a new species of cassiduloid echinoids, pygaulus baghinensis is reported for the first time from aptian sediments of baghin area, west of kerman, iran. the diagnostic features of the species are centrally positioned of the apical disc and approximately low profile of the test. variation in gonopore size in different individuals allows to conclude that p. baghinensis is sexually dimorphic. speci...

A number of mechanisms have been proposed for the massive extinction of biota at the Cretaceous-Tertiary transition some 65 million years ago. Most of them were reviewed recently (I). Two additional mechanisms have been proposed, however, since that review was compiled-the "greenhouse" mechanism (2) and the Arctic spillover model (3). In the first of these. McLean has proposed that the large la...