Nemegt

Nemegt is the name given to a Late Cretaceous sedimentary formation and the corresponding basin in the Gobi Desert of southern Mongolia. The formation is named after the Nemegt Valley, a locality within the basin. It dates to the Late Cretaceous, roughly around 70 to 80 million years ago, and represents a time near the end of the age of dinosaurs.

Geology and environment of deposition show a predominantly fluvial landscape, with evidence of river channels, braided streams, floodplains, and episodic lakes. The sedimentary rocks record dynamic water-rich conditions compared with contemporaneous dune-dominated formations nearby, contributing to the preservation of a diverse vertebrate fauna.

Paleobiota from the Nemegt Formation is diverse and notable for yielding some of Asia’s best-preserved dinosaur fossils. The assemblage includes theropods such as Tarbosaurus, large hadrosaurs, various sauropods, as well as ornithomimids, ankylosaurs, and therizinosaurs. In addition to dinosaurs, fossils of crocodilians, turtles, fish, and other organisms have been found, helping illuminate Late Cretaceous ecosystems in this region.

Research and significance: The Nemegt Formation has been central to Mongolian paleontology since early exploration and subsequent international fieldwork. Its well-preserved and relatively complete skeletons offer important insights into dinosaur anatomy, behavior, and interactions within a riverine ecosystem. Ongoing study continues to refine the timeline of faunal change and environmental conditions in Asia during the Late Cretaceous.