Oldest Dinosaur Tracksite In Northeast Asia Discovered: Evidence Shows Large Dinosaurs Ranges As Far As Northern Mongolia 120 Million Years Ago

 Two parallel trackways of large sauropods overlap and extend toward the upper left of the image, forming a series of large, oval-shaped depressions. The overlapping pattern indicates that one individual followed the exact path of another. Also visible on the same bedding surface are five trackways of large theropods, preserved as distinct three-toed footprints. The co-occurrence of both herbivorous sauropod and carnivorous theropod tracks on a single surface provides clear evidence of a shared habitat in northern Mongolia during the Early Cretaceous. CREDIT: Okayama University of Science

 April 26, 2026 

By Eurasia Review

An international research team consisting of scientists from the Institute of Paleontology, Mongolian Academy of Sciences (IP-MAS), the National University of Mongolia (NUM), and Okayama University of Science (OUS) has rediscovered a dinosaur tracksite in the Saizhurakh area of northern Mongolia. The site was originally reported about 70 years ago but had since been lost due to a lack of detailed documentation and follow-up investigation. The team conducted the first comprehensive study of the site.

Their findings revealed that footprints of both large herbivorous dinosaurs (sauropods) and large carnivorous dinosaurs (theropods) are preserved on the same bedding surface. This provides clear evidence that large dinosaurs inhabited regions as far north as northern Mongolia.

On April 2, Dr. Shinobu Ishigaki, Honorable Director of the Museum of Dinosaur Research at OUS, and Masato Fujita, Professor in the Department of Dinosaur Paleontology, announced the findings at a press conference held at the university.

Mongolia is one of the world’s top five countries for dinosaur fossil discoveries. However, most fossils come from the Late Cretaceous period (approximately 70–90 million years ago). Fossils from the Early Cretaceous (around 100–120 million years ago) are relatively scarce and consist mainly of small- to medium-sized dinosaurs such as Harpymimus, Psittacosaurus,Zavacephale, and Choyrodon. Furthermore, no definitive dinosaur tracksites from the Early Cretaceous had previously been confirmed in Mongolia.

Even at the Saijrakh site, a Mongolian geographer reported the “discovery of dinosaur footprints” in a brief two-page account about 70 years ago. However, the report lacked detailed descriptions and precise locality, and the site remained uninvestigated and effectively lost.

In 2024, a joint expedition by IP-MAS and OUS set out to relocate the site and conduct a detailed scientific investigation. With the assistance of local residents, the team successfully identified the location and discovered footprints of large theropods and sauropods. A more detailed paleontological and geological study was carried out in 2025.

The site is underlain by the Shinekhudag Formation, consisting of sediments deposited in a large lake during the Early Cretaceous (approximately 120 million years ago). Thin sand layers are occasionally interbedded within fine black clay deposited on the lake floor. These sand layers are thought to have formed during periods when the lake level dropped. The dinosaur tracks were likely made when such sandy surfaces were exposed above the water, allowing dinosaurs living in the area to walk across them.

Around 120 million years ago, Earth experienced a warm climate, and the rapid diversification of flowering plants was transforming ecosystems. During this time, dinosaurs from Asia were dispersing into North America. Mongolia represents a key region for comparing faunal assemblages between East Asia and North America; however, the scarcity of Early Cretaceous fossils has long posed a challenge for reconstructing ecological transitions between these regions. This new discovery demonstrates that large sauropods and theropods inhabited Mongolia during the Early Cretaceous and will significantly contribute to studies of ecosystem evolution linking Far Eastern Russia, North America, and East Asia—including China, South Korea, and Japan

A total of 31 dinosaur footprints were identified at the site. These include trackways from two large, long-necked and long-tailed sauropods (herbivorous dinosaurs exceeding 15 meters in length) and five large theropods (carnivorous dinosaurs exceeding 8 meters in length).

The two sauropods were similar in size, with hind footprints measuring approximately 70 cm in length. Their trackways largely overlap, indicating that one individual walked first and another followed along nearly the same path at a slightly slower pace. This type of behavior—where one animal follows the tracks of another—is also observed in modern elephants.

The forelimb impressions preserve both a primitive feature—a medially projecting first digit (thumb) claw—and a derived feature in the form of soft tissue pads. The trackways show a wide gauge, indicating a broad, outward stance during locomotion. These characteristics suggest that the tracks were made by titanosauriform sauropods.

The largest theropod footprint measures up to 57 cm in length. The toes are widely splayed, and the directions of 5 trackways appear random, with no evidence of gregarious behavior. While evidence of large predators from this period has been found in China, South Korea, and Japan, such evidence has been lacking in Mongolia and eastern Russia. This discovery therefore demonstrates that large theropods had expanded their range into northern Mongolia.

The body lengths of the sauropods and theropods are estimated to exceed 15 meters and 8 meters, respectively.

Near the tracksite, gravel-bearing sand layers have also been identified. Future investigations may lead to the discovery of skeletal remains of the track-making dinosaurs. The research team plans to continue exploring such fossils and to conduct detailed surveys of surrounding outcrops in search of additional tracksites.