In the Lab
Marisa Gilbert prepares a humerus from the Puijila fossil.
While still in the field, Natalia Rybczynski and Mary Dawson were able to tell that the fossil they'd found was some sort of swimming carnivore. Further study would have to wait for the return home to use specialized equipment in their museum laboratories.
To transport the fossil, the team wrapped the bones in toilet paper (an extra supply was brought for that purpose) and packed them in hard-case boxes.
The body elements went to the Canadian Museum of Nature (Rybczynski's home base). The skull elements went to the Carnegie Museum of Natural History (Dawson's home base).
Preparing the Fossil
Natalia Rybczynski setting up the skull under the 3D laser camera.
The fossil needed cleaning up before research could even begin. Researchers do not try to prepare the fossils while in the field because it is a delicate process that requires time and specific equipment.
When a fossil is found, it is usually embedded in rock or covered in sediment. A very fine, silty matrix was cemented to most of the new carnivore's fossil bones.
Marisa uses the micro air abrasive tool to clean sediment off one of Puijila's bones.
At the Canadian Museum of Nature, Marisa Gilbert prepared the body elements (post-cranial elements) using a micro air abrasive tool. This tool blasts the surface of the fossil with compressed air and baking soda; it is a delicate process that does not harm the fossil. Where the matrix was highly cemented, Gilbert used fine hand tools—dental picks and needles—while looking through a dissection microscope!
All the while, the researchers were trying to fit the fossil bone fragments together, much like a jigsaw puzzle. When a fit was found, the fragments were glued together with a consolidant. Slowly the fossil animal took shape.
The skull pieces were prepared by Alan Tabrum, a scientific preparator at the Carnegie Museum of Natural History. Alan employed a Micro-Jack air scribe to remove some rock from the base of the braincase (the basicranial region). Most of the skull was painstakingly prepared under a dissecting microscope using very fine needles held in a pin vise.
The Virtual Skeleton
Natalia and Alex Tirabasso (Nature's 3D Production Specialist) compare a wolverine skull to the 3D image of Puijila.
Once the bones were cleaned, they were brought to the Canadian Museum of Nature's Arius3D Imaging Centre. There, they were scanned using a high-resolution laser scanner. The precise positional and colour data gathered by the laser were then transformed by technicians using specialized software into three-dimensional, virtual reconstructions, which are images. These images are known as 3D models.
Working with 3D models has several advantages over the real thing. Perhaps the most significant benefit in the case of this fossil is that it helped the researchers reconstruct the skeleton, which was partially broken, very fragile and missing pieces. The skull was particularly challenging. The 3D approach allowed the researchers to reconstruct the top of the skull from the fragmentary remains; they could move the virtual parts around and reassemble them like a three-dimensional jigsaw puzzle.
