Abstract
Fossil Diodontidae in Tropical America consist mostly of isolated and fused beak-like jawbones, and tooth plate batteries. These durophagous fishes are powerful shell-crushing predators on shallow water invertebrate faunas from Neogene tropical carbonate bottom, rocky reefs and surrounding flats. We use an ontogenetic series of high-resolution micro CT of fossil and extant species to recognize external and internal morphologic characters of jaws and tooth plate batteries. We compare similar sizes of jaws and/or tooth-plates from both extant and extinct species. Here, we describe three new fossil species including †Chilomycterus exspectatus n. sp. and †Chilomycterus tyleri n. sp. from the late Miocene Gatun Formation in Panama, and †Diodon serratus n. sp. from the middle Miocene Socorro Formation in Venezuela. Fossil Diodontidae review included specimens from the Neogene Basins of the Proto-Caribbean (Brazil: Pirabas Formation; Colombia: Jimol Formation, Panama: Gatun and Tuira formations; Venezuela: Socorro and Cantaure formations). Diodon is present in both the Atlantic and Pacific oceans, whereas the distribution of Chilomycterus is highly asymmetrical with only one species in the Pacific. It seems that Diodon was as abundant in the Caribbean/Western Atlantic during the Miocene as it is there today. We analyze the paleogeographic distribution of the porcupinefishes group in Tropical America, after the complete exhumation of the Panamanian isthmus during the Pliocene.
Highlights
The uplift of the Central American isthmus [1,2,3] interrupted the Pacific-Atlantic seaway and drove large-scale rearrangement in the ocean circulation [4,5,6,7]
The specimen is housed at the Naturhistorisches Museum of Basel (NMB), Switzerland
Diodontidae fossil jawbones and tooth plate battery preserved in the sedimentary basins from the early to late Miocene Tropical Western Central Atlantic (TCWA) and from the Miocene Tropical Eastern Central Pacific (TECP), reveal a valuable opportunity to understand the paleobiogeography of Diodontidae fauna and contribute to elucidate the macroevolutionary responses in coastal faunule affected by the paleoceanographic and paleoenvironmental changes in the region caused by the tectonic dynamics and the severance of the Central American Seaway by the uplift of the Panamanian isthmus, the complete Atlantic-Pacific oceans isolation and the final configuration of the Caribbean Sea (Fig 9)
Summary
The uplift of the Central American isthmus [1,2,3] interrupted the Pacific-Atlantic seaway and drove large-scale rearrangement in the ocean circulation [4,5,6,7]. It produced environmental changes that distinguish today’s Eastern Pacific and Western Atlantic habitats. There are large Miocene-Pliocene hydrographic changes along the northern border of South America, including the Paleo Amazon-Magdalena-Orinoco fluvial system, with complex river delta systems producing high freshwater discharge to the South Caribbean and extensive estuarine environments [10,11, 12,13]. These early hydrographic system could be linked with the origins of marine-derived freshwater fishes, including extant pufferfishes species (Tetraodontiformes) [14]
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