fossil of an ancient mammal unearthed in China offers clues about evolution of the earliest mammals.

The newly discovered fossil, Megaconus mammaliaformis, is a 165 million-year-old proto mammal unearthed from the region of Inner Mongolia, China. This well preserved species is the long extinct relative of the modern mammal. It lived during the Jurassic Era along with other feathered dinosaurs and roamed the Earth 100 million years before the Tyrannosaurus.

The fossil discovered by an international team from the Paleontological Museum of Liaoning, University of Bonn in Germany and the University of Chicago, provides evidence that mammalian traits such as hair and fur originated much before the evolution of the ancient mammal.

"We finally have a glimpse of what may be the ancestral condition of all mammals, by looking at what is preserved in Megaconus. It allows us to piece together poorly understood details of the critical transition of modern mammals from pre-mammalian ancestors," Zhe-Xi Luo, professor of organismal biology and anatomy at the University of Chicago, said in a press statement.

The fossil, currently placed at the Paleontological Museum of Liaoning, China, has a halo of guard hairs and remains of underfur, making Megaconus- a terrestrial animal, the second known pre mammalian fossil with fur. It has long highly poisonous keratinous spur on its heel. Such types of spurs are present on the modern day egg-laying mammals like the male platypus. The presence of spur reveals that the fossil might have been male.

"Megaconus confirms that many modern mammalian biological functions related to skin and integument had already evolved before the rise of modern mammals," Luo explained.

He claims that these features are evidence of how the ancient mammalian ancestors during the Triassic-Jurassic transition, looked like.

Megaconus had a mammalian dental feature and jaw hinge. It was omnivorous and fed on insects, worms and small vertebrates with the help of the anterior teeth that had large cusps. Similar to the modern times unrelated mammalian specie rodent, Megaconus had teeth with high crowns and fused roots. It had a finger claws gait  very similar to the present days armadillos.

The non-mammalian characteristics include the primitive middle ear attached to the jaw similar to reptiles. Evidence from this fossil reveals that the adaptations of the modern mammals were already present in the ancient extinct relatives.

The findings are documented in the journal Nature.