Tertiary extinctions

There have been a number of suggestions in the past that an extraterrestrial object impacting on the. earth caused or could cause massive extinctions of life. E. J. Opik [11], for example, discussed the lethal effects which could be caused by the heat generated from such objects striking the earth, and H. C. Urey [12] stated specifically that a comet was probably the cause of the Cretaceous-Tertiary extinctions. There have also been science fiction stories and a movie relating to the effects. The events likely to occur if the sunlight were temporarily "turned off" have also been discussed [13]. Our deduction in contrast to the others is based on physical science data (the iridium anomaly) and is the only explanation we found which explained the Ir anomaloy could cause the massive extinction of life and was likely to occur in a period of 100 million years. 

Extraterrestrial Cause for the Cretaceous-Tertiary Extinction, Science 208, 1095-1108 (1980). 

Experimental Evidence in Support of an Extraterrestrial Trigger for the Cretaceous-Tertiary Extinctions, WS Trans. Am. Geophys. Union 60. 734 (1979). 

K-TEC group (P. Beland et al.), Cretaceous-Tertiary extinctions and Possible Terrestrial and Extraterrestrial Causes, Proceedings of Workshop, National Museum of Natural Sciences, Ottawa, 16 and 17 November 1976, pp. 144-149. 

Alvarez L. W., Alvarez W., Asaro F., and Michel H. V. (1980) Extraterrestrial cause for the Cretaceous-Tertiary extinction. Science 208, 1095—1108. 

O Keefe J. D. and Ahrens T. J. (1989) Impact production of CO2 by the Cretaceous/Tertiary extinction bolide and the resultant heating of the Earth. Nature 338, 247-249. 

R. Brett, The Cretaceous-Tertiary extinction a lethal mechanism involving anhydrite target rocks, Geochim. Cosmochim. Acta 56, pp. 3603 - 3606 (1992). 

K.O. Pope, K.H. Baines, A.C. Ocampo, and B.A. Ivanov, hnpact winter and the Cretaceous/Tertiary extinctions results of a Chiexulub asteroid impact model. 

J.D. O Keefe and T. J. Ahrens, The interaction of the Cretaceous/Tertiary extinction bolide with the atmosphere, ocean and solid Earth, Geol. Soc. Am. Sp. Paper 190, pp. 103-120(1982). 

Professor MacLeod is an internationally recognized leader in many areas of palaeontology. Prominent among these are (1) morphometries (the quantitative analysis of form variation), (2) the causes of Phanerozoic extinction events and (3) quantitative stratigraphical data analysis. Through his work in these areas, he has made significant contributions to the punctuated-equilibrium controversy and the Cretaceous-Tertiary extinction controversy, as well as being personally responsible for the development of several new morphometric data-analysis techniques. He is the co-editor of... 

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