Called Ravjaa ishiiithe brand-new types strolled Earth throughout the Cretaceous duration, around 90 million years back.

The ancient mammal was the size of a mouse and came from Zhelestidae, an eutherian mammal household extensively dispersed from Eurasia to North America in the Late Cretaceous.

“Numerous remarkably maintained mammal fossils uncovered from Late Cretaceous layers in the Gobi Desert of Mongolia have actually played an essential function in comprehending Mesozoic mammalian development,” stated Okayama University of Science doctoral prospect Tsukasa Okoshi and associates.

“These remarkable mammal fossils have actually been recuperated generally from the Baruungoyot and Djadokhta developments, however just 2 fragmentary remains of mammals have actually been gathered from the underlying Bayanshiree Formation.”

The brand-new zhelestid fossil was discovered in 2019 at the Bayan Shiree region of the Bayanshiree Formation.

The specimen is a 1-cm-long partial lower jaw with the distal part of a supreme premolar and the very first to the 3rd molars.

“Finding such a small fossil in the large area of the Gobi Desert seems like a present from the Gobi Desert. It’s absolutely nothing except amazing,” stated Okayama University of Science’s Professor Mototaka Saneyoshi.

“Its uncommonly high molars and distinct jaw shape vary from understood family members, and for that reason we put up a brand-new genus and types,” the paleontologists stated.

“The robust nature of the molars looks like those of seed and fruit-eating mammals, offering an appealing insight that early eutherians were currently making use of resources developed by blooming plants.”

According to the group, Ravjaa ishiii is the very first zhelestid from the Bayanshiree Formation and in truth the very first found in Mongolia.

Ravjaa ishiii possibly represents the earliest member amongst zhelestids or as old as the presently understood earliest zhelestids gathered in Uzbekistan, recommending the development of this group took place around the Early/Late Cretaceous limit to early Late Cretaceous,” the scientists stated.

Their paper was released online in the journal Acta Palaeontologica Polonica

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Tsukasa Okoshi et al2025. New Late Cretaceous zhelestid mammal from the Bayanshiree Formation, Mongolia. Acta Palaeontologica Polonica 70 (1 ): 193-203; doi: 10.4202/ app.01213.2024