Roy Larick

Early Pleistocene 40Ar/39Ar ages for Bapang Formation hominins, Central Jawa, Indonesia

The Sangiran dome is the primary stratigraphic window for the Plio-Pleistocene deposits of the Solo basin of Central Jawa. The dome has yielded nearly 80 Homo erectus fossils, around 50 of which have known findspots. With a hornblende 40Ar/39Ar plateau age of 1.66 ± 0.04 mega-annum (Ma) reportedly associated with two fossils [Swisher, C.C., III, Curtis, G. H., Jacob, T., Getty, A. G., Suprijo, A. & Widiasmoro (1994) Science 263, 1118–1121), the dome offers evidence that early Homo dispersed to East Asia during the earliest Pleistocene. Unfortunately, the hornblende pumice was sampled at Jokotingkir Hill, a central locality with complex lithostratigraphic deformation and dubious specimen provenance. To address the antiquity of Sangiran H. erectus more systematically, we investigate the sedimentary framework and hornblende 40Ar/39Ar age for volcanic deposits in the southeast quadrant of the dome. In this sector, Bapang (Kabuh) sediments have their largest exposure, least deformation, and most complete tephrostratigraphy. At five locations, we identify a sequence of sedimentary cycles in which H. erectus fossils are associated with epiclastic pumice. From sampled pumice, eight hornblende separates produced 40Ar/39Ar plateau ages ranging from 1.51 ± 0.08 Ma at the Bapang/Sangiran Formation contact, to 1.02 ± 0.06 Ma, at a point above the hominin-bearing sequence. The chronological sequence of 40Ar/39Ar ages follows stratigraphic order across the southeast quadrant. An intermediate level yielding four nearly complete crania has an age of about 1.25 Ma.

Way out of Africa: Early Pleistocene paleoenvironments inhabited by Homo erectus in Sangiran, Java

A sequence of paleosols in the Solo Basin, Central Java, Indonesia, documents the local and regional environments present when Homo erectus spread through Southeast Asia during the early Pleistocene. The earliest human immigrants encountered a low-relief lake-margin landscape dominated by moist grasslands with open woodlands in the driest landscape positions. By 1.5 Ma, large streams filled the lake and the landscape became more riverine in nature, with riparian forests, savanna, and open woodland. Paleosol morphology and carbon isotope values of soil organic matter and pedogenic carbonates indicate a long-term shift toward regional drying or increased duration of the annual dry season through the early Pleistocene. This suggests that an annual dry season associated with monsoon conditions was an important aspect of the paleoclimate in which early humans spread from Africa to Southeast Asia.

Lithostratigraphic Context for Kln-1993.05-SNJ, a Fossil Colobine Maxilla from Jokotingkir, Sangiran Dome

Jablonski and Tyler (1999) announced a new subspecies of colobine monkey based on a fossil partial maxilla from the Sangiran dome. The specimen is easily assigned to a living leaf monkey species—most extant Southeast Asian catarrhines differ only subspecifically from their Middle Pleistocene earliest local fossil ancestors. Yet Jablonski and Tyler (1999) reported an improbable provenance for the specimen; a mass-flow volcanic breccia generally considered late Pliocene in age. We show that the Lower Lahar was laid down amidst a range of paludal habitats and that its deposition predates the appearance of all-but-now extinct, water-tolerant mammals on emergent Java. No other catarrhine fossil has been ascribed to the Lower Lahar, not even hominins, which are the most gregarious members of the group. More probable provenance lies in the upper Sangiran or the lower Bapang formations. Either alternative would associate the specimen with other catarrhine fossils in more tenable Pleistocene environments. We also unravel errors and inconsistencies in the contextual report and in the discussion of dome geochronology. The various radiometric, paleomagnetic, and paleontologic studies cited show a discordance of about 300 Ka (thousand years) across the lithostratigraphic sequence. Plio-Pleistocene biogeographic hypotheses for Java must work with short and long chronologies.

Early Hominin Biogeography in Island Southeast Asia

The above article from Evolutionary Anthropology, published on 19 October 2015 in Wiley OnlineLibrary (www.onlinelibrary.wiley.com), and in Volume 24, Number 5, pp. 185‐213, has been retracted by Wiley Periodicals, Inc. The retraction has been made due to the inclusion without explicit permission of unpublished third‐party research data disclosed to the authors in personal correspondence. The Editor notes that the journal has since clarified its policy on citing unpublished research findings, and in particular those disclosed in personal correspondence, to avoid future instances of this nature.

Retracted: Early hominin biogeography in Island Southeast Asia: Early Hominin Biogeography in Island Southeast Asia

The above article from Evolutionary Anthropology, published on 19 October 2015 in Wiley OnlineLibrary (www.onlinelibrary.wiley.com), and in Volume 24, Number 5, pp. 185‐213, has been retracted by Wiley Periodicals, Inc. The retraction has been made due to the inclusion without explicit permission of unpublished third‐party research data disclosed to the authors in personal correspondence. The Editor notes that the journal has since clarified its policy on citing unpublished research findings, and in particular those disclosed in personal correspondence, to avoid future instances of this nature.

Retracted: Early hominin biogeography in Island Southeast Asia

The above article from Evolutionary Anthropology, published on 19 October 2015 in Wiley OnlineLibrary (www.onlinelibrary.wiley.com), and in Volume 24, Number 5, pp. 185‐213, has been retracted by Wiley Periodicals, Inc. The retraction has been made due to the inclusion without explicit permission of unpublished third‐party research data disclosed to the authors in personal correspondence. The Editor notes that the journal has since clarified its policy on citing unpublished research findings, and in particular those disclosed in personal correspondence, to avoid future instances of this nature.