Today, October 14, is National Fossil Day which is “an annual celebration held to highlight the scientific and educational value of paleontology and the importance of preserving fossils for future generations.”[1] Here at the museum, we’ve decided to share one of our fossils that is full of mystery.
Charles D. Walcott was the leading expert on Cambrian rocks and animals in 1887 when two men with the United States Geological Survey found some fossils. The fossils were sent to Walcott and he traveled to Cañon City in 1890 to examine the rock layers. He determined they were species of prehistoric jawless fish from the Ordovician period, from about 443.7 million years ago. The new species were named Astraspis desiderata and Eriptychius americanus and were the oldest known specimens of marine vertebrate life found on Earth at that time. During his time in Cañon City, Walcott also discovered another fossil he named Dictyorhabdus priscus in 1892.
Dictyorhabdus priscus is a fossil that has led to many questions. Walcott described it as a chordal sheath of a type of chimaera fish (fish with cartilage skeletons). However, that description has had its validity called into question. The material is calcium phosphate, making one theory that the fossil is a glass sponge inaccurate. The calcium phosphate material suggests the fossil may be part of a vertebrate with one theory presenting it as part of the eternal skeleton of an armored fish.[2] As of yet, Dictyorhabdus priscus does not have a place it fits in, but with future studies this may change.
Our museum holds a specimen of Dictyorhabdus priscus, as do both the Peabody Museum of Natural History and Smithsonian’s National Museum of Natural History. The holotype, a single type specimen upon which the description and name of a new species is based, resides in the Smithsonian collection.
[1] “National Fossil Day,” National Fossil Day, accessed October 14, 2020, https://www.nps.gov/subjects/fossilday/index.htm.
[2] Wayne Itano, “Helping the Fort Collins Museum of Discovery With Specimens and Ideas: Part 3 – Lyons Sandstone Footprints and Harding Sandstone Fish”, Trilobite Tales (Nov. 2017), accessed Oct. 14, 2020, https://www.academia.edu/35059266/Helping_the_Fort_Collins_Museum_of_Discovery_with_Specimens_and_Ideas_Part_3_Lyons_Sandstone_Footprints_and_Harding_Sandstone_Fish