• A new species of zhelestid mammal, Ravjaa ishii, has been identified from a fossil found in the Gobi Desert, dating back 90 million years.
• The mammal's dental structure suggests it consumed seeds and fruits, coinciding with the rise of flowering plants during the Cretaceous period.
• The discovery challenges previous understandings of the geographic distribution of Zhelestidae, indicating they inhabited inland regions as well as coastal areas.

The discovery of Ravjaa ishii, a new genus and species of zhelestid mammal, in the Bayanshiree Formation of Mongolia's Gobi Desert, has provided valuable insights into mammalian evolution during the Late Cretaceous period. The fossil, a partial lower jaw, dates back approximately 90 million years. Ravjaa ishii, the size of a modern mouse, belonged to the Zhelestidae family. Its unique molar structure suggests a diet of seeds and fruits, indicating early mammals were already exploiting resources created by flowering plants.

• What: Discovery of Ravjaa ishii, a new genus and species of zhelestid mammal from the Late Cretaceous period.
• Who: The discovery was made by an international team of paleontologists from Okayama University of Science and the Institute of Paleontology and Geology of the Mongolian Academy of Sciences. Key individuals include Tsukasa Okoshi and Professor Mototaka Saneyoshi.
• When: The fossil was found in 2019. The species lived approximately 90 million years ago during the Cretaceous period.
• Where: The fossil was unearthed in the Bayanshiree Formation in Mongolia's Gobi Desert.

The discovery of Ravjaa ishii is significant because it challenges previous assumptions about the geographical distribution of Zhelestidae mammals, suggesting they inhabited inland regions in addition to coastal areas. The mammal's dental structure provides valuable insights into the dietary adaptations of early mammals during the rise of flowering plants. This find also highlights the importance of the Bayanshiree Formation as a source of information about Cretaceous ecosystems.

Finding such a tiny fossil in the vast expanse of the Gobi Desert feels like a gift from the Gobi Desert. It’s nothing short of miraculous.

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.

The discovery of Ravjaa ishii enriches our understanding of mammalian evolution and the ecosystems of the Late Cretaceous period. This finding provides valuable data on the dietary habits and geographical distribution of early mammals, demonstrating their adaptability in response to the emergence of new food sources. Further research is anticipated to uncover more information about the diverse life forms that existed in the Gobi Desert during the age of dinosaurs.