1,721,046 research outputs found
THE ORAL APPARATUS OF MARSUPIALS IS MORE INTEGRATED BUT NOT LESS MORPHOLOGICALLY DIVERSE THAN THAT OF PLACENTAL CARNIVORES
No full textDifferent clades can display extremely different levels of morphological, taxonomical, and
ecological variability. Understanding the factors promoting or decreasing organismal
variability is a central question for paleobiologists. To answer this question, researchers
have focused on identifying the key innovations that have determined patterns of radiation
in specific clades. In this context, developmental constraints can have a major impact on
morphological variability (e.g., disparity) and the evolutionary trajectories of shape change.
Phenotypic integration, or covariation among traits, has been shown to play an important
role in shaping organismal disparity at both micro- and macro-evolutionary scales. A
longstanding proposition in the field of mammalian evolution has been that morphological
variability among marsupials was limited by developmental constraints, in particular,
constraints on the marsupial oral apparatus linked to the need for the embryo to access the
mother’s teat early in its ontogeny. In this study, we apply a recently proposed Geometric
Morphometric approach (i.e., global integration) to investigate phenotypic integration
intrinsic to a particular structure, in order to compare morphological disparity in the oral
apparatus of marsupial and placental carnivores. Our results show that the marsupial oral
apparatus is significantly more integrated than that of placentals; however, at least when
fossil specimens are included, morphological disparity among marsupials was not
significantly different to that found in placentals. Our findings underscore the importance
of including fossil material in evolutionary studies and show that phenotypic integration
alone cannot explain the lower morphological variation of extant marsupials. We suggest
that extrinsic variables, such as habitat fragmentation, are likely to have played a key role in
limiting marsupial disparity
apanese shrew‐moles
No full textHabitat segregation has been reported for the Japanese shrew-moles by several studies. However, there is a lack of surveys aimed at characterizing the ecological separation occurring between Urotrichus talpoides and Dymecodon pilirostris. In this paper, possible reasons for this ecological separation are proposed for the first time. A geometric morphometrics analysis was performed on first lower molars and mandibles of both fossil and extant specimens. The results evidenced that U. talpoides evolved a hypsodont configuration and a more robust mandible bearing an enlarged second incisor, while D. pilirostris maintained the primitive brachyodont morphology and a slender mandible. The fossil specimens proved to be very similar to their extant relatives. The shape analyses of m1 and the mandible suggest that U.talpoides possesses a more efficient feeding behaviour compared with that of D.pilirostris. Moreover, the derived state of the mandible morphology, associated with a larger size, suggests that U.talpoides largely displaced D.pilirostris and confined it to isolated highland areas by means of competition for food resources
THE ORAL APPARATUS OF MARSUPIALS IS MORE INTEGRATED BUT NOT LESS MORPHOLOGICALLY DIVERSE THAN THAT OF PLACENTAL CARNIVORES
No full textDifferent clades can display different levels of morphological, taxonomical and
ecological variability. Understanding the factors promoting or decreasing organismal
variability is a central question for paleobiologists. To answer this question researchers
have focused on identifying the key innovations that determined the patterns of radiation
in specific clades. In this context developmental constraints can have a major impact on
the evolution of morphological variability (e.g. disparity). Phenotypic integration, or
covariation among traits, has been shown to play an important role in shaping
organismal disparity at macro-evolutionary scale. A longstanding proposition about
mammalian evolution has been that morphological variability among marsupials was
limited by developmental constraints, in particular, constraints on the marsupial oral
apparatus linked to the need for the embryo to access the mother’s teat early in its
ontogeny. In this study we apply a recently proposed Geometric morphometric
approach, i.e., Global Integration, to investigate integration intrinsic to a particular
structure to compare the degree of oral apparatus morphological disparity between
marsupial and placental carnivores. Our results show that marsupial oral apparatus is
significantly more integrated than that of placentals, however, at least when fossil
specimens are included, morphological disparity among marsupials was not significantly
different to that found in placentals
Palaeoecological significance of the “wolf event” as revealed by skull ecometrics of the canid guilds
No full textCondylura (mammalia, talpidae) reloaded. new insights about the fossil representatives of the genus
No full textThe star nosed mole, Condylura cristata, due to its morphological and behavioural peculiarities, has been deeply investigated by different authors. By contrast, very little is known about the phylogenetic relationships, evolution and diversity of the fossil members of this genus. In the present study we provide new insights about the fossil specimens ascribed to Condylura taking into account systematic, palaeobiogeographical and palaeoecological aspects. Further, we provide a re-description of a fossil Condylura from the middle Miocene of Kazakhstan. We confirm that the Kazakh fossil belongs to the genus Condylura, based on humeral morphological features, and we discuss its implications and impact on the phylogenetic scenario and ecology of this peculiar talpid genus. This specimen represents the earliest record of the genus, thus suggesting an Eurasiatic origin instead of the most commonly accepted scenario of a
North American one. The presence of both plesiomorphic and apomorphic characters in Condylura strongly supports the hypothesis that this genus could be considered as sister clade of Talpinae
Did the Late Pleistocene climatic changes influence evolutionary trends in body size of the red deer? The study case of the Italian Peninsula
No full textVariations in the body size of red deer (Cervus elaphus) have been reported by several authors from several European fossiliferous localities for the Late Pleistocene and Holocene. Recently, several contributions focused on body size variation of red deer populations from the Italian Peninsula. Evolutionary trends of phenotypic traits may follow distinct tempos and modes of evolution such as Brownian, Ornstein-Uhlenbeck, stasis or random walk. Here, we investigated which evolutionary model better explained the temporal trend in body size of C. elaphus ssp. from the Italian Peninsula using modern statistical tools. We also tested the potential relationships between climate change and geographical variation through the Late Pleistocene. Our sample includes 1090 specimens from several peninsular Italian localities. For each specimen, we extracted the Size Variation Index calculated on postcranial elements. We found that stasis was the model better explaining the body size evolution in C. elaphus. We also found a nonsignificant interaction between body size and climate, whereas we detected a significant relationship with geography. We hypothesized that the red deer phenotypical plasticity was able to mitigate the selective constraints driven by climatic changes and geographical variability through the Late Pleistocene and Holocene, therefore returning a no neat variation in body size
New systematic insights about Plio-Pleistocene moles from Poland
Full text linkThe generic attribution of the Plio-Pleistocene Polish moles Neurotrichus? polonicus and
Neurotrichus? skoczeni has been questioned several times in the past. The fossil material
belonging to Neurotrichus? polonicus and Neurotrichus? skoczeni is re-evaluated here and a
new diagnosis is provided on the basis of qualitative considerations. In addition, a Geometric
Morphometric analysis of the humerus has been performed including both extant and extinct
Neurotrichini and Urotrichini taxa for comparison. Our results proved the unique morphology
of the Polish material suggesting a distinct taxonomic state. The morphological variations
evidenced by the humeral shape analysis agree with the observed qualitative differences and
support a new generic allocation. The new genus Rzebikia gen. nov. is proposed for all the
material previoulsly ascribed to Neurotrichus? polonicus and Neurotrichus? skoczeni
Talpa fossilis or Talpa europaea? Using geometric morphometrics and allometric trajectories of humeral moles remains from Hungary to answer a taxonomic debate
No full textThe taxonomic validity of Talpa fossilis has been subject to a longstanding debate. Talpa fossilis has been considered as a chronospecies, stratigraphic species, and finally as junior synonym of Talpa europaea. In this study, the large humeral sample of T. fossilis and T. europaea from the Plio-Pleistocene of Hungary is re-investigated using a geometric morphometrics analysis. Furthermore, the differences in the static allometric slopes under the allometric constraint hypothesis were tested. The results indicate that T. fossilis and T. europaea have significant differences in both size and shape. The allometric slopes of T. fossilis and T. europaea were found to be different, revealing that the two taxa follow different patterns of shape modification according to size. In light of this evidence, T. fossilis and T. europaea are supported as two distinct species
Talpa fossilis or Talpa europaea? Using geometric morphometrics and allometric trajectories of humeral mole remains from Hungary to answer a taxonomic debate
No full textThe taxonomic validity of Talpa fossilis has been subject to a longstanding debate.
Talpa fossilis has been considered as a chronospecies, stratigraphic species, and
finally as junior synonym of Talpa europaea. In this study, the large humeral sample of
T. fossilis and T. europaea from the Plio-Pleistocene of Hungary is re-investigated
using a geometric morphometrics analysis. Furthermore, the differences in the static
allometric slopes under the allometric constraint hypothesis were tested. The results
indicate that T. fossilis and T. europaea have significant differences in both size and
shape. The allometric slopes of T. fossilis and T. europaea were found to be different,
revealing that the two taxa follow different patterns of shape modification according to
size. In light of this evidence, T. fossilis and T. europaea are supported as two distinct
species
Marsupial Functional Morphology, Biomechanics, and Feeding Ecology
No full textResearchers have sought to infer the relationships between animal form and function for centuries. The study of biomechanics has become an increasingly important tool with which to quantify such relationships. Together analyses of shape and biomechanics can greatly inform our understanding of how animals interact with their environments and allow us to predict ecology in extinct species. They can also provide a sound basis from which we can gain insight into broader macroevolutionary processes. Because the acquisition and processing of food is clearly key to survival, the vertebrate feeding apparatus has received particular attention. Although clearly far less speciose than placental mammals, marsupials, and the broader metatherian clade to which they belong, are characterized by a long fossil history and considerable diversity. Consequently, they have been of critical importance in the study of evolutionary convergence. Assessments of convergence with placentals and predictions of feeding behavior in extinct species, such as the Thylacine (Thylacinus cynocephalus), Marsupial Lion (Thylacoleo carnifex), and the metatherian sabertooth (Thylacosmilus atrox), have generated particularly long-run controversy and debate. Here the study of form, function, and biomechanics in the feeding ecology of marsupials is reviewed, from nineteenth-century observation-based inference, through increasingly quantitatively founded studies incorporating two-dimensional shape analysis, lever mechanics, and beam theory in the twentieth century, to increasingly sophisticated recent investigations based on finite element analysis and three-dimensional morphometrics
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