Valéria Gallo

Atolchelys lepida, a new side-necked turtle from the Early Cretaceous of Brazil and the age of crown Pleurodira

We report a new pleurodiran turtle from the Barremian Morro do Chaves Formation, Sergipe-Alagoas Basin, Brazil. We tested the phylogenetic position of Atolchelys lepida gen. et sp. nov. by including it in a comprehensive cladistic analysis of pleurodires. The new species is a basal member of Bothremydidae and simultaneously the oldest unambiguous crown Pleurodira. The biogeographic and chronostratigraphic significance of the finding has implications for the calibration of molecular clocks studies by pushing back the minimum age of crown Pleurodira by more than 12 Ma (ca 125 Ma). The reanalysis of Pelomedusoides relationships provides evidence that the early evolution and relationships among the main lineages of side-necked turtles can be explained, at least partially, by a sequence of vicariance events.

REDESCRIPTION OF LEPIDOTES PIAUHYENSIS ROXO AND LÖFGREN, 1936 (NEOPTERYGII, SEMIONOTIFORMES, SEMIONOTIDAE) FROM THE ?LATE JURASSIC–EARLY CRETACEOUS OF BRAZIL

Abstract The semionotid Lepidotes piauhyensis Roxo and Löfgren, 1936, is redescribed on the basis of original and new material obtained from the Pastos Bons Formation, ?Upper Jurassic–Lower Cretaceous of the Parnaíba Basin, in northeastern Brazil. The species is a hump-backed semionotid reaching about 480 mm standard length. It exhibits, among other characters: dermal bones of the skull roof and circumorbital series densely ornamented with tubercles, suborbitals disposed in a single row, moderately developed crushing dentition, a bony lamina on the ventral portion of the anterior ceratohyal, a complete dorsal scale row, and smooth ganoid scales of lepisosteoid type. The analysis of well preserved specimens allows the description of anatomical structures previously unknown for the species, particularly of the hyoid arch and suspensorium. Some of these structures are comparable to those of the Jurassic species Lepidotes gloriae Thies, 1989 (Cuba), Lepidotes elvensis (Blainville, 1818) (Europe), and Lepidotes lennieri Sauvage, 1893 (Europe).

A NEW SPECIES OF LEPIDOTES (NEOPTERYGII: SEMIONOTIFORMES: SEMIONOTIDAE) FROM THE SANTANA FORMATION, LOWER CRETACEOUS OF NORTHEASTERN BRAZIL

Abstract A new species of Lepidotes is described on the basis of two nearly complete specimens from the ?Albian Romualdo Member of the Santana Formation, in the Araripe Basin, northeast Brazil. The new species differs from the other species of Lepidotes previously recorded in western Gondwanaland by the apomorphic presence of an axe-shaped hyomandibula, and by a unique combination of other characters. This is the first record of an articulated Lepidotes from the Santana Formation of the Araripe Basin.

Taxonomic review and phylogenetic analysis of Enchodontoidei (Teleostei: Aulopiformes)

Enchodontoidei are extinct marine teleost fishes with a long temporal range and a wide geographic distribution. As there has been no comprehensive phylogenetic study of this taxon, we performed a parsimony analysis using a data matrix with 87 characters, 31 terminal taxa for ingroup, and three taxa for outgroup. The analysis produced 93 equally parsimonious trees (L = 437 steps; CI = 0. 24; RI = 0. 49). The topology of the majority rule consensus tree was: (Sardinioides + Hemisaurida + (Nardorex + (Atolvorator + (Protostomias + Yabrudichthys ) + (Apateopholis + (Serrilepis + (Halec + Phylactocephalus ) + (Cimolichthys + (Prionolepis + ( (Eurypholis + Saurorhamphus ) + (Enchodus + (Paleolycus + Parenchodus ))))))) + ( (Ichthyotringa + Apateodus ) + (Rharbichthys + (Trachinocephalus + ( (Apuliadercetis + Brazilodercetis ) + (Benthesikyme + (Cyranichthys + Robertichthys ) + (Dercetis + Ophidercetis )) + (Caudadercetis + (Pelargorhynchus + (Nardodercetis + (Rhynchodercetis + (Dercetoides + Hastichthys )))))). The group Enchodontoidei is not monophyletic. Dercetidae form a clade supported by the presence of very reduced neural spines and possess a new composition. Enchodontidae are monophyletic by the presence of middorsal scutes, and Rharbichthys was excluded. Halecidae possess a new composition, with the exclusion of Hemisaurida. This taxon and Nardorex are Aulopiformes incertae sedis.

Distributional patterns of herbivore megamammals during the Late Pleistocene of South America

The geographic distribution of 27 species of the South American megafauna of herbivore mammals during the Late Pleistocene was analyzed in order to identify their distributional patterns. The distribution of the species was studied using the panbiogeographical method of track analysis. Six generalized tracks (GTs) and two biogeographic nodes were obtained. The GTs did not completely superpose with the areas of open savanna present in Pleistocene, nor with the biotic tracks of some arthropods typical of arid climate, indicating that these animals avoided arid environment. Overall, the GTs coincided with some biogeographic provinces defined on the basis of living taxa, indicating that certain current distributional patterns already existed in Pleistocene. The biogeographic nodes coincided with the borders between the main vegetal formations of the Pleistocene, showing that the type of vegetation had great influence in the distribution of the mammalian megafauna. The node 1 confirmed the existence of contact zones between paleobiogeographic regions near Argentina-Uruguay border. The node 2 connects the Brazilian Intertropical regions.

A possible chelonian egg from the Brazilian late cretaceous

This paper describes a possible fossil egg proceeding from the Bauru Group, Late Cretaceous of Paraná Basin, Brazil. External morphology, dimensions, texture and shell ornamentation examined under electron microscopy show close resemblance to the Recent podocnemidid chelonian eggs. Association with bony material in the outcrop suggests that it is related to a species of Podocnemis. Computerized tomography reveals a high density outer region corresponding to the shell component layers, and successive layers with decreasing density towards the nucleus. An area of high density in the central region may represent remains of an embryo.

Distributional patterns of †Mawsoniidae (Sarcopterygii: Actinistia)

Mawsoniidae are a fossil family of actinistian fish popularly known as coelacanths, which are found in continental and marine paleoenvironments. The taxon is considered monophyletic, including five valid genera (Axelrodichthys, Chinlea, Diplurus, Mawsonia and Parnaibaia) and 11 genera with some taxonomical controversy (Alcoveria, Changxingia, Garnbergia, Heptanema, Indocoelacanthus, Libys, Lualabaea, Megalocoelacanthus, Moenkopia, Rhipis and Trachymetopon). The genera restricted to the Northern Hemisphere (Diplurus and Chinlea) possess the oldest records (Late Triassic), whereas those found in the Southern Hemisphere (Mawsonia, Axelrodichthys, and Parnaibaia) extend from Late Jurassic to Late Cretaceous, especially in Brazil and Africa. We identified distributional patterns of Mawsoniidae, applying the panbiogeographical method of track analysis, and obtained three generalized tracks (GTs): GT1 (Northeastern Newark) in strata of the Newark Group (Upper Triassic); GT2 (Midwestern Gondwana) in the Lualaba Formation (Upper Jurassic); and GT3 (Itapecuru-Alcântara-Santana) in the Itapecuru-Alcântara-Santana formations (Lower Cretaceous). The origin of Mawsoniidae can be dated to at least Late Triassic of Pangaea. The tectonic events related to the breakup of Pangaea and Gondwana and the evolution of the oceans are suggested as the vicariant events modeling the distribution of this taxon throughout the Mesozoic.

Panbiogeographical analysis of the shark genus Rhizoprionodon (Chondrichthyes, Carcharhiniformes, Carcharhinidae)

The distributional patterns of the seven species of Rhizoprionodon were analysed using the panbiogeographical method of track analysis. The individual tracks of Rhizoprionodon suggest that the genus is mainly an Indian-Atlantic Ocean group. Five generalized tracks were found: (1) Caribbean, defined by R. porosus and R. terraenovae; (2) eastern coast of South America, defined by R. porosus and R. lalandei; (3) Indian Ocean, defined by R. acutus and R. oligolinx; (4) north-western Australia, defined by R. acutus, R. oligolinx and R. taylori; (5) north-north-eastern Australia, defined by R. acutus and R. taylori. Only R. longurio was not included in any generalized track, and its distribution is restricted to the eastern Pacific Ocean. Two biogeographical nodes were found at the intersection of the generalized tracks 1 and 2 (Caribbean Sea) and generalized tracks 4 and 5 (north Australia). The generalized tracks overlap with those found in several unrelated marine taxa. Overall, the generalized tracks are associated with warm currents. The biogeographical nodes found (Caribbean and Australian) are coincident with the global distribution of mangroves.

Parsimony analysis of endemicity of enchodontoid fishes from the Cenomanian

Parsimony analysis of endemicity was applied to analyze the distribution of enchodontoid fishes occurring strictly in the Cenomanian. The analysis was carried out using the computer program PAUP* 4.0b10, based on a data matrix built with 17 taxa and 12 areas. The rooting was made on an hypothetical all-zero outgroup. Applying the exact algorithm branch and bound, 47 trees were obtained with 26 steps, a consistency index of 0.73, and a retention index of 0.50. The topology found with a majority rule consensus was: ((Mexico) + (United States) + (Morocco + Italy) + (Lebanon + Israel) + (Italy-Slovenia) + (Brazil)) + (D.R. Congo) + (Sweden) + (Germany) + (England). The procedure delimited two areas of endemism in the Tethys Ocean. They are Morocco and southern Italy and Lebanon and Israel. The area of endemism formed by Morocco + Italy represents the North African region of the Tethys Ocean, and that formed by Lebanon + Israel is in the mid-Tethyan Ocean. Our results are in partial agreement with the patterns of geographical distribution of certain invertebrate biota.

A new pleuropholid, Gondwanapleuropholis longimaxillaris n. g., n. sp. (Actinopterygii: Teleostei) from the Jurassic of north east Brazil

A basal teleost fish is described for the first time from the Upper Jurassic Pastos Bons Formation, Parnaiba Basin, northeastern Brazil. This new material is identified as a new genus and a new species, Gondwanapleuropholis longimaxillaris. This taxon shares a number of synapomorphies with the pleuropholids. The family Pleuropholidae is confirmed as member of the Teleostei.