CHRONOLOGY AND SPATIAL DISTRIBUTION OF LARGE MAMMAL BONES IN PIT 91, RANCHO LA BREA

摘要: The Rancho La Brea tar pits represent a collection of Pleistocene fossils from an unusual sedimentary environment. A taphonomic analysis single seep, Pit 91, reveals complex history deposition and diagenesis for specimens found there. Radiometric dating 46 bones 91 documents at least two episodes deposition, one 45,000 to 35,000 yr another, shorter interval 26,500 23,000 yr. Interestingly, the law superposition was not upheld consistently in this case study, as some younger were greater depth than older bones, implying that time averaging took place. Bones are distributed disarticulated elements large concentrations span both depositional episodes. In general, long oriented horizontally, with little or no preference cardinal orientation. Degree weathering abrasion is correlated depth. Bone-on-bone contact (pit wear), however, increases depth, suggesting possible compaction through time. These results, combined disarticulation common nearly all recovered specimens, suggest postentrapment journey unique asphalt deposits.