Neurankylus: Click to enlarge
Work-in-progress Neurankylus turtle
In October 1995, the Denver Museum of Nature and Science opened Prehistoric Journey, covering the 3.5 billion-year history of life on Earth. Long before Prehistoric Journey, the DMNS had established a reputation for excellent dioramas (renditions of landscapes that are a combination of three-dimensional sculpted items in the foreground and painted backgrounds) based on real places. This exhibition continues that tradition. It features seven dioramas or "enviroramas" (displays the visitor walks through) based on actual fossil localities. Each of the seven re-created landscapes consists of two parts: the diorama or envirorama, and an evidence case showing the fossils the DMNS collected from that locality.

Stygimoloch: Click to enlarge
Stygimoloch head
Stygimoloch: Click to enlarge
Partially completed Stygimoloch dinosaur
How do exhibitors translate a fossil from bare bones to a fleshed-out animal? Techniques vary with each animal, but most follow the same general process. First, the artists study and measure the fossil bones. An understanding of anatomy and musculature is crucial to this process, and scientists are on hand for assistance. Relying on advice from the scientists, artists make a frame of the animal's basic shape, using wood, wire, and/or carved foam. Next, they flesh out the frame with clay, a thumbful at a time. When the clay model meets with the artist and scientist's satisfaction, the artist makes a cast of the model, using techniques similar to molding and casting in the fossil lab (see Preparation for more information). The completed cast is coated with uniform gray primer paint, then painted in lifelike colors.

Sometimes the most memorable effects come about by accident, and that was the case with a fossil entelodont in Prehistoric Journey, known to the staff as the "Terminator Pig." A far cry from cuddly "Babe," this pig was a fearsome carnivore. While exhibitors were working on the Terminator Pig, some liquid fiberglass accidentally oozed out of its open mouth in a serendipitous imitation of prehistoric drool. "Oh, cool!" said the exhibitors. The drool stayed, and they even added a little more.

Gazelle camel
In between the dioramas and enviroramas are more than 500 fossils as well as fossil casts. Like making fleshed-out replicas, mounting skeletons takes time and skill. Under the direction of chief preparator Dr. Ken Carpenter, preparators start by picking a realistic pose for the fossil skeleton, based on what kind of posture the bones will allow. Next they build the support frame out of metal and either bolt or weld it together. Support frames can be either internal (running though the bones) or external (outside the bones but unobtrusive to the visitor's view). Either kind of frame can be used with bones or casts, but in general, internal frames are easier for casts, and external frames are safer for bones.

Turtle in envirorama: Click to enlarge
Neurankylus turtle in the Cretaceous Creekbed
For many years, museums tried to make their casts look indistinguishable from original bones, especially for fossil mounts using both cast and original bone material. Museums generally don't do that anymore, and while they may paint the casts similar colors as the original bones, they allow their visitors to make pretty clear distinctions between the two. This new philosophy is driven largely by taphonomy, the study of how organisms died and what happened to the fossils after they were covered by sediment; studying what parts of the fossil were damaged or broken is as important to taphonomy as studying the parts of the fossil that were nicely preserved.

Neurankylus turtle carapace in evidence case
For more than 65 million years, the North Dakota Neurankylus turtle was a lonely fossil carapace in the badlands. Now it's featured twice in Prehistoric Journey. Its fleshed-out model is in the Cretaceous Creekbed envirorama, and the actual fossil is in the adjoining evidence case.

Runestad, Todd. 1994. "The making of the terminator pig" Museum Quarterly (Spring issue) 9-12

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