Fossil species named for U professor Kathleen Ritterbush

A newly described species of ammonoid, an ancient relative of today’s squid and octopus, has been named after Kathleen Ritterbush, assistant professor of geology and geophysics. Researchers David Taylor and Jean Guex described the species, Arnioceras ritterbushi, as found in Nevada’s Gabbs Valley mountain range in a rock layer known as the Sunrise Formation, dating to around 190 to 199 million years ago during the early Jurassic Period. Ammonoids were ocean-dwelling animals, living in large spiral-shaped shells that have been preserved as fossils.

Although Ritterbush and the researchers haven’t ever directly collaborated, the decision to name the species after her recognizes her doctoral dissertation work on rocks and fossils of the Sunrise Formation, specifically the Early Jurassic expansion of sea sponge meadows that flourished after a global mass extinction. Ritterbush currently researches the swimming efficiency of ammonite shells, which leans on the work of researchers like Taylor and Guex who discover and relate new species.

The researchers further designated the entire distinctive layer of fossil life, or faunal horizon, as the Ritterbushi horizon. A fossil specimen of A. ritterbushi resides in the collections of the Northwest Museum of Natural History in Oregon.

“It’s an incredible honor for these eminent researchers to give an ammonite species my name. That it is an Early Jurassic ammonite named in recognition of my fieldwork in the area is even more of a surprise and an honor.”

Ritterbush notes that she shares this species and horizon name with her mother, paleontologist Linda Ritterbush.

A fossil specimen of Arnioceras ritterbushi, named after U Geology & Geophysics assistant professor Kathleen Ritterbush.