David Button
My current work concerns my PhD, "cranial mechanics of sauropodomorph dinosaurs". My aim here is to profile characters of the skull (especially cranial suture morpholgy, which has yet to see a comprehensive review in the clade) which may represent adaptations towards feeding. The functional significance of these characters will be tested through the construction of Finite Element models of Camarasaurus and Diplodocus. This should then allow a deeper understanding of the assembly and evolution of cranial character complexes within the sauropodomorpha as a response to high-fibre herbivory during the Mesozoic.
My Masters thesis was an investigation into the consequences that the use of continuous characters can have on phylogenetic work, focussing upon impacts differing methods of character treatment and inclusion have upon the phylogeny of the Pterosauria.
Supervisors: Dr Emily Rayfield and Dr Paul Barrett
My Masters thesis was an investigation into the consequences that the use of continuous characters can have on phylogenetic work, focussing upon impacts differing methods of character treatment and inclusion have upon the phylogeny of the Pterosauria.
Supervisors: Dr Emily Rayfield and Dr Paul Barrett
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Papers by David Button
herbivores and pushed at the limits of vertebrate biomechanics
and physiology. Sauropods exhibit high craniodental
diversity in ecosystems where numerous species coexisted,
leading to the hypothesis that this biodiversity is
linked to niche subdivision driven by ecological specialisation.
Here, we quantitatively investigate feeding behaviour
hypotheses for the iconic sauropod Diplodocus. Biomechanical
modelling, using finite element analysis, was used to
examine the performance of the Diplodocus skull. Three
feeding behaviours were modelled: muscle-driven static biting,
branch stripping and bark stripping. The skull was found to be
‘over engineered’ for static biting, overall experiencing low
stress with only the dentition enduring high stress. When
branch stripping, the skull, similarly, is under low stress, with
little appreciable difference between those models. When simulated for bark stripping, the skull experiences far greater
stresses, especially in the teeth and at the jaw joint. Therefore,
we refute the bark-stripping hypothesis, while the hypotheses
of branch stripping and/or precision biting are both
consistent with our findings, showing that branch stripping
is a biomechanically plausible feeding behaviour
for diplodocids. Interestingly, in all simulations, peak
stress is observed in the premaxillary–maxillary ‘lateral
plates’, supporting the hypothesis that these structures
evolved to dissipate stress induced while feeding. These
results lead us to conclude that the aberrant craniodental
form of Diplodocus was adapted for food procurement
rather than resisting high bite forces.
Talks by David Button
The high craniodental diversity observed between sympatric sauropod taxa has often been used to support notions of niche partitioning. This is particularly so for the well-known fauna of the Morrison Formation of North America, which contains a high diversity (~9 genera) of sauropod taxa, with the common Camarasaurus and Diplodocus representing extreme end-members in the spectrum of sauropod cranial morphology. However, whilst biomechanical modelling has investigated potential specialized feeding behaviours in Diplodocus, no such work has been previously reported on Camarasaurus.
To rectify this deficit the skull of Camarasaurus was produced from CT scan data. Myological reconstruction, on the basis of osteological correlates, demonstrates a greater importance of the external adductor muscules relative to the pterygoideus musculature than in Diplodocus, although overall muscle volumes are similar. However, the more vertical arrangement of the muscles, coupled with the greater mechanical advantage of the jaw, enabled the production of substantially greater bite forces in Camarasaurus. Finite-element modelling demonstrates that Camarasaurus was well-adapted to resist high forces associated with biting, with stresses generally low throughout the skull, and is “stronger” under conditions of static biting than Diplodocus. Modelling of other behaviours hypothesised for sauropods on the basis of toothwear- bilateral and lateral stripping and tugging- also result in very low stresses and it hence seems likely that Camarasaurus would have been able to employ a variety of actions in a wide foraging repertoire.
The results here provide biomechanical evidence for niche partitioning between Morrison sauropod taxa, with Camarasaurus capable of dealing with greater range of coarser foodstuffs than sympatric diplodocoids.
The high craniodental diversity differentiating sympatric sauropod taxa has often been cited in support of niche partitioning. This is particularly so for the well-known Morrison Formation fauna, which contains a high diversity (~9 genera) of sauropod taxa. In particular, the abundant Diplodocus and Camarasaurus represent extreme end-members in the spectrum of sauropod cranial morphology and have been hypothesised as being adapted towards specialized branch-stripping and the production of higher bite forces, respectively. However, while biomechanical modelling has previously been used to investigate feeding behaviour in Diplodocus, no such work has been attempted on Camarasaurus. Here we rectify this deficit through muscle reconstruction, functional morphology and application of finite element analysis (FEA) to a skull of C. lentus. This model was then compared to that of Diplodocus allowing testing of the niche partitioning hypothesis in a biomechanical context.
Myological reconstruction demonstrates a greater importance of the external adductor group versus the pterygoideus musculature than in Diplodocus, although overall muscle volumes are similar. Despite this, the more mechanically efficient skull and more favourable lines of muscle action result in significantly greater calculated maximum bite forces for Camarasaurus. FEA indicates that the skull of Camarasaurus was well-adapted to resist forces resulting from biting and is “stronger” under conditions of static biting than that of Diplodocus, with lower stresses in the snout and palate. Under loading conditions simulating other hypothesised sauropod feeding behaviours (bilateral and lateral stripping/tugging) stresses are again very low, indicating that Camarasaurus would have been capable of exploiting a varied foraging repertoire.
The results here provide biomechanical evidence for niche partitioning between Morrison sauropod taxa, with Camarasaurus capable employing high bite forces and a range of behaviours to deal with a greater range of coarser foodstuffs than sympatric diplodocoids, which were instead more specialized in their feeding behaviours.
The high craniodental diversity differentiating sympatric sauropod taxa has often been cited as evidence of niche partitioning, especially so for the well-known and highly diverse Morrison Formation fauna. In particular, the abundant Morrison taxa Diplodocus and Camarasaurus represent extremes in the spectrum of sauropod craniodental morphology and have been hypothesised as being adapted towards branch-stripping and production of greater bite forces, respectively. However, these hypotheses have yet to be tested through comparison of these taxa within a rigorous biomechanical context. We rectify this deficit through cranial muscle reconstruction and finite-element modelling of a skull of C. lentus, allowing comparison with a pre-existing model of Diplodocus.
Results demonstrate significantly greater bite forces in Camarasaurus than Diplodocus. The skull of Camarasaurus is also “stronger” under loading conditions replicating static biting than Diplodocus, although this is due to compensatory effects of greater size as opposed to greater structural efficiency. Modelling other hypothesized feeding behaviours indicates that Camarasaurus would have been capable of exploiting a varied feeding repertoire.
The results here provide biomechanical evidence for niche partitioning between Morrison sauropod taxa, with Camarasaurus capable of employing higher bite forces and a range of behaviours to deal with a greater range of coarser foodstuffs than sympatric diplodocoids, which were more specialized in their foraging behaviour.
Understanding of skull function is imperative to the understanding of feeding within any clade. Craniodental anatomy and toothwear work have demonstrated great diversity in skull form within sauropods, which has been inferred as forming the basis of niche partitioning between sympatric taxa. This is particularly so for the well-known fauna of the Morrison Formation of North America, which contains a very high diversity (~9 genera) of sauropod taxa, with the common Camarasaurus and Diplodocus representing extreme end-members in the spectrum of sauropod cranial morphology. However, these hypotheses of niche partitioning based on skull function have yet to be tested within a rigorous biomechanical framework.
To rectify this deficit the skull of Camarasaurus was subjected to Finite Element Analysis (FEA), a modelling technique which allows biomechanical hypotheses to be tested in a quantitative manner. Such work has previously been conducted on Diplodocus, finding evidence for specialized feeding behaviour, but on no other sauropod taxa. This involved the production of a digital model from CT scan data, with correction of deformation. This was loaded with muscle forces calculated from the reconstruction of the cranial jaw musculature from osteological correlates, under scenarios of different feeding behaviours (static biting versus branch-stripping).
Comparison of the results with those of Diplodocus indicates that Camarasaurus was capable of exerting greater bite forces, and would have been capable of dealing with coarser plant material. However, the skull also performed nearly as well under loading conditions simulating both bilateral and lateral branch-stripping/tugging, indicating the potential of a varied series of behaviours being employed in its feeding repertoire. This, coupled with the greater absolute bite forces of Camarasaurus indicate that it would have been capable of dealing with a wide variety of coarse plant material, in constrast to the highly specialized feeding behaviour of Diplodocus.
"
herbivores and pushed at the limits of vertebrate biomechanics
and physiology. Sauropods exhibit high craniodental
diversity in ecosystems where numerous species coexisted,
leading to the hypothesis that this biodiversity is
linked to niche subdivision driven by ecological specialisation.
Here, we quantitatively investigate feeding behaviour
hypotheses for the iconic sauropod Diplodocus. Biomechanical
modelling, using finite element analysis, was used to
examine the performance of the Diplodocus skull. Three
feeding behaviours were modelled: muscle-driven static biting,
branch stripping and bark stripping. The skull was found to be
‘over engineered’ for static biting, overall experiencing low
stress with only the dentition enduring high stress. When
branch stripping, the skull, similarly, is under low stress, with
little appreciable difference between those models. When simulated for bark stripping, the skull experiences far greater
stresses, especially in the teeth and at the jaw joint. Therefore,
we refute the bark-stripping hypothesis, while the hypotheses
of branch stripping and/or precision biting are both
consistent with our findings, showing that branch stripping
is a biomechanically plausible feeding behaviour
for diplodocids. Interestingly, in all simulations, peak
stress is observed in the premaxillary–maxillary ‘lateral
plates’, supporting the hypothesis that these structures
evolved to dissipate stress induced while feeding. These
results lead us to conclude that the aberrant craniodental
form of Diplodocus was adapted for food procurement
rather than resisting high bite forces.
The high craniodental diversity observed between sympatric sauropod taxa has often been used to support notions of niche partitioning. This is particularly so for the well-known fauna of the Morrison Formation of North America, which contains a high diversity (~9 genera) of sauropod taxa, with the common Camarasaurus and Diplodocus representing extreme end-members in the spectrum of sauropod cranial morphology. However, whilst biomechanical modelling has investigated potential specialized feeding behaviours in Diplodocus, no such work has been previously reported on Camarasaurus.
To rectify this deficit the skull of Camarasaurus was produced from CT scan data. Myological reconstruction, on the basis of osteological correlates, demonstrates a greater importance of the external adductor muscules relative to the pterygoideus musculature than in Diplodocus, although overall muscle volumes are similar. However, the more vertical arrangement of the muscles, coupled with the greater mechanical advantage of the jaw, enabled the production of substantially greater bite forces in Camarasaurus. Finite-element modelling demonstrates that Camarasaurus was well-adapted to resist high forces associated with biting, with stresses generally low throughout the skull, and is “stronger” under conditions of static biting than Diplodocus. Modelling of other behaviours hypothesised for sauropods on the basis of toothwear- bilateral and lateral stripping and tugging- also result in very low stresses and it hence seems likely that Camarasaurus would have been able to employ a variety of actions in a wide foraging repertoire.
The results here provide biomechanical evidence for niche partitioning between Morrison sauropod taxa, with Camarasaurus capable of dealing with greater range of coarser foodstuffs than sympatric diplodocoids.
The high craniodental diversity differentiating sympatric sauropod taxa has often been cited in support of niche partitioning. This is particularly so for the well-known Morrison Formation fauna, which contains a high diversity (~9 genera) of sauropod taxa. In particular, the abundant Diplodocus and Camarasaurus represent extreme end-members in the spectrum of sauropod cranial morphology and have been hypothesised as being adapted towards specialized branch-stripping and the production of higher bite forces, respectively. However, while biomechanical modelling has previously been used to investigate feeding behaviour in Diplodocus, no such work has been attempted on Camarasaurus. Here we rectify this deficit through muscle reconstruction, functional morphology and application of finite element analysis (FEA) to a skull of C. lentus. This model was then compared to that of Diplodocus allowing testing of the niche partitioning hypothesis in a biomechanical context.
Myological reconstruction demonstrates a greater importance of the external adductor group versus the pterygoideus musculature than in Diplodocus, although overall muscle volumes are similar. Despite this, the more mechanically efficient skull and more favourable lines of muscle action result in significantly greater calculated maximum bite forces for Camarasaurus. FEA indicates that the skull of Camarasaurus was well-adapted to resist forces resulting from biting and is “stronger” under conditions of static biting than that of Diplodocus, with lower stresses in the snout and palate. Under loading conditions simulating other hypothesised sauropod feeding behaviours (bilateral and lateral stripping/tugging) stresses are again very low, indicating that Camarasaurus would have been capable of exploiting a varied foraging repertoire.
The results here provide biomechanical evidence for niche partitioning between Morrison sauropod taxa, with Camarasaurus capable employing high bite forces and a range of behaviours to deal with a greater range of coarser foodstuffs than sympatric diplodocoids, which were instead more specialized in their feeding behaviours.
The high craniodental diversity differentiating sympatric sauropod taxa has often been cited as evidence of niche partitioning, especially so for the well-known and highly diverse Morrison Formation fauna. In particular, the abundant Morrison taxa Diplodocus and Camarasaurus represent extremes in the spectrum of sauropod craniodental morphology and have been hypothesised as being adapted towards branch-stripping and production of greater bite forces, respectively. However, these hypotheses have yet to be tested through comparison of these taxa within a rigorous biomechanical context. We rectify this deficit through cranial muscle reconstruction and finite-element modelling of a skull of C. lentus, allowing comparison with a pre-existing model of Diplodocus.
Results demonstrate significantly greater bite forces in Camarasaurus than Diplodocus. The skull of Camarasaurus is also “stronger” under loading conditions replicating static biting than Diplodocus, although this is due to compensatory effects of greater size as opposed to greater structural efficiency. Modelling other hypothesized feeding behaviours indicates that Camarasaurus would have been capable of exploiting a varied feeding repertoire.
The results here provide biomechanical evidence for niche partitioning between Morrison sauropod taxa, with Camarasaurus capable of employing higher bite forces and a range of behaviours to deal with a greater range of coarser foodstuffs than sympatric diplodocoids, which were more specialized in their foraging behaviour.
Understanding of skull function is imperative to the understanding of feeding within any clade. Craniodental anatomy and toothwear work have demonstrated great diversity in skull form within sauropods, which has been inferred as forming the basis of niche partitioning between sympatric taxa. This is particularly so for the well-known fauna of the Morrison Formation of North America, which contains a very high diversity (~9 genera) of sauropod taxa, with the common Camarasaurus and Diplodocus representing extreme end-members in the spectrum of sauropod cranial morphology. However, these hypotheses of niche partitioning based on skull function have yet to be tested within a rigorous biomechanical framework.
To rectify this deficit the skull of Camarasaurus was subjected to Finite Element Analysis (FEA), a modelling technique which allows biomechanical hypotheses to be tested in a quantitative manner. Such work has previously been conducted on Diplodocus, finding evidence for specialized feeding behaviour, but on no other sauropod taxa. This involved the production of a digital model from CT scan data, with correction of deformation. This was loaded with muscle forces calculated from the reconstruction of the cranial jaw musculature from osteological correlates, under scenarios of different feeding behaviours (static biting versus branch-stripping).
Comparison of the results with those of Diplodocus indicates that Camarasaurus was capable of exerting greater bite forces, and would have been capable of dealing with coarser plant material. However, the skull also performed nearly as well under loading conditions simulating both bilateral and lateral branch-stripping/tugging, indicating the potential of a varied series of behaviours being employed in its feeding repertoire. This, coupled with the greater absolute bite forces of Camarasaurus indicate that it would have been capable of dealing with a wide variety of coarse plant material, in constrast to the highly specialized feeding behaviour of Diplodocus.
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