NH Notes: An Ancient Jawbone Found By Fishermen off the Coast of Taiwan

From a net pulled out of the ocean doesn’t seem a likely place to find an ancient human fossil.  But by scraping the bottom of the ocean,Taiwanese fishermen have been pulling up all sorts of unusual items in addition to their targeted prey.  Like some trawlers off the cost of Great Britain these fishermen have been selling or giving their odd finds away to local collectors (see my post Fishing for Fossils in the North Sea: Searching for the Lost World of Doggerland) .  Of the hundreds of fossils that have made their way from a collector back into the hands of researchers one stands out as especially interesting. This item is one half of the mandible of an archaic human being.  Researchers have spent five years examining this specimen and have now published their results (The first archaic Homo from Taiwan).  A summary of the results can be found here.

The jaw with a few teeth is quite unusual. It is much more robust with larger teeth than any modern humans.  The scientists spent considerable effort to try to date this fossil with little success. Minerals in the sea and lack of collagen meant that most forms of radiometric dating were not useful.  Despite variable results, the dating methods suggested at least that the mandible could be quite old (maybe 200,000 years).

But what about the location that this jaw was found.  Couldn’t this just be the jawbone of someone who fell over the side of ship or washed out to sea in a tsunami?  The researchers feel quite confident that this bone originated near the site that it was found and was from a hominid that was on dry land at the time. The reason is that hundreds of other fossils from the same area have been dredged up. These include many extinct hyenas, horses, elephants, bears and panthers. All of these bones are from long extinct species that existed at a time when the sea level was much lower.  Below is screenshot of Google maps showing Taiwan and southeast China. The ocean between the two is only 150 to 300 feet deep. During ice ages this area would have been dry land and the fossils buried in soils below this sea are a testimony to that time. There are too many dredged fossils to be explained by animals being swept from shore to a watery grave. The simpler explanation for this interesting set of fossils is they represent the remains of community of organisms that lived on the land between China and Taiwan in the past.

To have survived this long it could be that the bone came to be fossilized by being buried while still on land and ocean currents have now eroded the material above the bone making it possible for bottom trawlers to scrape up this bone out of the ground.  However this bone and the bones of other animals came to be preserved they are a source of new data for those interested in reconstructing past conditions in this part of the world.

References:

Chang et al., 2015.  Nature Communications.  The first archaic Homo from Taiwan.

Tseng, Z. J. & Chang, C.-H. A study of new material of Crocuta crocuta ultima (Carnivora: Hyaenidae) from the Quaternary of Taiwan. Collection Res. 20, 9–19 (2007).