Martin A. Becker

CHONDRICHTHYANS FROM THE ARKADELPHIA FORMATION (UPPER CRETACEOUS: UPPER MAASTRICHTIAN) OF HOT SPRING COUNTY, ARKANSAS

Abstract Erosion of the upper Arkadelphia Formation by the Ouachita River in Hot Spring County, Arkansas, has revealed a diverse and abundant, late Maastrichtian chondrichthyan fauna representing at least 17 species: Squatina hassei, Ginglymostoma lehneri, Plicatoscyllium derameei, Ondontaspis aculeatus, Carcharias cf. C. holmdelensis, Serratolamna serrata, Squalicorax kaupi, Galeorhinus girardoti, Rhinobatos casieri, Ischyrhiza avonicola, Ischyrhiza mira, Sclerorhynchus sp., Ptychotrygon cf. P. vermiculata, Raja farishi, Rhombodus binkhorsti, and Dasyatis sp. All of these species are widely known from the Upper Cretaceous of North America. An extremely rare species, Schizorhiza cf. S. stromeri, currently known only from Mexico and Africa, is also present. The chondrichthyan remains occur almost entirely as teeth scattered by river activity across the surface of the marl and marly clay of the Arkadelphia Formation and can be collected from within localized accumulations of river sediments. Also present with the chondrichthyan remains are teeth from actinopterygians and reptiles as well as molluscan steinkerns, echinoid spines, and fragments of branching corals. This fauna expands the known geographic distribution of late Maastrichtian chondrichthyans in North America, and provides an important biostratigraphic connection between fauna of the Gulf Coastal Plain and Western Interior Seaway. It also supports the idea of a significant chondrichthyan turnover across the Cretaceous–Tertiary boundary.

CHONDRICHTHYANS FROM THE LOWER FERRON SANDSTONE MEMBER OF THE MANCOS SHALE (UPPER CRETACEOUS: MIDDLE TURONIAN) OF EMERY AND CARBON COUNTIES, UTAH, USA

Abstract The Lower Ferron Sandstone Member of the Mancos Shale in southeastern Utah preserves a chondrichthyan assemblage of at least 13 taxa that include: Hybodus sp., Ptychodus cf. P. mammillaris Agassiz, 1843, Ptychodus whipplei Marcou, 1858, cf. Chiloscyllium sp., Scapanorhynchus raphiodon (Agassiz, 1843), Cretodus crassidens (Dixon, 1850), cf. Leptostyrax sp., cf. Cretalamna appendiculata (Agassiz, 1835), Squalicorax sp., Pseudohypolophus mcnultyi (Thurmond, 1971), Protoplatyrhina hopii Williamson, Kirkland and Lucas, 1993, Ischyrhiza schneideri (Slaughter and Steiner, 1968), and Ptychotrygon triangularis (Reuss, 1844). Although this assemblage is typical of other Turonian chondrichthyan faunas in North America, fossil teeth are preserved in two unique facies associations that consist of arenitic sandstones with mud interclasts and rounded chert, feldspar, and quartz pebbles. The coarser beds within these facies associations are previously interpreted to represent storm events and turbidity flows associated with a sea level lowstand. Chondrichthyan teeth occurring within these coarser beds are indicative of extensive transport and reworking and attest to the durable nature of chondrichthyan teeth for biostratigraphic and paleoecological interpretations. Similar studies of chondrichthyan teeth in shelf marine settings may also provide new insights for facies interpretations related to sequence stratigraphy and regional stratigraphic correlations.

Osteichthyans from an Arkadelphia Formation–Midway Group lag deposit (Late Maastrichtian–Paleocene), Hot Spring County, Arkansas, U.S.A.

ABSTRACT A lag deposit that separates the underlying late Maastrichtian Arkadelphia Formation marl from the overlying Paleocene Midway Group limestone in Hot Spring County, Arkansas, U.S.A., contains osteichthyan teeth, scales, and skeletal elements belonging to: Cylindracanthus ornatus Leidy, 1856, Atractosteus sp., Lepisosteus sp., cf. Hadrodus priscus Leidy, 1857, Pseudoegertonia cf. P. granulosus (Arambourg, 1952), Paralbula casei Estes, 1969, Enchodus ferox Leidy, 1855, Enchodus gladiolus (Cope, 1872), Enchodus petrosus (Cope, 1874), Enchodus sp., and Teleostei incertae sedis. Outcrop exposures of this lag deposit occur within the Ouachita River and are expressed as a series of partially submerged, steeply inclined fold limbs that strike obliquely to water flow. The co-occurring osteichthyans recovered in this study span a broad range of salinity tolerances, foraging behaviors, and dietary preferences. Concentration of these osteichthyans indicates transport, exhumation, and reburial associated with storm activity or sea level cyclicity across a shallow Late Cretaceous marine shelf. Arkadelphia—Midway osteichthyan taxa belong to groups that survive the Cretaceous—Paleocene extinction event.

Beryciform-Like Fish Fossils (Teleostei: Acanthomorpha: Euacanthopterygii) from the Late Cretaceous - Early Tertiary of New Jersey

ABSTRACT. Well-preserved fin spines, ornate opercular bones and thick ctenoid scales recovered from the unconsolidated marine sediments of the Cretaceous-Tertiary boundary interval in Upper Freehold Township, New Jersey, USA derive from at least one species of enigmatic euacanthopterygian fish. Within this group the fossils are most similar to corresponding bones of some beryciforms. The fin spines are less than 1.5 cm long, have complex basal articulation structures, and a narrow posterior sulcus extending almost to the distal tip. Most spines have lateral grooves, and some have prominent anterior dentations. A few are attached to broadly keeled pterygiophores. Beryciforms and more basal clades of Acanthomorpha first appear in the Late Cretaceous. The New Jersey fossils may expand the known geographic distribution of beryciforms across the K/T boundary beyond the better known Late Cretaceous beryciforms from the Western Interior of North America, Europe, and the Middle East.

Lamniform and Carcharhiniform Sharks from the Pungo River and Yorktown Formations (Miocene–Pliocene) of the Submerged Continental Shelf, Onslow Bay, North Carolina, USA

The submerged continental shelf of Onslow Bay, North Carolina, preserves hardbottom limestone scarps with underlying clays as small isolated exposures in progressively deeper water seaward from the modern-day shoreline. These scarps formed as a result of wave- and current-driven erosion, transport, and redeposition of bottom sediments due to glacioeustactic sea level cyclicity and the migration of the ancestral shoreline since the Pliocene. Fossiliferous lag deposits containing an abundance of lamniform and carcharhiniform teeth, including those belonging to megatoothed sharks, occur adjacent to these scarps. These specimens include teeth from: Alopias grandis, Carcharhinus falciformis, Carcharhinus priscus, Carcharias cf. C. taurus, Carcharodon carcharias, Carcharodon hastalis, Galeocerdo aduncus, Galeocerdo cuvier, Hemipristis serra, Isurus oxyrinchus, Negaprion brevirostris, Otodus chubutensis, Otodus megalodon, Parotodus benedinii, Physogaleus contortus, and Rhizoprionodon sp. Comparison of biostratigraphically significant lamniform and carcharhiniform taxa from the submerged shelf with those from land-based assemblages along the Atlantic Coastal Plain of the USA indicates that the shallower shelf (≈25 m deep) exposes the Miocene Pungo River Formation and intermediate and deeper shelf (≈30–35 m deep) expose the Pliocene Yorktown Formation. Many of the Onslow Bay lamniforms and carcharhiniforms also occur in Miocene and Pliocene shallow marine assemblages around the world and reinforce the migratory abilities of these chondrichthyans in the late Cenozoic and the utility of lamniform and carcharhiniform teeth in biostratigraphic and chronostratigraphic analyses.

OSTEICHTHYANS FROM THE TALLAHATTA–LISBON FORMATION CONTACT (MIDDLE EOCENE–LUTETIAN) PIGEON CREEK, CONECUH-COVINGTON COUNTIES, ALABAMA

# Doctoral Program in Earth and Environmental Sciences, City University of New York Graduate Center, New York, New York 10016, U.S.A., hmaisch@gc.cuny.edu * Department of Environmental Science, William Paterson University, 300 Pompton Road, Wayne, New Jersey 07470, U.S.A., beckerm2@wpunj.edu § Alabama News, Mobile, Alabama, Al.com ∫ Department of Earth and Environmental Sciences, Brooklyn College, 2900 Bedford Avenue, Brooklyn, New York 11210, U.S.A., johnc@brooklyn.cuny.edu