Limits...
Are cranial biomechanical simulation data linked to known diets in extant taxa? A method for applying diet-biomechanics linkage models to infer feeding capability of extinct species.

Tseng ZJ, Flynn JJ - PLoS ONE (2015)

Bottom Line: However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages.Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders.These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects.

View Article: PubMed Central - PubMed

Affiliation: Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, United States of America.

ABSTRACT
Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences.

No MeSH data available.


Related in: MedlinePlus

Cranial shape changes in morphed models, associated with A. input load / body size increase or decrease, and B. strain energy differences (higher or lower stiffness).Skulls were morphed from the model of O. herpestoides using trends from regression analyses of phylogenetic independent contrasts of input load, strain energy, and geometric skull shape.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4414467&req=5

pone.0124020.g006: Cranial shape changes in morphed models, associated with A. input load / body size increase or decrease, and B. strain energy differences (higher or lower stiffness).Skulls were morphed from the model of O. herpestoides using trends from regression analyses of phylogenetic independent contrasts of input load, strain energy, and geometric skull shape.

Mentions: In our analyses, size-based trends in biomechanical capability are correlated with changes in skull shape (albeit not statistically significant, p = 0.11), with larger species having a more dorsoventrally-arranged long axis through the rostrum and braincase, deeper muscle attachment regions, a more triangular dorsal skull profile, and broadening frontals (Fig 6). These rearrangements bring into alignment the long axes of the temporalis and masseter musculature with the dorsoventral axis of the skull, reorienting the effective force of the jaw-closing muscles into the dorsoventral direction, into the plane of jaw closure. A more vertically oriented skull also alters distribution of stress to a more dorsoventral direction (i.e. more compressive and less torsional forces) [14,37]. This change is consistent with mammalian cortical bone being strongest in compression, and not torsion or tension, and as a size-driven trend it cannot be uniquely correlated with specific feeding niches (e.g., large carnivorans such as ursids are omnivores and herbivores, whereas large canids and felids are hypercarnivores). Additional sources of variation, such as differences in distribution of cortical versus cancellous bone in the cranium, were not analyzed in this study. Differences in bone distribution and arrangement could contribute to the size-driven trends observed in this study, which held material properties constant in order to study the functional changes principally associated with skull shape differences.


Are cranial biomechanical simulation data linked to known diets in extant taxa? A method for applying diet-biomechanics linkage models to infer feeding capability of extinct species.

Tseng ZJ, Flynn JJ - PLoS ONE (2015)

Cranial shape changes in morphed models, associated with A. input load / body size increase or decrease, and B. strain energy differences (higher or lower stiffness).Skulls were morphed from the model of O. herpestoides using trends from regression analyses of phylogenetic independent contrasts of input load, strain energy, and geometric skull shape.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414467&req=5

pone.0124020.g006: Cranial shape changes in morphed models, associated with A. input load / body size increase or decrease, and B. strain energy differences (higher or lower stiffness).Skulls were morphed from the model of O. herpestoides using trends from regression analyses of phylogenetic independent contrasts of input load, strain energy, and geometric skull shape.
Mentions: In our analyses, size-based trends in biomechanical capability are correlated with changes in skull shape (albeit not statistically significant, p = 0.11), with larger species having a more dorsoventrally-arranged long axis through the rostrum and braincase, deeper muscle attachment regions, a more triangular dorsal skull profile, and broadening frontals (Fig 6). These rearrangements bring into alignment the long axes of the temporalis and masseter musculature with the dorsoventral axis of the skull, reorienting the effective force of the jaw-closing muscles into the dorsoventral direction, into the plane of jaw closure. A more vertically oriented skull also alters distribution of stress to a more dorsoventral direction (i.e. more compressive and less torsional forces) [14,37]. This change is consistent with mammalian cortical bone being strongest in compression, and not torsion or tension, and as a size-driven trend it cannot be uniquely correlated with specific feeding niches (e.g., large carnivorans such as ursids are omnivores and herbivores, whereas large canids and felids are hypercarnivores). Additional sources of variation, such as differences in distribution of cortical versus cancellous bone in the cranium, were not analyzed in this study. Differences in bone distribution and arrangement could contribute to the size-driven trends observed in this study, which held material properties constant in order to study the functional changes principally associated with skull shape differences.

Bottom Line: However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages.Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders.These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects.

View Article: PubMed Central - PubMed

Affiliation: Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, United States of America.

ABSTRACT
Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences.

No MeSH data available.


Related in: MedlinePlus