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

Journal of Morphology, Год журнала: 2025, Номер 286(2)

Опубликована: Янв. 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

Язык: Английский

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Mesopodial and Digit Number Variation in the Limb Reduced Salamander Family Amphiumidae

Ichthyology & Herpetology, Год журнала: 2025, Номер 113(2)

Опубликована: Май 19, 2025

Язык: Английский

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Osteology of Batrachuperus yenyuanensis (Urodela, Hynobiidae), a high-altitude mountain stream salamander from western China

PLoS ONE, Год журнала: 2019, Номер 14(1), С. e0211069 - e0211069

Опубликована: Янв. 25, 2019

Batrachuperus yenyuanensis, commonly known as Yenyuan Stream Salamander, is a hynobiid species inhabiting high-altitude (2440–4025 m above sea level) mountain stream and pond environments along the eastern fringe of Qinghai-Tibetan Plateau in western Sichuan Province, China. Although has been for almost 70 years since its initial discovery 1950, thorough osteological description never provided. Our study provides detailed account bony anatomy this species, based on micro computed tomography scanning multiple specimens collected from type locality Shuangertang at Bailinshan, Yanyuan County, several other localities Province. revised diagnosis utilizes both soft anatomical features. Comparative area with those nearby Xichang Mianning areas confirms that they all pertain to thereby removing doubt occurrence latter areas. With confirmation, distribution extended northwards some 180 km area, west east sides Yalong River, which major tributary upper Yangtze River. This pattern indicates biogeographic origin historical evolution are closely associated orogeny Hengduan Mountains formation Given basalmost position yenyuanensis relation congeneric molecular studies, however, early expansion by dispersal expected following genus early–middle Miocene Thus, may well have achieved current before drastic uplift Pliocene.

Язык: Английский

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Middle Jurassic stem hynobiids from China shed light on the evolution of basal salamanders

iScience, Год журнала: 2021, Номер 24(7), С. 102744 - 102744

Опубликована: Июнь 17, 2021

The Hynobiidae are an early-diverging clade of crown-group salamanders (urodeles) with important bearing on the evolution urodeles. Paleobiology and early-branching patterns remain unclear owing to a poorly documented fossil record. We reported newly referred specimen stem hynobiid, originally named as "Liaoxitriton daohugouensis," but here Neimengtriton daohugouensis comb. nov., predates previously estimated origination time for at least 8 Myr. interpret N. semiaquatic adult stage, unknown paleoecological preference among Mesozoic salamanders. Phenotypic variations enlighten unrecognized association between caudosacral vertebrae fertilization modes in early Our cladistic analyses based morphological characters not only recognize several hynobiids establish Panhynobia nomen cladinovum total-group also shed light sequential features this primitive urodele clade.

Язык: Английский

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A new stem hynobiid salamander (Urodela, Cryptobranchoidea) from the Upper Jurassic (Oxfordian) of Liaoning Province, China

Journal of Vertebrate Paleontology, Год журнала: 2019, Номер 39(2), С. e1588285 - e1588285

Опубликована: Март 4, 2019

Hynobiids are a group of small- to moderate-sized salamanders living primarily in Asia. They primitive crown-group clade, with poor fossil record. Several hynobiid-like taxa have been discovered from the Lower Cretaceous strata northern China during last 20 years, Liaoxitriton zhongjiani and Nuominerpeton aquilonaris identified as oldest known stem hynobiids. However, record pre-Cretaceous is only by daohugouensis, which both morphology congeneric status L. remain problematic. Here, we report on new salamander, Linglongtriton daxishanensis, gen. et sp. nov., basis two specimens Upper Jurassic Lanqi/Tiaojishan Formation (∼160 Ma) Liaoning Province, China. diagnosed unique combination features revealed observation under microscope micro-computed tomography (μCT) scan holotype, including nasals separated each other at midline; prootic, opisthotic, exoccipital retained discrete elements; dentary lateral groove; articular not ossified; metacarpal III enlarged; single centrale; distal tarsals 4 5 fused into element. Phylogenetic analysis several taxa, hynobiids, thereby extending temporal range least 40 Ma—from Early (Aptian–Barremian) Middle (Bathonian). Comparative study hynobiids sheds lights evolution developmental mechanisms characters, nasal separation tarsal elements.

Язык: Английский

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Increasing Hormonal Control of Skeletal Development: An Evolutionary Trend in Amphibians

Frontiers in Ecology and Evolution, Год журнала: 2021, Номер 9

Опубликована: Ноя. 4, 2021

The biphasic life history of amphibians includes metamorphosis, a complex developmental event that involves drastic changes in the morphology, physiology and biochemistry accompanying transition from larval to adult stage development. Thyroid hormones (THs) are widely known orchestrate this remodeling and, particular, mediate development bony skeleton, which is model system evolutionary morphological studies amphibians. Detailed experimental role THs craniogenesis diverse urodelan revealed (i) these affect both timing sequence bone formation, (ii) TH involvement increases parallel with increase divergence between skull (iii) among urodelans, TH-involvement minimum basal salamanders (Hynobiidae) most pronounced derived ones (Salamandridae Plethodontidae). Given increasing regulatory function evolution, we hypothesized stronger control skeletogenesis anurans their dramatic metamorphosis all Our study skeletal hypo- hyperthyroid yellow-bellied toad ( Bombina variegata : Bombinatoridae) supports greater mediation stages anuran cranial postcranial bones formation. Similar B. displays enhancing arise during ontogeny: while hormonal impact on early ossifications minimal, forming strictly TH-inducible. However, contrast bones, including earliest form, TH-dependent ; moreover, elements axial limb skeleton affected by THs. more accentuated demonstrates advanced inductive orchestration metamorphosis. Based findings, discuss amphibian evolution histories

Язык: Английский

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Palatal morphology predicts the paleobiology of early salamanders

eLife, Год журнала: 2022, Номер 11

Опубликована: Май 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

Язык: Английский

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Comparative osteology of the hynobiid complexLiua‐Protohynobius‐Pseudohynobius(Amphibia, Urodela): Ⅰ. Cranial anatomy ofPseudohynobius

Journal of Anatomy, Год журнала: 2020, Номер 238(2), С. 219 - 248

Опубликована: Сен. 22, 2020

Abstract Hynobiidae are a clade of salamanders that diverged early within the crown radiation and retain considerable number features plesiomorphic for group. Their evolutionary history is informed by fossil record extends to Middle Jurassic Bathonian time. Our understanding evolution total group has benefited considerably from recent discoveries stem hynobiids but constrained inadequate anatomical knowledge some extant forms. Pseudohynobius derived hynobiid consisting five seven species living endemic southwestern China. Although this been recognized over 37 years, osteological details these remain elusive, which undoubtedly contributed taxonomic controversies complex Liua ‐ Protohynobius . Here we provide bone‐by‐bone study cranium in ( Ps. flavomaculatus , guizhouensis jinfo kuankuoshuiensis shuichengensis ) based on x‐ray computer tomography data 18 specimens. results indicate each combination differences morphology, proportions articulation patterns both dermal endochondral bones. establishes range intraspecific will serve as organizing hypotheses future studies more extensive collections become available. Morphological terrestrial ecological adaptation summarized. Based results, also discuss development several potential synapomorphies Hynobiidae, including orbitosphenoid articular.

Язык: Английский

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Synchrotron microtomography applied to the volumetric analysis of internal structures of Thoropa miliaris tadpoles

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

Опубликована: Ноя. 3, 2020

Abstract Amphibians are models for studying applied ecological issues such as habitat loss, pollution, disease, and global climate change due to their sensitivity vulnerability changes in the environment. Developmental series of amphibians informative about biology, X-ray based 3D reconstruction holds promise quantifying morphological during growth—some with a direct impact on possibility an experimental investigation several topics listed above. However, resolution discrimination soft tissues have been difficult traditional computed tomography, without time-consuming contrast staining. Tomographic data were initially performed (pre-processing reconstruction) using open-source software tool SYRMEP Tomo Project. Data processing analysis reconstructed tomography volumes conducted segmentation semi-automatic settings Avizo Fire 8, which provide information each investigated tissues, organs or bone elements. Hence, volumetric analyses carried out quantify development structures different tadpole developmental stages. Our work shows that synchrotron microtomography phase-contrast mode resolves edges internal (as well overall morphology), facilitating tissues. Reconstruction algorithms played important role qualitative quantitative target structure Thoropa miliaris at stages development, providing volume, shape length. The use setup beamline Elettra Synchrotron, mode, allows access formation, eye nervous system notochordal (ontogeny) tadpoles cycloramphid frog . As key elements normal these any other tadpole, application comparative ontogenetic study, may hold interest researchers environmental disciplines.

Язык: Английский

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Osteological characteristics of the Setouchi salamander Hynobius setouchi (Urodela, Hynobiidae)

The Anatomical Record, Год журнала: 2021, Номер 305(6), С. 1316 - 1342

Опубликована: Сен. 30, 2021

This study described the detailed osteological features of Setouchi salamander Hynobius setouchi. H. setouchi, which is endemic to central Japan, was recently delineated from wide range nebulosus species based on molecular and external morphological characteristics. However, belonging genus have not been examined, has hindered understanding diversity in genus. To address this problem, elucidated using micro-computed tomography scanning whole-mount double staining methods. The articular, a part hypobranchial I, coracoid, pubis, carpus, tarsus were cartilaginous small-sized individuals partially or completely ossified large-sized individuals. degree ossification varied operculum, basibranchial II, ascending process palatoquadrate. associated with body size. lacrimal, manus, pes exhibited varying degrees articulation fusion irrespective Moreover, cranium setouchi several unique These characteristics will aid revising taxonomy phylogeny species.

Язык: Английский

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