Browsing by Author "Johnson, Ralph O."
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Additions to the ammonite fauna of the Upper Cretaceous Navesink Formation of New Jersey. American Museum novitates ; no. 3306(New York, NY : American Museum of Natural History, 2000) Kennedy, W. J. (William James); Landman, Neil H.; Cobban, William A., 1916-2015.; Johnson, Ralph O.New fossil collections provide additional information about the late Campanian and Maastrichtian ammonites from the Navesink Formation of New Jersey. Late Campanian ammonites include Pseudophyllites indra (Forbes, 1846), Nostoceras (N.) approximans (Conrad, 1855) (of which Nostoceras (N.) stantoni Hyatt, 1894, is a synonym), Nostoceras (N.) hyatti Stephenson, 1941, Nostoceras (N.) pauper (Whitfield, 1892), Didymoceras cf. D. draconis (Stephenson, 1941), Exiteloceras rude n. sp., Hoploscaphites pumilus (Stephenson, 1941), and Jeletzkytes cf. J. nodosus (Owen, 1852). Maastrichtian ammonites from the Navesink Formation include Pachydiscus (P.) neubergicas neubergicus (Hauer, 1858), Kitchinites sp., Nostoceras (N.) alternatum (Tuomey, 1854), Baculites sp., Eubaculites cf. E. labyrinthicus (Morton, 1834), Eubaculites sp.?, Jeletzkytes cf. J. plenus (Meek, 1876), Jeletzkytes criptonodosus Riccardi, 1983, and Discoscaphites gulosus (Morton, 1834). These faunas are correlated with those of Western Europe, the Gulf Coast, and the Western Interior of the United States. The older fauna from the basal phosphatic beds of the Navesink Formation at the classic Atlantic Highlands locality is referred to the Nostoceras (N.) hyatti zone. It is late Campanian in age and equivalent to the Nostoceras (N.) pozaryskii/Belemnella langei zone in Europe and the Baculites jenseni zone in the United States Western Interior. In addition, these beds contain ammonites that range into the early Maastrichtian, as well as Pachydiscus (P.) neubergicus, whose appearance marks the base of the Maastrichtian. Thus, these phosphatic beds represent a condensed sequence that spans the late Campanian to early Maastrichtian. Ammonites also occur at other localities in the Navesink Formation in New Jersey, and correspond to higher levels in the Maastrichtian. The youngest ammonite known from the Navesink Formation, Discoscaphites gulosus, from Sewell, New Jersey, indicates a correlation with the Hoploscaphites nicolletii or Jeletzkytes nebrascensis zone of the Western Interior.Item Cephalopods from the Cretaceous/Tertiary boundary interval on the Atlantic Coastal Plain, with a description of the highest ammonite zones in North America. Part 1, Maryland and North Carolina. American Museum novitates ; no. 3454(New York, NY : American Museum of Natural History, 2004) Landman, Neil H.; Johnson, Ralph O.; Edwards, Lucy E.The sedimentary deposits on the Atlantic Coastal Plain in New Jersey, Delaware, Maryland, North Carolina, South Carolina, and Georgia span the Cretaceous/Tertiary boundary. We investigate the ammonites of the Severn Formation on the western and eastern shore of Chesapeake Bay, Maryland, and the Peedee Formation, North Carolina. We describe three ammonite assemblages from the Severn Formation and their associated dinoflagellates, defining three successive ammonite zones in the Upper Maastrichtian. The lowest ammonite zone is the Discoscaphites conradi Assemblage Zone. It occurs near the top of the Severn Formation in Prince Georges County, Maryland, just below the Paleocene Brightseat Formation. The ammonite fauna consists of Sphenodiscus pleurisepta (Conrad, 1857), Sphenodiscus lobatus (Tuomey, 1856), Discoscaphites conradi (Morton, 1834), Discoscaphites gulosus (Morton, 1834), Jeletzkytes nebrascensis (Owen, 1852), Glyptoxoceras rugatum (Forbes, 1846), Baculites vertebralis Lamarck, 1801, and Eubaculites latecarinatus (Brunnschweiler, 1966). Dinoflagellates from a sample of matrix include Isabelidinium aff. I. cooksoniae (Alberti, 1959) Lentin & Williams, 1977, which correlates with calcareous nannofossil Zone CC25b, indicating the lower part of the Upper Maastrichtian (68.2-67.4 MaBP). The D. conradi Zone is also present in parts of the Corsicana Formation, Texas, the Prairie Bluff Chalk, Alabama and Mississippi, the Peedee Formation, North Carolina, and the Navesink and New Egypt Formations, New Jersey. The next higher zone is the Discoscaphites minardi Assemblage Zone, which occurs in the Severn Formation approximately 6 m below the base of the Hornerstown Formation at Lloyd Creek, Kent County, Maryland. The ammonite assemblage is dominated by Discoscaphites minardi, n.sp., B. vertebralis, and S. pleurisepta, with rare specimens of Sphenodiscus sp., Discoscaphites iris (Conrad, 1858), and E. latecarinatus. A sample of dinoflagellates from the same bed as the ammonites includes Deflandrea galatea (Lejeune-Carpentier, 1942) Lentin & Williams, 1973 and Thalassiphora pelagica (Eisenack, 1954) Eisenack & Gocht, 1960, which correlate with the Neophrolithus frequens calcareous nannofossil Zone between Subzones CC26a and CC26b, indicating the middle part of the Upper Maastrichtian (66.4-66.0 MaBP). The D. minardi Zone is also present in the New Egypt Formation, New Jersey. The highest zone is the D. iris Assemblage Zone, which occurs near the top of the Severn Formation at its type locality at Round Bay, Anne Arundel County, Maryland. The ammonite assemblage is dominated by D. iris and E. carinatus, although elsewhere this zone also includes Pachydiscus (Neodesmoceras) mokotibensis Collignon, 1952, Pachydiscus (Pachydiscus) jacquoti jacquoti Seunes, 1890, S. lobatus, S. pleurisepta, Discoscaphites sphaeroidalis Kennedy and Cobban, 2000, and E. latecarinatus. Dinoflagellates from a sample of matrix surrounding one of the ammonites include Palynodinium grallator Gocht, 1970 and T. pelagica indicative of the P. grallator Zone, Tpe subzone, which correlates with the upper part of calcareous nannofossil Zone CC26b, indicating the upper part of the Upper Maastrichtian (65.6-65.0 MaBP). The D. iris Zone is also present in the upper part of the Corsicana Formation, Texas, the Owl Creek Formation, Mississippi, Tennessee, and Missouri, and the New Egypt and Tinton Formations, New Jersey.Item Cephalopods from the Cretaceous/Tertiary boundary interval on the Atlantic Coastal Plain, with a description of the highest ammonite zones in North America. Part 2, Northeastern Monmouth County, New Jersey. Bulletin of the AMNH ; no. 287(New York, NY : American Museum of Natural History, 2004) Landman, Neil H.; Johnson, Ralph O.; Edwards, Lucy E.The sedimentary deposits of the New Jersey Coastal Plain span the Cretaceous/Tertiary boundary and reveal a complex stratigraphy in the northeastern part of their outcrop belt. Newly discovered exposures of the New Egypt Formation in northeastern Monmouth County, New Jersey, indicate that a tongue of this formation, previously thought to be restricted in outcrop to southwestern Monmouth County, extends to the northeast. This formation is sandwiched between the Tinton Formation below and the Hornerstown Formation above. The upper contact is unconformable. Fossils occur in the upper part of the New Egypt Formation and the basal part of the Hornerstown Formation and are concentrated at the formational contact--this accumulation is known as the Main Fossiliferous Layer. The Discoscaphites minardi Assemblage Zone occurs in the New Egypt Formation approximately 2 m below the base of the Hornerstown Formation and contains Discoscaphites minardi Landman et al., 2004, Discoscaphites sp., Eubaculites carinatus (Morton, 1834), Eubaculites sp., and Eutrephoceras dekayi (Morton, 1834). Associated dinoflagellates include Deflandrea galatea (Lejeune-Carpentier, 1942) Lentin & Williams, 1973, and Thalassiphora pelagica (Eisenack, 1954) Eisenack & Gocht, 1960. The D. minardi Zone represents the middle part of the Upper Maastrichtian corresponding to the upper part of calcareous nannofossil Subzone CC26a and the lower part of Subzone CC26b. The Discoscaphites iris Assemblage Zone occurs at the top of the New Egypt Formation in an interval at least 20 cm thick and contains Discoscaphites iris (Conrad, 1858), Discoscaphites gulosus (Morton, 1834), D. minardi, Eubaculites latecarinatus (Brunnschweiler, 1966), E. carinatus, Sphenodiscus pleurisepta (Conrad, 1857), Sphenodiscus sp., and Eutrephoceras dekayi. Associated dinoflagellates include Palynodinium grallator Gocht, 1970, and T. pelagica. The D. iris Zone represents the uppermost Maastrichtian, corresponding to the upper part of calcareous nannofossil Zone CC26b. The basal beds of the Hornerstown Formation contain a mixed assemblage of Cretaceous and Paleocene fossils. Paleocene dinoflagellates include Carpatella cornuta Grigorovich, 1969, and Senoniasphaera inornata (Drugg, 1970) Stover & Evitt, 1978, and suggest that these beds correspond to planktonic foraminiferal zones PO-P[alpha]. There is no enrichment of iridium ([greater than or equal to]0.1 ppb) or layer of spherules at the formational contact but a dinoflagellate specimen with pockmarked damage consistent with melting is present in the top of the New Egypt Formation. The formational contact spans the Cretaceous/Tertiary boundary but probably contains a hiatus of approximately 100 k.y. All of the Cretaceous fossils in the Main Fossiliferous Layer are reworked from the upper New Egypt Formation and reflect a period of erosion and winnowing, perhaps related to changes in sea level as well as events associated with the bolide impact at the end of the Cretaceous. Subsequently and simultaneously, the sea floor experienced extensive bioturbation, which may have further reworked fossils. Elsewhere on the Gulf and Atlantic Coastal Plain, the D. iris Zone also occurs immediately below the K/T boundary and is truncated by an erosional unconformity, commonly with reworked material in the overlying beds. The geographic distribution of the D. iris Zone and cores spanning the K/T boundary on the Gulf and Atlantic Coastal Plains help approximate the coastline of North America at that time and indicate a broad Mississippi embayment. However, there is no firm evidence that the Western Interior Seaway persisted until the end of the Cretaceous.Item Cephalopods from the Cretaceous/Tertiary boundary interval on the Atlantic Coastal Plain, with a description of the highest ammonite zones in North America. Part 3, Manasquan River Basin, Monmouth County, New Jersey ; Bulletin of the American Museum of Natural History, no. 303(New York, NY : American Museum of Natural History, 2007) Landman, Neil H.; Johnson, Ralph O.; Garb, Matthew P.; Edwards, Lucy E.; Kyte, Frank Thomas, 1949-Geological investigations in the upper Manasquan River Basin, central Monmouth County, New Jersey, reveal a Cretaceous/Tertiary (= Cretaceous/Paleogene) succession consisting of approximately 2 m of the Tinton Formation overlain by 2 m of the Hornerstown Formation. The top of the Tinton Formation consists of a very fossiliferous unit, approximately 20 cm thick, which we refer to as the Pinna Layer. It is laterally extensive and consists mostly of glauconitic minerals and some angular quartz grains. The Pinna Layer is truncated at the top and is overlain by the Hornerstown Formation, which consists of nearly equal amounts of glauconitic minerals and siderite. The base of the Hornerstown Formation is marked by a concentration of siderite nodules containing reworked fossils. This layer also contains a few fossils of organisms that were living in the environment during the time of reworking. At some downdip sites, there is an additional layer (the Burrowed Unit), which is sandwiched between the top of the Pinna Layer and the concentrated bed of nodules. This unit is very thin and is characterized by large burrows piping down material from above. The Pinna Layer is abundantly fossiliferous and represents a diverse, nearshore marine community. It contains approximately 110 species of bivalves, gastropods, cephalopods, echinoids, sponges, annelids, bryozoans, crustaceans, and dinoflagellates. The cephalopods include Eutrephoceras dekayi (Morton, 1834), Pachydiscus (Neodesmoceras) mokotibensis Collignon, 1952, Sphenodiscus lobatus (Tuomey, 1856), Eubaculites carinatus (Morton, 1834), Eubaculites latecarinatus (Brunnschweiler, 1966), Discoscaphites iris (Conrad, 1858), Discoscaphites sphaeroidalis Kennedy and Cobban, 2000, Discoscaphites minardi Landman et al., 2004b, Discoscaphites gulosus (Morton, 1834), and Discoscaphites jerseyensis, n.sp. The dinoflagellates include Palynodinium grallator Gocht, 1970, Thalassiphora pelagica (Eisenack, 1954) Eisenack & Gocht, 1960, Deflandrea galeata (Lejeune-Carpentier, 1942) Lentin & Williams, 1973, and Disphaerogena carposphaeropsis Wetzel, 1933. These ammonites and dinoflagellates are indicative of the uppermost Maastrichtian, corresponding to the upper part of calcareous nannofossil Subzone CC26b. The mode of occurrence of the fossils in the Pinna Layer suggests an autochthonous accumulation with little or no postmortem transport. Many of the benthic organisms are preserved in life position. For example, specimens of Pinna laqueata Conrad, 1858, are oriented in a vertical position, similar to that of modern members of this genus. The echinoids also occur in aggregations of hundreds of individuals, suggesting gregarious feeding behavior. In addition, there are monospecific clusters of baculites and scaphites. These clusters are biological in origin and could not have been produced by hydraulic means. Scaphite jaws are also present, representing the first reports of these structures in the Upper Cretaceous of the Atlantic Coastal Plain. They occur both as isolated specimens and inside the body chamber, and indicate little or no postmortem transport. The Pinna Layer represents a geologically short interval of time. The fact that most of the animals are mature suggests that the community persisted for at least 5-10 years. If multiple generations of animals are present, perhaps reflecting multiple episodes of colonization and burial, then this unit probably represents more time, amounting to several tens of years. The fact that the Pinna Layer is truncated at the top implies a still longer period of time, amounting to hundreds of years. These age estimates are consistent with observed rates of sedimentation in nearshore environments. Iridium analyses of 37 samples of sediment from three sites in the Manasquan River Basin reveal an elevated concentration of iridium of 520 pg/g, on average, at the base of the Pinna Layer. The iridium profile is aymmetric with an abrupt drop off above the base of this unit and a gradual decline below the base. The elevated concentration of iridium is not as high as that recorded from some other Cretaceous/Tertiary boundary sections. However, it is sufficiently above background level to suggest that it is related to the global Ir anomaly documented at many other localities, and attributed to a bolide impact. The position of the iridium anomaly at the base of the Pinna Layer is inconsistent with the biostratigraphic data, because this anomaly occurs below the unit containing fossils indicative of the uppermost Maastrichtian. We present two alternative hypotheses: (1) If the enriched concentration of iridium is in place, it marks the Cretaceous/Tertiary boundary by reference to the global stratotype section and point at El Kef, Tunisia. The position of the iridium anomaly further implies that the Pinna community was living at the moment of impact and may even have flourished in its immediate wake. Subsequently, the community may have been buried by pulses of mud-rich sediment, possibly associated with enhanced riverine discharge following the impact. The Burrowed Unit may represent a subsequent pulse of riverine discharge that scoured the top of the Pinna Layer. (2) The iridium anomaly was originally located at the top of the Pinna Layer and was displaced downward due to bioturbation and/or chemical diffusion. This hypothesis implies that the Pinna Layer was deposited prior to the deposition of the iridium. The Pinna community may have died before or at the moment of impact. Erosion of the top of the Pinna Layer and deposition of the Burrowed Unit may have been associated with events immediately following the impact. In both hypotheses, the sea floor experienced an extended period of erosion and reworking in the early Danian, which may have lasted for several hundred thousand years, producing a concentrated lag of siderite nodules containing reworked fossils in the basal part of the Hornerstown Formation. This lag deposit is equivalent to the Main Fossiliferous Layer at the base of the Hornerstown Formation elsewhere in New Jersey. This period of erosion and reworking was probably associated with a transgression in the early Danian. The post-impact community was greatly reduced in diversity, with most of the species representing Cretaceous survivors.