03-05-2025
New Mammal Species Discovered in the Age of Dinosaurs
INA-sources
A recent discovery in the Gobi Desert, Mongolia, has unveiled a new mammal species that dates back to the Late Cretaceous period, predating the rise of the dinosaurs by millions of years.
The Discovery of Ravjaa ishiii
The fossil in question belongs to a previously unknown genus and species of mammal named Ravjaa ishiii.
This tiny mammal, no larger than a mouse, was found in the Baynshire Formation during a joint expedition in 2019.
The species name honors Dulduityn Danzanravjaa, a respected 19th-century Buddhist monk, and the late Kenichi Ishii, who helped establish the research partnership between Mongolia and OUS.
A Tiny Fossil with Big Implications
The fossil, a one-centimeter partial lower jaw, has been identified as belonging to the Cretaceous mammal family Zhelestidae.
Despite its small size, the fossil displays some remarkable features. Its unusually tall molars and distinctive jaw shape set it apart from other known relatives, leading the study to conclude that it represents a new genus and species.
This is the first time a Zhelestid has been recorded in Mongolia. Scientists believed that Zhelestidae primarily thrived along ancient coastlines, but this discovery shows that they also inhabited inland areas during the Late Cretaceous period.
Ecological Insights from the Cretaceous Period
The age of the Baynshire Formation, where the fossil was found, corresponds with the early spread of angiosperms, or flowering plants.
These plants were an essential part of the terrestrial ecosystem during the Late Cretaceous, and their presence may have influenced the diets of early mammals.
The robust nature of the molars of Ravjaa ishiii suggests that it likely fed on seeds and fruits.
As Tsukasa Okoshi, the lead author and OUS doctoral candidate, remarked, 'Due to the COVID-19 pandemic, the publication process took longer than expected, but we were finally able to establish the scientific importance of this specimen.'
Source: Daily Galaxy
