BANDRINGA: THE “SPOONBILL DOGFISH” FROM MAZON CREEK, ILLINOIS

Mazon Creek (Francis Creek Shale Member, Carbondale Formation) in Northeastern Illinois is a near-shore marine and freshwater lagerstätte dating from the Middle Pennsylvanian (Westphalian D, 307mya). Fossils are found inside siderite concretions and show exceptional preservation of soft tissue and articulated body remains. Bandringa Zangerl, a shark genus (Chondrichthyes) known for an elongated snout comprising up to half of total body length, is among the most sought-after Mazon Creek vertebrates. Bandringa is represented by around ten concretion specimens assigned to two distinct species from two faunal deposits. Light, tan concretions from the marine Essex fauna, including the holotype of B. rayi Zangerl, show external soft tissue traces and body outlines but lack most endoskeletal remains. Dark, reddish concretions from the freshwater Braidwood fauna, all referred to B. herdinae Zangerl, are mostly represented by impressions of scales and endoskeletal cartilages. Re-examination of Bandringa specimens from both faunas showed species assignment to be dependent on differential taphonomy among the assemblages, allowing synonymization of the two taxa as B. rayi. As a monospecific genus, Bandringa illustrates how the different kinds of data available from two depositional regimes can be used to reconstruct the morphology of resident taxa in greater detail than available at other localities with a single dominant taphonomy. A new reconstruction of Bandringa is presented incorporating previously undescribed features. These include detailed eyes with sclerotic rings, extensive squamation consisting of pointed dermal denticles with stellate bases and different regional forms, branching lateral line and sensory canals supported by cylindrical or c-shaped scales, fin spines with costae, and new information on jaw morphology and articulation.