What is "pholidocercus"

Pholidocercus is an extinct monotypic genus of mammal related to and resembling the modern-day hedgehog with a single species, Pholidocercus hassiacus. Like the hedgehog, it was covered in thin spines. Unlike hedgehogs, it had scales on its head in a helmet-like formation, and had a long, thick, scaled tail. P. hassiacus has been found in the Messel Pit.