Sambungmacan is an open site on the south bank of the Solo River in central Java. An adult Homo erectus calotte, Sambungmacan 1, was discovered in 1973. Two other crania, Sambungmacan 3 (Delson et al, 2000, 2001; Marquez et al., 2001) and 4 (Baba et al., 2003) have also been recovered, the former being purchased in a New York curio shop after it had been removed from Java without a permit (Delson et al., 2000). In common with the other Javan H. erectus localities, the dating of Sambungmacan is problematic. The site was originally thought to be of lower-middle Pleistocene age, but ESR, Ar/Ar and U-series dates have provided conflicting results (Swisher et al., 1996; Indriati et al., 2011).
In 1996 Swisher and colleagues reported ESR and U-series dates for both Sambugmacan and Nagandong (Santa Luca, 1980) of 27-53 ka, indicating the post-Toba survival of H. erectus in Java and the overlap of H. erectus and H. sapiens populations in Asia. One of the implications of this remarkably young date, was that it was extremely unlikely that Javan H. erectus was ancestral to Australasian H. sapiens, as claimed in the multiregional model (Thorne and Wolpoff, 1981) as anatomically modern H. sapiens were known to be in the region at 40-50 ka (Lake Mungo and Niah Cave). There was simply too little time for Java H. erectus to have evolved into modern human form, and the genetic (Rasmussen, et al., 2011), behavioural and hominin fossil (Herto, Aduma and Klassies River Mouth) evidence indicated that African H. sapiens predated Sambungmacan by ~100 ka (White et al. 2003; Haile-Selassie et al., 2004; Rightmire and Deacon, 1991).
Most recently, a team containing some of the original authors, have reported new 40Ar/39Ar, ESR and U-series dates for Ngandong, Sambungmacan and the faunal site of Jigar (Indriati et al., 2011). They argue that the different dating methods indicate an age in the range of 546-612 ka, placing these three sites in the Middle Pleistocene and significantly older than previous estimates. However, they caution that the ESR/U-series date that complies with all modeling criteria is ~143 ka, still considerably older than the 1996 estimate of 27-53 ka. While the new estimates are more consistent with what you would expect from Sangiran, I am not convinced that any of them provide an accurate age, or even a range of ages, for either Sambungmacan or Ngandong. The precise relationship between the depositional history of these deposits and the fossils that they contain remains unknown, and direct methods of dating fossils of this age are problematic (Yokoyama et al. 2008).
|craniometric data for LB1 H. floresiensis, H. erectus and H. habilis|
Durband AC. 2008. Mandibular Fossa Morphology in the Ngandong and Sambungmacan Fossil Hominids. The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology 291(10):1212-1220.
The results of reseach by Art Durband support the hypothesis that the morphology of the mandibular fossa is autapomorphic (a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group) in the fossil specimens from Ngandong and in Sambungmacan 1 and 3. These specimens are characterized by the loss of the postglenoid process and an squamotympanic fissure that runs along the apex of the roof of the mandibular fossa for its entire length. Despite recent reports to the contrary, this configuration has not been found outside the Ngandong/Sambungmacan sample. If this potential autapomorphy remains unfalsified, these late-surviving Indonesian hominins are unlikely to be ancestral to modern humans in Australasia.
Yokoyama Y, Falguères C, Sémah F, Jacob T, and Grün R. 2008. Gamma-ray spectrometric dating of late Homo erectus skulls from Ngandong and Sambungmacan, Central Java, Indonesia. J Hum Evol 55(2):274-277.
Hominid fossils from Ngandong and Sambungmacan, Central Java, Indonesia, are considered to be the most anatomically derived and youngest representatives of Homo erectus. Nondestructive gamma-ray spectrometric dating of three of these Homo erectus skulls showed that all samples underwent uranium leaching. Nevertheless, we could establish minimum age estimates of around 40 ka, with an upper age limit of around 60 to 70 ka. This means that the Homo erectus of Java very likely survived the Toba eruption and may have been contemporaneous with the earliest Homo sapiens in Southeast Asia and Australasia.
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Swisher, C.C., Curtis, T., Jacob, T., Getty, A.G., Suprijo, A., Widiasmoro, 1994. Age of the earliest known hominid in Java, Indonesia. Science 263, 1118-1121.
Swisher, C.C., Rink, W.J., Anton, S.C., Schwarcz, H.P., Curtis, G.H., Suprijo, A., Widiasmoro, 1996. Latest Homo erectus of Java: Potential contemporaneity with Homo sapiens in Southeast Asia. Science 274, 1870-1874.
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Yokoyama, Y., Falguères, C., Sémah, F., Jacob, T., Grün, R., 2008 Gamma-ray spectrometric dating of late Homo erectus skulls from Ngandong and Sambungmacan, Central Java, Indonesia. Journal of Human Evolution 55, 274-277.