2016 Papers by Elizabeth Dumont
Geometric morphometrics (GM) and finite element analysis (FEA) are increasingly common techniques... more Geometric morphometrics (GM) and finite element analysis (FEA) are increasingly common techniques for the study of form and function. We show how principles of quantitative evolution in continuous phenotypic traits can link the two techniques, allowing hypotheses about the relative importance of different functions to be tested in a phylogenetic and evolutionary framework. Finite element analysis is used to derive quantitative surfaces that describe the comparative performance of different morphologies in a morphospace derived from GM. The combination of two or more performance surfaces describes a quantitative adaptive landscape that can be used to predict the direction morphological evolution would take if a combination of functions was selected for. Predicted paths of evolution also can be derived for hypotheses about the relative importance of multiple functions, which can be tested against evolutionary pathways that are documented by phylogenies or fossil sequences. Magnitudes of evolutionary trade-offs between functions can be estimated using maximum likelihood. We apply these methods to an earlier study of carapace strength and hydrodynamic efficiency in emydid turtles. We find that strength and hydrodynamic efficiency explain about 45% of the variance in shell shape; drift and other unidentified functional factors are necessary to explain the remaining variance. Measurement of the proportional trade-off between shell strength and hydrodynamic efficiency shows that throughout the Cenozoic aquatic turtles generally sacrificed strength for streamlining and terrestrial species favored stronger shells; this suggests that the selective regime operating on small to mid-sized emydids has remained relatively static.
Papers by Elizabeth Dumont
Nature, Jan 27, 2014
Previously known only from isolated teeth and lower jaw fragments recovered from the Cretaceous a... more Previously known only from isolated teeth and lower jaw fragments recovered from the Cretaceous and Palaeogene of the Southern Hemisphere, the Gondwanatheria constitute the most poorly known of all major mammaliaform radiations. Here we report the discovery of the first skull material of a gondwanatherian, a complete and well-preserved cranium from Upper Cretaceous strata in Madagascar that we assign to a new genus and species. Phylogenetic analysis strongly supports its placement within Gondwanatheria, which are recognized as monophyletic and closely related to multituberculates, an evolutionarily successful clade of Mesozoic mammals known almost exclusively from the Northern Hemisphere. The new taxon is the largest known mammaliaform from the Mesozoic of Gondwana. Its craniofacial anatomy reveals that it was herbivorous, large-eyed and agile, with well-developed high-frequency hearing and a keen sense of smell. The cranium exhibits a mosaic of primitive and derived features, the d...
Trends in Ecology & Evolution, 2013
Biological Journal of the Linnean Society, 2008
Biological Journal of the Linnean Society, 2011
Previously known only from isolated teeth and lower jaw fragments recovered from the Cretaceous a... more Previously known only from isolated teeth and lower jaw fragments recovered from the Cretaceous and Palaeogene of
the SouthernHemisphere, the Gondwanatheria constitute the most poorly knownof all majormammaliaform radiations.
Here we report the discovery of the first skull material of a gondwanatherian, a complete and well-preserved cranium
from Upper Cretaceous strata in Madagascar that we assign to a new genus and species. Phylogenetic analysis strongly
supports its placement within Gondwanatheria,which are recognized asmonophyletic and closely related tomultituberculates,
an evolutionarily successful clade ofMesozoicmammalsknownalmost exclusively fromtheNorthernHemisphere.
Thenewtaxon is the largestknownmammaliaform fromthe Mesozoic of Gondwana.Its craniofacial anatomyreveals that
it was herbivorous, large-eyed and agile, with well-developed high-frequency hearing and a keen sense of smell. The
cranium exhibits a mosaic of primitive and derived features, the disparity of which is extreme and probably reflective of
a long evolutionary history in geographic isolation.
Journal of Vertebrate Paleontology, 2014
ABSTRACT ABSTRACT-The nearly complete and well-preserved cranium of Vintana sertichi provides an ... more ABSTRACT ABSTRACT-The nearly complete and well-preserved cranium of Vintana sertichi provides an opportunity to investigate its dietary adaptations. We used a combination of comparative morphological and biomechanical analyses to reveal the direction of its power stroke during mastication, reconstruct the positions and relative sizes of its muscles of mastication, and predict its capacity to produce bite forces during incision and molariform occlusion. The orientation of dental wear striations on the upper molariform teeth of Vintana, in combination with the orientation of the enamel islets and synclines and the position of leading and trailing edges, demonstrates that the power stroke was primarily palinal (distally directed), with a significant buccally directed component that is absent in multituberculates, haramiyidans, and other gondwanatherians. The large palinal component of jaw movement was corroborated by biomechanical analyses of the moments generated by the primary jaw adductors around the dentary-squamosal joint axis. Similar analyses also confirmed the previously documented proal (mesially directed) power stroke of the extant rodent Myocastor. Finite element analyses predict that Vintana was capable of producing bite forces that were more than twice as high as the similarly sized Myocastor. Vintana was almost certainly an herbivore, as claimed previously for other sudamericid gondwanatherians. Its size and capacity to generate high bite forces at both the incisors and the molariform teeth suggest that it was a mixed feeder whose diet may have included relatively large, hard food items such as roots, seeds, twigs, or nut-like fruits.
The Journal of experimental biology, Jan 15, 2014
The olfactory recess - a blind pocket at the back of the nasal airway - is thought to play an imp... more The olfactory recess - a blind pocket at the back of the nasal airway - is thought to play an important role in mammalian olfaction by sequestering air outside of the main airstream, thus giving odorants time to re-circulate. Several studies have shown that species with large olfactory recesses tend to have a well-developed sense of smell. However, no study has investigated how the size of the olfactory recess relates to air circulation near the olfactory epithelium. Here we used a computer model of the nasal cavity from a bat (Carollia perspicillata) to test the hypothesis that a larger olfactory recess improves olfactory airflow. We predicted that during inhalation, models with an enlarged olfactory recess would have slower rates of flow through the olfactory region (i.e. the olfactory recess plus airspace around the olfactory epithelium), while during exhalation these models would have little to no flow through the olfactory recess. To test these predictions, we experimentally mo...
Anatomical record (Hoboken, N.J. : 2007), 2014
The olfactory recess (OR) is a restricted space at the back of the nasal fossa in many mammals th... more The olfactory recess (OR) is a restricted space at the back of the nasal fossa in many mammals that is thought to improve olfactory function. Mammals that have an olfactory recess are usually described as keen-scented, while those that do not are typically thought of as less reliant on olfaction. However, the presence of an olfactory recess is not a binary trait. Many mammal families have members that vary substantially in the size and complexity of the olfactory recess. There is also variation in the amount of olfactory epithelium (OE) that is housed in the olfactory recess. Among New World leaf-nosed bats (family Phyllostomidae), species vary by over an order of magnitude in how much of their total OE lies within the OR. Does this variation relate to previously documented neuroanatomical proxies for olfactory reliance? Using data from 12 species of phyllostomid bats, we addressed the hypothesis that the amount of OE within the OR relates to a species' dependence on olfaction, ...
Trends in Ecology & Evolution, 2013
Journal of Experimental Biology, 2011
SUMMARY Bite force is a measure of whole-organism performance that is often used to investigate t... more SUMMARY Bite force is a measure of whole-organism performance that is often used to investigate the relationships between performance, morphology and fitness. When in vivo measurements of bite force are unavailable, researchers often turn to lever models to predict bite forces. This study demonstrates that bite force predictions based on two-dimensional (2-D) lever models can be improved by including three-dimensional (3-D) geometry and realistic physiological cross-sectional areas derived from dissections.
Proceedings of the Royal Society B: Biological Sciences, 2012
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2016 Papers by Elizabeth Dumont
Papers by Elizabeth Dumont
the SouthernHemisphere, the Gondwanatheria constitute the most poorly knownof all majormammaliaform radiations.
Here we report the discovery of the first skull material of a gondwanatherian, a complete and well-preserved cranium
from Upper Cretaceous strata in Madagascar that we assign to a new genus and species. Phylogenetic analysis strongly
supports its placement within Gondwanatheria,which are recognized asmonophyletic and closely related tomultituberculates,
an evolutionarily successful clade ofMesozoicmammalsknownalmost exclusively fromtheNorthernHemisphere.
Thenewtaxon is the largestknownmammaliaform fromthe Mesozoic of Gondwana.Its craniofacial anatomyreveals that
it was herbivorous, large-eyed and agile, with well-developed high-frequency hearing and a keen sense of smell. The
cranium exhibits a mosaic of primitive and derived features, the disparity of which is extreme and probably reflective of
a long evolutionary history in geographic isolation.
the SouthernHemisphere, the Gondwanatheria constitute the most poorly knownof all majormammaliaform radiations.
Here we report the discovery of the first skull material of a gondwanatherian, a complete and well-preserved cranium
from Upper Cretaceous strata in Madagascar that we assign to a new genus and species. Phylogenetic analysis strongly
supports its placement within Gondwanatheria,which are recognized asmonophyletic and closely related tomultituberculates,
an evolutionarily successful clade ofMesozoicmammalsknownalmost exclusively fromtheNorthernHemisphere.
Thenewtaxon is the largestknownmammaliaform fromthe Mesozoic of Gondwana.Its craniofacial anatomyreveals that
it was herbivorous, large-eyed and agile, with well-developed high-frequency hearing and a keen sense of smell. The
cranium exhibits a mosaic of primitive and derived features, the disparity of which is extreme and probably reflective of
a long evolutionary history in geographic isolation.