Fig. 2

The large 3-D framework with long (610 mm) built-in vernier calipers designed to measure the orientation and position of the ammonites in the concretion. The main accumulation of ammonites (the “sculpture”) is visible in the foreground. The view is toward the southeast end of the sculpture and slightly above. The 3-D system is mounted on a wooden frame and consists of two calipers that have had their normal jaws removed from the vernier sliding bars. The rail or ruler of the second, movable one (Y axis or width, at the top of the photo from left to right) is attached (with drilled and tapped screws) to the sliding bar of the first, fixed one (X axis, or length, at the left side of the photo). The end of the second rail rests and slides on top of the wooden bar to the right as the two sliding bars are moved into a particular X, Y position. A hole was drilled through the sliding part of the second one for a brass rod that can be raised and lowered (Z axis, or height). X and Y are read from the metric scales on their respective rulers. Z is read at the top of the brass rod (above and out of the photo) using a metric ruler held alongside the rod. The bottom end of the rod is placed at the point to be measured, with the example shown at the umbilicus of AMNH 85455, a specimen of Hoploscaphites crassus