Healed Fractures in the Neural Spines of an Associated Skeleton of Dimetrodon: Implications for Dorsal Sail Morphology and Function

Rega, Elizabeth; Noriega, Ken; Sumida, Stuart S.; Huttenlocker, Adam K.; Lee, Andrew H.; Kennedy, Brett

doi:10.3158/2158-5520-5.1.104

Cited by 13 publications

(12 citation statements)

References 14 publications

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“…Breakages of vertebral laminae in humans (laminectomy) revealed that trauma arises when fragments displace into the spinal canal 43 . Breakages in Dimetrodon sails revealed a fast-healing system by osteoclastic resorption and deposition of lamellar bone 44 .…”

Section: Discussionmentioning

confidence: 98%

A new long-spined dinosaur from Patagonia sheds light on sauropod defense system

Gallina

Apesteguı́a

Canale

et al. 2019

Sci Rep

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Dicraeosaurids are a group of sauropod dinosaurs characterized by a distinctive vertebral column with paired, long, neural spines, present in an extreme fashion in the South American form Amargasaurus cazaui. This distinctive morphology has been interpreted as a support structure for a thermoregulatory sail, a padded crest for display, a dorsal hump acting as fat reservoir, and even as inner cores for dorsal horns. Other inferred functions (if any) of this structure were related to sexual display and/or defense strategies. Here we describe a new dicraeosaurid sauropod, Bajadasaurus pronuspinax gen. et sp. nov., from Patagonia which preserves the most complete skull of the group and has extremely elongate bifid cervical neural spines that point permanently forward, irrespective of the neck position. Although much shorter versions of this neural spine configuration were already recorded for other dicraeosaurid taxa, the long, anteriorly bent spines of this new dinosaur support the hypothesis that these elongate spines of dicraeosaurid sauropods served as passive defense structures.

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Section: Discussionmentioning

confidence: 98%

A new long-spined dinosaur from Patagonia sheds light on sauropod defense system

Gallina

Apesteguı́a

Canale

et al. 2019

Sci Rep

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“…B 281: 20141642 of the sail is usually framed in the context of activity during daylight conditions [42][43][44][45][46][47][48]. Several recent studies have questioned the thermoregulatory role of the sail [49][50][51][52], however, and alternative functions have been proposed that do not require Dimetrodon to have been diurnal (electronic supplementary material).…”

Section: Discussionmentioning

confidence: 99%

Nocturnality in synapsids predates the origin of mammals by over 100 million years

Angielczyk

Schmitz

2014

Proc. R. Soc. B.

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Nocturnality is widespread among extant mammals and often considered the ancestral behavioural pattern for all mammals. However, mammals are nested within a larger clade, Synapsida, and non-mammalian synapsids comprise a rich phylogenetic, morphological and ecological diversity. Even though non-mammalian synapsids potentially could elucidate the early evolution of diel activity patterns and enrich the understanding of synapsid palaeobiology, data on their diel activity are currently unavailable. Using scleral ring and orbit dimensions, we demonstrate that nocturnal activity was not an innovation unique to mammals but a character that appeared much earlier in synapsid history, possibly several times independently. The 24 Carboniferous to Jurassic non-mammalian synapsid species in our sample featured eye morphologies consistent with all major diel activity patterns, with examples of nocturnality as old as the Late Carboniferous (ca 300 Ma). Carnivores such as Sphenacodon ferox and Dimetrodon milleri, but also the herbivorous cynodont Tritylodon longaevus were likely nocturnal, whereas most of the anomodont herbivores are reconstructed as diurnal. Recognizing the complexity of diel activity patterns in non-mammalian synapsids is an important step towards a more nuanced picture of the evolutionary history of behaviour in the synapsid clade.

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“…Since the early 2000s, FEA has gained traction as a technique for studying the mechanical behavior and performance of extinct and extant organisms, most commonly vertebrates, with particular emphasis on studies of the vertebrate skull (Rayfield et al, 2001;Rayfield, 2007;Strait et al, 2007;Wroe et al, 2007;Wroe, 2008;Dumont et al, 2009Dumont et al, , 2014Tseng, 2009;Tseng and Wang, 2010;Fitton et al, 2012;Porro et al, 2013) or teeth (Spears and Macho, 1998;Macho and Spears, 1999;Anderson et al, 2011;Anderson and Rayfield, 2012;see D. Jones et al [2012a]; D. Jones et al [2012b]; Murdock et al [2014]; and Mart ınez-P erez et al [2014] for examples using FEA on conodont elements). Recently, FEA of the postcranial skeleton has been gaining attention (e.g., Schwarz-Wings et al, 2009;Piras et al, 2012;Rega et al, 2012;Brassey et al, 2013;O'Higgins and Milne, 2013). Typically these analyses assume a linear elastic behavior for bone and model loading under static rather than dynamic conditions (but see Wang et al, 2012).…”

Section: Finite Element Analysismentioning

confidence: 99%

Combining geometric morphometrics and finite element analysis with evolutionary modeling: towards a synthesis

Polly

Stayton

Dumont

et al. 2016

Journal of Vertebrate Paleontology

115

129

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ABSTRACT-Geometric morphometrics (GM) and finite element analysis (FEA) are increasingly common techniques for the study of form and function. We show how principles of quantitative evolution in continuous phenotypic traits can link the two techniques, allowing hypotheses about the relative importance of different functions to be tested in a phylogenetic and evolutionary framework. Finite element analysis is used to derive quantitative surfaces that describe the comparative performance of different morphologies in a morphospace derived from GM. The combination of two or more performance surfaces describes a quantitative adaptive landscape that can be used to predict the direction morphological evolution would take if a combination of functions was selected for. Predicted paths of evolution also can be derived for hypotheses about the relative importance of multiple functions, which can be tested against evolutionary pathways that are documented by phylogenies or fossil sequences. Magnitudes of evolutionary trade-offs between functions can be estimated using maximum likelihood. We apply these methods to an earlier study of carapace strength and hydrodynamic efficiency in emydid turtles. We find that strength and hydrodynamic efficiency explain about 45% of the variance in shell shape; drift and other unidentified functional factors are necessary to explain the remaining variance. Measurement of the proportional trade-off between shell strength and hydrodynamic efficiency shows that throughout the Cenozoic aquatic turtles generally sacrificed strength for streamlining and terrestrial species favored stronger shells; this suggests that the selective regime operating on small to mid-sized emydids has remained relatively static.SUPPLEMENTAL DATA-Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Polly, P. D., C. T. Stayton, E. R. Dumont, S. E. Pierce, E. J. Rayfield, and K. D. Angielczyk. 2016. Combining geometric morphometrics and finite element analysis with evolutionary modeling: towards a synthesis. Journal of Vertebrate Paleontology.

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Healed Fractures in the Neural Spines of an Associated Skeleton of Dimetrodon: Implications for Dorsal Sail Morphology and Function

Cited by 13 publications

References 14 publications

A new long-spined dinosaur from Patagonia sheds light on sauropod defense system

A new long-spined dinosaur from Patagonia sheds light on sauropod defense system

Nocturnality in synapsids predates the origin of mammals by over 100 million years

Combining geometric morphometrics and finite element analysis with evolutionary modeling: towards a synthesis

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