#FossilFriday

Thanks to Dr. Oksana Vernygora, our #FossilFriday is the type specimen of a Late Cretaceous freshwater fish called 𝐻𝑜𝑟𝑠𝑒𝑠ℎ𝑜𝑒𝑖𝑐ℎ𝑡ℎ𝑦𝑠 𝑎𝑟𝑚𝑎𝑠𝑒𝑟𝑟𝑎𝑡𝑢𝑠 specimen found in the Horseshoe Canyon Formation from the 68.4-million-year-old Albertosaurus bonebed of southern Alberta.

TMP 2001.045.0093 (holotype) is a rare articulated fossil clupeomorph (herring and relatives) from freshwater Late Cretaceous (Santonian — Maastrichtian) deposits of Alberta. This type of preservation is not common for fossil clupeomorphs that are commonly known from isolated elements found in the Cretaceous deposits of Alberta. Articulated specimens like this provide valuable information for evolutionary analysis and allow assignment of isolated elements to species. 𝐻𝑜𝑟𝑠𝑒𝑠ℎ𝑜𝑒𝑖𝑐ℎ𝑡ℎ𝑦𝑠 𝑎𝑟𝑚𝑎𝑠𝑒𝑟𝑟𝑎𝑡𝑢𝑠 is a member of the double-armoured herring group known for the presence of modified shield-like scales along their back and is the first freshwater described from the Upper Cretaceous of North America. Its name is derived from the location it was found (in the Horseshoe Canyon Formation), and from the serrated texture of its scales (Latin ‘arma’ for ‘shielded’ and ‘serrata’ for ‘serrated’)