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- Historical patterns of distribution in Pycnodontiform and Amiiform fishes in the context of moving plates
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Historical patterns of distribution in Pycnodontiform and Amiiform fishes in the context of moving plates
Abstract
Amiiformes and Pycnodontiformes are non-teleostean actinopterygians that were key members of most Mesozoic fish assemblages, appearing often associated throughout their fossil record. Their phylogenetic and biogeographic patterns, however, are strikingly different. For pycnodonts, whose record extends from around 215 to 40 million years ago, up to seven out of 12 palaeobiogeographical events correspond to dispersals from the Tethys sea. This was their center of radiation and their final refuge in their expanding-contracting distribution pattern. In turn, the distribution of amiiforms (195 million years ago to recent), although also initially associated with the Tethys sea, follows a mostly vicariant pattern; five main vicariant events out of a total of 15 events, which also include dispersal and radiation events, define their palaeobiogeography, in contrast with no vicariant event detected for pycnodonts. Ecologically, both appear closely associated with coastlines and continents, reaching an almost cosmopolitian distribution; they often occur associated in the same localities. This indicates that their dispersal during the same time intervals are not determined by moving plates alone. Data suggest that their taxonomic diversity and ecomorphological disparity may have played an important role in their dissimilar biogeographical patterns. Pycnodontiforms present a higher diversity and disparity, with variable body-fin shape and dentition; amiiforms are less diversified, with rather uniform body shape and dentition, their disparity being, then, quite low. This was a key factor of their different capacities to compete with teleosts, which would dominate fish faunas since the Late Cretaceous on. Therefore, internal factors play a crucial role to explain the historical patterns of distribution in these organisms.
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A propos de : Hugo MARTÍN-ABAD
Universidad Autónoma de Madrid, c/ Darwin, 2, Cantoblanco, 28049-Madrid, Spain ; E-mail: hugo.martin@uam.es
A propos de : Francisco José POYATO-ARIZA
Universidad Autónoma de Madrid, c/ Darwin, 2, Cantoblanco, 28049-Madrid, Spain ; E-mail: francisco.poyato@uam.es