Morphological and functional diversity in therizinosaur claws and the implications for theropod claw evolution

Lautenschlager, Stephan

doi:10.1098/rspb.2014.0497

Cited by 38 publications

(45 citation statements)

References 31 publications

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“…This requires much force, and the digging tool must be modified to resist said forces. Vertebrates that “scratch‐dig” extensively tend to have long, and disproportionately large, claws (Bramble, 1982; Lautenschlager, 2014; Taylor, 1978; Warner, Tucker, Filoramo, & Towey, 2006). The Savannah‐burrower taxa share this trait, as they are arguably the most proficient diggers of the Kimberley.…”

Section: Discussionmentioning

confidence: 99%

“…Claws built for puncturing wood would benefit from a very narrow tip (Cartmill, 1985), whereas burrowers may benefit from a wide claw as it would help transport soil (Hildebrand, 1985). Excluding the third dimension also prohibits investigating certain biomechanical principles by assessing lateral bending strengths (performed for teeth by Valkenburgh and Ruff (1987)), or conducting finite element modelling (Lautenschlager, 2014; Manning et al., 2009). Future studies should consider in what way medial‐lateral claw characters may influence claw function.…”

Section: Discussionmentioning

confidence: 99%

“…Large comparative studies of mammals have used claws/unguals to determine locomotor, and in particular fossorial, adaptations (MacLeod & Rose, 1993). Modern claws are often correlated with those of nonavian dinosaurs to extrapolate paleo‐behavior (Burnham, Feduccia, Martin, & Falk, 2011; Fowler, Freedman, Scannella, & Kambic, 2011; Lautenschlager, 2014). These studies quantified claw morphology in several ways, including Euclidean distance measures, claw curvature based on triangles, outline‐based morphometrics, and digital modelling (respective examples in Ribas et al., 2004; Feduccia, 1993; MacLeod & Rose, 1993; Manning et al., 2009).…”

Section: Introductionmentioning

confidence: 99%

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Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild

D’Amore

Clulow

Doody

et al. 2018

Ecology and Evolution

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Numerous studies investigate morphology in the context of habitat, and lizards have received particular attention. Substrate usage is often reflected in the morphology of characters associated with locomotion, and, as a result, claws have become well‐studied ecomorphological traits linking the two. The Kimberley predator guild of Western Australia consists of 10 sympatric varanid species. The purpose of this study was to quantify claw size and shape in the guild using geometric morphometrics, and determine whether these features correlated with substrate use and habitat. Each species was assigned a Habitat/substrate group based on the substrate their claws interact with in their respective habitat. Claw morphometrics were derived for both wild caught and preserved specimens from museum collections, using a 2D semilandmark analysis. Claw shape significantly separated based on Habitat/substrate group. Varanus gouldii and Varanus panoptes claws were associated with sprinting and extensive digging. Varanus mertensi claws were for shallow excavation. The remaining species’ claws reflected specialization for some form of climbing, and differed based on substrate compliance. Varanus glauerti was best adapted for climbing rough sandstone, whereas Varanus scalaris and Varanus tristis had claws ideal for puncturing wood. Phylogenetic signal also significantly influenced claw shape, with Habitat/substrate group limited to certain clades. Positive size allometry allowed for claws to cope with mass increases, and shape allometry reflected a potential size limit on climbing. Claw morphology may facilitate niche separation within this trophic guild, especially when considered with body size. As these varanids are generalist predators, morphological traits associated with locomotion may be more reliable candidates for detecting niche partitioning than those associated directly with diet.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild

D’Amore

Clulow

Doody

et al. 2018

Ecology and Evolution

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show abstract

“…Contours of the two-dimensional cross-sections were imported into tpsDig2.16 (Rohlf, 2010), digitized and saved as 1000 x/y-coordinate pairs. All outline data were subsequently analyzed in PAST 3.17 (Hammer et al, 2001) using fast Fourier transformation (FFT) and principal components analysis (PCA) with the hangle module as outlined in Crampton and Haines (1996) and Lautenschlager (2014a). Outlines were smoothed ten times to eliminate pixel noise, and 23 Fourier harmonics were found to describe the outlines of all sampled taxa sufficiently (average Fourier power > 99%) (see also Supplementary Material).…”

Section: Methodsmentioning

confidence: 99%

Sensory Evolution and Ecology of Early Turtles Revealed by Digital Endocranial Reconstructions

2018

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In the past few years, new fossil finds and novel methodological approaches have prompted intensive discussions about the phylogenetic affinities of turtles and rekindled the debate on their ecological origin, with very distinct scenarios, such as fossoriality and aquatic habitat occupation, proposed for the earliest stem-turtles. While research has focused largely on the origin of the anapsid skull and unique postcranial anatomy, little is known about the endocranial anatomy of turtles. Here, we provide 3D digital reconstructions and comparative descriptions of the brain, nasal cavity, neurovascular structures and endosseous labyrinth of Proganochelys quenstedti, one of the earliest stem-turtles, as well as other turtle taxa. Our results demonstrate that P. quenstedti retained a simple tube-like brain morphology with poorly differentiated regions and mediocre hearing and vision, but a well-developed olfactory sense. Endocast shape analysis indicates that an increase in size and regionalization of the brain took place in the course of turtle evolution, achieving an endocast diversity comparable to other amniote groups. Based on the new evidence presented herein, we further conclude that P. quenstedti was a highly terrestrial, but most likely not fossorial, taxon.

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“…Additional surface scans of the left and right frontal (MB.R.1377 and MB.R.1378) were taken using a photogrammetry approach and 123DCATCH BETA (). Visualization, segmentation and restoration steps were performed in AVIZO (v. 6 and 7) and BLENDER (v. 2.65; ).(iii) A museum-quality cast of the manual ungual of the Cretaceous therizinosaur Therizinosaurus cheloniformes [40] housed at the Sauriermuseum Aathal, Switzerland, was digitized using photogrammetry and AGISOFT PHOTOSCAN STANDARD (). Visualization and restoration steps were performed in BLENDER (v. 2.65).…”

Section: Methodsmentioning

confidence: 99%

Reconstructing the past: methods and techniques for the digital restoration of fossils

2016

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During fossilization, the remains of extinct organisms are subjected to taphonomic and diagenetic processes. As a result, fossils show a variety of preservational artefacts, which can range from small breaks and cracks, disarticulation and fragmentation, to the loss and deformation of skeletal structures and other hard parts. Such artefacts can present a considerable problem, as the preserved morphology of fossils often forms the basis for palaeontological research. Phylogenetic and taxonomic studies, inferences on appearance, ecology and behaviour and functional analyses of fossil organisms strongly rely on morphological information. As a consequence, the restoration of fossil morphology is often a necessary prerequisite for further analyses. Facilitated by recent computational advances, virtual reconstruction and restoration techniques offer versatile tools to restore the original morphology of fossils. Different methodological steps and approaches, as well as software are outlined and reviewed here, and advantages and disadvantages are discussed. Although the complexity of the restorative processes can introduce a degree of interpretation, digitally restored fossils can provide useful morphological information and can be used to obtain functional estimates. Additionally, the digital nature of the restored models can open up possibilities for education and outreach and further research.

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Morphological and functional diversity in therizinosaur claws and the implications for theropod claw evolution

Cited by 38 publications

References 31 publications

Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild

Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild

Sensory Evolution and Ecology of Early Turtles Revealed by Digital Endocranial Reconstructions

Reconstructing the past: methods and techniques for the digital restoration of fossils

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