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Oldest pathology in a tetrapod bone illuminates the origin of terrestrial vertebrates.

Bishop PJ, Walmsley CW, Phillips MJ, Quayle MR, Boisvert CA, McHenry CR - PLoS ONE (2015)

Bottom Line: Using high-resolution finite element analysis, we demonstrate that the oldest known broken tetrapod bone, a radius of the primitive stem tetrapod Ossinodus pueri from the mid-Viséan (333 million years ago) of Australia, fractured under a high-force, impact-type loading scenario.Augmenting this are new osteological observations, including a preferred directionality to the trabecular architecture of cancellous bone.Together, these results suggest that Ossinodus, one of the first large (>2m length) tetrapods, spent a significant proportion of its life on land.

View Article: PubMed Central - PubMed

Affiliation: Ancient Environments Program, Queensland Museum, 122 Gerler Rd, Hendra, Queensland, 4011, Australia; School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, 4000, Australia; Centre for Musculoskeletal Research, Griffith University, Southport, Queensland, 4222, Australia.

ABSTRACT
The origin of terrestrial tetrapods was a key event in vertebrate evolution, yet how and when it occurred remains obscure, due to scarce fossil evidence. Here, we show that the study of palaeopathologies, such as broken and healed bones, can help elucidate poorly understood behavioural transitions such as this. Using high-resolution finite element analysis, we demonstrate that the oldest known broken tetrapod bone, a radius of the primitive stem tetrapod Ossinodus pueri from the mid-Viséan (333 million years ago) of Australia, fractured under a high-force, impact-type loading scenario. The nature of the fracture suggests that it most plausibly occurred during a fall on land. Augmenting this are new osteological observations, including a preferred directionality to the trabecular architecture of cancellous bone. Together, these results suggest that Ossinodus, one of the first large (>2m length) tetrapods, spent a significant proportion of its life on land. Our findings have important implications for understanding the temporal, biogeographical and physiological contexts under which terrestriality in vertebrates evolved. They push the date for the origin of terrestrial tetrapods further back into the Carboniferous by at least two million years. Moreover, they raise the possibility that terrestriality in vertebrates first evolved in large tetrapods in Gondwana rather than in small European forms, warranting a re-evaluation of this important evolutionary event.

No MeSH data available.


Related in: MedlinePlus

Three-dimensional finite element models of the radius of Ossinodus.(a) Complete homogenous model in oblique posterolateral view; extent of proximal articulation surface shown in grey. This was the model used to assess fracture mechanics in the radius. (b) Incomplete homogenous model in anteromedial view; red shows exposed (homogenous) cancellous bone. (c) Incomplete heterogenous model in posteromedial view. (d) Incomplete heterogenous model in posteromedial view, sectioned in the mediolateral plane to illustrate variation in material properties within the volume of cancellous bone.
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pone.0125723.g004: Three-dimensional finite element models of the radius of Ossinodus.(a) Complete homogenous model in oblique posterolateral view; extent of proximal articulation surface shown in grey. This was the model used to assess fracture mechanics in the radius. (b) Incomplete homogenous model in anteromedial view; red shows exposed (homogenous) cancellous bone. (c) Incomplete heterogenous model in posteromedial view. (d) Incomplete heterogenous model in posteromedial view, sectioned in the mediolateral plane to illustrate variation in material properties within the volume of cancellous bone.

Mentions: In order to determine how and with what magnitude force the radius of Ossinodus would have fractured, the CT scan data was used to develop a high-resolution, three-dimensional, finite element model of the bone’s pre-fractured morphology in Strand7 2.4.4 (Strand7 Pty Ltd, Australia). The fossil’s preservation allowed for cortical bone and different components of the cancellous bone to be modelled separately based on density differences, thus enabling patterns of variation in material properties in the original, living bone to be accounted for. However, since a small part of the fossil was missing, knowledge of structural and material heterogeneity within the cancellous bone is incomplete. Thus, in the final model used, all cancellous bone elements were assigned a single set of material properties, distinct from those assigned to the cortical bone elements; each component (cortical and cancellous) was modelled as a homogenous material. This model is referred to herein as the ‘complete homogenous model’ (Fig 4a, Table 1).


Oldest pathology in a tetrapod bone illuminates the origin of terrestrial vertebrates.

Bishop PJ, Walmsley CW, Phillips MJ, Quayle MR, Boisvert CA, McHenry CR - PLoS ONE (2015)

Three-dimensional finite element models of the radius of Ossinodus.(a) Complete homogenous model in oblique posterolateral view; extent of proximal articulation surface shown in grey. This was the model used to assess fracture mechanics in the radius. (b) Incomplete homogenous model in anteromedial view; red shows exposed (homogenous) cancellous bone. (c) Incomplete heterogenous model in posteromedial view. (d) Incomplete heterogenous model in posteromedial view, sectioned in the mediolateral plane to illustrate variation in material properties within the volume of cancellous bone.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4418741&req=5

pone.0125723.g004: Three-dimensional finite element models of the radius of Ossinodus.(a) Complete homogenous model in oblique posterolateral view; extent of proximal articulation surface shown in grey. This was the model used to assess fracture mechanics in the radius. (b) Incomplete homogenous model in anteromedial view; red shows exposed (homogenous) cancellous bone. (c) Incomplete heterogenous model in posteromedial view. (d) Incomplete heterogenous model in posteromedial view, sectioned in the mediolateral plane to illustrate variation in material properties within the volume of cancellous bone.
Mentions: In order to determine how and with what magnitude force the radius of Ossinodus would have fractured, the CT scan data was used to develop a high-resolution, three-dimensional, finite element model of the bone’s pre-fractured morphology in Strand7 2.4.4 (Strand7 Pty Ltd, Australia). The fossil’s preservation allowed for cortical bone and different components of the cancellous bone to be modelled separately based on density differences, thus enabling patterns of variation in material properties in the original, living bone to be accounted for. However, since a small part of the fossil was missing, knowledge of structural and material heterogeneity within the cancellous bone is incomplete. Thus, in the final model used, all cancellous bone elements were assigned a single set of material properties, distinct from those assigned to the cortical bone elements; each component (cortical and cancellous) was modelled as a homogenous material. This model is referred to herein as the ‘complete homogenous model’ (Fig 4a, Table 1).

Bottom Line: Using high-resolution finite element analysis, we demonstrate that the oldest known broken tetrapod bone, a radius of the primitive stem tetrapod Ossinodus pueri from the mid-Viséan (333 million years ago) of Australia, fractured under a high-force, impact-type loading scenario.Augmenting this are new osteological observations, including a preferred directionality to the trabecular architecture of cancellous bone.Together, these results suggest that Ossinodus, one of the first large (>2m length) tetrapods, spent a significant proportion of its life on land.

View Article: PubMed Central - PubMed

Affiliation: Ancient Environments Program, Queensland Museum, 122 Gerler Rd, Hendra, Queensland, 4011, Australia; School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, 4000, Australia; Centre for Musculoskeletal Research, Griffith University, Southport, Queensland, 4222, Australia.

ABSTRACT
The origin of terrestrial tetrapods was a key event in vertebrate evolution, yet how and when it occurred remains obscure, due to scarce fossil evidence. Here, we show that the study of palaeopathologies, such as broken and healed bones, can help elucidate poorly understood behavioural transitions such as this. Using high-resolution finite element analysis, we demonstrate that the oldest known broken tetrapod bone, a radius of the primitive stem tetrapod Ossinodus pueri from the mid-Viséan (333 million years ago) of Australia, fractured under a high-force, impact-type loading scenario. The nature of the fracture suggests that it most plausibly occurred during a fall on land. Augmenting this are new osteological observations, including a preferred directionality to the trabecular architecture of cancellous bone. Together, these results suggest that Ossinodus, one of the first large (>2m length) tetrapods, spent a significant proportion of its life on land. Our findings have important implications for understanding the temporal, biogeographical and physiological contexts under which terrestriality in vertebrates evolved. They push the date for the origin of terrestrial tetrapods further back into the Carboniferous by at least two million years. Moreover, they raise the possibility that terrestriality in vertebrates first evolved in large tetrapods in Gondwana rather than in small European forms, warranting a re-evaluation of this important evolutionary event.

No MeSH data available.


Related in: MedlinePlus