Ecomorphology and feeding behavior of the Pleistocene South American equids (Mammalia, Perissodactyla, Equidae)

The fossil record of the South American Pleistocene presents two Equidae taxa: Hippidion Owen and Equus (Amerhippus) Hoffstetter. These equids were possibly sympatric and, although being considered closely related, present distinct cranial morphologies. This study aimed to verify possible variations on the masticatory patterns and dental wear between both genera, as well as to compare their rostral morphology and functional differences related to feeding habits. We performed quantitative analyses of macrowear and occlusion surface area of teeth from Toca dos Ossos (Bahia, Brazil). The morphofunctional analysis was conducted using photographs of specimens housed at the Museo de La Plata (La Plata, Argentina) and Museu de Ciências Naturais PUC Minas (Minas Gerais, Brazil), and based on the anatomy of the extant horse Equus caballus Linnaeus, due to its resemblance to E. (Amerhippus). Results showed that E. (Amerhippus) exhibits a more significant macrowear on the antero-posterior region of the teeth, while Hippidion has a more uniform wear. Analyses of occlusion surface area confirm the difference on the structure of dental enamel between genera, where Hippidion presents more complex folds. The morphofuctional analysis indicates that the rostral portion and the premaxillary shape of E. (Amerhippus) are similar to E. caballus. However, based on anatomical studies of the premaxillary region of other extinct ungulates, Hippidion exhibits morphological structures compatible with the presence of a vestibular proboscis and premaxillary region usually found on browsing ungulates. These results indicated that E. (Amerhippus) had the capacity to feed on more abrasive food items than Hippidion. Nevertheless, the morphofunctional dissimilarities on their skull suggest marked variations on their ecomorphological strategies. Therefore, these two different approaches corroborate our point of view that Hippidion and E. (Amerhippus), despite their possible sympatry, presented consistent mechanisms related to the reduction of niche overlap concerning the partition of food resources.Sesiones libresFacultad de Ciencias Naturales y Muse

Convergence and divergence in the evolution of cat skulls: temporal and spatial patterns of morphological diversity

Background: Studies of biological shape evolution are greatly enhanced when framed in a phylogenetic perspective. Inclusion of fossils amplifies the scope of macroevolutionary research, offers a deep-time perspective on tempo and mode of radiations, and elucidates life-trait changes. We explore the evolution of skull shape in felids (cats) through morphometric analyses of linear variables, phylogenetic comparative methods, and a new cladistic study of saber-toothed cats. Methodology/Principal Findings: A new phylogenetic analysis supports the monophyly of saber-toothed cats (Machairodontinae) exclusive of Felinae and some basal felids, but does not support the monophyly of various sabertoothed tribes and genera. We quantified skull shape variation in 34 extant and 18 extinct species using size-adjusted linear variables. These distinguish taxonomic group membership with high accuracy. Patterns of morphospace occupation are consistent with previous analyses, for example, in showing a size gradient along the primary axis of shape variation and a separation between large and small-medium cats. By combining the new phylogeny with a molecular tree of extant Felinae, we built a chronophylomorphospace (a phylogeny superimposed onto a two-dimensional morphospace through time). The evolutionary history of cats was characterized by two major episodes of morphological divergence, one marking the separation between saber-toothed and modern cats, the other marking the split between large and small-medium cats. Conclusions/Significance: Ancestors of large cats in the ‘Panthera’ lineage tend to occupy, at a much later stage, morphospace regions previously occupied by saber-toothed cats. The latter radiated out into new morphospace regions peripheral to those of extant large cats. The separation between large and small-medium cats was marked by considerable morphologically divergent trajectories early in feline evolution. A chronophylomorphospace has wider applications in reconstructing temporal transitions across two-dimensional trait spaces, can be used in ecophenotypical and functional diversity studies, and may reveal novel patterns of morphospace occupation

Anyone with a Long-Face? Craniofacial Evolutionary Allometry (CREA) in a Family of Short-Faced Mammals, the Felidae

Among adults of closely related species, a trend in craniofacial evolutionary allometry (CREA) for larger taxa to be long-faced and smaller ones to have paedomorphic aspects, such as proportionally smaller snouts and larger braincases, has been demonstrated in some mammals and two bird lineages. Nevertheless, whether this may represent a ‘rule’ with few exceptions is still an open question. In this context, Felidae is a particularly interesting family to study because, although its members are short-faced, previous research did suggest relative facial elongation in larger living representatives. Using geometric morphometrics, based on two sets of anatomical landmarks, and traditional morphometrics, for comparing relative lengths of the palate and basicranium, we performed a series of standard and comparative allometric regressions in the Felidae and its two subfamilies. All analyses consistently supported the CREA pattern, with only one minor exception in the geometric morphometric analysis of Pantherinae: the genus Neofelis. With its unusually long canines, Neofelis species seem to have a relatively narrow cranium and long face, despite being smaller than other big cats. In spite of this, overall, our findings strengthen the possibility that the CREA pattern might indeed be a ‘rule’ among mammals, raising questions on the processes behind it and suggesting future directions for its study

Hospital discharge planning and continuity of care for aged people in an Italian local health unit: does the care-home model reduce hospital readmission and mortality rates?

<p>Abstract</p> <p>Background</p> <p>Hospital discharge planning is aimed to decrease length of stay in hospitals as well as to ensure continuity of health care after being discharged. Hospitalized patients in Turin, Italy, who are in need of medical, social and rehabilitative care are proposed as candidates to either discharge planning relying on a care-home model (DPCH) for a period of about 30 days, or routine discharge care. The aim of this study was to evaluate whether a hospital DPCH that was compared with routine care, improved patients' outcomes in terms of reduced hospital readmission and mortality rates in patients aged 64 years and older.</p> <p>Methods</p> <p>In a retrospective observational cohort study a sample of 380 subjects aged 64 years and over was examined. Participants were discharged from the hospital S.Giovanni Bosco in Turin, Italy from March 1^st, 2005 to February 28^th, 2006. Of these subjects, 107 received routine discharge care while 273 patients were referred to care-home (among them, 99 received a long-term care intervention (LTCI) afterwards while 174 did not). Data was gathered from various administrative and electronic databases. Cox regression models were used to evaluate factors associated with mortality and hospital readmission.</p> <p>Results</p> <p>When socio-demographic factors, underlying disease and disability were taken into account, DPCH decreased mortality rates only if it was followed by a LTCI: compared to routine care, the Hazard Ratio (HR) of death was 0.36 (95% Confidence Interval (CI): 0.20 – 0.66) and 1.15 (95%CI: 0.77 – 1.74) for DPCH followed by LTCI and DPCH not followed by LTCI, respectively. On the other hand, readmission rates did not significantly differ among DPCH and routine care, irrespective of the implementation of a LTCI: HRs of hospital readmission were 1.01 (95%CI: 0.48 – 2.24) and 1.18 (95%CI: 0.71 – 1.96), respectively.</p> <p>Conclusion</p> <p>The use of DPCH after hospital discharge reduced mortality rates, but only when it was followed by a long-term health care plan, thus ensuring continuity of care for elderly participants.</p