James L. Bischoff

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Seventeen Middle Pleistocene crania from the Sima de los Huesos site (Atapuerca, Spain) are analyzed, including seven new specimens. This sample makes it possible to thoroughly characterize a Middle Pleistocene hominin paleodeme and to address hypotheses about the origin and evolution of the Neandertals. Using a variety of techniques, the hominin-bearing(More)
Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies, including microspherules, nanodiamonds, and iridium. Distributed across four continents at the Younger Dryas boundary (YDB), spherule peaks have been independently confirmed(More)
It has been proposed that fragments of an asteroid or comet impacted Earth, deposited silica- and iron-rich microspherules and other proxies across several continents, and triggered the Younger Dryas cooling episode 12,900 years ago. Although many independent groups have confirmed the impact evidence, the hypothesis remains controversial because some groups(More)
We report the discovery in Lake Cuitzeo in central Mexico of a black, carbon-rich, lacustrine layer, containing nanodiamonds, microspherules, and other unusual materials that date to the early Younger Dryas and are interpreted to result from an extraterrestrial impact. These proxies were found in a 27-m-long core as part of an interdisciplinary effort to(More)
Hominid remains found in 1994 from the stratified Gran Dolina karst-filling at the Atapuerca site in NE Spain were dated to somewhat greater than 780 ka based on palaeomagnetic measurements, making these the oldest known hominids in Europe (sensu stricto). We report new ESR and U-series results on teeth from four levels of the Gran Dolina deposit which(More)
This paper presents a multidisciplinary study on the size of the occupied surfaces, provisioning strategies and behaviour planning at the Romani rock-shelter, using the Middle Palaeolithic record of the level i. This level is dated around 46.000 BP through U/Th ages. A behavioural interpretation is proposed, which emphasises the activities and the systemic(More)
dO, dC, total organic carbon, total inorganic carbon, and acid-leachable Li, Mg and Sr concentrations on 443 samples from 32 to 83m depth in Owens Lake core OL-92 were analyzed to study the climatic and hydrological conditions between 60 and 155 ka with a resolution of B200 a. The multi-proxy data show that Owens Lake overflowed during wet/cold conditions(More)
Geochemical parameters of sediments from drill hole OL'92 indicate that Owens Lake was saline, alkaline, and highly productive during interglacial periods, and was hydrologically open and relatively unproductive during glacial periods. Abundance of C-aCOr, otganic carbon, and cation-exchange capacity of the clay fraction show cyclic variation down the core.(More)
Sediments of the Sima de los Huesos vary greatly over distances of a few meters. This is typical of interior cave facies, and caused by cycles of cut and fill. Mud breccias containing human bones, grading upwards to mud containing bear bones, fill an irregular surface cut into basal marks and sands. The lack of Bedding and the chaotic abundance of fragile(More)
Uranium series analyses of human bone samples from the Del Mar and Sunnyvale sites indicate ages of 11,000 and 8,300 years, respectively. The dates are supported by internal concordancy between thorium-230 and protactinium-231 decay systems. These ages are significantly younger than the estimates of 48,000 and 70,000 years based on amino acid racemization,(More)