Totoralia, a new conical-shaped mollusk from the Middle Cambrian of western Argentina

The new genus Totoralia from the Late Middle Cambrian of El Totoral (Mendoza Province, western Argentina) is described herein. It is a delicate, high, bilaterally symmetrical cone with a sub-central apex and five to seven prominent comarginal corrugations. In addition, its surface shows numerous fine comarginal lines, as well as thin, closely spaced radial lirae. Totoralia gen. nov., in most respects, resembles the Cambrian helcionellids Scenella BILLINGS and Palaeacmaea HALL and Whitfield. Although Scenella has been considered as a chondrophorine cnidarian by some authors in the past, now the predominant view is that it is a mollusk. Likewise, several aspects of Totoralia gen. nov. morphology indicate closer affinities with mollusks. The specimens studied constitute elevated cones that are rather consistent in height, implying that they were not flexible structures like those of the chondrophorines. The presence of a short concave slope immediately in front of the apex can also be interpreted as a mollusk feature. In addition, the numerous comarginal lines of the cone are uniform in prominence and constant in spacing, and are only represented on the dorsal surface of the shell; thus, they are most similar to the incremental growth lines of shells of mollusks. The morphology of Totoralia gen. nov. is regarded as primitive in the Helcionelloida because the ancestor of the class is likely to have had a minute, untorted limpet-shaped shell. Although the new genus herein described seems to be endemic to Argentina, the Cambrian occurrences of related scenellid genera suggest affinities with Laurentia

El Alisal: a new locality with trace fossils of the Puncoviscana Formation (late Precambrian-early Cambrian) in Salta Province. Argentina

The Puncoviscana, Suncho and Las Aguaditas/Negro Peinado formations represent a thick siliciclastic folded succession that crops out on a strip about 800 km long and 150 km wide in northwestern Argentina (Jujuy, Salta, Tucumán, Catamarca and La Rioja provinces). These sequences are lithologically characterized by very lowgrade metamorphic sediments grading from slates to schists; turbidites, pelagic clays, limestones and volcanic rocks. On the basis of paleoichnological data, these units have been assigned to the late Precambrian-early Cambrian. A new locality bearing well preserved trace fossils from the Puncoviscana Formation is described herein. The outcrop is located about 45 km west of Salta city (Salta Province), displaying an alternation of colored differentiated grayish-bluish slates and fine sandstones. Ichnofossils include Cochlichnus anguineus HITCHCOCK, Helminthoidichnites tenuis FITCH, Helminthoida isp., Monomorphichnus lineatus CRIMES, LEGG and MARCOS ARBOLEYA, Planolites isp. and Torrowangea? isp., as well as some limb marks and a few slightly bended smooth trails (indet.). An Early Cambrian age for the succession at El Alisal as well as some environmental considerations are allowed by the ichnological association. In addition, the ichnogenus Planolites is mentioned for the first time from the “red shales and conglomerate type” facies at the neighbor locality of Chorrillos

El Alisal : a new locality with trace fossils of the Puncoviscana Formation (late Precambrian-early Cambrian) in Salta Province. Argentina

The Puncoviscana, Suncho and Las Aguaditas/Negro Peinado formations represent a thick siliciclastic folded succession that crops out on a strip about 800 km long and 150 km wide in northwestern Argentina (Jujuy, Salta, Tucumán, Catamarca and La Rioja provinces). These sequences are lithologically characterized by very lowgrade metamorphic sediments grading from slates to schists; turbidites, pelagic clays, limestones and volcanic rocks. On the basis of paleoichnological data, these units have been assigned to the late Precambrian-early Cambrian. A new locality bearing well preserved trace fossils from the Puncoviscana Formation is described herein. The outcrop is located about 45 km west of Salta city (Salta Province), displaying an alternation of colored differentiated grayish-bluish slates and fine sandstones. Ichnofossils include Cochlichnus anguineus HITCHCOCK, Helminthoidichnites tenuis FITCH, Helminthoida isp., Monomorphichnus lineatus CRIMES, LEGG and MARCOS ARBOLEYA, Planolites isp. and Torrowangea? isp., as well as some limb marks and a few slightly bended smooth trails (indet.). An Early Cambrian age for the succession at El Alisal as well as some environmental considerations are allowed by the ichnological association. In addition, the ichnogenus Planolites is mentioned for the first time from the "red shales and conglomerate type" facies at the neighbor locality of Chorrillos

Totoralia, a new conical-shaped mollusk from the Middle Cambrian of western Argentina

The new genus Totoralia from the Late Middle Cambrian of El Totoral (Mendoza Province, western Argentina) is described herein. It is a delicate, high, bilaterally symmetrical cone with a sub-central apex and five to seven prominent comarginal corrugations. In addition, its surface shows numerous fine comarginal lines, as well as thin, closely spaced radial lirae. Totoralia gen. nov., in most respects, resembles the Cambrian helcionellids Scenella BILLINGS and Palaeacmaea HALL and Whitfield. Although Scenella has been considered as a chondrophorine cnidarian by some authors in the past, now the predominant view is that it is a mollusk. Likewise, several aspects of Totoralia gen. nov. morphology indicate closer affinities with mollusks. The specimens studied constitute elevated cones that are rather consistent in height, implying that they were not flexible structures like those of the chondrophorines. The presence of a short concave slope immediately in front of the apex can also be interpreted as a mollusk feature. In addition, the numerous comarginal lines of the cone are uniform in prominence and constant in spacing, and are only represented on the dorsal surface of the shell; thus, they are most similar to the incremental growth lines of shells of mollusks. The morphology of Totoralia gen. nov. is regarded as primitive in the Helcionelloida because the ancestor of the class is likely to have had a minute, untorted limpet-shaped shell. Although the new genus herein described seems to be endemic to Argentina, the Cambrian occurrences of related scenellid genera suggest affinities with Laurentia

Early Cambrian archaeocyathan limestone blocks in low-grade meta-conglomerate from El Jagüelito Formation (Sierra Grande, Río Negro, Argentina

Massive grey limestone blocks containing a fairly diverse but poorly preserved archaeocyath fauna were recovered from a meta-conglomerate bed in the El Jagüelito Formation (Sierra Grande area, Eastern North Patagonian Massif, Río Negro, Argentina). This is the first documented reference of the presence of archaeocyaths in continental Argentina. Seven different taxa were identified, preliminary described and figured. Recrystallization of the skeletons due to regional low-grade metamorphism and deformation of the unit does not allow observation of key detailed features and prevents identification to genera and species. Nevertheless, the specimens studied show general affinities with archaeocyathan assemblages from the Australia-Antarctica palaeobiogeographic province and indicate a middle Early Cambrian (Atdabanian-Botomian) maximum age for the deposition of the El Jagüelito Formation protoliths. The similarities between the North Patagonian Early Paleozoic El Jagüelito Formation and those rocks from Antarctica suggest a geologic and biologic common history of these regions on the same southwest margin of Gondwana during that time

El Alisal : a new locality with trace fossils of the Puncoviscana Formation (late Precambrian-early Cambrian) in Salta Province. Argentina

The Puncoviscana, Suncho and Las Aguaditas/Negro Peinado formations represent a thick siliciclastic folded succession that crops out on a strip about 800 km long and 150 km wide in northwestern Argentina (Jujuy, Salta, Tucumán, Catamarca and La Rioja provinces). These sequences are lithologically characterized by very lowgrade metamorphic sediments grading from slates to schists; turbidites, pelagic clays, limestones and volcanic rocks. On the basis of paleoichnological data, these units have been assigned to the late Precambrian-early Cambrian. A new locality bearing well preserved trace fossils from the Puncoviscana Formation is described herein. The outcrop is located about 45 km west of Salta city (Salta Province), displaying an alternation of colored differentiated grayish-bluish slates and fine sandstones. Ichnofossils include Cochlichnus anguineus HITCHCOCK, Helminthoidichnites tenuis FITCH, Helminthoida isp., Monomorphichnus lineatus CRIMES, LEGG and MARCOS ARBOLEYA, Planolites isp. and Torrowangea? isp., as well as some limb marks and a few slightly bended smooth trails (indet.). An Early Cambrian age for the succession at El Alisal as well as some environmental considerations are allowed by the ichnological association. In addition, the ichnogenus Planolites is mentioned for the first time from the "red shales and conglomerate type" facies at the neighbor locality of Chorrillos

First cladistic analysis of the trilobite family Olenidae from the Furongian and Ordovician

The Olenidae stands out for its abundance and biostratigraphical importance, especially in the Lower Palaeozoic rocks of northwestern Argentina. Their phylogenetic relationships have been traditionally determined stratigraphically and by direct morphological comparison. This study reports the first formal phylogenetic analysis of olenids. Eighty-six characters (24 quantitative and 62 qualitative) were coded for 65 taxa (58 olenids). Quantitative characters were treated both as discrete and as continuous variables. To explore the best way of character coding for this group, continuous characters were coded as: median, log-median, normalized and rescaled. Maximum parsimony and implied weighting were used as optimality criteria. A phylogenetic hypothesis more consistent with traditional taxonomy was reconstructed with both quantitative and qualitative partitions. All the trees obtained with quantitative characters coded as continuous and rescaled are better resolved, and those topologies were more similar among them. This treatment also reflects more effectively the behaviour of the original variables. Olenidae is not a monophyletic clade: Andrarina costata and Aphelaspis australis are included within the ingroup, as sister clade of Olenus gibbosus. Also, the results suggest that members of the Hypermecaspidinae constitute a new family within the Order Olenida. The traditional taxonomic scheme at subfamily level is partially supported. Triarthrinae and ‘pelturinds’ are recovered as monophyletic clades, but Oleninae is polyphyletic. This study proves, through a formal cladistic analysis, that characters disregarded by traditional taxonomy can be uncovered. Finally, this is the first step towards achieving a classification of the Olenidae taking into account the evolutionary process involved in its diversification history.Fil: Monti, Daniela Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Confalonieri, Viviana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin