Re-articulating a killer whale on St. Paul during Bering Sea Days.

Author: Mike Etnier | Portland State University

This past October I joined several other scientists in St. Paul to participate in the Pribilof School District’s annual “Bering Sea Days” (BSD), which is a weeklong science immersion for students at the local school.  We try to engage all of the students, who range from pre-K to 12th grade.  That means we have to adapt our various activities so that they are appropriate for each specific age group, which is a big challenge.

I typically describe myself as a “bone-ologist” because my work involves a mix of paleontology (old bones and teeth), zooarchaeology (old bones and teeth related in some way to human behavior), and modern ecology (modern bones and teeth).  It’s no coincidence, then, that the activities that I design for BSD typically deal with bones and teeth.

Last year, I had the amazing opportunity to help the 11th grade students excavate the skeleton of a killer whale calf that had been buried since 2011 (video clip).

Cleaning Vertebrae:  Students from the 11th Grade class brushing the tail vertebrae clean during the 2013 excavation of the killer whale calf.

Students from the 11th Grade class brushing the tail vertebrae clean during the 2013 excavation of the killer whale calf.

Now that the nearly-complete skeleton has been cleaned and dried, the main activities for the high school students this year centered on re-articulating the skeleton for display in the school library.

A St. Paul student threads the drilled vertebrae onto the steel rod that will support the articulated skeleton.

A St. Paul student threads the drilled vertebrae onto the steel rod that will support the articulated skeleton.

For the younger students, we focused on how fossils are made using examples from around the island of St. Paul—including 200,000-year-old fossil clams and the 6000-year-old mammoth teeth recovered from a lava tube near the airport.

One of the activities the younger students did was to make casts of fur seal teeth.  For this process, they first had to make a mold that represents a perfect imprint, or impression, of the original tooth.  They then removed the original tooth and filled the imprint with plaster of Paris.  This models the same process by which many kinds of fossils are created.

Studying the process of how fossils are formed also provided a nice transition to the re-articulation project because many of the pieces are missing from the killer whale skeleton.  While the animal was buried, foxes dug into the soft sand and removed several skull bones, as well as the entire left flipper.  We are also missing several teeth, which may have been lost during the excavation.

The high school students are going to use several different approaches to creating replacement pieces that will be used in the articulated skeleton.  The missing teeth will be replaced with plaster casts, using the same casting process the younger students learned.  In this case, we used the existing teeth as the “originals” for making the mold.

A variety of tooth sizes will be used to make replacement casts for the missing teeth.

A variety of tooth sizes will be used to make replacement casts for the missing teeth.

Relatively simple bones, such as the shoulder blade and limb bones, will be reproduced using modeling clay, or perhaps by hand-carving wooden blocks.  Finally, the students hope to access a 3D scanner to create virtual copies of the existing skull bones.  Once they have the 3D images, they can be mirrored and/or scaled to match the missing skull bones.  Finally, a 3D printer will be used to “print” an epoxy replica of the missing bones.

KillerWhales

 

Header image: Killer whales in Vega Bay, Kiska Island by B. Hornbeck 2014

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