A trackway site in northern Mongolia, first reported in 1950 but lost to science for over seven decades, has finally been rediscovered, and it contains 31 enormous dinosaur footprints.
The Saizhurakh area in the country’s north had been insufficiently documented when first noted decades ago, leaving its coordinates effectively unknown.
Two parallel dinosaur trackways in the Saizhurakh area of northern Mongolia of large sauropods overlap and extend toward the upper left of the image, forming a series of large, oval-shaped depressions.
But the original documentation was too vague to pinpoint the location, and it remained effectively lost until its recent rediscovery.
Five Theropods at the Same Spot and the Questions That RaisesThe more unsettling part of the discovery involves theropods.
A trackway site in northern Mongolia, first reported in 1950 but lost to science for over seven decades, has finally been rediscovered, and it contains 31 enormous dinosaur footprints.
Mongolia is one of the least densely populated countries on Earth. Once outside Ulaanbaatar, the landscape stretches into near-infinite emptiness, which goes a long way toward explaining how footprints up to 70 centimeters long could simply vanish from scientific record. The Saizhurakh area in the country’s north had been insufficiently documented when first noted decades ago, leaving its coordinates effectively unknown. Its rediscovery has now opened a window into a world that existed roughly 120 million years ago.
The significance of this find extends well beyond the sheer spectacle of giant prints pressed into ancient mud. Prior to this discovery, giant dinosaurs had been documented in what is now China, Japan, and South Korea during the early Cretaceous, but their absence from Mongolia and eastern Russia had been a persistent and unexplained gap. Scientists could not rule out the possibility that extreme seasonal conditions, including bitterly cold winters in the northern interior, far from the sea’s moderating influence, had simply kept large dinosaurs away. These tracks suggest otherwise.
A Lake Floor Frozen in Deep Time
The prints were made in the Shinekhudag Formation, a geological layer of clay and sand deposited around 120 million years ago on the fluctuating floor of an ancient lake during the early Cretaceous period. When water levels dropped low enough, sand layers formed at the surface, and it was across these exposed flats that the animals passed, possibly in search of remaining water sources. The mud hardened around their steps and preserved them across geological time.
Two parallel dinosaur trackways in the Saizhurakh area of northern Mongolia 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 – © Journal Ichnos
The site, located in the Saizhurakh area, was first mentioned in a 1950 report, according to the study published in the journal Ichnos. But the original documentation was too vague to pinpoint the location, and it remained effectively lost until its recent rediscovery. What researchers found there surpassed expectations: 31 prints spread across two distinct types of trackways, belonging to very different categories of animals.
Two Sauropod Giants, Moving Together
Two of the trackways were made by sauropods, long-necked herbivores estimated to have been more than 15 meters, or about 49 feet, in length. The two animals appear to have been of similar size, and based on the overlap of their prints, one seems to have been following closely behind the other, a pattern that calls to mind the way herds of elephants move in single file.
Impressive Twin Sauropod Dinosaur Models Standing in Arid Prehistoric Landscape – © zorotoo’s Images / Canva
The conditions that preserve footprints and bones are not always the same, and the two do not necessarily occur together at the same site. However, the scientists who made the rediscovery noted the presence of nearby gravel-bearing sand layers, which they believe might contain bones or teeth belonging to the very animals that left these tracks, a prospect that could significantly deepen what is already a remarkable record.
Five Theropods at the Same Spot and the Questions That Raises
The more unsettling part of the discovery involves theropods. According to the study, there are suspected tracks from five of them, with the animals estimated to have been between 7.4 and 8.8 meters, roughly 24 to 29 feet, in length, based on the size and spacing of their footprints. Only one of the five trackways is considered definitive, but the implication of five large carnivores walking the same patch of ground, likely on the same day before the mud hardened, raises questions as large as the animals themselves.
Ecosystems cannot sustain too many large predators simultaneously. The largest of the theropods left a footprint 57 centimeters long. As IFLScience reported, the directions in which the different theropods were moving appear to be random rather than coordinated, which makes a hunting-pack explanation unlikely. The researchers suggest instead that some rich feeding opportunity drew all of them independently to the same location.
North America had well-documented large theropods during this same early Cretaceous period, and it was already known that many dinosaur species were moving between Asia and North America at the time, making their presence in east Asia plausible, if previously unconfirmed this far north.
