A new elasmobranch fauna from the Middle Jurassic of southern Thailand

A new elasmobranch fauna from the Middle Jurassic of southern Thailand


English :
We describe a new elasmobranch fauna from the lower part of the Khlong Min Formation in Thailand. The fauna includes Hybodus sp., Asteracanthus sp., Lonchidion reesunderwoodi sp. nov., Belemnobatis aominensis sp. nov., and possibly a second species of Belemnobatis. This fauna supports a Bathonian-Callovian age for the Khlong Min Formation, and suggests a close taxonomic relationship between the Middle Jurassic elasmobranch faunas of Europe and Thailand. The presence of a monolayered enameloid in Belemnobatis aominensis sp. nov. and other primitive batoids is interpreted as the retention of a primitive character for neoselachians, which would suggest a divergence time between the batoids and the rest of the neoselachian sharks as early as the Carboniferous-Permian boundary. ? The Geological Society of London 2009.