Influence of semicircular canal morphology on the VOR and swimming activity in larval amphibians: a comparative study in Xenopus and axolotl

Frontiers in Neurology, Год журнала: 2025, Номер 16

Опубликована: Май 19, 2025

Gaze stabilization and locomotion rely often on an accurate sensory detection of head movements by the vestibular system. A functional relationship between sensitivity, locomotor skills semicircular canal morphology has been suspected in vertebrates as adaptation to eco-physiological species-specific needs, but only partially indirectly documented. However, evaluating vestibulo-ocular reflexive activity efficiency simultaneously with rotational sensor geometry remains absent from literature. From such a perspective, this study attempted provide simultaneous quantification response, swimming salamander axolotl frog Xenopus laevis , two amphibian species comparable lifestyle identical systems at larval stages. Animals were studied equivalent developmental period: late pre-metamorphic stage where hindlimbs start differentiate. Larval demonstrated angular reflex (aVOR) gain ~83% lower than . Like earlier stages, aVOR increased indicating later onset. The morphological comparison canals both revealed that horizontal was thinner, less curved coplanar plane compared Additionally, ampulla rounder elongated axolotl. All these parameters are critical for endolymph flow consequently capacity perceive motion. Interestingly, reduced activity, more episodic resulting frequent exposure important accelerations. Altogether, our results correlative evidences clear link morphology, influencing performance, also species, representative anuran amphibians. This study, even preliminary, should open pathway further complete demonstrations relationship, seems be commonly shared during evolution.

Язык: Английский

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Ontogeny of the Massospondylus labyrinth: implications for locomotory shifts in a basal sauropodomorph dinosaur

Palaeontology, Год журнала: 2018, Номер 62(2), С. 255 - 265

Опубликована: Окт. 5, 2018

Abstract Ontogeny is a vital aspect of life history sometimes overlooked in palaeontological studies. However, the changing geometry anatomical structures during growth can be informative regarding ecological and functional reconstructions. The inner ear, or labyrinth, an ideal ontogenetic study system because it has strong signal its morphology that linked to locomotor mode. Yet almost nothing known about labyrinth development dinosaurs. We quantified scale through ontogeny Early Jurassic dinosaur Massospondylus carinatus , which exceptional fossil record hypothesized have undergone gait change, from quadrupedal juvenile bipedal adult. To test whether this putative shift reflected morphology, computed microtomography (μ CT ) propagation phase‐contrast synchrotron radiation ( PPC ‐ SR μ were used obtain labyrinths eight specimens, ranging near‐hatchling Labyrinths grow substantially but with slight negative allometry compared skull length throughout ontogeny, first time been documented Geometric morphometric analysis using sliding semilandmark approach shows some morphological change little evidence supporting shift. These results implications for our understanding sauropodomorph provide better locomotory evolution.

Язык: Английский

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Endocranial anatomy and life habits of the Early Triassic archosauriformProterosuchus fergusi

Palaeontology, Год журнала: 2019, Номер 63(2), С. 255 - 282

Опубликована: Ноя. 20, 2019

Abstract Proterosuchids are an important group of carnivorous basal archosauriforms characterized by a bizarre and enigmatic downturned premaxilla that overhangs the lower jaw. They particularly significant because they radiated in immediate aftermath Permian–Triassic mass extinction represent one best known ‘disaster taxa’ following event. While traditionally considered to be semi‐aquatic, recent histological studies geological data have suggested it is more likely inhabited terrestrial environments. By using computed tomographic ( CT ) data, we virtually reconstruct brain endocast endosseous labyrinths two adult specimens Proterosuchus fergusi from earliest Triassic South Africa, attempt understand its life habits within context archosauriform evolution. Endocasts reveal cavity tubular shape highly pyramidal. The angle lateral semicircular canal suggests P. naturally held head upwards ~17°, while length cochlear duct auditory abilities were specialized towards low‐frequency sounds. Furthermore, beam theory analysis rostrum resistant both bending torsion when compared modern crocodilians, although this resistance neither enhanced nor reduced overhanging premaxilla. Comparative anatomical analyses suggest was probably generalist apex predator capable surviving harsh environmental perturbations Early Triassic.

Язык: Английский

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

Scientific Reports, Год журнала: 2020, Номер 10(1)

Опубликована: Июнь 9, 2020

Abstract Spinosauridae, a theropod group characterized by elongated snouts, conical teeth, enlarged forelimbs, and often neural spines, show evidence for semiaquatic adaptations piscivory. It is currently debated if these animals represent terrestrial carnivores with piscivorous diet, or they largely lived foraged in aquatic habitats. The holotype of Irritator challengeri , nearly complete skull from the late Early Cretaceous Santana Formation northeastern Brazil, includes one few preserved spinosaurid braincases can provide insights into neuroanatomical structures that might be expected to reflect ecological affinities. We generated digital models cavities within braincase, using computer tomography (CT) data. cranial endocast generally similar other non-maniraptoriform theropods, weakly developed distinctions hindbrain midbrain features, relatively pronounced flexures long olfactory tracts. endosseous labyrinth has anterior semicircular canal, posteriorly inclined common crus very large floccular recess fills area between canals. These features indicate had ability fast well-controlled pitch-down head movements. table lateral canal plane are strongly angled another, suggesting downward angling approximately 45° snout, which reduces interference snout field vision . consistent fast, snatching movements act predation, such as needed

Язык: Английский

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A new pelomedusoid turtle,Sahonachelys mailakavava, from the Late Cretaceous of Madagascar provides evidence for convergent evolution of specialized suction feeding among pleurodires

Royal Society Open Science, Год журнала: 2021, Номер 8(5)

Опубликована: Май 1, 2021

The Maevarano Formation in northwestern Madagascar has yielded a series of exceptional fossils over the course last three decades that provide important insights into evolution insular ecosystems during latest Cretaceous (Maastrichtian). We here describe new genus and species pelomedusoid turtle from this formation, Sahonachelys mailakavava , based on nearly complete skeleton. A phylogenetic analysis suggests close affinities with coeval Madagascan Sokatra antitra . These two taxa are only known representatives newly recognized clade Sahonachelyidae which is sister to speciose formed by Bothremydidae Podocnemidoidae relationship Indian turtles Kurmademydini notably absent. functional assessment was specialized suction feeder preyed upon small-bodied invertebrates vertebrates. This unique feeding strategy among crown pelomedusoids convergent documented numerous other clades highlights distinct evolutionary pathways taken

Язык: Английский

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