New Mammal Species Unearthed in Mongolia’s Gobi Desert Sheds Light on Ancient Ecosystems.

A collaborative team of paleontologists has uncovered a previously unidentified genus and species of mammal in the Gobi Desert of Mongolia, dating back to the Late Cretaceous period (approximately 100–66 million years ago). The newly named species, Ravjaa ishiii, was found in fossil-rich layers of the Baynshire Formation and represents a significant addition to our understanding of prehistoric mammalian diversity.

The mouse-sized creature's name pays tribute to two influential figures: Dulduityn Danzanravjaa, a respected 19th-century Buddhist monk, and Kenichi Ishii, the late director of the Hayashibara Museum of Natural Sciences, whose contributions were pivotal in forming the Mongolia–Okayama University of Science (OUS) research alliance.

The discovery was documented in the scientific journal Acta Palaeontologica Polonica. The research team involved scientists from both OUS in Japan and the Institute of Paleontology and Geology at the Mongolian Academy of Sciences (IPMAS).

The fossil, a one-centimeter segment of the lower jaw, was uncovered during a joint expedition to the Baynshire Formation in 2019. Upon examination, it was identified as a member of the extinct mammalian family Zhelestidae. However, unique traits such as its notably tall molars and distinctive jaw structure set it apart from known relatives, prompting researchers to classify it as a new genus and species.

This find marks the first zhelestid fossil reported in Mongolia, challenging earlier assumptions that these mammals lived exclusively near ancient coastal regions. Instead, this evidence suggests they also flourished deep within inland ecosystems.

The Baynshire Formation is believed to date from a time when flowering plants (angiosperms) were beginning to dominate terrestrial landscapes. The strong, complex molars of Ravjaa ishiii resemble those of modern seed- and fruit-eating mammals, hinting that early Eutherians may have already been adapting to and benefiting from these emerging plant resources.

Lead author and OUS doctoral candidate Tsukasa Okoshi commented on the research journey, noting that the COVID-19 pandemic delayed publication but did not diminish the importance of the find. "We were finally able to demonstrate the specimen's scientific significance. We hope this work opens the door to more taxonomic studies on small vertebrates from this site, shedding light on the broader biodiversity—including dinosaurs—that once thrived here."

Professor Mototaka Saneyoshi of OUS echoed this sentiment, reflecting on the rarity and significance of the discovery: "Finding such a tiny fossil in the vastness of the Gobi Desert feels like a gift. It's truly miraculous."

Source:https://phys.org/news/2025-04-fossil-mammal-species-age-dinosaurs.html

This is non-financial/medical advice and made using AI so could be wrong.