Problems of permo‐triassic terrestrial vertebrate extinctions

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Abstract
The problems posed by apparent extinctions of terrestrial vertebrates at the Permo‐Triassic (P.T) transition are treated in context of three questions: (1) its reality, geographic extent and rapidity, (2) the problems of correlation relative to (1) and (3), and (3) the causes of the putative extinction. The major differences between the vertebrate faunas before and just after the P T transition give evidence of a massive, widespread extinction of terrestrial animals and plants. The geographic distribution is broad, but not sufficient to affirm conclusively a world‐wide extinction event. Correlation of both terrestrial and terrestrial‐marine deposits, crucial in determining the rate and causes of the extinctions, both marine and non‐marine, cannot currently be sufficiently resolved. Physical studies are aiding in resolving this problem. In China, in particular, studies of siderophiles. carbon 12/13 ratios, and palaeomagnetism at the P.T boundary suggest a catastrophic event took place. Evidence points either to massive vulcanism or the effects of an impact by an extraterrestrial object. Possibly both may have been involved in the extinctions, but widespread tectonic effects cannot be ruled out. More extensive world‐wide study of physical events at the P/T transition zone may provide solutions to many of the current problems.