Dinosaurs: Four Legs Good, Two Legs Bad

Sander, P. Martin; Lallensack, Jens N.

doi:10.1016/j.cub.2018.08.025

Cited by 4 publications

(6 citation statements)

References 15 publications

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“…These non‐sauropodan sauropodomorphs closely related to sauropods would have reached body masses of a dozen of tons, comparable to early sauropods (e.g. Vulcanodontidae, Shunosaurus ; Apaldetti et al, 2018 ; McPhee et al, 2018 ; Sander & Lallensack, 2018 ). Moreover, the acquisition of quadrupedality would have been anterior to the appearance of the columnar limbs in sauropods (McPhee et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the acquisition of quadrupedality would have been anterior to the appearance of the columnar limbs in sauropods (McPhee et al, 2018 ). However, columnar limbs are still supposed to be the innovation that allowed sauropods to diversify in very diverse forms reaching a range of extreme gigantism, that is exceeding several dozens of tons, masses never reached by non‐sauropodan sauropodomorphs (Sander et al, 2011 ; Sander & Lallensack, 2018 ). In addition, caution is needed for body mass estimations as the methods used are sensitive to the inferred posture, which is estimated with uncertainties for numerous non‐sauropodan‐sauropodomorphs (Campione et al, 2014 ; Campione & Evans, 2012 ; Peyre de Fabrègues & Allain, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

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A path to gigantism: Three‐dimensional study of the sauropodomorph limb long bone shape variation in the context of the emergence of the sauropod bauplan

Lefebvre

Houssaye

Mallison³

et al. 2022

Journal of Anatomy

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Sauropodomorph dinosaurs include the largest terrestrial animals that ever lived on Earth. The early representatives of this clade were, however, relatively small and partially to totally bipedal, conversely to the gigantic and quadrupedal sauropods. Although the sauropod bauplan is well defined, notably by the acquisition of columnar limbs, the evolutionary sequence leading to its emergence remains debated. Here, we aim to tackle this evolutionary episode by investigating shape variation in the six limb long bones for the first time using three‐dimensional geometric morphometrics. The morphological features of the forelimb zeugopod bones related to the sauropod bauplan tend to appear abruptly, whereas the pattern is more gradual for the hindlimb zeugopod bones. The stylopod bones tend to show the same pattern as their respective zeugopods. The abrupt emergence of the sauropod forelimb questions the locomotor abilities of non‐sauropodan sauropodomorphs inferred as quadrupeds. Features characterizing sauropods tend to corroborate a view of their locomotion mainly based on stylopod retraction. An allometric investigation of the shape variation in accordance with size highlight differences in hindlimb bone allometries between the sauropods and the non‐sauropodan sauropodomorphs. These differences notably correspond to an unexpected robustness decrease trend in the sauropod hindlimb zeugopod. In addition to forelimb bones that appear to be proportionally more gracile than in non‐sauropodan sauropodomorphs, sauropods may have relied on limb architecture and features related to the size increase, rather than general robustness, to deal with the role of weight‐bearing.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A path to gigantism: Three‐dimensional study of the sauropodomorph limb long bone shape variation in the context of the emergence of the sauropod bauplan

Lefebvre

Houssaye

Mallison³

et al. 2022

Journal of Anatomy

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“…All OPEK members display consistent linear relationships between pes length, width, and trackway width with medial rotation of pes and the concave inward curvature of digit and claw traces ( Lockley et al, 2023 ). These are defined as “otozoid” characters of the prosauropod foot and contrast with the non-OPEK tracks made by derived sauropod trackmakers ( e.g ., Eosauropus ; Sander & Lallensack, 2018 ; Lockley et al, 2023 ). Given the morphology of Tetrasauropus , it fits within the “otozoid” morphologies and can be considered within the OPEK plexus, as has been recently discussed by Lockley et al (2023) .…”

Section: Discussionmentioning

confidence: 99%

“…This locomotory adaptation is often linked to increases in body size and coupled with forelimb robusticity in the absence of columnar limb posture ( e.g ., Lessemsaurus , Ledumahadi , and Ingentia ; Apaldetti et al, 2018 ; McPhee et al, 2017 , 2018 ; Pol et al, 2021 ). The latter, along with unflexed limbs and other adaptations, enabled sauropod dinosaurs to increase body size and evolve graviportalism without compromising their physiology ( e.g ., Sander & Lallensack, 2018 ). Understanding the locomotion of ancestral forms of sauropods is important for unlocking how sauropods developed their specialized form of quadrupedality, which had both palaeobiological and palaeoecological consequences for post-Triassic sauropod dominance.…”

Section: Introductionmentioning

confidence: 99%

Basal sauropodomorph locomotion: ichnological lessons from the Late Triassic trackways of bipeds and quadrupeds (Elliot Formation, main Karoo Basin)

Sciscio,

Bordy,

Lockley

et al. 2023

PeerJ

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Using modern ichnological and stratigraphic tools, we reinvestigate two iconic sauropodomorph-attributed tetradactyl ichnogenera, Pseudotetrasauropus and Tetrasauropus, and their stratigraphic occurrences in the middle Upper Triassic of Lesotho. These tracks have been reaffirmed and are stratigraphically well-constrained to the lower Elliot Formation (Stormberg Group, Karoo Basin) with a maximum depositional age range of <219–209 Ma (Norian). This represents the earliest record of basal sauropodomorph trackways in Gondwana, if not globally. Track and trackway morphology, the sedimentary context of the tracks, and unique features (e.g., drag traces) have enabled us to discuss the likely limb postures and gaits of the trackmakers. Pseudotetrasauropus has bipedal (P. bipedoida) and quadrupedal (P. jaquesi) trackway states, with the oldest quadrupedal Pseudotetrasauropus track and trackway parameters suggestive of a columnar, graviportal limb posture in the trackmaker. Moreover, an irregularity in the intermanus distance and manus orientation and morphology, in combination with drag traces, is indicative of a non-uniform locomotory suite or facultative quadrupedality. Contrastingly, Tetrasauropus, the youngest trackway, has distinctive medially deflected, robust pedal and manual claw traces and a wide and uniform intermanus distance relative to the interpedal. These traits suggest a quadrupedal trackmaker with clawed and fleshy feet and forelimbs held in a wide, flexed posture. Altogether, these trackways pinpoint the start of the southern African ichnological record of basal sauropodomorphs with bipedal and quadrupedal locomotory habits to, at least, c. 215 Ma in the middle Late Triassic.

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“…A pronounced outward rotation of the pes impressions is also considered to be characteristic of sauropods. Tetrasauropus from Lesotho is similar to Eosauropus, but has medially deflected claws and only a weak outward rotation of the pes (Klein & Lucas, 2021); these tracks possibly relate to sauropodomorphs more basal than the producers of Eosauropus (Sander & Lallensack, 2018). This specific Penarth track is therefore attributed to a sauropodomorph, and probably sauropodiform, trackmaker based on its deflected claws and entaxonic pes structure.…”

Section: B Possible Trackmakersmentioning

confidence: 99%

Late Triassic dinosaur tracks from Penarth, south Wales

et al. 2021

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Evidence of Late Triassic large tetrapods from the UK is rare. Here, we describe a track-bearing surface located on the shoreline near Penarth, south Wales, United Kingdom. The total exposed surface is c. 50 m long and c. 2 m wide, and is split into northern and southern sections by a small fault. We interpret these impressions as tracks, rather than abiogenic sedimentary structures, because of the possession of marked displacement rims and their relationship to each other with regularly spaced impressions forming putative trackways. The impressions are large (up to c. 50 cm in length), but poorly preserved, and retain little information about track-maker anatomy. We discuss alternative, plausible, abiotic mechanisms that might have been responsible for the formation of these features, but reject them in favour of these impressions being tetrapod tracks. We propose that the site is an additional occurrence of the ichnotaxon Eosauropus, representing a sauropodomorph trackmaker, thereby adding a useful new datum to their sparse Late Triassic record in the UK. We also used historical photogrammetry to digitally map the extent of site erosion during 2009–2020. More than 1 m of the surface exposure has been lost over this 11-year period, and the few tracks present in both models show significant smoothing, breakage and loss of detail. These tracks are an important datapoint for Late Triassic palaeontology in the UK, even if they cannot be confidently assigned to a specific trackmaker. The documented loss of the bedding surface highlights the transient and vulnerable nature of our fossil resources, particularly in coastal settings, and the need to gather data as quickly and effectively as possible.

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Dinosaurs: Four Legs Good, Two Legs Bad

Cited by 4 publications

References 15 publications

A path to gigantism: Three‐dimensional study of the sauropodomorph limb long bone shape variation in the context of the emergence of the sauropod bauplan

A path to gigantism: Three‐dimensional study of the sauropodomorph limb long bone shape variation in the context of the emergence of the sauropod bauplan

Basal sauropodomorph locomotion: ichnological lessons from the Late Triassic trackways of bipeds and quadrupeds (Elliot Formation, main Karoo Basin)

Late Triassic dinosaur tracks from Penarth, south Wales

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