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What have we unearthed this week? How's the preparation of Zed, the Columbian mammoth, going? Do the excavators ever wash their clothes?
For answers to these questions and many more, please check out our frequently updated excavation blog, The Excavatrix.
Zed is the nickname given to the first near-complete, semi-articulated skeleton of a Columbian mammoth (Mammuthus columbi) from Rancho La Brea (RLB), and is one of the biggest fossil finds from Project 23. Zed is of particular interest for a number of reasons:
His size and the width of his teeth tell us he was a male, and wear patterns on his teeth suggest that he was between 48 and 50 years old when he died. He features typical preservation by asphalt saturation. However, for the first time at Rancho La Brea, we've found permineralization (replacement of bone by minerals) on several of his ribs and on part of his right humerus. Thus far, there is no evidence of carcass scavenging.
Paleontologists in the Fishbowl Lab are opening the plaster jackets that encase Zed's bones and are preparing them in view of the public. Plaster jackets are an unusual sight at Rancho La Brea — usually the fossils arrive in the lab with most of their matrix (dirt) already removed. Zed gives lab staff and volunteers an exciting opportunity to excavate. Most of the matrix surrounding Zed's bones can be removed with dental picks and brushes; however, some bones contain a harder matrix and they require the use of small pneumatic tools like zip scribes.
Of the thousands of microfossils recovered from Zed's matrix, freshwater molluscs are the most common. This taphonomic evidence suggests a rapid burial, inaccessible to scavengers along a large stream channel.
Preparation of Zed's bones began in September of 2008 and is expected to continue into 2010. Elements prepared thus far include Zed's lower jaw, pelvis, right humerus, left femur, several sections of vertebrae, and most of his ribs. Eventually we hope to place his skeleton on display, but as yet there are no definite plans. For the latest on Zed, please visit the excavators' blog, The Excavatrix.