Late Cretaceous Elopomorpha (Actinopterygii: Teleostei) from the Mahajanga Basin of Madagascar and impacts on paleobiogeography

Abstract

The Upper Cretaceous deposits of Madagascar have produced a rich terrestrial vertebrate fauna. Studies of Madagascar's endemic fossils and recent fauna have led to multiple hypotheses surrounding the origin of these clades on the island following its complete isolation 88 m.y.a. This report is the first published description of several representatives of fossil Elopomorpha (Teleostei) from the Late Cretaceous of Madagascar. Elopomorphs are primarily marine fishes and one of the most morphologically diverse groups within teleosts. Fragmentary fossil elopomorph elements often consist of tooth plates and vertebrae. The tooth plates and dentary reported here are diagnostic and identifiable to the generic classification of Albula, Egertonia, and Paralbula. The vertebrae are numerous and morphologically variable, which indicates the abundance and importance of elopomorphs in the coastal environment of Madagascar during the Late Cretaceous. Most Cretaceous elopomorphs are from localities in the Northern Hemisphere. While several species of Cretaceous elopomorphs are also found in the Southern Hemisphere, there are not as many in number or kind. These Madagascar fossils represent the oldest Albula and Paralbula fossils recorded from Gondwana, increasing their known spatial range. The Egertonia material described here represents one of the earliest occurrences of the genus, adding to its record during the Cretaceous of Gondwana. The presence of these fishes supports a more global distribution of these genera during the Late Cretaceous and a higher diversity of Elopomorpha in the Southern Hemisphere during the Mesozoic than previously documented.

The Fossil Record and Diversity of Pycnodondiform Fishes in Non-Marine Environments

“…Only one possible freshwater pycnodont represented by an incomplete vomerine tooth plate assigned to Coelodus sp. has been reported from Madagascar up to now, which is Maastrichtian in age [242]. This specimen comes from the Anembalemba Member of the Maevarano Formation in Boeny, which is interpreted as a coastal alluvial plain that was subject to strong seasonality with intense rainfall followed by periods of drought based on sedimentary features in the facies deposits showcasing alternating episodes of turbulent flow and mass flow [243][244][245].…”

A large, freshwater chanid fish (Ostariophysi: Gonorynchiformes) from the Upper Cretaceous of Madagascar

“…These include the fishes Lepisosteus sp. and Parabula sp., the frog Beelzebufo ampinga , the turtle Kinkonychelys rogersi , the snake Kelyophis hechti , the crocodyliforms Simosuchis clarki , Miadanasuchus oblita , and Mahajangasuchus insignis , the sauropod dinosaur Rapetosaurus krausei , the theropod dinosaur Majungasaurus crenatissimus , and the mammal Vintana sertichi (Evans et al, 2014; Krause et al, 2014; Krause & Hoffmann, 2023; Ostrowski, 2021; Pritchard et al, 2014; Rogers et al, 2013:table 1).…”