Dorsal view of the dermal armor of the newly identified fossil fish species, Phyllolepis thomsoni. Credit: Academy of Natural Sciences of Drexel University.

In 370 million-year-old red sandstone deposits in a highway roadcut, scientists have discovered a new species of armored fish in north central Pennsylvania.

Fossils of armored fishes like this one, a phyllolepid placoderm, are known for the distinctive ornamentation of ridges on their exterior plates. As with many such fossils, scientists often find the remains of these species as impressions in stone, not as three-dimensional versions of their skeletons. Therefore, in the process of studying and describing this fish’s anatomy, scientists took advantage of a technique that may look a lot like it was stolen from crime scene investigators.

In the video below, Dr. Ted Daeschler shows the fossil and a rubber cast made by pouring latex into its natural impression in the rock. Once the…