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July 14, 2010
Posted by Dan Pickering
The dawning of a new project in PaleoLab….
Our vast collection of fossils is visited quite regularly by scholars intent upon gaining some new insight or reinforcing an existing one. By studying these old bones they can collect data upon which to test hypotheses, develop understanding, and draw conclusions. Some of our fossils are very fragile, so we need to assure that researchers can come here to study our fossils without there being any risk of damage while handling them.
Our precious sauropod skulls—Apatosaurus, Dipplodocus, and Camarasaurus, much in demand by researchers—are in need of new study/storage mounts. Customized cradles made for these delicate skulls enable us to secure their continued existence for those insights yet to come!
Preparator Dan Pickering works on the Apatosaurus skull
These are some of our greatest treasures here at Carnegie Museum. Not very many sauropod skulls have been found. They are so delicately constructed that they don’t tend to survive the millions of years between life and their re-emergence as fossils. Factors such as scavengers at the time of death, surging flood waters at time of burial, accumulating layers of earth crushing the bones over time, and erosion and exposure to the elements just prior to discovery all conspire to limit the number of skulls available.
This time of caretaking also gives me the opportunity to refurbish and refine the prior preparation work that has been performed on the Apatosaurus skull over the years.
The tools we use are very delicate, dental types...no heavy vibrations! Maybe at times a lightweight air scribe will be used (mini jackhammer), but we mostly use hand tools.
Views of the Apatosaurus skull. Note the CAT scans near the fossils. We use this contemporary technology as a way to aid in accurate restoration. These images help us to better distinguish the bone from the encasing rock.
The whole restoration process involves many stages. First comes stabilization of
the cracks and reattaching the snout with glue, putty, and a unifying surface skim of tinted plaster. We use tools to more clearly define the margins between the actual bone and the surrounding rock, removing old restorations that covered surface bone. We then give a uniform appearance to the rock left in place. The differing materials of the previous restorations battled each other and were visually distracting. All fossil restorations using non-real bone material should have the same plain look. We don’t want to confuse the scientists with restored bits on research specimens like this, but certain delicate sections need some support in order to remain intact.
Another problem is that these old restorations were at times made to look too much like the real bone. It’s not good if we as scientists can not tell where the real ends and the fake begins. We don’t want to obscure Mother Nature’s work and distract from “just the facts."
Next, cradles will be constructed like two halves of a big sandwich bolted together along a common edge so the specimen can be flipped over easily and safely, never lifting or stressing the actual fossil. The end goal here is to create a lightweight, rigid yet cushioned “sandwich “ around the skulls so that they can be manipulated without handling the actual bones.
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