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San Miguel de Tucumán, Argentina

Argot C.,CNRS Center for Research on Palaeobiodiversity and Palaeoenvironments | Babot J.,Fundacion Miguel Lillo
Palaeontology | Year: 2011

Callistoe vincei Babot et al., 2002 is a Paleogene borhyaenoid known from exceptionally complete postcranial elements, which provides rare information about the anatomy and evolutionary history of metatherian predators during the South American Cenozoic. The axial skeleton of Callistoe is characterized by the peculiar transverse processes of the cervical vertebrae emphasizing lateral instead of sagittal traction. There is no clavicle and eighteen thoracolumbar vertebrae, of which only five are lumbars. The shoulder and elbow joints suggest movements restricted to parasagittal flexion/extension that are consistent with primarily terrestrial locomotion, as is also emphasized in Borhyaena tuberata and Lycopsis longirostrus. On the manus, the pollex is not reduced and the ungual phalanges indicate very long claws, similar to those observed in some extant digging taxa. This feature is unique to C. vincei among borhyaenoids. The knee joint is characterized by the presence of ossified patellae but shallow femoral trochleae. This joint suggests that the leg was nearly parasagittal, a position also inferred for Borhyaena. The astragalus shape is consistent with parasagittal flexion/extension, as in all Miocene-Pliocene borhyaenoids. The hind foot is characterized by reduced claws in comparison with the manus as well as the slenderness of the first and fifth digits, another peculiarity of C. vincei. The habitat of Callistoe was a temperate humid forest and according to the known fossil record, Callistoe was the largest mammalian predator of its time, sharing the predator ecological niche with crocodiles. © The Palaeontological Association.

Babot J.,Fundacion Miguel Lillo | Lopez D.A.G.,Instituto Miguel Lillo | Gaudin T.J.,University of Tennessee at Chattanooga
Journal of Vertebrate Paleontology | Year: 2012

In this study we describe an isolated petrosal from the middle Eocene of northwestern Argentina assigned to Dasypodinae (Mammalia, Xenarthra, Cingulata). The specimen was recovered from the Geste Formation, Antofagasta de la Sierra, Catamarca, Argentina. The material is an incomplete right petrosal preserving the pars cochlearis and the anterior third of the pars canalicularis. It is described in detail and compared with extant and fossil cingulates. Additionally, we performed a cladistic analysis in order to define its phylogenetic position. The most remarkable traits of this petrosal include an anteromedially-posterolaterally elongated promontorium, open cavum supracochleare, wide and smooth crista interfenestralis, roof of the post-promontorial tympanic sinus triangular, reduced, and well separated from the stapedius fossa, and poorly developed epitympanic wing and crista petrosa. The phylogenetic analysis reveals affinities with Dasypus and Stegotherium that are supported by the weakly developed crista petrosa and the reduced dorsal and ventral extension of the cerebellar surface of the pars cochlearis in relation to the size of the internal acoustic meatus. The information provided by this element indicates the existence of several characters that were already present in the Eocene, such as an elongated promontorium, and a step between the stapedius fossa and the roof of the post-promontorial tympanic sinus. We propose hypotheses of evolutionary change in the auditory region of cingulates, including the medial expansion of the roof of the post-promontorial tympanic sinus and the emergence of a conspicuous crista petrosa. © 2012 Taylor & Francis Group, LLC.

Suarez G.M.,Fundacion Miguel Lillo | Suarez G.M.,National University of Tucuman | Schiavone M.M.,National University of Tucuman
Darwiniana | Year: 2013

The genus Pohlia is reported as a new record for Uruguay, where it is represented by two species: P. wahlenbergii and P. humilis (=P. tenuifolia). Pohlia humilis is also recorded as new for Colombia. We propose P. loriformis, a poorly known species described from Bolivia, as new synonym of P. humilis. We select lectotypes for P. loriformis and Mielichhoferia brachycarpa. We also include a key to the Pohlia species from Uruguay, and the South American synonyms, brief comments, distribution, and illustrations for P. humilis.

Mangione S.,Fundacion Miguel Lillo | Mangione S.,National University of Salta | Garcia G.,National University of Salta | Cardozo O.M.,National University of Salta
Acta Zoologica | Year: 2011

In this study, we made a morphological analysis by optic microscopy of the dorsal and ventral skin of the body of Ceratophrys cranwellii, Lepidobatrachus llanensis and Chacophrys pierotti to verify if there exist shared integumental characters in relation to the Eberth-Katschenko layer (E-K layer). The presence of cells associated with this layer, historically considered acellular, is one of the leading characters. This study contributes to support that the E-K layer would be the remnant of an ancestral dermal skeleton and not a physiologically significant formation. Hence, the presence of cells associated with the E-K layer would represent a synapomorphy for Ceratophrydae. © 2010 The Authors. Acta Zoologica © 2010 The Royal Swedish Academy of Sciences.

We studied the floristic composition and distribution of the riparian forest of two hydrographical systems in a subtropical Andean region. Using uni and multivariate techniques, we tested the hypotheses that a differentiable riparian forest exists, composed by native vegetation typical of the Yungas phytogeographical province, and that the distribution of vegetation varied significantly with geomorphologic characteristics. Parallel transects along the water courses were used to collect presence-absence data of vegetation in eleven sites. Detrended Correspondence Analysis defined a group of common riparian species for the studied area (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium and Eugenia uniflora) and identified two reference sites. The distribution of the riparian vegetation varied significantly with the geomorphic characteristics along the studied sites. Riparian habitats were composed by native and exotic species. A distinct riparian flora, different in structure and function from adjacent terrestrial vegetation, could not be identified. Riparian species were similar to the adjacent terrestrial strata. These species would not be limited by the proximity to the river. Anthropogenic impacts were important factors regulating the introduction and increase of exotic vegetation. The lack of regulation of some activities in the zone could cause serious problems in the integrity of this ecosystem.

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