Middle Jurassic fossils document an early stage in salamander evolution

Proceedings of the National Academy of Sciences, Journal Year: 2022, Volume and Issue: 119(30)

Published: July 11, 2022

Salamanders are an important group of living amphibians and model organisms for understanding locomotion, development, regeneration, feeding, toxicity in tetrapods. However, their origin early radiation remain poorly understood, with fossil stem-salamanders so far represented by larval or incompletely known taxa. This poor record also limits the Lissamphibia (i.e., frogs, salamanders, caecilians). We report fossils from Middle Jurassic Scotland representing almost entire skeleton enigmatic stem-salamander Marmorerpeton. use computed tomography to visualize high-resolution three-dimensional anatomy, describing morphologies that were characterized including braincase, scapulocoracoid, lower jaw. these data context a phylogenetic analysis intended resolve relationships stem-salamanders, representation outgroups alongside imaging extant species. Marmorerpeton is united Karaurus, Kokartus, others Jurassic-Lower Cretaceous Asia, providing evidence robustly built neotenous stem-salamanders. These taxa display morphological specializations similar cryptobranchid "giant" salamanders. Our demonstrates stem-group affinities larger sample species than previously recognized, highlighting unappreciated diversity cautioning against single (e.g., Karaurus) as exemplars anatomy. findings, combined knowledge near-complete skeletal anatomy Mamorerpeton, advance our evolutionary changes on salamander stem-lineage provide salamanders origins Batrachia Lissamphibia.

Language: Английский

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The anatomy and feeding mechanism of the Japanese giant salamander (Andrias japonicus)

Journal of Anatomy, Journal Year: 2024, Volume and Issue: 244(5), P. 679 - 707

Published: Jan. 12, 2024

The fully aquatic Japanese giant salamander (Andrias japonicus) is a member of the Cryptobranchidae, and currently distributed in western Japan, with other members this group restricted to China North America. Their feeding behaviour characterized by form suction that includes asymmetric movements jaw hyobranchial apparatus. Previous studies on American species, Cryptobranchus alleganiensis, have suggested specialized movement produced flexible quadrate-articular joint combined loosely connected lower symphysis including two small fibrocartilaginous pads. However, little known about Asian nor three-dimensional been investigated any Cryptobranchidae. In study, we explore A. japonicus using three methods: (1) dissection musculoskeletal structures; (2) filming understand which situations used; (3) analysis 3D jaws skull. third component, fresh (from frozen) specimens were manipulated replicate symmetric movements, CT scanned after each step obtain morphology at different positions. These positions their Euler angles from resting (closed) position calculated for or Our revealed are linked prey relation snout, closest opening asymmetrically. Moreover, action allows simultaneously grasp one side mouth while ejecting water side, if first attempt fails. performed mainly rotation mandible its long axis, very limited lateral movements. During posterior ends maxilla quadrate move slightly. permitted mobile formed wide, round cartilages, fibrocartilage pads within act as cushions during rotation. Some these soft tissue structures leave traces skull, allowing mode be reconstructed fossil taxa. Understanding cryptobranchid thus requires comprehensive assessment not only symphysial but also cranial elements.

Language: Английский

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Comparing novel sperm extenders for the internally-fertilizing tiger salamander (Ambystoma tigrinum)

Frontiers in Amphibian and Reptile Science, Journal Year: 2024, Volume and Issue: 1

Published: Jan. 19, 2024

Due to the concentrated nature and small volume of spermic milt that is typically produced from internally-fertilizing salamanders, an extender needed analyze sperm for quality quantity metrics. Techniques diluting salamander analysis have thus far utilized low osmolality media, which are likely physiologically distinct female reproductive tract. Application mammalian extenders could maintain motility morphology in storage longer due similar internal fertilization both taxa. Several were tested including: Multipurpose Handling Medium, Sperm Washing Modified Ham’s F-10 Basal Medium (HAM’s), Refrigeration 10% Holtfreter’s solution as a control. The experimental treatments divided into two groups: diluted (90 mOsm, approximate sperm) undiluted (280-320 mOsm). Milt samples collected male tiger salamanders (N=11) 1:50 with each measured progressive motility, total normal every 10 minutes one hour. When comparing versus same extender, there was no difference (p>0.05) any response variables. In addition, we found best maintaining while HAM’s retaining over time. Overall, not key driver influencing but rather other factors such ionic composition or pH be affecting form function.

Language: Английский

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Temporal framework for the Yanliao Biota and timing of the origin of crown mammals

Earth and Planetary Science Letters, Journal Year: 2023, Volume and Issue: 617, P. 118246 - 118246

Published: June 12, 2023

Establishing the temporal sequence of Middle-Late Jurassic Yanliao Biota is essential as it anchors timing many key evolutionary innovations in vertebrates. Lack sufficiently reliable high-precision ages fossil-bearing horizons hinders our ability to reconstruct tempo and mode vertebrate evolution. Here, we frame a with precise age constraints for iconic vertebrates, proposing that major vertebrate-bearing strata span from 164 Ma 157 age. The increasing ecological diversity mammaliaforms well illustrated by Early Cretaceous Jehol Biota. Incorporation updated frameworks Bayesian tip-dated mammaliaform phylogeny reveals Triassic haramiyidans are separate taxa unrelated crown Mammalia. Tip-dated supports long-fuse model mammal evolution, featured Late root interordinal diversification Mammalia, showing consistency molecular-based timetrees divergence timing.

Language: Английский

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Anatomy of the Critically‐Endangered Anji Salamander (Hynobius amjiensis) Provides New Insights Into Morphological Evolution of Salamanders

Journal of Morphology, Journal Year: 2025, Volume and Issue: 286(2)

Published: Jan. 29, 2025

ABSTRACT The Anji Salamander ( Hynobius amjiensis ) is a critically‐endangered amphibian endemic to the Tianmushan Mountain area in southeastern China. As most of its congeneric species ancestral salamander family Hynobiidae, osteology H . has remained essentially unknown and hampered efforts understanding morphological evolutionary patterns early salamanders. Here, we investigate skeletal anatomy based on microcomputed tomography scans post‐metamorphosed juvenile adult specimens. Our results reveal Hynobiidae more early‐tetrapod‐like plesiomorphic characters than expected, as stapedial foramen middle ear two centralia centrale‐radius contact limb. We demonstrate that first known living with whose absence was believed unite salamanders anurans, hence opens major questions evolution modern amphibians: if some caecilians had inherited from their common ancestor, when how many times lost independently amphibians, did this structural loss impact phylogenetic clades? findings hyper‐ossified pectoral pelvic girdles postminimus pes functional features hynobiids are potentially informative phylogeny ontogeny

Language: Английский

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Re‐examination of the oldest known frog from South America: New data prompt new evolutionary interpretations

The Anatomical Record, Journal Year: 2025, Volume and Issue: unknown

Published: March 17, 2025

Abstract Available paleontological evidence, although scarce, points to the early diversification of salientian lissamphibians in Triassic and Early Jurassic. This study provides new key anatomical information on earliest mostly articulated frog currently known, thereby improving our understanding evolution this lissamphibian lineage. Herein, available specimens Jurassic Vieraella herbstii from Patagonia, which consist dorsal ventral imprints incomplete, partially skeleton a single individual, are thoroughly redescribed. Although we comment its known features, focus those that had been misinterpreted or overlooked previously. Among other address relative proportions skull regions limbs, morphology vomers, peculiar articulation palatine flanges premaxilla maxilla suggests presence well‐developed cristae subnasales, prepollex. The most surprising, significant findings stapes, indicating possibility complete tympanic middle ear, short, tapering urostyle postsacral vertebral elements. Based information, present partial reconstructions pectoral girdle aspect. Discussion evolutionary significance these features perusal phylogenetic functional analyses included taxon sampling highlight necessity thorough revision scorings measurements, incorporating presented herein. reassessment will be relevant not only clarify relationships but also provide sound insights into frogs.

Language: Английский

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A chronostratigraphic and biostratigraphic framework for the Yanliao Biota of northeastern China: Implications for Jurassic terrestrial ecosystems and evolution

Palaeogeography Palaeoclimatology Palaeoecology, Journal Year: 2023, Volume and Issue: 630, P. 111818 - 111818

Published: Sept. 19, 2023

Language: Английский

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Biogeographic history of Palearctic caudates revealed by a critical appraisal of their fossil record quality and spatio-temporal distribution

Royal Society Open Science, Journal Year: 2022, Volume and Issue: 9(11)

Published: Nov. 1, 2022

The disjunct geographical range of many lineages caudates points to a complex evolutionary and biogeographic history that cannot be disentangled by only considering the present-day distribution salamander biodiversity. Here, we provide critical reappraisal published fossil record from Palearctic quantitatively evaluate quality group's record. Stem-Urodela Karauridae were widespread in Middle Jurassic, suggesting an earlier, unsampled diversification for this group. Cryptobranchidae reached Europe no later than Oligocene, but clade was subsequently extirpated continent, as well western central Asia. relatively recent appearance hynobiids (Early Miocene) is most likely artefact taphonomic bias against preservation high-mountain, stream-type environments which early members inhabited. Salamandroids first appear Europe, expanding into Asia Miocene. apparently enigmatic extant caudate therefore explained wider past range, testified record, fragmented during late Cenozoic combination tectonic (i.e. uplift Tibetan Plateau) climatic drivers, resulting regional extirpations.

Language: Английский

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The northernmost occurrence of non-karaurid salamanders (Lissamphibia, Caudata) in the Mesozoic

Cretaceous Research, Journal Year: 2023, Volume and Issue: 152, P. 105686 - 105686

Published: Aug. 27, 2023

Language: Английский

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Palatal morphology predicts the paleobiology of early salamanders

eLife, Journal Year: 2022, Volume and Issue: 11

Published: May 16, 2022

Ecological preferences and life history strategies have enormous impacts on the evolution phenotypic diversity of salamanders, but yet established reliable ecological indicators from bony skeletons hinder investigations into paleobiology early salamanders. Here, we statistically demonstrate by using time-calibrated cladograms geometric morphometric analysis 71 specimens in 36 species, that both shape palate many non-shape covariates particularly associated with vomerine teeth are ecologically informative stem- basal crown-group Disparity patterns within morphospace preferences, strategies, taxonomic affiliations were analyzed detail, evolutionary rates ancestral states reconstructed. Our results show is heavily impacted convergence constrained feeding mechanisms also exhibits clear stepwise alternative configurations to cope similar functional demand. Salamanders diversified before Middle Jurassic achieved all their present Early Cretaceous. reveal last common ancestor salamanders share other modern amphibians a unified biphasic preference, metamorphosis significant expansion ecomorphospace

Language: Английский

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