First hominin fossils recovered from submerged Sundaland
Sandee Oster
contributing writer
Lisa Lock
scientific editor
Robert Egan
associate editor
The Sunda Shelf is home to a rich Pleistocene hominin fossil record, including specimens of Homo floresiensis, Homo luzonensis, Homo erectus, and archaic Homo. Much of the Sunda Shelf is submerged. At times during the Pleistocene, however, the shelf was exposed, forming the large landmass known as Sundaland.
Knowledge about the rich and complex evolutionary and migratory history of the hominins that once lived there is hampered by large swaths of the Sundaland landmass being submerged today.
Dr. Harold Berghuis and his colleagues recently had the opportunity to examine fossils that had been dredged as part of a construction project. Among the fossils, they found the first ever hominin remains from submerged Sundaland, and one of them belonged to H. erectus. Their study is in the journal Quaternary Environments and Humans.
In 2014 and 2015, the port company Berlian Manyar Sejahtera (BMS) commissioned the development of an artificial island for cargo handling.
In the process, they dredged more than 5 million m3 of sand to build a 100-hectare island. During later inspection of the artificial island, vertebrate fossils were noted—in total, 6,732 specimens were recovered.
In the past decade, the extraction site has been the subject of various geological studies. During this time, a number of deep drillings have been made, which make it possible to reconstruct the geological setting of the underwater sand extraction site.
In addition to these two, OLS dates were taken from fluvial sandstone, yielding ages of 162 ± 31 and 119 ± 27 ka. This places the extraction site within Marine Isotope Stage 6.
Dr. Berghuis explains how they were able to determine that the fossils came from the specific MIS6 valley fill rather than being reworked from older deposits.
"Fluvial reworking of fossils from older deposits is always something that must be considered. But in this particular setting, there are several indications that this has not been the case.
"One: We are looking at large-scale valley systems in a lowland setting. The downcutting and infilling of these valleys were primarily controlled by the large amplitude Middle Pleistocene sea-level fluctuations. This is much different than the inland setting of Java, where incision and sedimentation are much more intricate and variable processes, controlled by the combined effects of local tectonism, volcanic supply, developing local drainage systems, and sea-level fluctuations.
"Two: The submerged valley reaches a depth of 50 m below sea level, whereas we only dredged down to 32 m below sea level. This implies that we stayed far above the basal conglomerates of the valley.
"Three: uniform state of mineralization and the absence of rounding do not point to a heterogeneous background or extensive transport. However, I admit that this last point is certainly not decisive. I would say one and two are most convincing."
It seems that during the MIS6, the area was home to various species, including Stegodon trigonocephalus, Duboisia santeng, Epileptobos groeneveldtii, and Axis lydekkeri, indicating a dry and open landscape.
Among the fossil finds were also two hominin fossils, Madura Strait 1 and 2 (MS 1 and 2).
To determine the species from which they came, Dr. Berghuis's team compared the fossils to various other specimens, including H. erectus species from China and Java from different time periods, H. floresiensis, and archaic Homo.
They found that MS1 was morphologically most similar to the late Middle Pleistocene Javanese Homo erectus (140–92 ka).
While MS2 could not be identified to species, it was most similar to archaic Homo.
The two fossils are the first ever hominin fossils from submerged Sundaland and demonstrate that Homo erectus populations extended beyond Java onto the exposed lowland plains during the Middle Pleistocene.
It is likely that other hominin populations migrated south in a similar manner; however, limited fossil evidence complicates the understanding of the evolution and migration of these species. It is likely that more fossils are to be found on the submerged Sundaland seabed.
However, getting a hold of fossils from the seabed is expensive and typically can only be done for construction work, explains Dr. Berghuis. "Extracting seabed sand is very expensive. You will only get this done for construction work. So, the only thing we can do is keep in good contact with the local port authorities and with developers.
"There may, of course, one day be a new sand extraction work scheduled here, or in a nearby site. It is essential that paleontologists will, in that case, be involved."
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More information: H.W.K. Berghuis et al, The late Middle Pleistocene Homo erectus of the Madura Strait, first hominin fossils from submerged Sundaland, Quaternary Environments and Humans (2025).
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