The relationship between body shape, body size and locomotor mode in extant lepidosaurs

Grinham, Luke R.; Norman, D. B.

doi:10.1111/jzo.12771

Cited by 6 publications

(4 citation statements)

References 51 publications

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“…What is the degree of quadrupedality in a facultative quadruped? While some recent studies have clarified these questions at more narrow phylogenetic scales (Grinham & Norman, 2020a , 2020b ), there are to our knowledge no quantitative studies to clarify this term across a broad sample and the literature lacks ethological case studies with temporal data. Of these ambiguous cases, hopping mammals (e.g.…”

Section: Methodsmentioning

confidence: 99%

Locomotor and postural diversity among reptiles viewed through the prism of femoral microanatomy: Palaeobiological implications for some Permian and Mesozoic taxa

et al. 2023

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The water‐to‐land transition by the first tetrapod vertebrates represents a key stage in their evolution. Selection pressures exerted by this new environment on animals led to the emergence of new locomotor and postural strategies that favoured access to different ecological niches and contributed to their evolutionary success. Today, amniotes show great locomotor and postural diversity, particularly among Reptilia, whose extant representatives include parasagittally locomoting erect and crouched bipeds (birds), sub‐parasagittal ‘semi‐erect’ quadrupeds (crocodylians) and sprawling quadrupeds (squamates and turtles). But the different steps leading to such diversity remain enigmatic and the type of locomotion adopted by many extinct species raises questions. This is notably the case of certain Triassic taxa such as Euparkeria and Marasuchus . The exploration of the bone microanatomy in reptiles could help to overcome these uncertainties. Indeed, this locomotor and postural diversity is accompanied by great microanatomical disparity. On land, the bones of the appendicular skeleton support the weight of the body and are subject to multiple constraints that partly shape their external and internal morphology. Here we show how microanatomical parameters measured in cross‐section, such as bone compactness or the position of the medullocortical transition, can be related to locomotion. We hypothesised that this could be due to variations in cortical thickness. Using statistical methods that take phylogeny into account (phylogenetic flexible discriminant analyses), we develop different models of locomotion from a sample of femur cross‐sections from 51 reptile species. We use these models to infer locomotion and posture in 7 extinct reptile taxa for which they remain debated or not fully clear. Our models produced reliable inferences for taxa that preceded and followed the quadruped/biped and sprawling/erect transitions, notably within the Captorhinidae and Dinosauria. For taxa contemporary with these transitions, such as Terrestrisuchus and Marasuchus , the inferences are more questionable. We use linear models to investigate the effect of body mass and functional ecology on our inference models. We show that body mass seems to significantly impact our model predictions in most cases, unlike the functional ecology. Finally, we illustrate how taphonomic processes can impact certain microanatomical parameters, especially the eccentricity of the section, while addressing some other potential limitations of our methods. Our study provides insight into the evolution of enigmatic locomotion in various early reptiles. Our models and methods could be used by palaeontologists to infer the locomotion and posture in other extinct reptile taxa, especially when considered in combination with other lines of evidence.

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Section: Methodsmentioning

confidence: 99%

Locomotor and postural diversity among reptiles viewed through the prism of femoral microanatomy: Palaeobiological implications for some Permian and Mesozoic taxa

et al. 2023

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“…Although the morphological patterns of body shape evolution are well-studied in vertebrates, including squamate reptiles ( Wiens & Slingluff, 2001 ; Bergmann et al, 2020 ; Grinham & Norman, 2020 ), fishes ( Strauss, 1985 ; Mehta et al, 2010 ; Ward & Mehta, 2010 ; Friedman et al, 2019 ), and, more recently, carnivoran mammals ( Law, 2021a ; Law, 2022 ), few have investigated evolutionary allometry between body shape and size. In Indo-Pacific shore fishes, body size explains 3–50% of body shape variation depending on taxonomic families, and larger fishes tend to exhibit more elongate bodies ( Friedman et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Scaling patterns of body plans differ among squirrel ecotypes

Linden

Burtner

Rickman

et al. 2023

PeerJ

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Body size is often hypothesized to facilitate or constrain morphological diversity in the cranial, appendicular, and axial skeletons. However, how overall body shape scales with body size (i.e., body shape allometry) and whether these scaling patterns differ between ecological groups remains poorly investigated. Here, we test whether and how the relationships between body shape, body size, and limb lengths differ among species with different locomotor specializations, and describe the underlying morphological components that contribute to body shape evolution among squirrel (Sciuridae) ecotypes. We quantified the body size and shape of 87 squirrel species from osteological specimens held at museum collections. Using phylogenetic comparative methods, we first found that body shape and its underlying morphological components scale allometrically with body size, but these allometric patterns differ among squirrel ecotypes: chipmunks and gliding squirrels exhibited more elongate bodies with increasing body sizes whereas ground squirrels exhibited more robust bodies with increasing body size. Second, we found that only ground squirrels exhibit a relationship between forelimb length and body shape, where more elongate species exhibit relatively shorter forelimbs. Third, we found that the relative length of the ribs and elongation or shortening of the thoracic region contributes the most to body shape evolution across squirrels. Overall, our work contributes to the growing understanding of mammalian body shape evolution and how it is influenced by body size and locomotor ecology, in this case from robust subterranean to gracile gliding squirrels.

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“…Although the morphological patterns of body shape evolution are well-studied in vertebrates, including squamates (Wiens and Slingluff 2001; Grinham and Norman 2020; Bergman et al 2020), fishes (Ward and Mehta 2010; Mehta et al 2010; Friedman et al 2019, Strauss 1985), and, more recently, carnivoran mammals (Law et al 2019; Law 2021a), few have investigated evolutionary allometry between body shape and size. In fishes, body size explains 3–50% of body shape variation depending on taxonomic families, and larger fishes tend to exhibit more elongate bodies (Friedman et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Scaling patterns of body plans differ among squirrel ecotypes

Linden

Burtner

Rickman

et al. 2022

Preprint

View full text Add to dashboard Cite

Body size is often hypothesized to facilitate or constrain morphological diversity in the cranial, appendicular, and axial skeletons. However, how overall body shape scales with body size (i.e., body shape allometry) and whether these scaling patterns differ between ecological groups remains poorly investigated. Here, we test whether and how the relationships between body shape, body size, and limb lengths differ among species with different locomotory specializations, and describe the underlying morphological components that contribute to body shape variation among squirrel (Sciuridae) ecotypes. We quantified the body size and shape of 87 squirrel species from osteological specimens held at museum collections. Using phylogenetic comparative methods on these data, we found that 1) body shape and its underlying morphological components scale allometrically with body size, but these allometric patterns differ among squirrel ecotypes; 2) only ground squirrels exhibit a relationship between forelimb length and body shape, where more elongate species exhibit relatively shorter forelimbs; and 3) the relative length of the ribs and elongation or shortening of the thoracic region contributes the most to body shape variation across squirrels. Overall, our work contributes to the growing understanding of mammalian body shape evolution and how it is influenced by body size and locomotor ecology, in this case from robust subterranean to gracile gliding squirrels.

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The relationship between body shape, body size and locomotor mode in extant lepidosaurs

Cited by 6 publications

References 51 publications

Locomotor and postural diversity among reptiles viewed through the prism of femoral microanatomy: Palaeobiological implications for some Permian and Mesozoic taxa

Locomotor and postural diversity among reptiles viewed through the prism of femoral microanatomy: Palaeobiological implications for some Permian and Mesozoic taxa

Scaling patterns of body plans differ among squirrel ecotypes

Scaling patterns of body plans differ among squirrel ecotypes

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