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Sabretoothed carnivores and the killing of large prey.

Andersson K, Norman D, Werdelin L - PLoS ONE (2011)

Bottom Line: For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed.The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations.We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom. andersson.ki@gmail.com

ABSTRACT
Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than that of their present-day nonsabretoothed relatives. However, the precise functional advantage of the sabretooth bite, particularly in relation to prey size, is unknown. Here, we present a new point-to-point bite model and show that, for sabretooths, depth of the killing bite decreases dramatically with increasing prey size. The extended gape of sabretooths only results in considerable increase in bite depth when biting into prey with a radius of less than ∼10 cm. For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed. The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations. Furthermore, our results demonstrate how sabretoothed carnivorans are likely to have evolved along a functionally continuous trajectory: beginning as an extension of a jaw-powered killing bite, as adopted by present-day pantherine cats, followed by neck-powered biting and thereafter shifting to neck-powered shear-biting. We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions. We also expect that our model for point-to-point biting and bite depth estimations will yield new insights into the behaviours of a broad range of extinct predators including therocephalians (gorgonopsian + cynodont, sabretoothed mammal-like reptiles), sauropterygians (marine reptiles) and theropod dinosaurs.

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Bite depth increase with increasing jaw size.Bite depth (h, z-axis) plotted against jaw size (x-axis) and prey size (Y-axis) in 10 cm increments for a jaw with fixed canine clearance and jaw length proportion of 0.667 (i.e. 15 cm jaw length and 10 cm canine clearance).
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pone-0024971-g004: Bite depth increase with increasing jaw size.Bite depth (h, z-axis) plotted against jaw size (x-axis) and prey size (Y-axis) in 10 cm increments for a jaw with fixed canine clearance and jaw length proportion of 0.667 (i.e. 15 cm jaw length and 10 cm canine clearance).

Mentions: By fixing the canine clearance to jaw size proportion the model can be used to predict how bite depth changes with increasing size. In figure 4 bite depth is presented for an 0.66 proportion (i.e.15 cm jaw and 10 cm canine clearance). For comparison the same value for the extant Panthera is 0.625. Throughout the size range larger predators deliver deeper bites than their smaller counterparts. The relationship between predator size and bite depth changes as prey become larger, however. For prey with 10 cm radius bite depth increases exponentially (y = 0.37041.1185x, R2 = 0.989, P<0.0001) with increasing jaw size. For large prey (100 cm radius) the increase is close to linear, changing at a rate of 0.856 cm per 10 cm (y = −0.2458+0.0856x, R2 = 0.993, P<0.0001). Thus, in terms of bite depth, for the predator there is a relatively greater advantage in becoming larger when opting for small and medium sized prey than for large prey.


Sabretoothed carnivores and the killing of large prey.

Andersson K, Norman D, Werdelin L - PLoS ONE (2011)

Bite depth increase with increasing jaw size.Bite depth (h, z-axis) plotted against jaw size (x-axis) and prey size (Y-axis) in 10 cm increments for a jaw with fixed canine clearance and jaw length proportion of 0.667 (i.e. 15 cm jaw length and 10 cm canine clearance).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198467&req=5

pone-0024971-g004: Bite depth increase with increasing jaw size.Bite depth (h, z-axis) plotted against jaw size (x-axis) and prey size (Y-axis) in 10 cm increments for a jaw with fixed canine clearance and jaw length proportion of 0.667 (i.e. 15 cm jaw length and 10 cm canine clearance).
Mentions: By fixing the canine clearance to jaw size proportion the model can be used to predict how bite depth changes with increasing size. In figure 4 bite depth is presented for an 0.66 proportion (i.e.15 cm jaw and 10 cm canine clearance). For comparison the same value for the extant Panthera is 0.625. Throughout the size range larger predators deliver deeper bites than their smaller counterparts. The relationship between predator size and bite depth changes as prey become larger, however. For prey with 10 cm radius bite depth increases exponentially (y = 0.37041.1185x, R2 = 0.989, P<0.0001) with increasing jaw size. For large prey (100 cm radius) the increase is close to linear, changing at a rate of 0.856 cm per 10 cm (y = −0.2458+0.0856x, R2 = 0.993, P<0.0001). Thus, in terms of bite depth, for the predator there is a relatively greater advantage in becoming larger when opting for small and medium sized prey than for large prey.

Bottom Line: For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed.The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations.We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom. andersson.ki@gmail.com

ABSTRACT
Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than that of their present-day nonsabretoothed relatives. However, the precise functional advantage of the sabretooth bite, particularly in relation to prey size, is unknown. Here, we present a new point-to-point bite model and show that, for sabretooths, depth of the killing bite decreases dramatically with increasing prey size. The extended gape of sabretooths only results in considerable increase in bite depth when biting into prey with a radius of less than ∼10 cm. For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed. The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations. Furthermore, our results demonstrate how sabretoothed carnivorans are likely to have evolved along a functionally continuous trajectory: beginning as an extension of a jaw-powered killing bite, as adopted by present-day pantherine cats, followed by neck-powered biting and thereafter shifting to neck-powered shear-biting. We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions. We also expect that our model for point-to-point biting and bite depth estimations will yield new insights into the behaviours of a broad range of extinct predators including therocephalians (gorgonopsian + cynodont, sabretoothed mammal-like reptiles), sauropterygians (marine reptiles) and theropod dinosaurs.

Show MeSH
Related in: MedlinePlus