A quantitative method for inferring locomotory shifts in amniotes during ontogeny, its application to dinosaurs and its bearing on the evolution of posture

Chapelle, Kimberley E. J.; Benson, Roger B. J.; Stiegler, Josef; Otero, Alejandro; Zhao, Qi; Choiniere, Jonah N.

doi:10.1111/pala.12451

Cited by 33 publications

(27 citation statements)

References 56 publications

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“…For instance, changes in labyrinth geometry associated with the evolution of bipedality within dinosaurs, particularly the elongation of the vertical semicircular canals, have been recorded for dinosaurs 60 . On the other hand, these changes could not be found in an ontogenetic labyrinth series of the dinosaur Massospondylus carinatus 61 , which experiences a change from quadrupedality to bipedality during ontogeny 62 .…”

Section: Vestibular Anatomy As a Guide To Ecological Reconstructions?mentioning

confidence: 83%

Neuroanatomy of the spinosaurid Irritator challengeri (Dinosauria: Theropoda) indicates potential adaptations for piscivory

Schade

Rauhut

Evers

2020

Sci Rep

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Spinosauridae, a theropod group characterized by elongated snouts, conical teeth, enlarged forelimbs, and often elongated neural spines, show evidence for semiaquatic adaptations and piscivory. It is currently debated if these animals represent terrestrial carnivores with adaptations for a piscivorous diet, or if they largely lived and foraged in aquatic habitats. The holotype of Irritator challengeri, a nearly complete skull from the late Early Cretaceous Santana Formation of northeastern Brazil, includes one of the few preserved spinosaurid braincases and can provide insights into neuroanatomical structures that might be expected to reflect ecological affinities. We generated digital models of the neuroanatomical cavities within the braincase, using computer tomography (CT) data. The cranial endocast of Irritator is generally similar to that of other non-maniraptoriform theropods, with weakly developed distinctions of hindbrain and midbrain features, relatively pronounced cranial flexures and relatively long olfactory tracts. The endosseous labyrinth has a long anterior semicircular canal, a posteriorly inclined common crus and a very large floccular recess fills the area between the semicircular canals. These features indicate that Irritator had the ability for fast and well-controlled pitch-down head movements. The skull table and lateral semicircular canal plane are strongly angled to one another, suggesting a downward angling of approximately 45° of the snout, which reduces interference of the snout with the field of vision of Irritator. These neuroanatomical features are consistent with fast, downward snatching movements in the act of predation, such as are needed for piscivory. Spinosauridae is a large-bodied theropod group within Megalosauroidea known from the Cretaceous, although their phylogenetic relationships indicate that the clade must have originated in the Jurassic 1. Spinosaurids are characterized by a long and slender skull, conical teeth, strongly developed forelimbs with exceptionally large thumb claws and elongated neural spines 2-6. Due to superficial similarities in cranial form with piscivorous Crocodilia, such as the gharial, and the wealth of fossil fish within the assemblages they were found in, spinosaurids were repeatedly associated with a semiaquatic lifestyle and piscivory [e.g. 3,7-12 ]. Direct evidence for piscivory comes from acid-etched fish scales in the stomach contents of Baryonyx walkeri 3 , although the same individual also includes terrestrial dinosaur bones of a juvenile ornithopod. Predation on pterosaurs has also been shown for spinosaurids 13. Thus, direct evidence for spinosaurid diets indicates a mix, or opportunistic behaviour with a tendency towards relatively small prey items. Additional evidence to support semiaquatic adaptations beyond dietary preference in spinosaurids comes from: isotope signals acquired from tooth enamel of samples from different geographical contexts, which show that spinosaurids spent a significant amount of their lifetime in water 8,14,15...

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Section: Vestibular Anatomy As a Guide To Ecological Reconstructions?mentioning

confidence: 83%

Neuroanatomy of the spinosaurid Irritator challengeri (Dinosauria: Theropoda) indicates potential adaptations for piscivory

Schade

Rauhut

Evers

2020

Sci Rep

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“…Campione & Evans, 2012; Campione et al ., 2014; McPhee et al ., 2018), which can change through ontogeny (e.g. Zhao et al ., 2013; Chapelle et al ., 2020 a ), so the locomotion of the individual or group in question should also be taken into account when using this metric to assess maturity. We also recommend that the specific proportions used are reported, not simply describing an individual as having immature proportions without stating what those proportions are.…”

Section: Methods Of Assessing Maturitymentioning

confidence: 99%

“…Legendre et al ., 2016; Legendre & Davesne, 2020), posture change and ecological role (e.g. Zhao et al ., 2013, 2019; Otero et al ., 2019; Chapelle et al ., 2020 a ), sexual dimorphism (e.g. Raath, 1990; Klein & Sander, 2008; Saitta, 2015; Griffin & Nesbitt, 2016 a , b ), population structure and taphonomy (Badgley, 1986; Erickson et al ., 2009 a , 2010), heterochrony (Gould, 1977; Bhullar et al ., 2012), and reproductive biology (e.g.…”

Section: Introductionmentioning

confidence: 99%

Assessing ontogenetic maturity in extinct saurian reptiles

et al. 2020

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Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life‐history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least‐inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260‐million‐year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. ‘juvenile’, ‘mature’) and provide routes for better clarity and cross‐study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method‐specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, ‘Ontogenetic Assessment’, be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well‐represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well‐constrained, empirically tested methods.

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“…While the same computational models were used in the present study and that of Otero et al (2019), they were analyzed and interpreted differently (one mechanistically, the other statistically), such that the consilience of interpretations further supports a shift in locomotor mode as Mussaurus matured. Ontogenetic changes in locomotor mode have been proposed for other extinct terrestrial archosaurs (e.g., Heinrich et al 1993;Dilkes 2001;Zhao et al 2013;Słowiak et al 2019;Chapelle et al 2020), and it would be interesting to explore the applicability of the current study's approach to testing these interpretations in the future.…”

Section: Taxonmentioning

confidence: 97%

“…Predicting Locomotion in Extinct Archosaurs.-A secondary aim of this study was to develop a quantitative framework that could be used to help predict locomotor habit in extinct terrestrial archosaurs, and that bipeds and quadrupeds were largely distinct in PC space has facilitated this. Although beyond the scope of the present study, this new framework has the potential to provide new rigor to assessments of locomotor evolution within Archosauria, such as the frequency and phyletic distribution of shifts from quadrupedalism to bipedalism (facultative and obligate; Kubo and Kubo 2012;McPhee et al 2018;Grinham et al 2019;Chapelle et al 2020). This would first require the generation of digital volumetric models for additional taxa, particularly those surrounding inferred transitions, which can be a nontrivial and time-intensive process.…”

Section: Taxonmentioning

confidence: 99%

Relationships of mass properties and body proportions to locomotor habit in terrestrial Archosauria

Bishop

Bates²,

Allen³

et al. 2020

Paleobiology

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Throughout their 250 Myr history, archosaurian reptiles have exhibited a wide array of body sizes, shapes, and locomotor habits, especially in regard to terrestriality. These features make Archosauria a useful clade with which to study the interplay between body size, shape, and locomotor behavior, and how this interplay may have influenced locomotor evolution. Here, digital volumetric models of 80 taxa are used to explore how mass properties and body proportions relate to each other and locomotor posture in archosaurs. One-way, nonparametric, multivariate analysis of variance, based on the results of principal components analysis, shows that bipedal and quadrupedal archosaurs are largely distinguished from each other on the basis of just four anatomical parameters (p < 0.001): mass, center of mass position, and relative forelimb and hindlimb lengths. This facilitates the development of a quantitative predictive framework that can help assess gross locomotor posture in understudied or controversial taxa, such as the crocodile-line Batrachotomus (predicted quadruped) and Postosuchus (predicted biped). Compared with quadrupedal archosaurs, bipedal species tend to have relatively longer hindlimbs and a more caudally positioned whole-body center of mass, and collectively exhibit greater variance in forelimb lengths. These patterns are interpreted to reflect differing biomechanical constraints acting on the archosaurian Bauplan in bipedal versus quadrupedal groups, which may have shaped the evolutionary histories of their respective members.

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A quantitative method for inferring locomotory shifts in amniotes during ontogeny, its application to dinosaurs and its bearing on the evolution of posture

Cited by 33 publications

References 56 publications

Neuroanatomy of the spinosaurid Irritator challengeri (Dinosauria: Theropoda) indicates potential adaptations for piscivory

Neuroanatomy of the spinosaurid Irritator challengeri (Dinosauria: Theropoda) indicates potential adaptations for piscivory

Assessing ontogenetic maturity in extinct saurian reptiles

Relationships of mass properties and body proportions to locomotor habit in terrestrial Archosauria

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