Tilefish (Teleostei, Malacanthidae) remains from the Miocene Calvert Formation, Maryland and Virginia: taxonomical and paleoecological remarks

ABSTRACT

The spectacularly fossiliferous Calvert Formation is largely exposed in Maryland and Virginia and comprises the best available record of middle Miocene life in the northeastern United States. Lopholatilus ereborensis, sp. nov., a new tilefish from the middle Miocene (Langhian) of the Calvert Formation, is described herein based on 15 well-preserved three-dimensional partially complete articulated skeletons. These fossils consist primarily of cranial remains and represent the earliest known occurrence of the genus Lopholatilus in the record. Lopholatilus ereborensis is characterized by moderately deep head and short snout, occipital region of the neurocranium obliquely sloping, epioccipital spine extending posteriorly beyond the supraoccipital crest, remarkably shortened ascending process of the premaxilla, villiform teeth on dentary restricted to the symphyseal region, horizontal arm of the preopercle short, and angle formed by vertical and horizontal arms of the preopercle measuring about 120°. Taphonomic and paleoecological considerations suggest that Lopholatilus ereborensis inhabited long funnel-shaped vertical burrows self-excavated within the stable and cohesive bottoms of the outer continental shelf of the Salisbury Embayment, and possibly of other parts of the western North Atlantic outer shelf and upper slope that were characterized by relatively warm oxygenated waters. In that context, the three-dimensional preservation of the articulated skeletons of Lopholatilus ereborensis might represent the product of an abrupt burial resulting from the collapse of the upper part of the burrows. Cylindrical-shaped trace fossils (domichnia) penetrating the fine-grained sands of the middle part of the Calvert Formation are proposed to have been produced by Lopholatilus ereborensis.

ACKNOWLEDGMENTS

We thank W. Landini (Dipartimento di Scienze della Terra, Università di Pisa, Pisa) for useful suggestions and critical review of an early draft of the text. We are particularly obliged to J. Nance (Calvert Marine Museum, Solomons, Maryland), D. J. Bohaska, J. Clayton, and G. D. Johnson (National Museum of Natural History, Smithsonian Institution, Washington, D.C.), and A. Dooley (VMNH) for access to fossil and extant material in their care, to R. Weems (Paleo Quest) for information that helped in the creation of the Calvert Cliffs stratigraphy figure, and to W. Johns for logistic support. We are much indebted to F. Giudice (Torino) for useful suggestions. Research of S.J.G. was made possible by funding from the Board of Calvert County Commissioners, the citizens of Calvert County, and the Clarissa and Lincoln Dryden Endowment for Paleontology at the Calvert Marine Museum. Visits to Solomons and Washington by G.C. in 2011 and 2012 were supported by the Clarissa and Lincoln Dryden Endowment for Paleontology and a Smithsonian Short-term Fellowship.

Handling editor: Matt Friedman.