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Anna Holden aholden at amnh.org
Thu Nov 17 10:34:48 CST 2016


Would you please post the following message with the title "Anna Holden of the American Museum of Natural History is seeking entomologists interested in helping to identify insect fossils from the La Brea Tar Pits":

Hello, my name is Anna Holden (aholden at amnh.org<mailto:aholden at amnh.org>) and I am a PHD candidate from the American Museum of Natural History (http://www.amnh.org/our-research/staff-directory/students/anna-holden/<https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.amnh.org%2Four-research%2Fstaff-directory%2Fstudents%2Fanna-holden%2F&data=01%7C01%7Caholden%40amnh.org%7C7ca834737e614adfe7eb08d40e23f43b%7Cbe0003e8c6b9496883aeb34586974b76%7C1&sdata=Pv%2B1TYa3s2%2F%2FozOC7G7eQFER95RqYrA1jFErTY14rxs%3D&reserved=0>) and focus on insects from the La Brea Tar Pits as paleoenvironmental indicators.
Below is a link to a Flickr account that I have created of ~44,000k year old insects from a unique assemblage. These fossils are in near pristine preservation due to a rapid entrapment event that compacted this material into a camel (Camelops hesternus) skull. I created the account to showcase this material but also to gather help in its identification. This account is both for general interest in this fascinating view of insect history, but in hopes that some of you might find your research organisms showcased (especially beetles). I am interested in any comments that you may have on identifications and ecology.


Please also see a blog post on Dr. Kipling Will's website (UC Berkeley): https://pterostichini.wordpress.com/2016/11/14/enigmatic-la-brea-tar-pit-insect-fossils/<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpterostichini.wordpress.com%2F2016%2F11%2F14%2Fenigmatic-la-brea-tar-pit-insect-fossils%2F&data=01%7C01%7Caholden%40amnh.org%7C7ca834737e614adfe7eb08d40e23f43b%7Cbe0003e8c6b9496883aeb34586974b76%7C1&sdata=jW8GTzkR9ZTiO1xmcwOHcRUenbndQlhbm4B418DaLc8%3D&reserved=0><https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpterostichini.wordpress.com%2F2016%2F11%2F14%2Fenigmatic-la-brea-tar-pit-insect-fossils%2F&data=01%7C01%7Caholden%40amnh.org%7C7ca834737e614adfe7eb08d40e23f43b%7Cbe0003e8c6b9496883aeb34586974b76%7C1&sdata=jW8GTzkR9ZTiO1xmcwOHcRUenbndQlhbm4B418DaLc8%3D&reserved=0><https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpterostichini.wordpress.com%2F2016%2F11%2F14%2Fenigmatic-la-brea-tar-pit-insect-fossils%2F&data=01%7C01%7Caholden%40amnh.org%7C7ca834737e614adfe7eb08d40e23f43b%7Cbe0003e8c6b9496883aeb34586974b76%7C1&sdata=jW8GTzkR9ZTiO1xmcwOHcRUenbndQlhbm4B418DaLc8%3D&reserved=0>

Most fossils move around in the tar pits over time due to additional seepage, causing elements of quite different ages to mix. The camel skull was excavated in a tabular deposit (or tar pit) that indicated that the animal had been trapped and subsequently sealed off, and was thus unaffected by fluid movement within the asphalt. Radiocarbon dates of Clyde's skull and rib, and insect and plant contents resulted in relatively consistent dates, approximately 44,000 years old.
Remarkably, these fossil insects show minimal or no apparent asphalt impregnation after solvent preparation. The exquisite preservation of these specimens, often semi-articulated and indiscernible from modern material, also includes delicate ant wings and soft-bodied damselflies that would have degraded in extended periods in water or would have been saturated in asphalt under alternative depositional scenarios.
Most likely, a nearby water body served as a means to transport insect and plant material collected along stream or river margins into the skull, indicated by the type of sediment surrounding the asphalt deposit and the types of aquatic insects identified so far.
The unusual amount pigmentation and surface sculpture allows for more confident identifications. This a great opportunity to research and identify new groups at the tar pits.
All insect IDs at the tar pits this far, are extant with the exception of a scarab that is presumed to have specialized on the dung now-extinct megafuana. And except for widespread species, the majority still live in southern California, nearby, and the southwest.

Thank you,

Anna Holden
PhD Candidate
Richard Gilder Graduate School
Division of Invertebrate Zoology
American Museum of Natural History
Central Park West at 79th Street
New York, NY 10024

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