A newly discovered fossil reveals the evolutionary adaptations of a 165-million-year-old proto-mammal, providing evidence that traits such as hair and fur originated well before the rise of the first true mammals. The biological features of this ancient mammalian relative, named Megaconus mammaliaformis, are described by scientists from the University of Chicago in the Aug 8 issue of Nature.
“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,” said Zhe-Xi Luo, professor of organismal biology and anatomy at the University of Chicago.
Discovered in Inner Mongolia, China, Megaconus is one of the best-preserved fossils of the mammaliaform groups, which are long-extinct relatives to modern mammals. Dated to be around 165 million years old, Megaconus co-existed with feathered dinosaurs in the Jurassic era, nearly 100 million years before Tyrannosaurus Rex roamed Earth.
Preserved in the fossil is a clear halo of guard hairs and underfur residue, makingMegaconus only the second known pre-mammalian fossil with fur. It was found with sparse hairs around its abdomen, leading the team to hypothesize that it had a naked abdomen. On its heel, Megaconus possessed a long keratinous spur, which was possibly poisonous. Similar to spurs found on modern egg-laying mammals, such as male platypuses, the spur is evidence that this fossil was most likely a male member of its species.
Read more at: Phys.org