Musculoskeletal development of the Central African caecilian Idiocranium russeli (Amphibia: Gymnophiona: Indotyphlidae) and its bearing on the re-evolution of larvae in caecilian amphibians

Theska, Tobias; Wilkinson, Mark; Gower, David J.; Müller, Hendrik

doi:10.1007/s00435-018-0420-0

Cited by 10 publications

(8 citation statements)

References 43 publications

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“…For example, direct-developing hemiphractid frogs have retained some biphasic embryonic features (e.g., oral structures) inside the egg 53,58 . The same is true for the reversal in Desmognathus salamanders 59 and Seychellean caecilians 60 . Reversals may therefore be viable only if key larval features were retained.…”

Section: Frequencies and Transitions Of Reproductive Modesmentioning

confidence: 59%

The evolution of reproductive modes and life cycles in amphibians

2022

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Amphibians have undergone important evolutionary transitions in reproductive modes and life-cycles. We compare large-scale macroevolutionary patterns in these transitions across the three major amphibian clades: frogs, salamanders, and caecilians. We analyse matching reproductive and phylogenetic data for 4025 species. We find that having aquatic larvae is ancestral for all three groups and is retained by many extant species (33–44%). The most frequent transitions in each group are to relatively uncommon states: live-bearing in caecilians, paedomorphosis in salamanders, and semi-terrestriality in frogs. All three groups show transitions to more terrestrial reproductive modes, but only in caecilians have these evolved sequentially from most-to-least aquatic. Diversification rates are largely independent of reproductive modes. However, in salamanders direct development accelerates diversification whereas paedomorphosis decreases it. Overall, we find a widespread retention of ancestral modes, decoupling of trait transition rates from patterns of species richness, and the general independence of reproductive modes and diversification.

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Section: Frequencies and Transitions Of Reproductive Modesmentioning

confidence: 59%

The evolution of reproductive modes and life cycles in amphibians

2022

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“…This lack is associated with a proportionately larger maxillary portion of the maxillopalatine in G. carnosus. The sphenethmoid is not exposed dorsally in G. carnosus and G. ramaswamii but is in H. rostratus (slightly) and I. russeli Theska et al 2018;Marshall et al 2019). The expansion of the parietal towards the os basale in G. carnosus and (lesser in) G. ramaswamii is also observed in Idiocranium russeli but not in other grandisoniids (Parker 1941;Wake 1987;Wilkinson et al 2011;Theska et al 2018;Marshall et al 2019).…”

Section: Discussionmentioning

confidence: 96%

“…Descriptions of caecilian skeletal morphology are generally sparse, and that is true also for grandisoniids. However, the osteology of Hypogeophis rostratus has received some attention over the last 150 years (e.g., Wiedersheim 1879, Peter 1894, Wake 2003), and a few studies have examined the osteology of Grandisonia species (e.g., Straub 1985) and Idiocranium russeli (a small, possibly miniaturized taxon) (Wake 1986;Theska et al 2018;Marshall et al 2019). Wake (1987) examined the osteology of Sylvacaecilia grandisonae, and Taylor (1970) briefly described the skull of Indotyphlus battersbyi.…”

Section: Discussionmentioning

confidence: 99%

Osteology of the caecilian Gegeneophis carnosus (Beddome, 1870) (Amphibia: Gymnophiona: Grandisoniidae) from the Western Ghats of peninsular India

Palakkool¹,

Gower²,

Kotharambath³

2022

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The osteology of the poorly known grandisoniid caecilian Gegeneophis carnosus is described for the first time by applying high-resolution X-ray micro-computed tomography to some recently collected material. The ossified skeleton comprises a stegokrotaphic skull, lower jaw, and vertebral column. The braincase, composed of the sphenethmoid and os basale, is covered by eight other cranial elements viz. nasopremaxilla, frontal, parietal, squamosal, pterygoquadrate, maxillopalatine, vomer, and stapes. The eye is covered by the maxillopalatine, and an (open) orbit is absent. The sphenethmoid is not exposed and lacks a solum nasi or a ventral flange. The olfactory chamber lacks an olfactory eminence. Slight asymmetries were observed in the structure and/or size of the left and right frontals and parietals and in the number and size of some foramina. Except for pterygoquadrate and stapes, all bones are pierced by foramina for nerves and/or blood vessels. The lower jaw shows a typical caecilian pattern with dentigerous pseudodentary and edentulous pseudoangular. Numbers of vertebrae range from 123–130 (mean 126). The vertebrae are somewhat heterogenous, varying in size and proportions along the column. Comparisons are made with other caecilians, especially other grandisoniids. Aspects of the cranial osteology of Gegeneophis, such as the closed orbit, subterminal mouth, and stegokrotaphy are possible adaptations to dedicated fossoriality, but functional, behavioural, and field ecological data are not yet available to test this.

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“…2). Muscle nomenclature is based on homologies with jaw musculature in other amphibians and in caecilian larvae (Haas, 2001;Kleinteich and Haas, 2007;Theska et al, 2018). Prior to dissection, specimens used for morphological analyses that were stored in a 70% aqueous ethanol solution were rehydrated in water for 15-20 min.…”

Section: Dissection and Muscle Propertiesmentioning

confidence: 99%

The relationship between head shape, head musculature and bite force in caecilians (Amphibia: Gymnophiona)

Lowie

Kegel

Wilkinson

et al. 2022

Journal of Experimental Biology

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Caecilians are enigmatic limbless amphibians that, with a few exceptions all have an at least partly burrowing lifestyle. Although it has been suggested that caecilian evolution resulted in sturdy and compact skulls as an adaptation to their head-first burrowing habits, no relationship between skull shape and burrowing performance has been demonstrated to date. However, the unique dual jaw-closing mechanism and the osteological variability of their temporal region suggest a potential relationship between skull shape and feeding mechanics. Here, we explored the relationships between skull shape, head musculature, and in vivo bite forces. Although there is a correlation between bite force and external head shape, no relationship between bite force and skull shape could be detected. Whereas our data suggest that muscles are the principal drivers of variation in bite force, the shape of the skull is constrained by factors other than demands for bite force generation. However, a strong covariation between the cranium and mandible exists. Moreover, both cranium and mandible shape covary with jaw muscle architecture. Caecilians show a gradient between species with a long retroarticular process associated with a large and pennate-fibered m. interhyoideus posterior and species with a short process but long and parallel-fibered jaw adductors. Our results demonstrate the complexity of the relationship between form and function of this jaw system. Further studies that focus on factors such as gape distance or jaw velocity will be needed in order to fully understand the evolution of feeding mechanics in caecilians.

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Musculoskeletal development of the Central African caecilian Idiocranium russeli (Amphibia: Gymnophiona: Indotyphlidae) and its bearing on the re-evolution of larvae in caecilian amphibians

Cited by 10 publications

References 43 publications

The evolution of reproductive modes and life cycles in amphibians

The evolution of reproductive modes and life cycles in amphibians

Osteology of the caecilian Gegeneophis carnosus (Beddome, 1870) (Amphibia: Gymnophiona: Grandisoniidae) from the Western Ghats of peninsular India

The relationship between head shape, head musculature and bite force in caecilians (Amphibia: Gymnophiona)

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