Ulnar dimensions and fossoriality in armadillos

Ulnar dimensions were measured in 14 species of armadillos (Xenarthra: Dasypodidae). An index of fossorial ability (IFA) was constructed, relating the length of the olecranon process to the remaining length of the ulna. For comparative purposes, the same measurements were taken in 14 other species of mostly South American mammals belonging to 3 orders and 11 families. The fossorial habits of these mammals were classified into 3 categories: (1) species mostly cursorial and non-digging; (2) species that often dig, but to which digging plays no essential part in their alimentary strategy and are not burrowers; and (3) species that are burrowers. IFA means of the studied mammal orders were compared using one-way analysis of variance on log-transformed data. Bivariate size allometry between ulnar dimensions and body mass was assessed by fitting (least squares and geometric mean) linear regressions of log-transformed data. It is concluded that the IFA discriminates among the species according to their fossorial habits within orders, but it is not equally useful in distinguishing fossorial species between orders. In armadillos, the relationships between ulnar dimensions and body mass are isometrical. Finally, the IFA is independent of body size.Facultad de Ciencias Naturales y Muse

Balance or imbalance? Paleoecology of the Pleistocene of North and South America

In recent years, the validity of the model proposed by Damuth about the paleoecology of past and present mammalian faunas has been addressed. In previous works such model had been applied to the fauna of Rancho La Brea (North American late Pleistocene), Venta Micena (European early Pleistocene) and to other faunas in South America. In the case of Rancho La Brea, the model had shown that it behaved as expected, i.e., keeping the balance between number of herbivorous species and primary productivity, and between number of carnivore species and secondary productivity. In other words, that the primary productivity was enough to feed the herbivores in the community, and that the secondary productivity (which is the meat available for carnivores to eat) was fully consumed by the carnivores, as in modern, actualistic examples of communities with large mammals. In the South American Lujanian Age (late Pleistocene-early Holocene), an imbalance was proposed, namely that the herbivores did not have enough food to eat according to reconstructions of their environment, and, on the other hand, that the carnivores had too much. In this work twenty six faunas from North America were studied, as well as fifteen from South America. For their study the same model and equations were applied. The results showed that those North American faunas that had number of mammalian species large enough to infer that the community was well represented were balanced, while those with few species or a low number of carnivores were not. In addition, all the Pleistocene South American faunas from diverse origins in the subcontinent were imbalanced. A possible explanation already stated was that in South America there was a great diversity of xenarthrans. In the North American faunas, such diversity was not high, and also not higher than that of any other order of mammals.Sesiones libresFacultad de Ciencias Naturales y Muse

El vuelo de un gigante

Hasta principios de la década de los 70, muchos investigadores entendían que ese era el límite máximo ele tamaño para que un ave fuese capaz de volar. Sin embargo, en 1981 los paleontólogos Kenneth Campbell, del Los Angeles County Museum, Estados Unidos de América, y Eduardo Tonni, del Museo de La Plata, dieron a conocer un ave voladora extinguida cinco veces más grande, a la que bautizaron con el grandilocuente nombre de Argeníavis magnificens. El fósil fue descubierto en Salinas Grandes de Hidalgo, provincia de La Pampa, en sedimentos del Mioceno tardío (con una antigüedad aproximada de seis millones de años).Fundación Museo La Plat

El legado del megaterio

No es común que un solo animal pueda hacer tantas y tan profundas contribuciones en el campo de las ciencias biológicas. Es aún menos común que esto ocurra cuando el animal es conocido únicamente como fósil. Pero este es precisamente el caso de Megatherium americanum, un mamífero sudamericano extinguido. Esta especie ha jugado un rol sumamente significativo en la historia y el desarrollo de la paleontología de vertebrados y del estudio de la evolución biológica

Ulnar dimensions and fossoriality in armadillos

Ulnar dimensions were measured in 14 species of armadillos (Xenarthra: Dasypodidae). An index of fossorial ability (IFA) was constructed, relating the length of the olecranon process to the remaining length of the ulna. For comparative purposes, the same measurements were taken in 14 other species of mostly South American mammals belonging to 3 orders and 11 families. The fossorial habits of these mammals were classified into 3 categories: (1) species mostly cursorial and non-digging; (2) species that often dig, but to which digging plays no essential part in their alimentary strategy and are not burrowers; and (3) species that are burrowers. IFA means of the studied mammal orders were compared using one-way analysis of variance on log-transformed data. Bivariate size allometry between ulnar dimensions and body mass was assessed by fitting (least squares and geometric mean) linear regressions of log-transformed data. It is concluded that the IFA discriminates among the species according to their fossorial habits within orders, but it is not equally useful in distinguishing fossorial species between orders. In armadillos, the relationships between ulnar dimensions and body mass are isometrical. Finally, the IFA is independent of body size.Facultad de Ciencias Naturales y Muse

Collagen sequence analysis of the extinct giant ground sloths <i>Lestodon</i> and <i>Megatherium</i>

For over 200 years, fossils of bizarre extinct creatures have been described from the Americas that have ranged from giant ground sloths to the 'native' South American ungulates, groups of mammals that evolved in relative isolation on South America. Ground sloths belong to the South American xenarthrans, a group with modern although morphologically and ecologically very different representatives (anteaters, armadillos and sloths), which has been proposed to be one of the four main eutherian clades. Recently, proteomics analyses of bone collagen have recently been used to yield a molecular phylogeny for a range of mammals including the unusual 'Malagasy aardvark' shown to be most closely related to the afrotherian tenrecs, and the south American ungulates supporting their morphological association with condylarths. However, proteomics results generate partial sequence information that could impact upon the phylogenetic placement that has not been appropriately tested. For comparison, this paper examines the phylogenetic potential of proteomicsbased sequencing through the analysis of collagen extracted from two extinct giant ground sloths, Lestodon and Megatherium. The ground sloths were placed as sister taxa to extant sloths, but with a closer relationship between Lestodon and the extant sloths than the basal Megatherium. These results highlight that proteomics methods could yield plausible phylogenies that share similarities with other methods, but have the potential to be more useful in fossils beyond the limits of ancient DNA survival.Facultad de Ciencias Naturales y Muse

El legado del megaterio

No es común que un solo animal pueda hacer tantas y tan profundas contribuciones en el campo de las ciencias biológicas. Es aún menos común que esto ocurra cuando el animal es conocido únicamente como fósil. Pero este es precisamente el caso de Megatherium americanum, un mamífero sudamericano extinguido. Esta especie ha jugado un rol sumamente significativo en la historia y el desarrollo de la paleontología de vertebrados y del estudio de la evolución biológica.Fundación Museo La Plat

El legado del megaterio

No es común que un solo animal pueda hacer tantas y tan profundas contribuciones en el campo de las ciencias biológicas. Es aún menos común que esto ocurra cuando el animal es conocido únicamente como fósil. Pero este es precisamente el caso de Megatherium americanum, un mamífero sudamericano extinguido. Esta especie ha jugado un rol sumamente significativo en la historia y el desarrollo de la paleontología de vertebrados y del estudio de la evolución biológica.Fundación Museo La Plat

El legado del megaterio

No es común que un solo animal pueda hacer tantas y tan profundas contribuciones en el campo de las ciencias biológicas. Es aún menos común que esto ocurra cuando el animal es conocido únicamente como fósil. Pero este es precisamente el caso de Megatherium americanum, un mamífero sudamericano extinguido. Esta especie ha jugado un rol sumamente significativo en la historia y el desarrollo de la paleontología de vertebrados y del estudio de la evolución biológica.Fundación Museo La Plat

Evaluating predictive pharmacogenetic signatures of adverse events in colorectal cancer patients treated with fluoropyrimidines

The potential clinical utility of genetic markers associated with response to fluoropyrimidine treatment in colorectal cancer patients remains controversial despite extensive study. Our aim was to test the clinical validity of both novel and previously identified markers of adverse events in a broad clinical setting. We have conducted an observational pharmacogenetic study of early adverse events in a cohort study of 254 colorectal cancer patients treated with 5-fluorouracil or capecitabine. Sixteen variants of nine key folate (pharmacodynamic) and drug metabolising (pharmacokinetic) enzymes have been analysed as individual markers and/or signatures of markers. We found a significant association between TYMP S471L (rs11479) and early dose modifications and/or severe adverse events (adjusted OR = 2.02 [1.03; 4.00], p = 0.042, adjusted OR = 2.70 [1.23; 5.92], p = 0.01 respectively). There was also a significant association between these phenotypes and a signature of DPYD mutations (Adjusted OR = 3.96 [1.17; 13.33], p = 0.03, adjusted OR = 6.76 [1.99; 22.96], p = 0.002 respectively). We did not identify any significant associations between the individual candidate pharmacodynamic markers and toxicity. If a predictive test for early adverse events analysed the TYMP and DPYD variants as a signature, the sensitivity would be 45.5 %, with a positive predictive value of just 33.9 % and thus poor clinical validity. Most studies to date have been under-powered to consider multiple pharmacokinetic and pharmacodynamic variants simultaneously but this and similar individualised data sets could be pooled in meta-analyses to resolve uncertainties about the potential clinical utility of these markers