scholarly journals Constructing a Timescale of Biotic Recovery across the Cretaceous–Paleogene Boundary, Corral Bluffs, Denver Basin, Colorado

2019 ◽  
Author(s):  
Anthony J. Fuentes ◽  
William C. Clyde ◽  
Ken Weissenburger ◽  
Antoine Bercovici ◽  
Tyler R. Lyson ◽  
...  
Keyword(s):  
Mass Extinctions ◽  
Denver Basin ◽  
Palynological Analysis ◽  
Sedimentary Deposits ◽  
Biotic Recovery ◽  
Recovery Dynamics ◽  
Land Mammal ◽  
Mammal Faunas ◽  
Significant Mass ◽  
Age Estimates

ABSTRACTThe Cretaceous–Paleogene (K–Pg) boundary interval represents one of the most significant mass extinctions and ensuing biotic recoveries in Earth history. Earliest Paleocene fossil mammal faunas corresponding to the Puercan North American Land Mammal Age (NALMA) are thought to be highly endemic and potentially diachronous, necessitating precise chronostratigraphic controls at key fossil localities to constrain recovery dynamics in continental biotas following the K–Pg mass extinction. The Laramide synorgenic sedimentary deposits within the Denver Basin preserve one of the most continuous and fossiliferous records of the K–Pg boundary interval in North America. However, poor exposure in much of the Denver Basin makes it difficult to correlate between outcrops. In order to constrain fossil localities across the basin, previous studies have relied upon chronostratigraphic methods such as magnetostratigraphy. Here we present a new high-resolution magnetostratigraphy of 10 lithostratigraphic sections spanning the K–Pg boundary interval at Corral Bluffs located east of Colorado Springs in the southern part of the Denver Basin. Fossil localities from Corral Bluffs have yielded limited dinosaur remains, mammal fossils assigned to the Puercan NALMA, and numerous fossil leaf localities. Palynological analysis identifying the K–Pg boundary in three sections and two independent but nearly identical206Pb/238U age estimates for the same volcanic ash, provide key temporal calibration points. Our paleomagnetic analysis has identified clear polarity reversal boundaries from Chron C30n to Chron C28r across the sections. It is now possible to place the fossil localities at Corral Bluffs within the broader basin-wide chronostratigraphic framework and evaluate them in the context of K–Pg boundary extinction and recovery.

scholarly journals Constructing a time scale of biotic recovery across the Cretaceous–Paleogene boundary, Corral Bluffs, Denver Basin, Colorado, U.S.A.

2019 ◽  
Vol 54 (2) ◽  
pp. 133-153
Author(s):  
Anthony J. Fuentes ◽  
William C. Clyde ◽  
Ken Weissenburger ◽  
Antoine Bercovici ◽  
Tyler R. Lyson ◽  
...  
Keyword(s):  
Mass Extinctions ◽  
Denver Basin ◽  
East Central ◽  
Sedimentary Deposits ◽  
Biotic Recovery ◽  
Recovery Dynamics ◽  
Land Mammal ◽  
Mammal Faunas ◽  
Significant Mass ◽  
Age Estimates

ABSTRACT The Cretaceous–Paleogene (K–Pg) boundary interval represents one of the most significant mass extinctions and ensuing biotic recoveries in Earth history. Earliest Paleocene fossil mammal faunas corresponding to the Puercan North American Land Mammal Age (NALMA) are thought to be highly endemic and potentially diachronous, necessitating precise chronostratigraphic controls at key fossil localities to constrain recovery dynamics in continental biotas following the K–Pg mass extinction. The Laramide synorgenic sedimentary deposits within the Denver Basin in east-central Colorado preserve one of the most continuous and fossiliferous records of the K–Pg boundary interval in North America. Poor exposure in much of the Denver Basin, however, makes it difficult to correlate between outcrops. To constrain fossil localities in coeval strata across the basin, previous studies have relied upon chronostratigraphic methods such as magnetostratigraphy. Here, we present a new high-resolution magnetostratigraphy of 10 lithostratigraphic sections spanning the K–Pg boundary interval at Corral Bluffs located east of Colorado Springs in the southern part of the Denver Basin. Fossil localities from Corral Bluffs have yielded limited dinosaur remains, mammal fossils assigned to the Puercan NALMA, and numerous fossil leaf localities. Palynological analyses identifying the K–Pg boundary in three sections and two independent, but nearly identical, 206Pb/238U age estimates for the same volcanic ash, provide key temporal calibration points. Our paleomagnetic analyses have identified clear polarity reversal boundaries from chron C30n to chron C28r across the sections. It is now possible to place the fossil localities at Corral Bluffs within the broader basin-wide chronostratigraphic framework and evaluate them in the context of K–Pg boundary extinction and recovery.

Within- and among-genus components of size evolution during mass extinction, recovery, and background intervals: a case study of Late Permian through Late Triassic foraminifera

Paleobiology ◽  
2012 ◽  
Vol 38 (4) ◽  
pp. 627-643 ◽  
Author(s):  
Brianna L. Rego ◽  
Steve C. Wang ◽  
Demir Altiner ◽  
Jonathan L. Payne
Keyword(s):  
Mass Extinction ◽  
Extinction Risk ◽  
Maximum Size ◽  
Size Reduction ◽  
Late Triassic ◽  
Mass Extinctions ◽  
Late Permian ◽  
Biotic Recovery ◽  
Size Evolution ◽  
Selective Extinction

One of the best-recognized patterns in the evolution of organismal size is the tendency for mean and maximum size within a clade to decrease following a major extinction event and to increase during the subsequent recovery interval. Because larger organisms are typically thought to be at higher extinction risk than their smaller relatives, it has commonly been assumed that size reduction mostly reflects the selective extinction of larger species. However, to our knowledge the relative importance of within- and among-lineage processes in driving overall trends in body size has never been compared quantitatively. In this study, we use a global, specimen-level database of foraminifera to study size evolution from the Late Permian through Late Triassic. We explicitly decompose size evolution into within- and among-genus components. We find that size reduction following the end-Permian mass extinction was driven more by size reduction within surviving species and genera than by the selective extinction of larger taxa. Similarly, we find that increase in mean size across taxa during Early Triassic biotic recovery was a product primarily of size increase within survivors and the extinction of unusually small taxa, rather than the origination of new, larger taxa. During background intervals we find no strong or consistent tendency for extinction, origination, or within-lineage change to move the overall size distribution toward larger or smaller sizes. Thus, size stasis during background intervals appears to result from small and inconsistent effects of within- and among-lineage processes rather than from large but offsetting effects of within- and among-taxon components. These observations are compatible with existing data for other taxa and extinction events, implying that mass extinctions do not influence size evolution by simply selecting against larger organisms. Instead, they appear to create conditions favorable to smaller organisms.

Some Studies of Terrestrial Impact Cratering Rate

2011 ◽  
Vol 20 (2) ◽  
Author(s):  
L. Jetsu
Keyword(s):  
Oort Cloud ◽  
Impact Craters ◽  
Periodic Signal ◽  
Mass Extinctions ◽  
Impact Cratering ◽  
Periodicity Detection ◽  
The Difference ◽  
Aperiodic Component ◽  
Human Signal ◽  
Age Estimates

AbstractIn 1984, a 28.4 Myr periodicity was detected in the ages of terrestrial impact craters and a 26 Myr periodicity in the epochs of mass extinctions of species. Periodic comet showers from the Oort cloud seemed to cause catastrophic events linked to mass extinctions of species. Our first study revealed that the only significant detected periodicity is the “human signal” caused by the rounding of these data into integer numbers. The second study confirmed that the original 28.4 Myr periodicity detection was not significant. The third study revealed that the quality and the quantity of the currently available data would allow detection of real periodicity only if all impacts have been periodic, which cannot be the case. The detection of a periodic signal, if present, requires that more craters should be discovered and the accuracy of age estimates improved. If we sometimes will be able to find the difference between the craters caused by asteroid and comet impacts, the aperiodic component could be removed. The lunar impact craters may eventually provide the required supplementary data.

Vertebrate paleontology, geology, and geochronology of the Tapera de López and Scarritt Pocket, Chubut Province, Argentina

1986 ◽  
Vol 60 (4) ◽  
pp. 920-951 ◽  
Author(s):  
Larry G. Marshall ◽  
Richard L. Cifelli ◽  
Robert E. Drake ◽  
Garniss H. Curtis
Keyword(s):  
South America ◽  
Middle Eocene ◽  
Lower Boundary ◽  
Vertebrate Paleontology ◽  
Early Eocene ◽  
Local Fauna ◽  
Early Oligocene ◽  
Land Mammal ◽  
Mammal Faunas ◽  
Upper Boundary

Fossil land mammals were collected by G. G. Simpson in 1933–1934 at and near the Tapera de López in central Chubut Province, Patagonia, southern Argentina, from rocks now mapped as the Sarmiento Formation. These fossils are assigned to land mammal faunas of Casamayoran (Early Eocene), Mustersan (Middle Eocene), and Deseadan (late Early Oligocene through Early Miocene) age.40K-40Ar age determinations of eight basalt and two tuff units associated with the Deseadan age local fauna at Scarritt Pocket establish a geochronologic framework that calibrates the biostratigraphic record at this locality. The radioisotope dates obtained at Scarritt Pocket range from 23.4 Ma to about 21.0 Ma, and equate with earliest Miocene time. The Scarritt Pocket local fauna is the youngest dated Deseadan age fauna yet known in South America.Seven other localities have, or were reputed to have, local faunas of Deseadan age associated with dated volcanic units. Six of these localities are in Argentina (Gran Barranca, Cerro Blanco, Valle Hermoso, Pico Truncado, Cañadón Hondo, Quebrada Fiera de Malargüe) and one in Bolivia (Estratos Salla in the Salla-Luribay Basin). The stratigraphic relationships of the volcanic units with these local faunas is discussed, and the taxonomic content of each is reassessed.The Deseadan Land Mammal Age is defined by the earliest record of the land mammal genus Pyrotherium, which is from below a basalt dated at 33.6 Ma at Pico Truncado. Other early records of Pyrotherium occur below basalts dated at about 29 Ma at the Gran Barranca and Valle Hermoso, and from a 28.5 Ma level of the Estratos Salla. Thus, the lower boundary for Deseadan time is about 34 Ma.The youngest record of Pyrotherium is in the upper levels of the Estratos Salla dated at about 24 Ma. However, the Scarritt Pocket local fauna, which lacks Pyrotherium, permits placement of the upper boundary for Deseadan time at about 21.0 Ma. Late Deseadan time is surely, and the end of Deseadan time is apparently, marked by the last record of such groups as Proborhyaeninae (Proborhyaena), Rhynchippinae (Rhynchippus), Archaeohyracidae (Archaeohyrax), and the genera Platypittamys (Octodontidae), Scarrittia (Leontiniidae), Propachyrucos and Prohegetotherium (Hegetotheriidae), and Argyrohyrax (Interatheriidae), as these taxa are recorded in the Scarritt Pocket local fauna. Thus, Deseadan time extends from about 34.0 Ma to about 21.0 Ma, making it the Land Mammal Age with the longest known duration in South America.

scholarly journals Fossil horses from the Late Pleistocene of Tapalqué Creek (Buenos Aires Province, Argentina)

2019 ◽  
Vol 294 (3) ◽  
pp. 285-305
Author(s):  
José L. Prado ◽  
Ricardo Bonini ◽  
Cristian Favier-Dubois ◽  
Gustavo N. Gómez ◽  
Pamela Steffan ◽  
...  
Keyword(s):  
South America ◽  
Buenos Aires ◽  
Buenos Aires Province ◽  
South American ◽  
Fluvial Deposits ◽  
Sedimentary Deposits ◽  
Diagenetic Processes ◽  
Taphonomic Analysis ◽  
Land Mammal ◽  
New Evidence

A comparative study was made with the known record of equids species in South America, identifying the remains as Equus neogeus, Hippidion devillei, and Hippidion principale. These data increase the record of Equidae in South America and provide new evidence about the chronological and geographical distribution. The sedimentary deposits of the Lujan Formation outcropping at Tapalqué creek (4 to 120 ky) were accumulated through fluvial processes. This Formation comprises a rich vertebrate fauna corresponding to the Lujanian South American Land Mammal Age, which includes numerous and diverse vertebrate remains. The taphonomic analysis indicates that the faunistic assemblage was formed and was subject to diagenetic processes without distinction of its action in the fossiliferous levels, that can be recognized as fluvial deposits.

Climate change

2004 ◽  
Author(s):  
Tony Hallam
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Fossil Fuels ◽  
Ice Sheets ◽  
Global Scale ◽  
Mass Extinctions ◽  
Load Range ◽  
Ice Caps ◽  
Sedimentary Deposits ◽  
Climatic Cooling

Unlike the other factors that have been invoked to account for mass extinctions, climate change is manifest to us all, whether we travel from the tropics to the poles or experience the seasonal cycle. Over a longer timescale, the issue of global warming in the recent past and likely future, and its probable consequences for other aspects of the environment, has occupied a considerable amount of media attention. Those people who are unaware of the likely consequences of the burning of fossil fuels cannot count themselves as well educated. Over a longer timescale, geologists have been aware for many decades of significant climatic changes on a global scale leading to the appearance and disappearance of polar ice caps on a number of occasions. Steve Stanley, the distinguished palaeobiologist at Johns Hopkins University in Baltimore, has actively promoted the view that episodes of climatic cooling are the most likely cause of mass extinctions. However, we must consider also the significance of global warming, and for the continents, at any rate, the possible effects of changes in the humidity–aridity spectrum. Before examining the relationships between climatic change and mass extinctions we need to examine the criteria from the stratigraphic record that geologists use to determine ancient climates, or palaeo-climates. The most obvious way of detecting cold conditions in the past is to find evidence of the presence of ice. At the present day the sedimentary deposits associated with glaciers and ice sheets, which occur where melting ice dumps its rock load, range in grain size from boulders and pebbles to finely ground rock flour. Such deposits are known as boulder clay or till, and ancient examples consolidated into resistant rock as tillites. The surfaces of hard rock that have underlain substantial ice sheets bear characteristic linear striations indicating the former direction of ice movement, such as glaciers moving up or down a U-shaped valley. The striations are produced by pebbles embedded in the ice, and are a unique marker for glacial action. In the 1830s Louis Agassiz, the great Swiss naturalist, extrapolated from his knowledge of the margins of Alpine glaciers to propose that the whole of northern Europe had been covered by one or more ice sheets in the recent geological past.

Biotic Recovery from Mass Extinctions

2007 ◽  
pp. 202-206 ◽  
Author(s):  
D. J. Bottjer
Keyword(s):  
Mass Extinctions ◽  
Biotic Recovery

scholarly journals Interpreting the Carbon Isotope Record of Mass Extinctions

Elements ◽  
2019 ◽  
Vol 15 (5) ◽  
pp. 331-337 ◽  
Author(s):  
Martin Schobben ◽  
Bas van de Schootbrugge ◽  
Paul B. Wignall
Keyword(s):  
Carbon Isotope ◽  
Large Scale ◽  
Stable Carbon Isotope ◽  
Global Scale ◽  
Mass Extinctions ◽  
Sedimentary Deposits ◽  
Igneous Provinces ◽  
Rapid Changes ◽  
Isotope Record ◽  
Sedimentary Carbonate

Mass extinctions are global-scale environmental crises marked by the loss of numerous species from all habitats. They often coincide with rapid changes in the stable carbon isotope ratios (13C/12C) recorded in sedimentary carbonate and organic matter, ratios which can indicate substantial inputs to the surface carbon reservoirs and/or changes in the cycling of carbon. Models to explain these changes have provided much fuel for debate on the causes and consequences of mass extinctions. For example, the escape of methane from gas hydrate deposits or the emission of huge volumes of gaseous carbon from large-scale volcanic systems, known as large igneous provinces, may have been responsible for decreases of 13C/12C in sedimentary deposits. In this article, we discuss the challenges in distinguishing between these, and other, alternatives.

Miocene Tayassuidae (Mammalia) from the Chesapeake Group of the Mid-Atlantic coast and their bearing on marine-nonmarine correlation

1987 ◽  
Vol 61 (3) ◽  
pp. 604-618 ◽  
Author(s):  
David B. Wright ◽  
Ralph E. Eshelman
Keyword(s):  
Atlantic Coast ◽  
The Other ◽  
Western North America ◽  
Terrestrial Mammal ◽  
Marine Strata ◽  
Terrestrial Mammals ◽  
Size And Morphology ◽  
Land Mammal ◽  
Mammal Faunas ◽  
Early Late

Four morphologically distinct tayassuid species are present in the marine strata of the lower Chesapeake Group in Maryland and Virginia. The oldest of these, an unnamed species, occurs in bed 2 of the Calvert Formation and is the only terrestrial mammal yet known from this unit. In the upper Calvert and lower Choptank Formations three tayassuid species resemble closely in size and morphology taxa known from the middle and upper Miocene Olcott and Valentine Formations in Nebraska. “Cynorca proterva” and “Prosthennops” xiphidonticus are present in beds 10 and 14, respectively, of the Calvert Formation. “Prosthennops” niobrarensis occurs in bed 17 of the Choptank Formation. These taxa, considered together with the other known terrestrial mammals from the Chesapeake Group, indicate the following correlations with land mammal faunas from western North America: bed 2, ?late Arikareean or early Hemingfordian; bed 10, late Hemingfordian or early Barstovian; bed 14, early late Barstovian; bed 17, late late Barstovian. These correlations are largely concordant with micropaleontogical correlations for the Chesapeake Group, but the age indicated for bed 17 is younger than an age estimate based on diatoms.

Post–Permo-Triassic terrestrial vertebrate recovery: southwestern United States

Paleobiology ◽  
2012 ◽  
Vol 38 (4) ◽  
pp. 644-663 ◽  
Author(s):  
David A. Tarailo ◽  
David E. Fastovsky
Keyword(s):  
Taxonomic Diversity ◽  
American Southwest ◽  
Coarse Grained ◽  
Late Triassic ◽  
Marine Biodiversity ◽  
Mass Extinctions ◽  
Terrestrial Vertebrate ◽  
Biotic Recovery ◽  
Marine Realm ◽  
Early Middle Triassic

Recovery of marine biodiversity following the Permo-Triassic extinction is thought to have been delayed relative to other mass extinctions. Terrestrial vertebrate biodiversity is said to have taken as much as 15 Myr longer to recover than the marine. The present study tests, at the scale of an individual fossil community, whether a disparity in biodiversity existed in the American Southwest, between the Moenkopi Formation, containing an early Middle Triassic (Anisian) terrestrial tetrapod fauna, and the Chinle Formation, containing a successor Late Triassic (Norian) tetrapod fauna. Taking Chinle faunal biodiversity to represent full biotic recovery, comparison of taxonomic and guild diversity of faunas from similar depositional and taphonomic environments in these two formations allowed us to assess the possibility of incipient terrestrial recovery of biodiversity in the Anisian.Comparisons were made between the Holbrook Member fauna of the Moenkopi, a unit best characterized as a low-sinuosity medium- to coarse-grained fluvial deposit, and each of four Chinle stratigraphic units, representing fluvial settings from sandy low-sinuosity to muddy high-sinuosity. Three metrics were applied: generic and familial taxonomic diversity and guild diversity; these were compared by rarefaction. Simpson and Shannon diversity metrics augmented the analysis. Units of extraordinary preservation in the Chinle—the so-called blue layers—were removed from the analysis. In all tests the biodiversity of the Holbrook Member fauna is within the variation seen in Chinle faunas.If the results of our study represent global conditions, they suggest that by at least early Anisian time (∼6 Myr after the P/T extinction) biodiversity had reached levels comparable to those seen in the Late Triassic. This potentially brings the terrestrial vertebrate recovery in line with the 4–8 Myr it took for recovery in the marine realm.

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