skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Impact theory of mass extinctions and the invertebrate fossil record

Abstract

There is much evidence that the Cretaceous-Tertiary boundary was marked by a massive meteorite impact. Theoretical consideration of the consequences of such an impact predicts sharp extinctions in many groups of animals precisely at the boundary. Paleontological data clearly show gradual declines in diversity over the last 1 to 10 million years in various invertebrate groups. Reexamination of data from careful studies of the best sections shows that, in addition to undergoing the decline, four groups (ammonites, cheilostomate bryozoans, brachiopods, and bivalves) were affected by sudden truncations precisely at the iridium anomaly that marks the boundary. The paleontological record thus bears witness to terminal-Cretaceous extinctions on two time scales: a slow decline unrelated to the impact and a sharp truncation synchronous with and probably caused by the impact. 50 references, 4 figures.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Univ. of California, Berkeley
OSTI Identifier:
5808167
Resource Type:
Journal Article
Resource Relation:
Journal Name: Science (Washington, D.C.); (United States); Journal Volume: 223:4641
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; INVERTEBRATES; BIOLOGICAL EXTINCTION; METEORITES; ENVIRONMENTAL IMPACTS; BOUNDARY LAYERS; CRETACEOUS PERIOD; FOSSILS; IRIDIUM; PALEONTOLOGY; SPECIES DIVERSITY; TERTIARY PERIOD; ANIMALS; CENOZOIC ERA; ELEMENTS; GEOLOGIC AGES; LAYERS; MESOZOIC ERA; METALS; PLATINUM METALS; TRANSITION ELEMENTS; 510100* - Environment, Terrestrial- Basic Studies- (-1989); 580100 - Geology & Hydrology- (-1989)

Citation Formats

Alvarez, W., Kauffman, E.G., Surlyk, F., Alvarez, L.W., Asaro, F., and Michel, H.V. Impact theory of mass extinctions and the invertebrate fossil record. United States: N. p., 1984. Web. doi:10.1126/science.223.4641.1135.
Alvarez, W., Kauffman, E.G., Surlyk, F., Alvarez, L.W., Asaro, F., & Michel, H.V. Impact theory of mass extinctions and the invertebrate fossil record. United States. doi:10.1126/science.223.4641.1135.
Alvarez, W., Kauffman, E.G., Surlyk, F., Alvarez, L.W., Asaro, F., and Michel, H.V. 1984. "Impact theory of mass extinctions and the invertebrate fossil record". United States. doi:10.1126/science.223.4641.1135.
@article{osti_5808167,
title = {Impact theory of mass extinctions and the invertebrate fossil record},
author = {Alvarez, W. and Kauffman, E.G. and Surlyk, F. and Alvarez, L.W. and Asaro, F. and Michel, H.V.},
abstractNote = {There is much evidence that the Cretaceous-Tertiary boundary was marked by a massive meteorite impact. Theoretical consideration of the consequences of such an impact predicts sharp extinctions in many groups of animals precisely at the boundary. Paleontological data clearly show gradual declines in diversity over the last 1 to 10 million years in various invertebrate groups. Reexamination of data from careful studies of the best sections shows that, in addition to undergoing the decline, four groups (ammonites, cheilostomate bryozoans, brachiopods, and bivalves) were affected by sudden truncations precisely at the iridium anomaly that marks the boundary. The paleontological record thus bears witness to terminal-Cretaceous extinctions on two time scales: a slow decline unrelated to the impact and a sharp truncation synchronous with and probably caused by the impact. 50 references, 4 figures.},
doi = {10.1126/science.223.4641.1135},
journal = {Science (Washington, D.C.); (United States)},
number = ,
volume = 223:4641,
place = {United States},
year = 1984,
month = 3
}
  • A carbon-rich black layer, dating to ~;12.9 ka, has beenpreviously identified at ~;50 Clovis-age sites across North America andappears contemporaneous with the abrupt onset of Younger Dryas (YD)cooling. The in situ bones of extinct Pleistocene megafauna and Clovistool assemblages occur below this black layer but not within or above it.Causes for the extinctions, the YD cooling, and the termination of Clovisculture have long been controversial. In this paper, we provide evidencefor an extraterrestrial (ET) impact event at ?12.9 ka, which, wehypothesize, caused abrupt environmental changes that contributed to YDcooling, major ecological reorganization, broad-scale extinctions, andrapid human behavioral shifts at themore » end of the Clovis Period. Clovis-agesites in North American are overlain by a thin, discrete layer withvarying peak abundances of: (1) magnetic grains with iridium, (2)magnetic microspherules (3) charcoal, (4) soot, (5) carbon spherules, (6)glass-like carbon, and (7) fullerenes with ET helium, all of which areevidence for an ET impact and associated biomass burning at ~;12.9 ka.This layer also extends throughout at least fifteen Carolina Bays, whichare unique, elliptical wetlands, oriented to thenorthwest across theAtlantic Coastal Plain. We propose that one or more large, low-density ETobjects exploded over northern North America, partially destabilizing theLaurentide Ice Sheet and triggering YD cooling. The shock wave, thermalpulse, and event-related environmental effects (e.g., extensive biomassburning, food limitations) contributed to the end-Pleistocene megafaunalextinctions and adaptive shifts among PaleoAmericans in NorthAmerica.« less
  • Evidence indicates that the collision of Earth and a large piece of Solar System derbris such as a meteoroid, asteroid or comet caused the great extinctions of 65 million years ago, leading to the transition from the age of the dinosaurs to the age of the mammals.
  • On the Australian continent the fossil record of the initial appearance and radiation of higher metazoans is strongly influenced by the distribution of facies suitable for fossil preservation. The limited stratigraphic range of the [open quotes]Ediacaran[close quotes] fauna, the seemingly abrupt appearance and radiation of Cambrian-aspect traces, and the apparently late appearance of skeletogenous organisms are all functions of the spatial and temporal distributions of key habitats. The principal controls on the formation of these habitats appear to have been changes in climate and siliciclastic sediment supply coupled with cyclic changes in sea level. Aspects of the artifactual bias documentedmore » in Australia are recognized (but rarely documented) in Precambrian-Cambrian boundary sections worldwide. This bias may ultimately form a major stumbling block to detailed reconstruction of early metazoan evolution. 43 refs., 3 figs.« less
  • The evolution of oxygen transport hemoglobins occurred on at least two independent occasions. The earliest event led to myoglobin and red blood cell hemoglobin in animals. In plants, oxygen transport 'leghemoglobins' evolved much more recently. In both events, pentacoordinate heme sites capable of inert oxygen transfer evolved from hexacoordinate hemoglobins that have unrelated functions. High sequence homology between hexacoordinate and pentacoordinate hemoglobins in plants has poised them for potential structural analysis leading to a molecular understanding of this important evolutionary event. However, the lack of a plant hexacoordinate hemoglobin structure in the exogenously ligand-bound form has prevented such comparison. Heremore » we report the crystal structure of the cyanide-bound hexacoordinate hemoglobin from barley. This presents the first opportunity to examine conformational changes in plant hexacoordinate hemoglobins upon exogenous ligand binding, and reveals structural mechanisms for stabilizing the high-energy pentacoordinate heme conformation critical to the evolution of reversible oxygen binding hemoglobins.« less