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Publications
Publications (46)
Ammonites are present in ancient hydrocarbon seep deposits, ranging from the Devonian to the Cretaceous. The presence of large concentrations of ammonites in a deposit indicates that they were living at the site. This suggests that the depth of the site did not exceed the implosion depth of these cephalopods. The isotopic composition of well-preser...
A fundamental geochemical process operating at methane seeps is the anaerobic oxidation of methane (AOM) by which methane is oxidized and sulfate is reduced. This process takes place in the sulfate-methane transition zone (SMTZ), generally located below the sediment-water interface. Methane has a low δ13C signature, and this is transferred to the d...
Echinoderms are present, although rare, in Paleozoic, Mesozoic and Cenozoic ancient hydrocarbon seep deposits. They include regular and irregular echinoids, feather star comatulid crinoids, ophiuroids (brittlestars), asteroids (starfish) and stalked crinoids. The rarity of echinoderms may be due to their low preservation potential. However, at some...
The seemingly aberrant coiling of heteromorphic ammonoids suggests that they underwent more significant changes in hydrostatic properties throughout ontogeny than their planispiral counterparts. Such changes may have been responses to different selective pressures at different life stages. The hydrostatic properties of three species of Didymoceras...
Seep deposits in the Upper Cretaceous US Western Interior appear today as prominent geomorphic features in the landscape and are called “tepee buttes.” They are widespread and occur, in general, from the Campanian to early Maastrichtian, persisting for approximately 7 Myr. The presence of methane has been confirmed by isotopic analyses of the seep...
Articulated brittle stars are rare fossils because the skeleton rapidly disintegrates after death and only fossilises intact under special conditions. Here, we describe an extraordinary mass occurrence of the ophiacanthid ophiuroid Brezinacantha tolis gen. et sp. nov., preserved as articulated skeletons from an upper Campanian (Late Cretaceous) met...
Ammonites, as well as other fauna, were common in methane seeps of the Late Cretaceous Western Interior Seaway (WIS) of North America. Biogeochemical processes at the seeps, in particular the anaerobic oxidation of methane, produced a dissolved inorganic carbon reservoir with a low 13C, manifested in the carbon isotope
composition of the inorganic...
Ar/³⁹Ar dating of a bentonite associated with a cold methane seep deposit in the upper Campanian Baculites compressus Zone of the Pierre Shale in South Dakota yields an age of 73.79 ± 0.36 Ma. This is in close agreement with the previously published age of 74.05 ± 0.39 Ma for this zone (Obradovich, 1993) and nearly identical to an unpublished age o...
Betelgeusia brezinai new species (Radiasteridae, Paxillosida, Asteroidea) is described from diversely fossiliferous Upper Cretaceous methane seep deposits of South Dakota. Asteroids are rare at modern chemosynthetic settings, although a hydrothermal vent occurrence is known, and two possible fossil methane seep occurrences have been reported. The R...
We report the discovery of lower jaws of Baculites (Ammonoidea) from the Upper Cretaceous U.S. Western Interior. In the lower Campanian Smoky Hill Chalk Member of the Niobrara Chalk of Kansas, most of the jaws occur as isolated elements. Based on their age, they probably belong to Baculites sp. (smooth). They conform to the description of rugaptych...
Despite a rich and varied record, Mesozoic stalked crinoids are relatively rare in the Western Interior Seaway of North America compared to those found in Northern Europe. A unique example of Mesozoic stalked crinoid is described from cold methane seeps (hydrocarbon seep mounds also called “tepee buttes”) from the Upper Cretaceous (upper Campanian)...
Methane seeps in the Upper Cretaceous Pierre Shale of the U.S. Western interior contain a rich fauna including ammonites (Baculites, Hoploscaphites, Didymoceras, Placenticeras, Solenoceras), bivalves (Lucina), gastropods, sponges, and crinoids. Occasionally, the shell material in the seeps is very well preserved, retaining the original mineralogy a...
Color patterns on ammonoid cephalopods are rarely preserved despite the fact that millions of the shells of these extinct animals have been recovered from Devonian through the Upper Cretaceous rocks that were deposited in a wide variety of marine environments around the world. New information on this biological feature continues to be slowly discov...
We describe a new species of scaphitid ammonite from the Upper Cretaceous (lower Maastrichtian) of North America. Hoploscaphites sargklofak, n. sp., is endemic to the U.S. Western Interior, but closely resembles H. constrictus Sowerby, 1817, from the Maastrichtian of northern Europe.
ABSTRACT We describe a small crab inside the phragmocone of a heteromorph cephalopod Baculites sp. smooth from the Gammon Ferruginous member (lower Campanian) of the pierre Shale in Butte County, South Dakota. The crab Ferricorda kimberlyae (Bishop, 1987) is well preserved with its carapace and pereiopods parallel to and between two septa of the ph...
Despite a rich and varied record, Mesozoic stalked crinoids are relatively rare in the Western Interior Seaway of North America compared to those found in Northern Europe. A unique example of Mesozoic stalked crinoid is described from cold methane seeps (hydrocarbon seep mounds also locations in the Upper Cretaceous of North America that provide a...
We describe Hoploscaphites gilberti, n. sp. (Ammonoidea: Ancyloceratina), from the Upper Cretaceous (middle-upper Campanian) Pierre Shale spanning the zones of Baculites scotti and Didymoceras nebrascense in Colorado, Wyoming, Montana, and South Dakota. This species is strongly dimorphic and is characterized by a compressed whorl section, with a ro...
Methane seep deposits are common in the Upper Cretaceous Pierre Shale of the U.S. Western Interior. They contain a rich fauna including ammonites, bivalves, gastropods, sponges, corals, echinoids, crinoids, and fish. In an effort to understand the role of ammonites in these ecosystems, we examined a seep from the upper Campanian Didymoceras cheyenn...
Scaphitid ammonites (scaphites) are among the most common ammonites in the Upper Cretaceous of the U.S. Western Interior. We have examined species of Hoploscaphites from the Campanian and Maastrichtian Pierre Shale and Bearpaw Shale for clues about their mode of life and habitat. Like most other ammonites, scaphites exhibit determinate growth. The...
Methane seep deposits are common in the Upper Cretaceous Pierre Shale of
the U.S. Western Interior. They contain a rich fauna including ammonites
(Baculites, Hoploscaphites, Didymoceras, Placenticeras, Solenoceras),
bivalves (Lucina), gastropods, sponges, and crinoids. In an effort to
understand the environment of these systems and their influence...
Morphologic analyses of a large quantity of teudopseid coleoids from the Upper Cretaceous (Cenomanian) of Lebanon has yielded a much higher diversity than previously assumed and revealed numerous extraordinarily well-preserved soft-part characters. The Teudopseina is represented by three families (only the Muensterellidae are still unknown in the L...
Morphologic analyses of a large collection of coleoid cephalopods from the Lebanese Upper Cretaceous yielded a much higher diversity than previously assumed and revealed numerous extraordinarily well-preserved, soft-part characters. An analysis of the Prototeuthidina, a gladius-bearing group with a slender torpedo-shaped body, revealed two species:...
Methane seep deposits are common in the Upper Cretaceous Pierre Shale of the U.S. Western Interior. They contain a rich fauna including ammonites (Baculites, Hoploscaphites, Didymoceras, Placenticeras, Solenoceras), bivalves (Lucina), gastropods, sponges, and crinoids. In an effort to understand the environment of these systems, we have examined a...
Scaphitid ammonites (scaphites) are common in the Upper Cretaceous Pierre Shale and Bearpaw Shale of the Western Interior of North America. We redescribe Hoploscaphites nodosus (Owen, 1852) and H. brevis (Meek, 1876) from the Baculites compressusB. cuneatus zones of the upper Campanian. The types of both of these species were collected in the mid-1...
Giant squids and octopi have captivated the imagination of researchers and the public for more than a century. From books to scientific articles to new discoveries on the web, our knowledge of these recent giants is growing but what we know of giant fossil coleoids is limited to only a few scientific papers. The Krakens of the Cretaceous, like thei...
We report on well-preserved upper and lower jaws found inside the body chambers of two specimens of Didymoceras nebrascense (Meek and Hayden, 1856) from the Upper Cretaceous Pierre Shale of the USA. The finds are described and compared to existing material, and their possible functions are discussed.
The scaphitid ammonite genus Ponteixites Warren, 1934, has remained poorly known and poorly represented in collections up to the present. All previously described specimens of
Ponteixites, including the original type specimens, are small and appear to be juveniles. A larger, clearly adult specimen was recently
discovered in the Pierre Shale of east...
Like other molluscs, every ammonite carries a record of its ontogeny and, commonly, its death, in its shell. Traumatic life
events such as bites, diseases, epizoa, and diet all left evidence in the shell as scars, blisters, disfigurations, holes,
nicks, crushing, attachments, and abnormalities, along with slow, rapid, stunted, or enlarged growth. I...
The seminal discovery by Meek and Hayden (1865) of an aptychus preserved inside the body chamber of a Late Cretaceous scaphite in close association with what is unmistakably an upper jaw demonstrated that the aptychus is part of the lower jaw. Lower jaws are known from many ammonites, but, surprisingly, these structures have rarely been reported in...
We describe upper and lower jaws of Placenticeras Meek, 1876, from the Upper Cretaceous (upper Campanian) Bearpaw Shale and Pierre Shale of the Western Interior of North America and lower jaws of the related ammonite Metaplacenticeras Spath, 1926, from the Campanian Yasukawa Formation of Hokkaido, Japan. One lower jaw is preserved inside the body c...
A series of specimens of the Late Cretaceous (Campanian) recoiled scaphite Rhaeboceras halli (MEEK &H AYDEN, 1856), from the Bearpaw Shale of Montana include well-preserved upper and lower jaws, associated with what are interpreted as radular teeth. The radular elements are hollow, and up to 21.8 mm long, equivalent to 50 % of the length of the upp...
Late Cretaceous pachydiscid ammonites Menuites oralensis Cobban and Kennedy, 1993 and Menuites portlocki (Sharpe, 1855) complexus (Hall and Meek, 1856) from the Western Interior of the United States show four kinds of markings on the phragmocone and body chamber. These markings are preserved on internal molds that retain traces of the original shel...
W. A. "Bill" Cobban is one of the most highly respected and published geologist/paleontologists. He is an extraordinary fieldworker, biostratigrapher, paleontologist, geologist and mapmaker. With a career that has spanned more than 60 years he has fundamentally changed our understanding of the Upper Cretaceous Western Interior and made it explicabl...