... Peter M. Sheehan, Department de Geologie, Universite' de Montre'al, CP 6128, Mon-tr... more ... Peter M. Sheehan, Department de Geologie, Universite' de Montre'al, CP 6128, Mon-treal, Quebec ... David M. Raup, Department of Geological Sciences, University of Rochester, Roches-ter, New York ... there is no com-pelling evidence for a general increase in the number of ...
In the terrestrial latest Cretaceous Hell Creek (HC) Formation, both non-biotic events and patter... more In the terrestrial latest Cretaceous Hell Creek (HC) Formation, both non-biotic events and patterns of extinction and survivorship are consistent with an asteroid impact causing the extinctions. Environments through the last 2--3 million-year interval represented by the HC remained relatively constant: an aggrading coastal lowland dissected by meandering rivers. The K-T boundary occurred during an abrupt change to impeded drainage represented by coals and pond deposits formed under low-energy conditions. Because of the close temporal proximity of the sediments of the Paleocene Cannonball Sea to the K-T boundary in South Dakota, impeded drainage in the earliest Paleocene in eastern Montana may be attributable to riverine base-level changes associated with a renewed transgression of the western interior sea during the K-T transition. Patterns within the biota mirror those of the paleoenvironments. The ecological diversity of HC dinosaurs remains statistically unchanged through HC time...
A population of the Early Devonian brachiopod Discomyorthis musculosa, from Quebec, Canada, was p... more A population of the Early Devonian brachiopod Discomyorthis musculosa, from Quebec, Canada, was preyed upon by a boring carnivore, possibly a gastropod. The predator preferentially attacked this species and selected a specific size range of prey. Large size seems to have provided a refuge from predation. Predation was a significant contribution to mortality during part of the life history of the population. Examination of survivorship curves reveals the number of individuals which would have lived through the interval of predation was reduced by more than 50% because of predation. This may be an early Phanerozoic example of diversity regulation by predation.
... Titre du document / Document title. Late Ordovician (Ashgillian) brachiopods from the region ... more ... Titre du document / Document title. Late Ordovician (Ashgillian) brachiopods from the region of the Sambre and Meuse Rivers, Belgium = Brachiopodes de l'Ordovicien supérieur, Ashgill, provenant de la région de la Sambre et de la Meuse, Belgique. Auteur(s) / Author(s). ...
Detailed stratigraphic sections through Upper Ordovician-Lower Silurian shelf strata of the Easte... more Detailed stratigraphic sections through Upper Ordovician-Lower Silurian shelf strata of the Eastern Great Basin were measured in two Utah localities, Barn Hills (Confusion Range) and Lakeside Mountains. Six major subfacies occur in these strata: mud-cracked and crinkly laminated subfacies, Laminated mudstone subfacies, cross-bedded grainstone subfacies, cross-laminated packstone subfacies, grainy bioturbated subfacies, muddy bioturbated subfacies, and thalassinoides burrowed subfacies. These occur in 1--10 m thick cycles in three facies: muddy cyclic laminite facies (tidal flats), cross-bedded facies (subtidal shoals), and bioturbated facies (moderate to low-energy shelf). The vertical facies succession, stacking patterns of meter-scale cycles, and exposure surfaces define correlatable sequences. The authors recognize four Upper Ordovician sequences (Mayvillian to Richmondian). An uppermost Ordovician (Hirnantian) sequence is missing in these sections but occurs basinward. Lower Sil...
At the end of the Ordovician many marine benthonic and planktonic faunas underwent a global extin... more At the end of the Ordovician many marine benthonic and planktonic faunas underwent a global extinction that has been attributed to climatic changes and glacio-eustatic fluctuations in sea-level (Berry and Boucot, 1973; Sheehan, 1973, 1975; Brenchley, 1984). Raup and Sepkoski (1982) found that the Late Ordovician-Early Silurian extinction event was one of the five major Phanerozoic mass extinctions.
J. Alistair Crame and Alan W. Owen, 2002, Geological Society of London Special Publication 194, G... more J. Alistair Crame and Alan W. Owen, 2002, Geological Society of London Special Publication 194, Geological Society, London, 206 p. (Hardcover, US $108.00) ISBN: 1-86239-106-8. This book resulted from the 2001 Lyell Meeting where Alistair Crame and Alan Owen brought together two groups of paleontologists whose interests are so widely separated in geologic time that they would seldom rub elbows. As study of the great radiations of life begins to compete with the extinction debates as a major focus, paleontology will lose some of the attention it has received because of the appeal of catastrophes to the general public. However, the future will be no less contentious within the paleontological community. Even sorting out what radiations are and how they proceeded will take some time. This book takes a look at two radiations—a straightforward task at first sight, but the radiations are so different that comparisons are no easy matter. The Ordovician Radiation was abrupt, taking place, for the most part, in the Arenig, with a sudden pulse in the Late Arenig at about the base of the Laurentian Whiterock. In terms of biogeography the primary phase of the Ordovician radiation took place in such a short interval that the continental positions were essentially stable. The Mesozoic–Cenozoic radiation took place during such a long interval that plate motions provided a means of distribution and interrupted pathways of dissemination. Entire climatic regimes changed. Even the initiation of the radiations differed. As yet no unusual biotic event has been recognized preceding the Ordovician radiation (although one is suggested here) while the largest mass extinction in earth history set the stage for the Mesozoic radiation. Most contributions are detailed examinations of specific biotic changes that took place during one or the other of the radiations, with little space devoted to comparisons of groups …
... p. 411–423. Ward, P., 1995, The K/T trial: Paleobiology, v. 21, p. 245–247. REPLY SH Hurlbert... more ... p. 411–423. Ward, P., 1995, The K/T trial: Paleobiology, v. 21, p. 245–247. REPLY SH Hurlbert JD Archibald Department of Biology, San Diego State University, SanDiego, California 92182 Sheehan et al. (1991) could not address ...
... Peter M. Sheehan, Department de Geologie, Universite' de Montre'al, CP 6128, Mon-tr... more ... Peter M. Sheehan, Department de Geologie, Universite' de Montre'al, CP 6128, Mon-treal, Quebec ... David M. Raup, Department of Geological Sciences, University of Rochester, Roches-ter, New York ... there is no com-pelling evidence for a general increase in the number of ...
In the terrestrial latest Cretaceous Hell Creek (HC) Formation, both non-biotic events and patter... more In the terrestrial latest Cretaceous Hell Creek (HC) Formation, both non-biotic events and patterns of extinction and survivorship are consistent with an asteroid impact causing the extinctions. Environments through the last 2--3 million-year interval represented by the HC remained relatively constant: an aggrading coastal lowland dissected by meandering rivers. The K-T boundary occurred during an abrupt change to impeded drainage represented by coals and pond deposits formed under low-energy conditions. Because of the close temporal proximity of the sediments of the Paleocene Cannonball Sea to the K-T boundary in South Dakota, impeded drainage in the earliest Paleocene in eastern Montana may be attributable to riverine base-level changes associated with a renewed transgression of the western interior sea during the K-T transition. Patterns within the biota mirror those of the paleoenvironments. The ecological diversity of HC dinosaurs remains statistically unchanged through HC time...
A population of the Early Devonian brachiopod Discomyorthis musculosa, from Quebec, Canada, was p... more A population of the Early Devonian brachiopod Discomyorthis musculosa, from Quebec, Canada, was preyed upon by a boring carnivore, possibly a gastropod. The predator preferentially attacked this species and selected a specific size range of prey. Large size seems to have provided a refuge from predation. Predation was a significant contribution to mortality during part of the life history of the population. Examination of survivorship curves reveals the number of individuals which would have lived through the interval of predation was reduced by more than 50% because of predation. This may be an early Phanerozoic example of diversity regulation by predation.
... Titre du document / Document title. Late Ordovician (Ashgillian) brachiopods from the region ... more ... Titre du document / Document title. Late Ordovician (Ashgillian) brachiopods from the region of the Sambre and Meuse Rivers, Belgium = Brachiopodes de l'Ordovicien supérieur, Ashgill, provenant de la région de la Sambre et de la Meuse, Belgique. Auteur(s) / Author(s). ...
Detailed stratigraphic sections through Upper Ordovician-Lower Silurian shelf strata of the Easte... more Detailed stratigraphic sections through Upper Ordovician-Lower Silurian shelf strata of the Eastern Great Basin were measured in two Utah localities, Barn Hills (Confusion Range) and Lakeside Mountains. Six major subfacies occur in these strata: mud-cracked and crinkly laminated subfacies, Laminated mudstone subfacies, cross-bedded grainstone subfacies, cross-laminated packstone subfacies, grainy bioturbated subfacies, muddy bioturbated subfacies, and thalassinoides burrowed subfacies. These occur in 1--10 m thick cycles in three facies: muddy cyclic laminite facies (tidal flats), cross-bedded facies (subtidal shoals), and bioturbated facies (moderate to low-energy shelf). The vertical facies succession, stacking patterns of meter-scale cycles, and exposure surfaces define correlatable sequences. The authors recognize four Upper Ordovician sequences (Mayvillian to Richmondian). An uppermost Ordovician (Hirnantian) sequence is missing in these sections but occurs basinward. Lower Sil...
At the end of the Ordovician many marine benthonic and planktonic faunas underwent a global extin... more At the end of the Ordovician many marine benthonic and planktonic faunas underwent a global extinction that has been attributed to climatic changes and glacio-eustatic fluctuations in sea-level (Berry and Boucot, 1973; Sheehan, 1973, 1975; Brenchley, 1984). Raup and Sepkoski (1982) found that the Late Ordovician-Early Silurian extinction event was one of the five major Phanerozoic mass extinctions.
J. Alistair Crame and Alan W. Owen, 2002, Geological Society of London Special Publication 194, G... more J. Alistair Crame and Alan W. Owen, 2002, Geological Society of London Special Publication 194, Geological Society, London, 206 p. (Hardcover, US $108.00) ISBN: 1-86239-106-8. This book resulted from the 2001 Lyell Meeting where Alistair Crame and Alan Owen brought together two groups of paleontologists whose interests are so widely separated in geologic time that they would seldom rub elbows. As study of the great radiations of life begins to compete with the extinction debates as a major focus, paleontology will lose some of the attention it has received because of the appeal of catastrophes to the general public. However, the future will be no less contentious within the paleontological community. Even sorting out what radiations are and how they proceeded will take some time. This book takes a look at two radiations—a straightforward task at first sight, but the radiations are so different that comparisons are no easy matter. The Ordovician Radiation was abrupt, taking place, for the most part, in the Arenig, with a sudden pulse in the Late Arenig at about the base of the Laurentian Whiterock. In terms of biogeography the primary phase of the Ordovician radiation took place in such a short interval that the continental positions were essentially stable. The Mesozoic–Cenozoic radiation took place during such a long interval that plate motions provided a means of distribution and interrupted pathways of dissemination. Entire climatic regimes changed. Even the initiation of the radiations differed. As yet no unusual biotic event has been recognized preceding the Ordovician radiation (although one is suggested here) while the largest mass extinction in earth history set the stage for the Mesozoic radiation. Most contributions are detailed examinations of specific biotic changes that took place during one or the other of the radiations, with little space devoted to comparisons of groups …
... p. 411–423. Ward, P., 1995, The K/T trial: Paleobiology, v. 21, p. 245–247. REPLY SH Hurlbert... more ... p. 411–423. Ward, P., 1995, The K/T trial: Paleobiology, v. 21, p. 245–247. REPLY SH Hurlbert JD Archibald Department of Biology, San Diego State University, SanDiego, California 92182 Sheehan et al. (1991) could not address ...
There have been five major mass extinctions among the marine biota during the ∼0.6 by history of ... more There have been five major mass extinctions among the marine biota during the ∼0.6 by history of metazoan life on Earth. These mass extinctions have been ranked from the largest to the smallest by the severity of taxonomic diversity losses, but they have not been ranked by the ...
The richness of Mesozoic Dinosauria is examined through the use of a new global database. Mesozoi... more The richness of Mesozoic Dinosauria is examined through the use of a new global database. Mesozoic dinosaurs show a steadily increasing rate of diversification, in part attributable to the development of new innovations driving an increasing variety of behavioral ...
The Ecological Architecture of Major Events in the Phanerozoic History of Marine Invertebrate Lif... more The Ecological Architecture of Major Events in the Phanerozoic History of Marine Invertebrate Life David J. Bottjer, Mary L. Droser ... Examples include starfish in rocky intertidal communities (Paine 1969), kangaroo rats in desert shrub habitats (Brown and Heske 1990), snow ...
and that the melts produced have several characteristics typical of to describe the H20-undersatu... more and that the melts produced have several characteristics typical of to describe the H20-undersaturated melting behavior of quartzofeldspathic rocks containing somewhat F-enriched biotite. Our ex-periments demonstrated that F significantly increases the ...
... producers. When dust, smoke, and aerosols blocked photosynthesis for five months or more (Too... more ... producers. When dust, smoke, and aerosols blocked photosynthesis for five months or more (Toon, et al., 1994), stream communities preferentially survived. Streams have little primary production and rely on detritus input from land. ...
... 30, Dorset, VT 05251; 802-867-5581, FAX 802-867-4464 Mid-Atlantic: Richard Teeling, 28 Kimber... more ... 30, Dorset, VT 05251; 802-867-5581, FAX 802-867-4464 Mid-Atlantic: Richard Teeling, 28 Kimberly Place, Wayne, NJ 07470; 201-904 ... Tim Appenzeller's article "Hope for magnetic storm warnings" (Research News, 21 Feb., p. 922) was an excellent overview of coronal mass ...
Special Paper 307: The Cretaceous-Tertiary Event and Other Catastrophes in Earth History, 1996
... In the marine benthos, deposit feeders preferentially sur-vived (Arthur et al., 1987; Sheehan... more ... In the marine benthos, deposit feeders preferentially sur-vived (Arthur et al., 1987; Sheehan and ... Rhodes and Thayer, 1991), and animals with developmental stages that did not require planktonic ... The mass extinction of the chalk-producing groups led to total cessation of chalk ...
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