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Mar del Plata, Argentina

Lichenodraculus matti gen. et sp. nov. is described, along with its conspicuous diurnal calling song and some aspects of its interesting ecology and life history. The song allowed a complete acoustic assessment of the altitudinal distribution of this otherwise very cryptic canopy-dwelling insect. The nymph perfectly mimics epiphytic lichens growing in the same elevation range, and apparently the downside of this camouflage is a strictly lichenous diet. Copyright © 2011 · Magnolia Press. Source

Fernandez M.S.,Museo de La Plata | Talevi M.,National University of Rio Negro
Geological Magazine | Year: 2014

The oldest ophthalmosaurian records worldwide have been recovered from the Aalenian-Bajocian boundary of the Neuquén Basin in Central-West Argentina (Mendoza and Neuquén provinces). Although scarce, they document a poorly known period in the evolutionary history of parvipelvian ichthyosaurs. In this contribution we present updated information on these fossils, including a phylogenetic analysis, and a redescription of 'Stenopterygius grandis' Cabrera, 1939. Patagonian ichthyosaur occurrences indicate that during the Bajocian the Neuquén Basin palaeogulf, on the southern margins of the Palaeopacific Ocean, was inhabited by at least three morphologically discrete taxa: the slender Stenopterygius cayi, robust ophthalmosaurian Mollesaurus periallus and another indeterminate ichthyosaurian. Rib bone tissue structure indicates that rib cages of Bajocian ichthyosaurs included forms with dense rib microstructure (Mollesaurus) and forms with an 'osteoporotic-like' pattern (Stenopterygius cayi). Copyright © Cambridge University Press 2013. Source

During the Mesozoic, one of the most significant evolutionary processes was the secondary adaptation of tetrapods to life in water. Several non-related lineages invaded from the terrestrial realms and from the oceans of the entire world. Among these lineages, ichthyosaurs were particularly successful. Advance parvipelvian ichthyosaurs were the first tetrapods to evolve a fish-shaped body profile. The deep skeletal modifications of their bodies, as well as their biology, depict advance ichthyosaurs as the paradigm of secondary adaptation of reptiles tomarine life. Functional inferences point to themas off-shore cruising forms, similar to a living tuna, and some of them were capable of deep diving. Bone histology of some genera such as Temnodontosaurus, Stenopterygius, Ichthyosaurus, and Caypullisaurus, characterized by overall cancellous bone, is consistent with the idea of a fish-shaped ichthyosaurs as fast and far cruisers. Here, we provide histological examination of the ribs of the Middle Jurassic parvipelvian Mollesaurus. Contrasting with the bone histology of other parvipelvian, Mollesaurus ribs are characterized by a compact and thick cortex. Our data indicate that the rib cage was heavy and suggest that not all advanced ichthyosaurs were fast cruisers. The compact and dense ribs in these parvipelvian show that advance ichthyosaurs were ecologically more diverse than previously thought and that the lightening of the skeleton reversed, as also occurred in the evolution of cetacean, at least once along the evolutionary history of ichthyosaurs. © Springer-Verlag 2012. Source

Three new thyasirid species from the Sub-Antarctic and Antarctic waters are described: Thyasira patagonica, Mendicula sudamericana, and Axinulus antarcticus. T. patagonica is characterized by its strong commarginal sculpture, shell as height as length or higher than long, posterior auricle delimited by a deep submarginal sulcus, and a long and sloping straight anterior half of dorsal margin. M. sudamericana distinguished by its longer than high shell outline, elongated tooth-like enlargement anterior to beak, gills with only one demibranch at each side, and foot with a marked heel. A. antarcticus has a minute, subquadrate shell, hinge with a small swelling anterior to beak, gills with a single demibranch, and the lateral body pouch elongated and almost smooth. The present study provides the first reliable record of thyasirids, with a single demibranch from the Southern Ocean. Moreover, characters for a better definition of Mendicula are provided. © 2009 Springer-Verlag. Source

Picasso M.B.J.,Museo de La Plata
Journal of Zoology | Year: 2012

The greater rhea (Rhea americana) is the largest flightless bird of South America and has a cursorial locomotion style. The objective of this study was to explore how the leg configuration of this species changes from juveniles to adult, and the possible implications of these changes for the locomotor style of this bird. In this regard, it is interesting to study the presence of allometries during growth (ontogenetic allometry), because it may provide information about morpho-functional aspects. Growth of femur, tibiotarsus and tarsometatarsus were studied in individuals of different ages, ranging from 1 month to adulthood. Allometric analysis was performed on a total of 21 measurements of limb bones to evaluate ontogenetic changes. Ten measurements were allometric, correlating positively and negatively with body mass. Some of them, like the positive allometry of the tarsometatarsus length, the negative allometry of the distal region of the tibiotarsus and the proximal segment of the tarsometatarsus, seem to be associated with cursoriality. On the other hand, the positive allometric growth of the distal segment of the femur may be related to the large body size of these birds. © 2011 The Author. Journal of Zoology © 2011 The Zoological Society of London. Source

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