Fractal Dimension of Dental Crowns: An Innovative Method for Age Estimation in Toxodonts.

Toxodonts constitute a group of extinct native South American ungulates that have been subject of extensive paleobiological research. Among the traits analyzed, enamel crest complexity (ECC; through fractal dimension) and occlusal surface tooth area (OTA) have recently been studied. However, they have not yet been applied to evaluate differences between ontogenetic stages, (e.

Fractal Dimension and Suture Complexity During Postnatal Ontogeny in Neotropical Deer in Relation to Sexual Dimorphism and Other Biological Features.

In mammals, the increase in cranial suture complexity throughout postnatal ontogeny has been linked to mechanical forces that load on the skull, including compression forces from mastication and the presence and use of cranial appendages in ungulates. Suture complexity, or interdigitation, provides a large absorptive capacity for mechanical stress. Deer are unique among ungulates by the presence of antlers only in males.

The hind limb of Octodontidae (Rodentia, Mammalia): Functional implications for substrate preferences.

Octodontids are South American caviomorph rodents endemic to mesic and arid biomes displaying a wide range of substrate preferences, from terrestrial to subterranean habits. However, the hind limb morphology of these rodents remain relatively poorly understudied, particularly from an ecomorphological perspective. To investigate the association between hind limb morphology and substrate preference-epigean, semifossorial, fossorial, and subterranean- this study analyzed six skeletal measurements of femur and tibia, along with five morphological indices.

The Commerson's dolphin as Subantarctic sentinel of POPs: Insights into the pollutant status in one of the southernmost coastal areas of the globe.

Persistent organic pollutants (POPs) are halogenated contaminants found globally. Cetaceans are impacted by these pollutants, and nowadays, it is essential to understand their presence to mitigate their impacts. This study aimed to establish baseline levels of POPs in the blubber of Commerson's dolphins (Cephalorhynchus commersonii) within the Subantarctic ecosystem.

A three-dimensional geometric morphometric analysis of the morphological transformation of lower jaw during post-hatching ontogeny.

Shape ontogenetic changes of the lower jaw in crocodylians are poorly understood. In order to answer some questions related to the inter- and intraspecific morphological variation of the mandible of two extant species, we performed a three-dimensional geometric morphometric approach. For this purpose, we used landmarks and semilandmarks on two ontogenetic mandibular series of 48 and 15 post-hatching specimens of and , respectively.

High Trypanosoma cruzi prevalence in armadillo (Zaedyus pichiy; Xenarthra: Chlamyphoridae) populations from Mendoza, Argentina.

Armadillos are considered important reservoir hosts for Trypanosoma cruzi, the causative agent of Chagas disease. The first report of T. cruzi infection in pichis (Zaedyus pichiy), a small armadillo species endemic to central Argentina and Chile, dates back to 1935.

An ecomorphological approach to the relationship between craniomandibular morphology and diet in sigmodontine rodents from central-eastern Argentina.

The key role of the skull in food intake and processing implicates its morphology should be to some extent adapted to the functional demands present in different diets, while also showing similarities between those which are closely related. Sigmodontine rodents, with a generalist body plan and broad dietary habits, are an interesting case study to explore these relationships. We used linear morphometrics to assess craniomandibular morphology, and explored its relationship with dietary composition and phylogeny in a sample of sigmodontines from central-eastern Argentina, representative of this subfamily's morphological and ecological diversity.

Biodiversity of vertebrates in Argentina: patterns of richness, endemism and conservation status.

Optimising conservation efforts requires an accurate record of the extant species as well as their geographic distributions. Nevertheless, most current conservation strategies start from an incomplete biodiversity inventory. Argentina has an extraordinary diversity of species, however, until now an updated inventory of its fauna has not been carried out.

The forelimbs of Octodontidae (Rodentia: Mammalia): substrate use, morphology, and phylogenetic signal.

Rodents of the family Octodontidae, endemic to South America, represent a group with low taxonomic richness group (six genera and 14 species) but have great ecomorphological diversity with epigean, semi-fossorial, fossorial, and subterranean forms. We analyzed morphometric variation in humerus and ulna, the possible relationship with substrate preference use, and the presence of a phylogenetic signal in the forelimbs traits (five biomechanical indices). Our results show that, in octodontids, the forelimb variation was not primarily associated with their phylogeny and some attributes are highly explanatory in terms of function, with a clear differentiation between the substrate use gradient extremes (i.

Effect of host and environment-related factors on fleas of the pichi, an armadillo from Argentina.

The pichi (Zaedyus pichiy; Cingulata: Chlamyphoridae) is an armadillo whose ectoparasite fauna is composed of ticks and fleas. Fleas were collected from 218 pichis in southern Mendoza, Argentina, in summer and winter of 2015 and 2016. Prevalences were analyzed and differences in the intensities of the total number of fleas related to host (age, sex, weight, size and physical condition) and environment-related (seasonality and year) factors evaluated.

A geometric morphometric approach to the analysis of skull shape in Triassic dicynodonts (Therapsida, Anomodontia) from South America.

Dicynodont therapsids were a major component of the Permo-Triassic terrestrial ecosystems across Pangea and have been regarded as specialized herbivores. In South America, the group was represented by several taxa of the clade Kannemeyeriiformes spanning from the Middle to the Late Triassic. In order to evaluate if cranial differences among taxa are potentially related to differences in feeding function, we performed a geometric morphometric analysis on 28 South American dicynodont crania.

Solving a long-standing nomenclatorial controversy: designation of a neotype for the southern sea lion Otaria flavescens (Shaw, 1800).

During almost two centuries, two available specific epithets have competed for the southern sea lions of the genus Otaria Péron, 1816 (Fig. 1), which is classically regarded as monotypic (but see below). The species distributes more or less continuously along the Atlantic coast from southern Brazil south to Cape Horn and along the Pacific from northern Peru to the west South American Pacific coast .

Skull ontogeny of extant caimans: a three-dimensional geometric morphometric approach.

Ontogenetic variation of cranial characters used in crocodylian phylogenetic systematics has never been studied. Furthermore, the relationship between diet and skull morphological transformation during ontogeny has not been properly explored yet. We quantify the inter- and intraspecific skull morphological variation in extant caiman species focusing on those areas relevant to systematics and, also investigate the relation between diet and morphological changes during ontogeny.

Differential influences of allometry, phylogeny and environment on the rostral shape diversity of extinct South American notoungulates.

Understanding the mechanisms responsible for phenotypic diversification, and the associated underlying constraints and ecological factors represents a central issue in evolutionary biology. Mammals present a wide variety of sizes and shapes, and are characterized by a high number of morphological convergences that are hypothesized to reflect similar environmental pressures. Extinct South American notoungulates evolved in isolation from northern mammalian faunas in highly disparate environments.

Prevalence and intensity of fleas parasitizing an isolated population of screaming hairy armadillo in Buenos Aires province, Argentina: host-related factors and temporal dynamics.

Fleas (Siphonaptera) of an isolated population of Chaetophractus vellerosus (Mammalia: Xenarthra) from Magdalena (Buenos Aires province) were studied, and their presence was associated with host-related factors (age, sex, weight, size, and physical condition) and temporal dynamics (seasonality and year). Three species of fleas were identified: Polygenis (Polygenis) platensis (Rhopalopsyllidae), Tunga penetrans (Tungidae), and Pulex irritans (Pulicidae). Prevalences were significant for year, season, and physical condition.