Roca dels Bous (archaeological site) interesting archaeological site indeed. Furthermore, it is to be noted that the samples used for the 14C AMS dating were obtained from deep strata at the site. The oldest Neanderthal sites known in the nearby areas date back to around 40,000 BP. The first settlements attributed to “anatomically modern” Homo sapiens sapiens in Northern Spain are dated around 39,000-38,000 BP. All this would suggest that Neanderthals could have persisted in this particular area longer than previously believed, preceding the arrival of the first Homo sapiens to the area. Research work began in 1988. This wide period of time has contributed
Reference materials for stable isotope analysis N (Böhlke "et al.," 2003). USGS-34 is useful because it allows researchers to directly measure the N/N of NO in natural samples against the standard and report observations relative to N without having to first convert the sample to N gas. Primary, calibration, and reference materials are only available in small quantities and purchase is often limited to once every few years. Depending on the specific isotope systems and instrumentation, a shortage of available reference materials can be problematic for daily instrument calibrations or for researchers attempting to measure isotope ratios in a large number of natural samples. Rather than