In North America, the earliest dog remains were found in Lawyer’s Cave on the Alaskan mainland east of Wrangell Island in the Alexander Archipelago of southeast Alaska, radiocarbon dating indicates 10,150 YBP. A genetic-based estimate indicates that this dog's lineage had split from the Siberian Zhokhov Island dog lineage 16,700 YBP. This timing coincides with the suggested opening of the North Pacific coastal route into North America. Stable isotope analysis can be used to identify some chemical elements, allowing researchers to make inferences about the diet of a species. An isotope analysis of bone collagen indicates a marine diet. The next earliest dogs were found in Illinois and radiocarbon dating indicates 9,900 YBP. These include three isolated burials at the Koster Site near the lower Illinois River in Greene County, and one burial 35 km away at the Stilwell II site in Pike County. These dogs were medium-sized adults around in height and around in weight, with very active lifestyles and varied morphologies. Stable isotope analysis indicates a diet consisting largely of freshwater fish. Similar dog burials across Eurasia are thought to be due to the dog's importance in hunting to people who were trying to adapt to the changing environments and prey species during the Pleistocene-Holocene transition. In these places, the dog had gained an elevated social status.