PaleoLab

Project: Stegosaurus

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January 22, 2007 05:10 PM
posted by Lauren Stevens

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Dan working on Cervical Vertebrae

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Dan working on Cervical Ribs

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Allen working on Ribs

December 06, 2006 03:24 PM
posted by Lauren Stevens

All that is left on the mount is the pelvis. It is much too big of a project for us to tackle here at the museum so we have contracted Phil Fraley's crew to come in and take it down for us. They have rigged up an incredible system using the bone hoist and cables to support the heavy bone. They then slipped a beautifully built platform underneath the pelvis that was secured to the pole. The pole was then cut and the pelvis was slowly lowered to the ground and then rolled into PaleoLab to await stripping and restoration.

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November 12, 2006 04:35 PM
posted by Lauren Stevens

While working on the ribs we discovered many adjustments the previous preparators made when originally mounting the skeleton that we had to correct for. You can see how these "adjustments" really altered the original anatomical positioning of the fossils or added quite a bit of unnecessary length to the rib. We were extremely amazed at how often we came across this problem. We commonly found that if we removed the plaster between a break point that we would find a true contact surface. This took a lot of work and even more patience. After removing these plaster sections with our airscribes the ribs would sometimes be in 10 or more pieces that we would have to carefully glue together at the correct angle and then fill the gaps with epoxy resin. This is very difficult to do since the ribs are so long, heavy, and curve and a strange angle.

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Right Ribhead 11 with plaster added

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Right Ribhead 11 without the plaster added; in correct anatomical position

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Right Ribhead 6 with plaster added

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Right Ribhead 6 with plaster removed; in correct anatomical position

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Epoxy recontructed rib end added to rib head incorrectly (Rib 1)

October 30, 2006 04:06 PM
posted by Lauren Stevens


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Ribs wrapped in cellaphane

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Ribs attached with plaster and epoxy resin

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Rib attached to armature with screw

October 14, 2006 02:28 PM
posted by Lauren Stevens

As we continue to work on Stegosaurus, many other aspects to the project have begun. We have had to make sure that we are thorough with our labeling, both on the specimen and on the armature, so that we will not confuse our skeletal elements and we will know exactly where they belong on the mount and were the different pieces of armature meet. We use office white out for this because it can easily and safely be removed from the fossils and write on it with permanent marker - surprisingly with a little touch of acetone it is not so permanent and washes right off!

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Lauren and Allen labeling the feet Stegosaurus

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Lauren labeling feet of Stegosaurus

Over the years many many layers of shellac and brown paint have been applied to the specimen, and many times before the dust has even been cleaned off. In efforts to restore and conserve the specimen, this all must be removed. We do this by soaking pieces of cheesecloth in denatured alcohol and then apply it to the fossil. We cover it with aluminum foil to prevent evaporation of the alcohol and let it sit for at least 15 minutes. We then gently scrub the saturated surface with a tooth brush to remove the shellac. We repeat as necessary, sometimes 6 or 7 times. This takes a lot of time and a lot of work, especially since this is such a large dinosaur, and we are very grateful for all of the hard work and time our volunteers have dedicated to helping with this project. Thanks everyone!

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skeletal elements ready to be stripped in the fumehood

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Daniel Anaya stripping skeletal elements in the funehood


October 03, 2006 02:45 PM
posted by Lauren Stevens

The dismantling of Stegosaurus is well on its way! We have successfully removed its head and neck, dorsal plates and spikes, tail, scapula, chevrons, and feet. The work is slow as we have to be extremely careful not to break any of the bones or to hurt ourselves in the process. These bones are extremely heavy (the plates weigh up to 50 lbs each and the scapula is close to 100 lbs!) and delicate (65 years of being mounted and fighting gravity has caused many breaks and cracks). As more and more bones come off, the mount has become top heavy and causes the specimen to wobble back and forth. This is very dangerous and are we worried that the fossils will break, fall, and shatter. We have added support to the mount with a series of cable wires that hold it all in place and have wrapped all of the ribs in cellophane to hold them together in the event they break.

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We first removed as many of the plates as we could. This was an interesting challenge. I would usually work from the top of the lift on one side while Allen would stand on a ladder on the other. This was complicated by the fact that the mount was surrounded with plexiglass and fauna. The ladder was away from the mount by 3 feet so Allen would have to do a very impressive balancing act on the ladder to reach out with one arm to loosen the screws. We had to place the lift high above Stegosaurus in order to clear all of the ribs, which meant I would have to lay on my stomach and reach beneath me to hold the heavy plates while Allen unscrewed them and then lift them up over my head, over the lift railing, and onto the lift to where Allen had hopefully run to in time to meet me and help. Robert and Sandy also ran to the rescue many times!

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Allen readjusting the lift

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Lauren removing a plate

Removing the vertebrae presented other challenges. Almost every vertebra is held in place with its own armerature which had to be unscrewed. Over the years the humidity has caused most of the screws to rust, fusing them to the metal mount. We had to use tons of WD-40 and some serious muscle power to loosen those suckers, but we managed to get most unscrewed. In addition, any and all space between the fossil and the metal was filled in with plaster to hold it in place. We would have to chisel it away to be able to remove the vertebra off of the mount. It wasn't mush of a problem towards the tip of the tail where the vertebrae are small and low to the ground, but as we worked our way up towards the back, the vertebrae got increasingly bigger, heavier, and higher, and the mount was beginning to wobble, so we would sometimes need 3 people just to remove one vertebra.

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Lauren removing tail vertebrae

We have also gotten most of the removed fossils stripped and cleaned and Dan has just begun the restoration.

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Dan working on a vertebra

August 06, 2006 02:01 PM
posted by Lauren Stevens

We will soon begin disarticulating and cleaning the Stegasaurus specien. I have completed the stripping and cleaning of a dorsal plate to help give us an idea as to how long this project will take and what we can expect. The alcohol tends to soften and weaken areas where plaster has been used to fill cracks as expected, but, unfortunately, this will cause many elemnts to break into multiple pieces and will have to be repaired. Below you can compare the stripped plate with an unstripped plate.

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Stripped Stegosaurus plate

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Unstripped Stegosaurus plate

June 09, 2006 04:41 PM
posted by Allen Shaw

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Stegosaurus mount in the old dinosaur hall.

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