The Utility of Linear Morphometrics as a Tool for Dietary Inference in Fossil Shrews
Location
D.P. Culp Center Ballroom
Start Date
4-5-2024 9:00 AM
End Date
4-5-2024 11:30 AM
Poster Number
138
Name of Project's Faculty Sponsor
Joshua Samuels
Faculty Sponsor's Department
Geosciences
Competition Type
Competitive
Type
Poster Presentation
Presentation Category
Science, Technology and Engineering
Abstract or Artist's Statement
Linear morphometrics have been used extensively to infer the ecology of fossil organisms, including locomotory mode and dietary preference. While this technique has been applied to many groups of mammals, there are some which have not yet been thoroughly explored, like shrews of the mammal family Soricidae. Some recent work has used linear morphometrics to explore locomotory mode in shrews, but much less has been done in the exploration of their dietary ecology. Though often considered to have a homogenous insectivorous diet, direct dietary observation in shrews suggests their dietary diversity is substantial and underappreciated. Many species appear to have distinct preferences for prey of specific hardness, while others have been documented including notable amounts of plant, fungus, or vertebrate material into their diets. Dietary diversity of this nature is well established to have influenced the morphology of the skull in other mammal clades, so similar patterns are hypothesized to be detectable in shrews. Here, we examine the link between known diet and morphological disparity in extant shrews using linear morphometrics and use that framework to infer the dietary ecology of fossil taxa. A series of 41 linear measurements were gathered that characterize elements of the shrew dentition, mandible, and cranium which should reflect dietary specializations. The extant taxa included over 20 species (> 100 individuals) and represents a phylogenetically diverse sample with documented dietary information. Taxa were classified using two distinct schemes: 1) based on the hardness of the most abundant documented prey items (hard, intermediate, and soft bodied feeders), and 2): functional morphology of their dentition (slicing, crushing, and mixed processing). In addition to this sample of extant species, three fossil taxa from the Early Pliocene Gray Fossil Site (GFS) of eastern Tennessee were also characterized: “Blarinella”, Crusafontina, and Tregosorex. These three taxa show considerable morphological differences between them and thus were expected to provide an exceptional test of this modern framework’s ability to infer diet in fossil shrews. The results of a principal component analysis reveal substantial morphological variation among studied taxa and suggest that while phylogenetic history has influenced the dental morphology of shrews, dietary and functional differences are evident within clades. Within this context, soft feeders having generally more elongate shearing surfaces and reduced grinding areas compared to hard or mixed feeders. A discriminant function analysis found the studied metrics can differentiate extant shrews with different diets (63.2 % correct classification) and was able to classify the GFS shrews as soft and intermediate feeders. Findings from this study supports the utility of linear morphometrics as a tool for dietary inference in fossil shrews and other “insectivorous” mammals more broadly.
The Utility of Linear Morphometrics as a Tool for Dietary Inference in Fossil Shrews
D.P. Culp Center Ballroom
Linear morphometrics have been used extensively to infer the ecology of fossil organisms, including locomotory mode and dietary preference. While this technique has been applied to many groups of mammals, there are some which have not yet been thoroughly explored, like shrews of the mammal family Soricidae. Some recent work has used linear morphometrics to explore locomotory mode in shrews, but much less has been done in the exploration of their dietary ecology. Though often considered to have a homogenous insectivorous diet, direct dietary observation in shrews suggests their dietary diversity is substantial and underappreciated. Many species appear to have distinct preferences for prey of specific hardness, while others have been documented including notable amounts of plant, fungus, or vertebrate material into their diets. Dietary diversity of this nature is well established to have influenced the morphology of the skull in other mammal clades, so similar patterns are hypothesized to be detectable in shrews. Here, we examine the link between known diet and morphological disparity in extant shrews using linear morphometrics and use that framework to infer the dietary ecology of fossil taxa. A series of 41 linear measurements were gathered that characterize elements of the shrew dentition, mandible, and cranium which should reflect dietary specializations. The extant taxa included over 20 species (> 100 individuals) and represents a phylogenetically diverse sample with documented dietary information. Taxa were classified using two distinct schemes: 1) based on the hardness of the most abundant documented prey items (hard, intermediate, and soft bodied feeders), and 2): functional morphology of their dentition (slicing, crushing, and mixed processing). In addition to this sample of extant species, three fossil taxa from the Early Pliocene Gray Fossil Site (GFS) of eastern Tennessee were also characterized: “Blarinella”, Crusafontina, and Tregosorex. These three taxa show considerable morphological differences between them and thus were expected to provide an exceptional test of this modern framework’s ability to infer diet in fossil shrews. The results of a principal component analysis reveal substantial morphological variation among studied taxa and suggest that while phylogenetic history has influenced the dental morphology of shrews, dietary and functional differences are evident within clades. Within this context, soft feeders having generally more elongate shearing surfaces and reduced grinding areas compared to hard or mixed feeders. A discriminant function analysis found the studied metrics can differentiate extant shrews with different diets (63.2 % correct classification) and was able to classify the GFS shrews as soft and intermediate feeders. Findings from this study supports the utility of linear morphometrics as a tool for dietary inference in fossil shrews and other “insectivorous” mammals more broadly.