THE FIRST MESOZOIC RECORD OF WALPIA HERMITENSIS, AN INVERTEBRATE TRACE FOSSIL PREVIOUSLY KNOWN ONLY FROM THE PERMIAN OF THE AMERICAN SOUTHWEST

We document a new record of Walpia hermitensis White, 1929, an invertebrate trace fossil associated with the Scoyenia ichnofacies that has previously been reported only from the Permian of the American Southwest. The specimen (Yale Peabody Museum of Natural History, YPM IP 150780) was collected from the Early Jurassic (Hettangian) Turners Falls Sandstone, Newark Supergroup, of Franklin County, Massachusetts. YPM IP 150780 contains several epichnial, semi-endostratal burrows on the upper surface of a large mud draped sandstone slab. The burrows are typically 1 cm wide and extend to as much as 13 cm in length. Courses are typically straight with gentle curves. Intersections are seen. The burrows are partially to completely covered by small, variably aligned nodules. They are assigned to Walpia based on overall similarity to the holotype material. Walpia, a monospecific taxon, was erected based on very limited material from the Early Permian Hermit Shale in the Grand Canyon, Arizona. Recent findings of Walpia from the late Early Permian of Lake Kemp and Castle Peak, Texas, demonstrate that individual burrows may display morphologic variations not seen on the type material. The Yale Walpia specimen similarly displays these variable features, which can take the form of a central sulcus along the burrow course. Consequently, these variant forms indicate that Walpia is in need of revision, as well as to clarify its relationship with the nereitids. Although previously thought to have been coprolitic in origin and made by worms or crustaceans, Walpia was more probably produced by foraging coleopterans that excavated sediment packets with specialized forelimbs adapted for digging. Walpia remains a poorly known and infrequently cited ichnogenus despite its relatively long nomenclatural history. It may be that overall Walpia is a rare, highly scarce ichnotaxon as exemplified by YPM IP 150780 being the only example found within the Yale collection. However, Walpia’s rarity may also be facies related or due to a lack of recognition and consequent under reporting by collectors. YPM IP 150780 significantly extends the biostratigraphic record of Walpia from the Paleozoic to the Mesozoic, as well as extending its North American distribution beyond the American Southwest.