The taxonomic status of Parathrinaxodon proops (Therapsida: Cynodontia), with comments on the morphology of the palate in basal cynodonts

The holotype and only specimen of Parathrinaxodon proops, a cynodont from the Upper Permian Kawinga Formation, Tanzania, is redescribed. Upper postcanines from the middle of the tooth row are ovoid in outline, presenting a large main cusp and tiny anterior and posterior accessory cusps on the sectorial margin. Anterior and posterior lingual cusps on the crown indicate the presence of a lingual cingulum. The overall postcanine morphology is remarkably similar to that of Procynosuchus delaharpeae, a Late Permian cynodont particularly common in the lower Beaufort Group of South Africa. The presence of a complete osseous palate and a medial palatal opening between the maxillae (=vomerine fossa) in Parathrinaxodon proops remain the main differences previously reported between this species and Procynosuchus delaharpeae. Restudy of the palate of Parathrinaxodon proops indicates that there exists some degree of deformation, particularly notable in the broken and distorted vomer. The supposed presence of the complete secondary palate and of the medial palatal opening in Parathrinaxodon proops are interpreted as resulting from a slight horizontal displacement of the long, and originally free, palatal processes of the maxilla and palatine. It is concluded that Parathrinaxodon proops is synonymous with Procynosuchus delaharpeae. This synonymy is problematic because Parathrinaxodon proops Parrington 1936 would have priority over Procynosuchus delaharpeae Broom 1937, but the latter is the best known Late Permian cynodont. Consequently, we propose to conserve Procynosuchus delaharpeae as the valid name for this cynodont based on article 23, section 9 (Reversal of precedence) of the International Code of Zoological Nomenclature. An analysis of the Kawinga fauna, using genus as the taxonomic unit for comparison, indicates strong similarity (67%) with faunas from theTropidostoma, Cistecephalus and Dicynodon assemblage zones from the SouthAfrican Karoo.Financial support was provided by the University of the Witwatersrand through a Postdoctoral Research Fellowship awarded to FA. The Royal Society of London and PAST (Palaeontology Scientific Trust, Johannesburg) provided FAgrants that enabled a research visit to the United Kingdom

Taxonomic studies of the genus Phymaturus (IGUANIA: LIOLAEMIDAE): Description of four new species.

After the study of a diverse collection of Phymaturus from three Argentinian institutions and additional samples collected in the last two years we discovered several populations of uncertain taxonomic status. Based on 93 morphological characters of squamation, color pattern, gular and nuchal folds, precloacal pores, and morphometric data, we conclude that at least four of those are independent lineages which require formal description. Characters related to sexual dimorphism and dichromatism as well as the ontogenetic change of several others, from juvenile to adult specimens, are described. According to the most recent revision of the genus (Lobo and Quinteros, 2005a) and considering the descriptions made in the last four years, the taxonomic composition of the genus was raised to 23 species. In this study we provide the formal description of four additional new taxa, including their diagnosis and detailed comparisons with other members of their species groups. Two new species belong to the patagonicus group (provinces of Chubut and Rio Negro, in Patagonia between 46° and 41° of latitude) while the other two belong to the palluma group (Neuquén and Catamarca provinces, western Argentina, 39° and 27‑26°30’of latitude respectively). With the exception of one case for which four localities are reported, all new species are restricted to their type localities. This fact confirms a common historical distributional pattern for most species of the genusPhymaturus from three Argentinian institutions and additional samples collected in the last two years we discovered several populations of uncertain taxonomic status. Based on 93 morphological characters of squamation, color pattern, gular and nuchal folds, precloacal pores, and morphometric data, we conclude that at least four of those are independent lineages which require formal description. Characters related to sexual dimorphism and dichromatism as well as the ontogenetic change of several others, from juvenile to adult specimens, are described. According to the most recent revision of the genus (Lobo and Quinteros, 2005a) and considering the descriptions made in the last four years, the taxonomic composition of the genus was raised to 23 species. In this study we provide the formal description of four additional new taxa, including their diagnosis and detailed comparisons with other members of their species groups. Two new species belong to the patagonicus group (provinces of Chubut and Rio Negro, in Patagonia between 46° and 41° of latitude) while the other two belong to the palluma group (Neuquén and Catamarca provinces, western Argentina, 39° and 27‑26°30’of latitude respectively). With the exception of one case for which four localities are reported, all new species are restricted to their type localities. This fact confirms a common historical distributional pattern for most species of the genuspatagonicus group (provinces of Chubut and Rio Negro, in Patagonia between 46° and 41° of latitude) while the other two belong to the palluma group (Neuquén and Catamarca provinces, western Argentina, 39° and 27‑26°30’of latitude respectively). With the exception of one case for which four localities are reported, all new species are restricted to their type localities. This fact confirms a common historical distributional pattern for most species of the genuspalluma group (Neuquén and Catamarca provinces, western Argentina, 39° and 27‑26°30’of latitude respectively). With the exception of one case for which four localities are reported, all new species are restricted to their type localities. This fact confirms a common historical distributional pattern for most species of the genus.Fil: Lobo Gaviola, Fernando Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Abdala, Cristian Simón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Valdecantos, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentin

Las formas de intervenir en la escuela de las familias de sectores populares : El caso de una institución educativa urbano marginal de la ciudad de Tunuyán, Mendoza

Si bien la participación de las familias es un derecho según la Ley de Educación Nacional, en las escuelas que atienden a sectores populares los docentes señalan como problema la ausencia de los padres. Por otro lado, estudios etnográficos dan cuenta de “otras maneras de intervenir” de estos sectores. En este trabajo presentamos los avances del proyecto de investigación “Las familias de sectores populares y sus relaciones con la escuela. El caso de una institución educativa urbano marginal de la ciudad de Tunuyán, Mendoza” desarrollado en el IES T_004 Normal de Tunuyán (INFD Convocatoria 2013/ N° 2054). Su objetivo es comprender las relaciones con la escuela de las familias de sectores populares. ¿En qué actividades escolares participan los padres? ¿Cómo interpretan sus vínculos con la escuela? ¿Cuáles son sus maneras de intervenir? ¿Cómo se articulan sus prácticas de intervención en la institución escolar con sus estrategias familiares, sus trayectorias sociales y los recursos económicos y culturales que poseen? La estrategia metodológica es el estudio de caso. Las técnicas utilizadas son el análisis de documentos escolares y datos de los registro, la observación de situaciones escolares y entrevistas abiertas a docentes y a integrantes de las familias.Mesa 16: Estructura social de la Argentina. Desigualdades, estructura y movilidad social en la Argentina contemporáneaFacultad de Humanidades y Ciencias de la Educació

First record of non-mammalian cynodonts (Therapsida) in the Sanga do Cabral Formation (Early Triassic) of southern Brazil

New material from the Sanga do Cabral Formation in southern Brazil is described, including one distal and three proximal portions of femora, and a distal portion of a humerus. Comparative studies indicate affinities of the proximal femora and the distal humerus with non-mammalian cynodonts, whereas the distal femur cannot be attributed with certainty to this group. These postcranial elements are the first record of non-mammalian cynodonts for the Sang a do Cabral Formation and demonstrate the presence of small- to medium-sized representatives of this group in the Early Triassic fauna of Brazil.Palaeo-Anthropology Scientific Trust; French Embassy in South Africa; Co-operation and Cultural Service

Enhanced D1 and D2 inhibitions induced by low-frequency trains of conditioning stimuli : differential effects on H- and TReflexes and possible mechanisms

Mechanically evoked reflexes have been postulated to be less sensitive to presynaptic inhibition (PSI) than the H-reflex. This has implications on investigations of spinal cord neurophysiology that are based on the T-reflex. Preceding studies have shown an enhanced effect of PSI on the H-reflex when a train of ~10 conditioning stimuli at 1 Hz was applied to the nerve of the antagonist muscle. The main questions to be addressed in the present study are if indeed T-reflexes are less sensitive to PSI and whether (and to what extent and by what possible mechanisms) the effect of low frequency conditioning, found previously for the H-reflex, can be reproduced on T-reflexes from the soleus muscle. We explored two different conditioning-to-test (C-T) intervals: 15 and 100 ms (corresponding to D1 and D2 inhibitions, respectively). Test stimuli consisted of either electrical pulses applied to the posterior tibial nerve to elicit H-reflexes or mechanical percussion to the Achilles tendon to elicit T-reflexes. The 1 Hz train of conditioning electrical stimuli delivered to the common peroneal nerve induced a stronger effect of PSI as compared to a single conditioning pulse, for both reflexes (T and H), regardless of C-T-intervals. Moreover, the conditioning train of pulses (with respect to a single conditioning pulse) was proportionally more effective for Treflexes as compared to H-reflexes (irrespective of the C-T interval), which might be associated with the differential contingent of Ia afferents activated by mechanical and electrical test stimuli. A conceivable explanation for the enhanced PSI effect in response to a train of stimuli is the occurrence of homosynaptic depression at synapses on inhibitory interneurons interposed within the PSI pathway. The present results add to the discussion of the sensitivity of the stretch reflex pathway to PSI and its functional role

Late Permian terrestrial faunal connections invigorated: the first whaitsioid therocephalian from China

The record of therocephalian therapsids from the late Permian of China has recently been greatly expanded by the discovery of severalnew taxa of Akidnognathidae, a group previously known principally from South Africa and Russia. Continuing this string of discoveries,we present here the first Chinese record of a whaitsiid therocephalian. This is also the first record published of a tetrapod fromJingtai, Gansu, a late Permian locality that also yields remains of other groups such as dicynodonts, captorhinids, and chroniosuchians.This is the third taxon of whaitsiid therocephalian recognized in North Pangea. The new therocephalian is similar to the RussianMoschowhaitsia vjuschkovi in overall appearance, and although they are only recovered as sister-taxa in 6 out of 30 most parsimonioustrees in our phylogenetic analysis, it is tentatively referred to Moschowhaitsia as a new species,M. lidaqingi. The phylogeny obtained islargely similar to previous hypotheses, recovering three main lineages of Eutherocephalia: Akidnognathidae, Whaitsioidea andBaurioidea. However, it differs from previous analyses in finding Chthonosauridae (comprising the Russian Chthonosaurus andZambian Ichibengops) to be deeply nested within Whaitsioidea. Therocephalians were among the largest carnivores in the late Permianof North China, and may have represented the top predators in some faunas.Fil: Liu, Jun. Chinese Academy of Sciences; República de ChinaFil: Abdala, Nestor Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina. University of the Witwatersrand; Sudáfric

Late Permian terrestrial faunal connections invigorated: the first whaitsioid therocephalian from China

The record of therocephalian therapsids from the late Permian of China has recently been greatly expanded by the discovery of severalnew taxa of Akidnognathidae, a group previously known principally from South Africa and Russia. Continuing this string of discoveries,we present here the first Chinese record of a whaitsiid therocephalian. This is also the first record published of a tetrapod fromJingtai, Gansu, a late Permian locality that also yields remains of other groups such as dicynodonts, captorhinids, and chroniosuchians.This is the third taxon of whaitsiid therocephalian recognized in North Pangea. The new therocephalian is similar to the RussianMoschowhaitsia vjuschkovi in overall appearance, and although they are only recovered as sister-taxa in 6 out of 30 most parsimonioustrees in our phylogenetic analysis, it is tentatively referred to Moschowhaitsia as a new species,M. lidaqingi. The phylogeny obtained islargely similar to previous hypotheses, recovering three main lineages of Eutherocephalia: Akidnognathidae, Whaitsioidea andBaurioidea. However, it differs from previous analyses in finding Chthonosauridae (comprising the Russian Chthonosaurus andZambian Ichibengops) to be deeply nested within Whaitsioidea. Therocephalians were among the largest carnivores in the late Permianof North China, and may have represented the top predators in some faunas.Fil: Liu, Jun. Chinese Academy of Sciences; República de ChinaFil: Abdala, Nestor Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina. University of the Witwatersrand; Sudáfric

The emblematic South African therocephalian Euchambersia in China: A new link in the dispersal of late Permian vertebrates across Pangea

Therapsids were widely distributed in Pangea in the late Permian. South Africa in Gondwana and Russia in Laurasia are the principal areas recording tetrapods (including therapsids) of this age. More recent field explorations have increased the importance of Chinese late Permian fossil assemblages. This is clearly reflected in the discovery of several new therocephalians from the Naobaogou Formation in Nei Mongol. Here, we report a therocephalian from that unit identified as a new species of the emblematic South African taxon Euchambersia. The new species, Euchambersia liuyudongi, is represented by a well-preserved skull and mandible showing a well-developed maxillary fossa and the absence of postcanine teeth. This is the third akidnognathid therocephalian recovered from the Naobaougou Formation, but oddly, the two basal Chinese akidnognathids previously known were recovered from a younger unit of the formation than the derived E. liuyudongi. This is the first time that the same therocephalian genus has been recorded in northern and southern continents, making the record of the Naobaougou Formation key to understanding the evolution of late Permian continental fauna in general, and of akidnognathid therocephalians in particular.Fil: Liu, Jun. Chinese Academy of Sciences; República de ChinaFil: Abdala, Nestor Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina. Fundación Miguel Lillo; Argentina. University of the Witwatersrand; Sudáfric

Evolution and identity of synapsid carpal bones

To date there is little information on carpal bone homology in late Palaeozoic and Mesozoic Synapsida. Crucial to the understanding of homology in synapsid carpal elements is the fact that different nomenclatures are used for the carpals of non-mammaliamorph Synapsida (Gegenbauer?s canonical nomenclature) and Mammaliaformes (mammalian nomencla-ture). The homologies of the carpals of non-mammaliamorph synapsids and mammals were established early last century and have not been reviewed since then. Here we provide a detailed study of the carpal bones of synapsids ranging in age from the early Permian to Late Cretaceous. The mammaliamorph lunate, previously considered the homologue of the intermedium of non-mammaliamorph synapsids, is interpreted here as homologous to their lateral centrale. We interpret the single mammaliamorph centrale as a homologue of the medial centrale of non-mammaliamorph synapsids. In some synapsid specimens, we found that one or two centralia are fused to the radiale (e.g., the gorgonopsian Arctognathus and tritylodontid Bienotheroides), supporting a digging habit. A third centrale is present in the therocephalian Theriognathus, very likely an abnormal duplication. An additional medial bone in a biarmosuchian was interpreted as a prepollex/sesamoid. A cartilaginous prepollex/sesamoid may also have been present in several non-mammaliamorph synapsids, which have an open space proximal to distal carpal I. Distal carpal V is completely lost in dicynodonts and it is mainly fused to distal carpal IV in the adult stage of most other therapsid groups, but showed a delayed development in most non-mammaliamorph cynodonts. In mammaliamorphs, distal carpal V is not present. Our observations provide an up-dated revision of synapsid carpal homologies, mainly on the basis of position and anatomical contacts and also taking into account the results of embryological studiesFil: Kummell, S.. University Witten/herdecke; AlemaniaFil: Abdala, Nestor Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Sassoon, J.. University Of Bristol; Reino UnidoFil: Abdala, Virginia Sara Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentin