Major trends in the evolution of Permian ammonoids

Abstract

The phylogeny of major families of Permian ammonoids is analyzed. The evolution of most families followed a typical scenario with distinct stages of early evolution, diversification, and decline. A smaller group followed a different evolutionary narrative, with indistinct stages. The former group includes families with both simple and complex morphology and a wide range of variation. The nature and trends in the evolution of the families may change depending on their phylogenetic stage. The Early Permian (Asselian), the second half of the Artinskian, and the beginning of the Middle Permian were marked by the most significant evolutionary changes. The Late Permian was the time of the decline of Paleozoic ammonoid orders and of the onset of the evolution of the Mesozoic order Ceratitida.