从地质历史演化趋势分析恐龙的灭绝

摘要

It is a significant subject of astronomy,geology,biology and other disciplines about dinosaur extinction.There are about 130 kinds of theories about dinosaur extinction which could roughly be summarized for extraterrestrial and terrestrial factors and the factor of physiological structure of dinosaurs.The first kind of factors mainly refer to the impact of asteroid or comet impact and sunspot.The second kind of factors include volcanic eruptions,plate tectonics and climate change.And the third kind of factors mainly refer to eggshell morbid or the imbalanced ratio of male and female.The theory of asteroid impact became the mainstream version,for the iridium anomaly in Cretaceous-Paleogene (K/Pg) boundary.Evidences of eggshell,continuous transition of K/Pg,and deposition of the global ocean made asteroid impact being questioned gradually.It is easily to find out that every species have the trend of extinction when we make a general survey of geo-history evolution.Therefore,we should analysis the factors about dinosaur extinction.%恐龙灭绝一直是天文学、地质学、生物学等学科研究的课题.至今有130余种恐龙灭绝的观点或学说解释,大致可概括为地外因素(小行星或彗星撞击说、太阳黑子等)、地内因素(火山喷发、板块运动、气候巨变等)和恐龙生理结构因素(恐龙蛋壳病态和雌雄比例失调等).由于全球不少地区的白垩系/古近系地层中存在铱(Ir)元素异常,因此撞击说成了导致恐龙灭绝的主流学说;但是恐龙蛋壳病态、白垩系/古近系(K/Pg)连续过渡沉积以及海洋沉积等证据的出现,撞击说渐渐受到质疑.纵观地质历史时期的数次生物大灭绝,不难发现许多物种都有萌生→发展→壮大→衰退→灭绝的过程.因此,应多因素地从地史演化趋势的角度分析恐龙的灭绝.