An Exceptionally Preserved Fossil Fish from the Silurian of China Illuminates Jaw Evolution

摘要

Osteichthyans(bony fishes and tetrapods)have the maxillary,premaxillary,and dentary bones,all with facial laminae,whereas placoderms(jawed stem gnathostomes)have supposedly nonhomologous gnathal plates that lack facial laminae.The discovery of Entelognathus from the Late Silurian(Ludlow)Xiaoxiang vertebrate fauna of Yunnan,China in 2013,revealed the presence of maxilla,premaxilla,