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1 September 2015 A New Fossil Actinistian from the Early Jurassic of Chile and Its Bearing on the Phylogeny of Actinistia
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We present the description and taxonomic reassignment of a new genus and species, Atacamaia solitaria, gen. et sp. nov., from Lower Jurassic strata of northern Chile, South America. The fish was previously reported as a new genus of Mawsoniidae, based on one unprepared specimen. The fish is characterized by a combination of numerous intriguing characters, such as the presence of a broad parietal bone partially covered laterally by a series of a few large supraorbital bones, a series of sclerotic bones, a lachrymojugal expanded anteriorly and markedly angled, and a metapterygoid with a well-developed ventral process that is ventral to the dorsal margin of the pterygoid plate. Addition of Atacamaia to previously published matrices produces unexpected collapses of certain nodes in the currently accepted phylogenetic hypothesis of Actinistia, creating many polytomies in the consensus tree. Our cladistic analysis suggests that Atacamaia, gen. et sp. nov., Axelia, and Wimania are closely related and together with Piveteauia, Guizhoucoelacanthus, and Whiteia are members of the order Coelacanthiformes. Based on previous analyses and our results, we recognize this grouping as the family Whiteiidae. Members of Whiteiidae are Triassic forms, except Atacamaia solitaria, gen. et sp. nov., from the Early Jurassic. The new fossil actinistian represents the youngest member of the family and the first discovered on the Paleopacific side of Gondwana; all other members are from China, Madagascar, and Spitsbergen. After comparison of previous hypotheses, we review the higher level taxonomy of Actinistia concerning the monophyly of Coelacanthiformes, Latimeroidei, Mawsoniidae, and Latimeriidae and propose a family diagnosis for Whiteiidae.

© by the Society of Vertebrate Paleontology
Gloria Arratia and Hans-Peter Schultze "A New Fossil Actinistian from the Early Jurassic of Chile and Its Bearing on the Phylogeny of Actinistia," Journal of Vertebrate Paleontology 35(5), (1 September 2015).
Received: 26 July 2014; Accepted: 1 October 2014; Published: 1 September 2015

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