Bioerosive traces in fossil penguin bones (Aves, Sphenisciformes) from the Eocene of Marambio/Seymour Island (West Antarctica)

We examined a set of penguin bones from different Eocene levels of the Submeseta Formation in Marambio/ Seymour Island (James Ross Basin, Antarctic Peninsula) and found the bioerosive traces fossils presented here. Traces were assigned to ?Machichnus bohemicus, Machichnus indeterminate, Nihilichnus nihilicus, Centrichnidae indeterminate, and other ambiguous structures grouped into morphologic descriptive categories such as ‘shallow pits with radial scratches’, ‘indeterminate tunnels’, ‘rounded to sub-rounded shallow holes’, ‘oval deep traces’. According to the possible interpretations of these trace fossils, the taphonomic history of the remains, although different in all the cases, would include the primary deposition in a marine environment, transportation and subaerial exposure.