Escamas de peces de aletas radiadas del jurásico tardío de la antártida

This paper reports the discovery of late Jurassic scales of marine actinopterygian fishes from the basal portion of the Ameghino Formation (= Nordenskjöld) in Longing Gap, Antarctic Peninsula. Two additional fish-bearing horizons have been recognized in the sequence, supplementing the three previously known. The identified scales are of two types: large rounded (= elasmoid) of amioid-type, and large rhombic (= ganoid). Elasmoid scales of amioid-type exhibit five distinct morphotypes attributed to Amiiformes, whereas ganoid scales comprise six morphotypes assigned to indeterminate Ginglymodi and Actinopterygii. The macromorphological characteristics of each scale morphotype are presented. Scale regeneration is briefly explored for elasmoid scales of amioid-type. We evaluate the potential role of marine pathways (i.e., the Hispanic and Mozambique corridors) in facilitating the migration of these actinopterygians from their center of origin in the Tethys Sea to the Larsen Basin in the Antarctic Peninsula during the Jurassic. The taphonomic processes that affected the preservation of the material are briefly discussed. The evidence presented here represents the first record of Amiiformes in Antarctica and the southernmost records for both Amiiformes and Ginglymodi worldwide.