Deep beneath the sea, off the coast of Indonesia, a discovery is challenging long-held beliefs about early human life in Southeast Asia, said a report by the Daily Galaxy.

In a stretch of ocean between the islands of Java and Madura, scientists have uncovered the remnants of what they describe as the first underwater hominin fossil site ever found in the region. What they believe they’ve found is more than a collection of fossils—it may be the first physical evidence of the prehistoric continent known as Sundaland, a landmass that once connected much of Southeast Asia during the Pleistocene epoch.

The discovery centers around two skull fragments identified as belonging to Homo erectus, an early ancestor of modern humans. According to ScienceDirect, The bones, buried for more than 140,000 years beneath layers of silt and sand, were recovered from the Madura Strait during marine sand mining operations in 2011. But it wasn’t until recently that researchers, led by archaeologist Harold Berghuis from the University of Leiden in the Netherlands, confirmed the age and species of the remains.

A Chance Find Yields Thousands of Fossils

The breakthrough came as workers near Surabaya, the provincial capital of East Java, were dredging sediment from the seabed. During reclamation activities, they discovered fossilized remains that included over 6,000 specimens of vertebrates. The site, preserved by the dense accumulation of sand and marine deposits, revealed a surprising array of species: Komodo dragons, buffalo, deer, and a now-extinct genus of elephant-like herbivore known as Stegodon, which once stood more than 13 feet tall.

Among the remains were two human skull fragments—one frontal, one parietal. Their morphology closely resembled Homo erectus fossils previously found at the Sambungmacan site in Java. The fossils were dated using Optically Stimulated Luminescence (OSL), a method that determines when sediment was last exposed to sunlight. Researchers concluded the valley and its contents date to between 162,000 and 119,000 years ago.

In addition to the skeletal remains, geological analysis revealed the buried outline of a river system once part of the ancient Solo River, which likely flowed eastward across what is now the Sunda Shelf. According to sedimentary records, this river supported a vibrant fluvial ecosystem during the late Middle Pleistocene. The valley where the fossils were found had once been home to a diverse mix of herbivores and predators, including species of deer whose bones and teeth were found scattered throughout the area.

These details provide rare insight into a region that was eventually submerged by rising sea levels between 14,000 and 7,000 years ago. Scientists estimate that melting glaciers from the last Ice Age raised ocean levels by over 120 meters, drowning the low-lying plains of Sundaland and severing the connections between the Southeast Asian mainland and its islands.

Further analysis of the animal bones revealed distinct cut marks—evidence, researchers say, of deliberate butchery. These markings suggest that early hominins in the region employed tools to hunt and process large animals. “This period is characterized by great morphological diversity and mobility of hominin populations in the region,” Berghuis said. The findings indicate that the ancient population adapted to their environment using relatively advanced techniques for the time.

Fossils of antelope-like species, which generally prefer open grasslands, support the idea that this submerged landscape resembled a savanna more than a dense jungle. The presence of large herbivores and deer further suggests that the area provided ample food sources for both animals and early humans.

The skull fragments recovered from the Madura Strait extend the known range of Homo erectus in Southeast Asia. These early humans are known for their taller, more upright stature, longer legs, and shorter arms—features that brought them closer to modern human proportions. Their presence in Sundaland offers new perspectives on early human migration and adaptation across the region’s shifting landscapes.

What began as an accidental discovery by sand miners has become a pivotal moment in the study of early human history in Asia. By combining archaeological, geological, and paleoenvironmental methods, researchers are uncovering a lost chapter of human evolution—one that has remained hidden beneath the sea for millennia.