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[Biological crisis at the end of the Cretaceous and the extinction of the dinosaurs. Validity of the cosmic hypothesis].
Bull Acad Natl Med. 2001; 185(7):1307-26.BA

Abstract

The history of life, which appeared more than 500 million years ago, has been characterized by a constant faunal and floral turnover. On five occasions, the background extinctions has become a mass extinction (ME), i.e. a major biotic crisis collapsing the upward curve of the biodiversity. The mass extinction of the end of the Permian is the most murderous but the end-Cretaceous one, which experiences dinosaur's death, is the most well-known. In fact, these land-dwelling reptiles with upright limbs, as well as the pterosaurs, the mosasaurs and numerous invertebrates die as far as the last. There exists a lot of hypotheses tending to explain their death but they are often extravagant and/or impossible to be verified. The last one, referring to a collapse between the earth and a heavenly large bolide has given rise, since more than 20 years, to heated debates between catastrophists and gradualists, even if the reality of the impact seems no more doubtful (discovery of Chicxulub impact crater, iridium anomaly, tektite glass, shocked quartz, spinels with high nickel concentrations). It is now the extent of the deleterious effects (regional or worldwide repercussion) which is debating. By referring to the obtained data in oceanic environment and, if necessary, in terrestrial environment where fossil record is too often incomplete, it can be noticed an important fact corresponding to a selective character of extinctions, the event of the C/T boundary killing off some taxa while others are preserved. This remark does not really correspond to the hypothesis of a sudden planetary catastrophe of large magnitude. Consequently, it seems to be reasonable to make arise intrinsic factors associated to the dynamics of the globe (volcanic eruptions, marine regression, fall of temperature) over a long period. The collapse with the Chicxulub asteroid should then come up, especially in Western North-America, as a "coup de grâce" in a weakened ecosystem.

Authors

Magnol JP
No affiliation info available

MeSH

AnimalsClimateDinosaursDisastersFossilsMeteoroidsModels, TheoreticalPopulation Dynamics

Pub Type(s)

English Abstract
Journal Article

Language

fre

PubMed ID

11975326

Citation

Magnol, J P.. "[Biological Crisis at the End of the Cretaceous and the Extinction of the Dinosaurs. Validity of the Cosmic Hypothesis]." Bulletin De l'Academie Nationale De Medecine, vol. 185, no. 7, 2001, pp. 1307-26.
Magnol JP. [Biological crisis at the end of the Cretaceous and the extinction of the dinosaurs. Validity of the cosmic hypothesis]. Bull Acad Natl Med. 2001;185(7):1307-26.
Magnol, J. P. (2001). [Biological crisis at the end of the Cretaceous and the extinction of the dinosaurs. Validity of the cosmic hypothesis]. Bulletin De l'Academie Nationale De Medecine, 185(7), 1307-26.
Magnol JP. [Biological Crisis at the End of the Cretaceous and the Extinction of the Dinosaurs. Validity of the Cosmic Hypothesis]. Bull Acad Natl Med. 2001;185(7):1307-26. PubMed PMID: 11975326.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - [Biological crisis at the end of the Cretaceous and the extinction of the dinosaurs. Validity of the cosmic hypothesis]. A1 - Magnol,J P, PY - 2002/4/27/pubmed PY - 2002/5/15/medline PY - 2002/4/27/entrez SP - 1307 EP - 26 JF - Bulletin de l'Academie nationale de medecine JO - Bull Acad Natl Med VL - 185 IS - 7 N2 - The history of life, which appeared more than 500 million years ago, has been characterized by a constant faunal and floral turnover. On five occasions, the background extinctions has become a mass extinction (ME), i.e. a major biotic crisis collapsing the upward curve of the biodiversity. The mass extinction of the end of the Permian is the most murderous but the end-Cretaceous one, which experiences dinosaur's death, is the most well-known. In fact, these land-dwelling reptiles with upright limbs, as well as the pterosaurs, the mosasaurs and numerous invertebrates die as far as the last. There exists a lot of hypotheses tending to explain their death but they are often extravagant and/or impossible to be verified. The last one, referring to a collapse between the earth and a heavenly large bolide has given rise, since more than 20 years, to heated debates between catastrophists and gradualists, even if the reality of the impact seems no more doubtful (discovery of Chicxulub impact crater, iridium anomaly, tektite glass, shocked quartz, spinels with high nickel concentrations). It is now the extent of the deleterious effects (regional or worldwide repercussion) which is debating. By referring to the obtained data in oceanic environment and, if necessary, in terrestrial environment where fossil record is too often incomplete, it can be noticed an important fact corresponding to a selective character of extinctions, the event of the C/T boundary killing off some taxa while others are preserved. This remark does not really correspond to the hypothesis of a sudden planetary catastrophe of large magnitude. Consequently, it seems to be reasonable to make arise intrinsic factors associated to the dynamics of the globe (volcanic eruptions, marine regression, fall of temperature) over a long period. The collapse with the Chicxulub asteroid should then come up, especially in Western North-America, as a "coup de grâce" in a weakened ecosystem. SN - 0001-4079 UR - https://www.unboundmedicine.com/medline/citation/11975326/[Biological_crisis_at_the_end_of_the_Cretaceous_and_the_extinction_of_the_dinosaurs__Validity_of_the_cosmic_hypothesis]_ L2 - https://medlineplus.gov/disasterpreparationandrecovery.html DB - PRIME DP - Unbound Medicine ER -