Diversification and faunal shift of Siluro‐Devonian vertebrates of China

Abstract

AbstractA database including all major groups of early vertebrates in the mid‐Palaeozoic of China was analysed to unravel the diversity pattern at the generic level through this period. It was revealed that early vertebrates from China experienced six macroevolutionary intervals during the mid‐Palaeozoic. They are: (1) the origination interval lasting from the Telychian (Llandovery) to the end of the Wenlock; (2) the survival interval lasting from the Ludlow to the Přídolí; (3) the radiation interval lasting from the Lochkovian to the Emsian; (4) the decline interval lasting from the Eifelian to the Givetian; (5) the survival interval during the Frasnian and (6) the recovery interval during the Famennian. Two major evolutionary faunas, that is, the stem‐gnathostome fauna and the crown‐gnathostome fauna, can be recognized during the mid‐Palaeozoic. The stem‐gnathostome fauna included mainly endemic armoured agnathans (e.g. galeaspids and thelodonts), placoderms and acanthodians, and constituted the chief components of Chinese vertebrates during the period. Although the crown‐gnathostome fauna comprising chondrichthyans and osteichthyans only accounted for about 29% of the total vertebrate genera in the mid‐Palaeozoic of China, it ascended to the partial dominance during the period from the Lochkovian to the Frasnian, and then rapidly increased in importance during the Famennian. Two fish faunal turnovers, occurring at the end of mid‐Emsian and the end‐Devonian, respectively, facilitated the faunal shift from the stem‐gnathostome fauna to the crown‐gnathostome fauna.The early vertebrates mainly inhabited shallow marine niches, which are sensitive to sea‐level fluctuations. The diversification of early vertebrates in the Silurian and Early Devonian of China provides an example of major morphological innovations in tropical nearshore environments. The faunal shift of early vertebrates in the mid‐Palaeozoic of China was mainly affected by sea‐level changes and biotic interactions among organisms, suggesting differential responses of two component faunas to physical environmental transitions (e.g. the removal of barriers during the Emsian). Copyright © 2007 John Wiley & Sons, Ltd.