Biogeografia histórica de Celacantos (Sarcopterygii: Actinistia)

Abstract

Actinistiais a fossil family of actinistians popularly known as coelacanth, represented mainly in fossil record. The group has a great temporal distribution, occurring from Lower Devonian to Recent, with no occurrences in Paleocene period of Cenozoic. It is considered monophyletic and includes five families that appears in the majority of phylogenies proposed to group: Latimeriidae, Laugiidae, Mawsoniidae, Sasseniidae and Rebellatricidae, besides of many genera, species and specimens undetermined (Actinistiaundet), that are not allocated to mentioned families. In this work is realized a biogeography of Actinistia, applying the pan-biogeographic method of track analysis and the Parsimony Analysis of Endemicity (PAE). Concerning the panbiogeographic method, it is obtained 29 individual tracks and four generalized tracks. Based on pattern found, it is suggested that the origin of group occured from Lower/Middle Devoniano of ocidental Pangea, from records of EoactinistiaGavinia and Styloichthys, with subsequente expansion in Carboniferous, corroborated mainly by records of Rhabdoderma.The expansion of the group towards the Western Gondwana occurred in the Lower Cretaceous, with records of Mawsonia and Axelrodichthys. PAE indicates two endemic areas: InSerpukhovian of France and Belgium and during the interval Berriasian/Hauterivian of Democratic Republic of Congo and Brazil, being suported byRhabdodermahuxlei, R. stensioei and Rhabdoderma sp. in Carboniferous &Mawsoniagigas and Mawsonia sp. in Lowe Cretaceous. The phylogenetic analysis was realized including the genus Changxingia, and it is indicated as belonging to Mawsoniidae, being the first taxon of group that occurs during the Paleozoic and in Asia, thus changing the origin of group, which was previously related to Triassic of United States. The phylogeny used will also serve as a basis toward a future aplication of cladistic biogeography, used for obtaining secundary homology biogeographic (The methods of track analysis and PAE obtains only primary homology). They are also reported new occurrences of coelacanths (Actinistiaundet.) in Carboniferous (Mississipian) and Permian (Lopigian) of Poti and Rio do Rasto formations (Brazil), and in Late Cretaceous of Haqil (Lebanon), expanding the range of distribution of Actinistia in ocidental Pangea and in region of Tethys sea. It isalso verified the presence of lungs in Chagrinia, emphasizing the presence of this structure in coelacanthiforms. The results herein obtained accentuated the potential of the panbiogeographical method and of analisys of parsominyendemicity, for obtaining the distribution patterns and, consequently, the areas of endemism of Actinistia, throughout all geologic era