One half of the mold of the tip of the left tusk of the Bristle Mammoth. Researchers painted polyester resin onto the surface of the mold, then combined it with the other half to yield a cast of the tip of this tusk.

Lang DeLancey (left) and Bill Sanders apply polyurethane molding compound to produce a mold that will be used to make a fiberglass cast of one of the tusks.

U-M undergraduate Lang DeLancey brushes polyester resin onto a segment of the mold of one part of the left tusk of the Bristle Mammoth. The casts produced in this way were then assembled to make fiberglass copies of the tusks.

U-M College of Engineering undergraduate Luke Stull brushes polyurethane molding compound onto the base of the left tusk of the Bristle Mammoth. Researchers used the mold to make a fiberglass cast of the tusk that is now on display at the U-M Museum of Natural History.

Researchers cut a block from the base of the right tusk. This sample will be used to determine the animal’s season of death.

A scientist fills the cracks in one of the mammoth tusks using epoxy.

Closeup of the bone core, from which a smaller block was cut for radiocarbon dating.

Paleontologist Dan Fisher uses a drill with a coring bit to extract a wine cork-size bone sample from one of the mammoth’s shoulder blades. The sample was sent to an independent laboratory for radiocarbon dating.

Paleontologist Dan Fisher works in the classroom to identify the ancient bones.

Mammoth skull and tusks hoisted from the excavation pit at the Bristle farm, near Chelsea, on Oct. 1, 2015.

Former U-M archaeology graduate student Ashley Lemke, PhD ‘16 (left), with U-M paleontologists Daniel Fisher (right) and Joe El-Adli (center), inspects a fragment of stone found while uncovering one of the mammoth tusks in the muddy excavation pit.

U-M PhD candidate Joe El-Adli holds a mammoth vertebra recovered during the dig.

James Bristle’s farm near Chelsea on Oct. 1, 2015, the date of the U-M-led mammoth dig.