October 11, 2017 is National Fossil DayTM. This year, the logo features heterostracans (Greek for “different shields”), which are a group of extinct fish who lived between the early Silurian and late Devonian period (358 million years ago). According to their website,
The heterostracans were characterized by an external covering of bony armor plates and by having only one common gill opening on each side of the head region. These early fish lacked any paired or mid-line fins and in many cases developed extensions of the armor plates that were not flexible but helped provide control in the water. Heterostracans lived in shallow marine environments around an ancient continent known as the Old Red Sandstone (ORS) Continent, which was composed of present day North America, the Canadian Arctic, and Western Europe….
The heterostracan species illustrated in the logo are Panamintaspis snowii in the foreground and Phyllonaspis taphensis in the background. Panamintaspis is named after the Panamint Mountains in Death Valley, which is where the original fossils were found and the species name recognizes the individual who helped to discover the specimen. Phyllonaspis taphensis means “leaf shield from the tomb” referring to the fact that the specimen comes from Death Valley. Phyllonaspis is particularly interesting as it is a member of a group that is otherwise only known from the Canadian Arctic, suggesting dispersal of these organisms from the arctic and around the margins of the Old Red Sandstone Continent.
Go to the NFD website to read more about heterostracans and David Elliott, a paleontologist who studies them and even found some in Death Valley National Park. There are also several activities you can do to celebrate the day.
To further celebrate National Fossil Day, Paleoaerie has a great article about the fossils that can be found in Arkansas.