Joshua Tree National Park: paleontological resources inventory

Tocci, Alaina; Santucci, Vincent; Tweet, Justin; Springer, Kathleen; Scott, Eric

Joshua Tree National Park: Paleontological Resources Inventory was created to synthesize information about the paleontology, geology, stratigraphy, and history of those studies in Joshua Tree National Park (JOTR) into a cohesive report to assist in compliance with laws, regulations, policy, and management guidelines of paleontological resources. This report is also intended to facilitate future research, management, curation, protection, and public interpretation of these resources at JOTR. The information in this inventory should be useful for bolstering and expanding JOTR’s current interpretive efforts regarding its paleontological resources, and can also inform other topics, including geology, climate, and the human history of the park. This inventory should also help to improve the visibility of these significant resources in JOTR planning and management. The content includes a detailed history of paleontological investigations in JOTR followed by a description of fossiliferous sedimentary formations found in the park and their faunal assemblages. The taxonomy of fossils found in JOTR is described, and a long-range interpretive plan and further recommendations are provided. The bedrock geology of JOTR is dominated by unfossiliferous igneous and metamorphic rocks formed during a series of tectonic events which took place over approximately 1.7 billion years. Fossils are confined to relatively small areas of sedimentary deposits, but have been found in abundance in some locations. The best record comes from the sediments of the informally named Pinto Formation, a lake unit from the time of the most recent ice age near the end of the Pleistocene Epoch, including a span of time approximately 25,000 to 16,500 years ago. Numerous vertebrate fossils have been found in these sediments, including bones and teeth of extinct Pleistocene megafauna such as mammoths, horses, camels, and llamas. Packrat middens preserved in protected rock shelters throughout the park overlap the Pinto Formation record. Together these records illustrate shifts in JOTR’s ecology and climate from cooler, wetter conditions to the present. In addition, some fossils have been found in older sediments, as old as approximately 8 million years. Fossils were first reported from what is now JOTR in 1935, a year before it was established. Paleontological investigations occurred occasionally within the park for several decades, including the investigations of George Jefferson beginning in the late 1960s and the investigations of Adella Schroth in the late 1980s and early 1990s. A more formal system of investigation began in 2000, heralded by a paleontological resources inventory scoping session in March 2000. Paleontologists from the San Bernardino County Museum conducted work from 2003 to 2015, and have continued their investigations after going to different institutions. The Pinto Formation in JOTR represents one of the most fossiliferous vertebrate assemblages in the region, and packrat middens collected in the park show a diverse plant community. These resources present a significant opportunity to study the paleoecology of southeast California from the Pleistocene to today and will be of great interest to the public. These paleontological resources are acknowledged in JOTR’s enabling legislation, legitimizing its study, curation, protection, and education. However, fast-paced erosion and fossil instability in the eastern Pinto Basin present long-term challenges to paleontological resource management at JOTR. Sustained efforts to document and collect specimens are necessary to preserve the quality of data and reveal biotic responses to environmental change that occurred throughout the late Quaternary.

Joshua Tree National Park: paleontological resources inventory

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