Soft-tissue anatomy of the Plesiosaur pectoral girdle inferred from basal Eosauropterygia taxa and the extant phylogenetic bracket

Araújo, Ricardo; Correia, Fernando

doi:10.26879/446

Cited by 11 publications

(49 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We also allow for the possibility that the animal’s downstroke and upstroke take different amounts of time ( Fig 3B ). This is in recognition of the observation that plesiosaurs may have had stronger musculature governing the downstroke of their limbs [ 7 , 9 , 14 ]. We add one more degree of freedom for each sinusoid to specify its degree of time asymmetry.…”

Section: Resultsmentioning

confidence: 90%

“…Stroke hypotheses include a rowing stroke akin to the oar of a boat [ 4 ], a flight stroke [ 5 , 3 ] akin to penguins and turtles [ 11 , 12 ], and a modified flight stroke [ 6 ] akin to sea lions [ 13 ]. Study of plesiosaurian musculature does not rule out either rowing or flight strokes [ 14 ]. Gait hypotheses include synchronous motion with all four limbs moving in phase [ 15 ], asynchronous motion with the forelimbs and hindlimbs out of phase [ 12 , 7 ], and semi-synchronous motion [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Computer Simulations Imply Forelimb-Dominated Underwater Flight in Plesiosaurs

Liu

Smith

et al. 2015

PLoS Comput Biol

View full text Add to dashboard Cite

Plesiosaurians are an extinct group of highly derived Mesozoic marine reptiles with a global distribution that spans 135 million years from the Early Jurassic to the Late Cretaceous. During their long evolutionary history they maintained a unique body plan with two pairs of large wing-like flippers, but their locomotion has been a topic of debate for almost 200 years. Key areas of controversy have concerned the most efficient biologically possible limb stroke, e.g. whether it consisted of rowing, underwater flight, or modified underwater flight, and how the four limbs moved in relation to each other: did they move in or out of phase? Previous studies have investigated plesiosaur swimming using a variety of methods, including skeletal analysis, human swimmers, and robotics. We adopt a novel approach using a digital, three-dimensional, articulated, free-swimming plesiosaur in a simulated fluid. We generated a large number of simulations under various joint degrees of freedom to investigate how the locomotory repertoire changes under different parameters. Within the biologically possible range of limb motion, the simulated plesiosaur swims primarily with its forelimbs using an unmodified underwater flight stroke, essentially the same as turtles and penguins. In contrast, the hindlimbs provide relatively weak thrust in all simulations. We conclude that plesiosaurs were forelimb-dominated swimmers that used their hind limbs mainly for maneuverability and stability.

show abstract

Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Computer Simulations Imply Forelimb-Dominated Underwater Flight in Plesiosaurs

Liu

Smith

et al. 2015

PLoS Comput Biol

View full text Add to dashboard Cite

show abstract

“…The absence of (ossified) prootics suggests that TW480000375 had not yet reached skeletal maturity, which is inconsistent with the observation that the external cranial sutures appear well ossified. Prolonged or truncated physical and osteohistological maturation is a well-known trend in organisms secondarily adapted to an aquatic lifestyle [ 6 , 9 , 17 , 92 , 138 – 144 ]. This predominantly affects the postcranium in secondarily-adapted Mesozoic marine reptiles [ 9 ], but the specimen described here exhibits important cranial paedomorphism as well.…”

Section: Discussionmentioning

confidence: 99%

“…The cranial morphology of Nothosaurus marchicus exhibits profound dorsoventral flattening, wide orbits, large and strongly elongated temporal fenestrae, and a dentition with protruding needle-like fangs [ 6 ]. The corresponding postcranium represents that of an agile paraxial swimmer [ 15 – 17 ] with a propulsive bias on the anterior limbs [ 18 ]. Such observations are consistent with reconstructions of Nothosaurus marchicus as a piscivorous marine predator.…”

Section: Introductionmentioning

confidence: 99%

Synchrotron microtomography of a Nothosaurus marchicus skull informs on nothosaurian physiology and neurosensory adaptations in early Sauropterygia

Voeten¹,

Reich²,

Araújo³

et al. 2018

PLoS ONE

View full text Add to dashboard Cite

Nothosaurs form a subclade of the secondarily marine Sauropterygia that was well represented in late Early to early Late Triassic marine ecosystems. Here we present and discuss the internal skull anatomy of the small piscivorous nothosaur Nothosaurus marchicus from coastal to shallow marine Lower Muschelkalk deposits (Anisian) of Winterswijk, The Netherlands, which represents the oldest sauropterygian endocast visualized to date. The cranial endocast is only partially encapsulated by ossified braincase elements. Cranial flattening and lateral constriction by hypertrophied temporal musculature grant the brain a straight, tubular geometry that lacks particularly well-developed cerebral lobes but does potentially involve distinguishable optic lobes, suggesting vision may have represented an important sense during life. Despite large orbit size, the circuitous muscular pathway linking the basisphenoidal and orbital regions indicates poor oculomotor performance. This suggests a rather fixed ocular orientation, although eye placement and neck manoeuvrability could have enabled binocular if not stereoscopic vision. The proportionally large dorsal projection of the braincase endocast towards the well-developed pineal foramen advocates substantial dependence on the corresponding pineal system in vivo. Structures corroborating keen olfactory or acoustic senses were not identified. The likely atrophied vomeronasal organ argues against the presence of a forked tongue in Nothosaurus, and the relative positioning of external and internal nares contrasts respiratory configurations proposed for pistosauroid sauropterygians. The antorbital domain furthermore accommodates a putative rostral sensory plexus and pronounced lateral nasal glands that were likely exapted as salt glands. Previously proposed nothosaurian ‘foramina eustachii’ arose from architectural constraints on braincase development rather than representing functional foramina. Several modifications to brain shape and accessory organs were achieved through heterochronic development of the cranium, particularly the braincase. In summary, the cranium of Nothosaurus marchicus reflects important physiological and neurosensory adaptations that enabled the group’s explosive invasion of shallow marine habitats in the late Early Triassic.

show abstract

“…8 FIGURE 7. Plesiosaur muscle attachments to humerus and scapulocoracoid (Based on Araújo and Correia, 2015). Postaxial, ventral, and preaxial views of the affected left humerus GLAHM V1799 (top row) and the same of a healthy humerus (GLAHM V1828), as well as the ventral view of the pectoral girdle of GLAHM V1799 (bottom).…”

Section: Discussionmentioning

confidence: 99%