Morphology and function of the feeding apparatus in Dermophis mexicanus (Amphibia: Gymnophiona)

Bemis, William E.; Schwenk, Kurt; Wake, Marvalee H.

doi:10.1111/j.1096-3642.1983.tb01722.x

Cited by 84 publications

(107 citation statements)

References 20 publications

(15 reference statements)

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“…Thus, our observations that caecilians frequently use long-axis body rotations when feeding, combined with the fact that these rotations impart significant torques on the head and jaws of the animal, may explain the origin of the unique jaw configuration in derived caecilians (Bemis et al 1983;Nussbaum 1983;O'Reilly 2000;Summers & Wake 2005), which allows them to generate large bite forces with their jaws closed (Summers & Wake 2005). While the reduction of oversized food items remains the most common explanation for long-axis body rotations during feeding, existing data on prey diameter and gape size (Delêtre & Measey 2004) suggest that caecilian prey are rarely oversized.…”

Section: G J Measey and A Herrel Spinning Caeciliansmentioning

confidence: 89%

“…In association with their burrowing habit, most terrestrial species have sturdy, compact skulls, recessed mouths and reduced eyes sometimes covered by the bones of the skull roof. As the head-first burrowing lifestyle of caecilians puts severe constraints on maximal head diameter ( Wake 1993;O'Reilly 2000), the external jaw closer muscles, positioned at the side of the head, are strongly reduced in size in derived caecilians (Bemis et al 1983;Nussbaum 1983;O'Reilly 2000). However, the presence of a mobile quadrate (streptostyly) and a unique jaw-closing system involving the large and well-developed interhyoideus posterior muscle, positioned in line with the head (and thus not increasing the head diameter), suggests that these animals can generate considerable bite forces with the mouth closed (Summers & Wake 2005).…”

Section: Introductionmentioning

confidence: 99%

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Rotational feeding in caecilians: putting a spin on the evolution of cranial design

Measey

Herrel

2006

Biol. Lett.

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Caecilians are a poorly known group of amphibians with a highly derived skull and cranial musculature that has evolved in response to their specialized head-first burrowing lifestyle. They possess a unique jaw-closing system, which is shown to be capable of generating considerable bite forces for its head width (1.09±0.34 and 0.62±0.31 N for Schistometopum thomense and Boulengerula taitanus , respectively). However, comprehensive dietary studies indicate that there is no need for large bite forces, since most caecilians appear to be generalist predators of subterranean macrofauna. Here, we demonstrate, based on in vivo external and X-ray video recordings of animals feeding, that long-axis body rotations are used independent of prey size by these two species of caeciliid caecilians when feeding underground. Further, we show that individuals are capable of generating a substantial spinning force, which is greater than their bite force (1.35±0.26 and 1.02±0.18 N, respectively). These observations shed light on the functional and the evolutionary significance of several unique features of the cranial design in derived caecilians; spinning may allow the individuals to judge prey size and subsequently reduce oversized prey within gape limits.

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Section: G J Measey and A Herrel Spinning Caeciliansmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Rotational feeding in caecilians: putting a spin on the evolution of cranial design

Measey

Herrel

2006

Biol. Lett.

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“…The ventral bending of the skull follows the pattern of cranial kinesis that was previously predicted for caecilians by Iordansky (Iordansky, 1990;Iordansky, 2000). However, although much attention has been paid to the skull roof as an adaptation for burrowing (Peter, 1898;Nussbaum, 1977;Wake and Hanken, 1982;Bemis et al, 1983;Nussbaum, 1983;Wake, 1993), the role of the palate during burrowing has been neglected. Preliminary examination of the nature of the sutures between palatal bones reveals broadly overlapping joints filled by a dense network of collagen fibers, suggesting at least minimal kinesis in this region (H.C.M., personal observation).…”

Section: Discussionmentioning

confidence: 99%

Is solid always best? Cranial performance in solid and fenestrated caecilian skulls

Kleinteich

Maddin

Herzen

et al. 2012

Journal of Experimental Biology

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Accepted 23 November 2011 SUMMARY Caecilians (Lissamphibia: Gymnophiona) are characterized by a fossorial lifestyle that appears to play a role in the many anatomical specializations in the group. The skull, in particular, has been the focus of previous studies because it is driven into the substrate for burrowing. There are two different types of skulls in caecilians: (1) stegokrotaphic, where the squamosal completely covers the temporal region and the jaw closing muscles, and (2) zygokrotaphic, with incomplete coverage of the temporal region by the squamosal. We used 3-D imaging and modeling techniques to explore the functional consequences of these skull types in an evolutionary context. We digitally converted stegokrotaphic skulls into zygokrotaphic skulls and vice versa. We also generated a third, akinetic skull type that was presumably present in extinct caecilian ancestors. We explored the benefits and costs of the different skull types under frontal loading at different head angles with finite element analysis (FEA). Surprisingly, the differences in stress distributions and bending between the three tested skull types were minimal and not significant. This suggests that the open temporal region in zygokrotaphic skulls does not lead to poorer performance during burrowing. However, the results of the FEA suggest a strong relationship between the head angle and skull performance, implying there is an optimal head angle during burrowing. Supplementary material available online at

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“…Using electromyography, Bemis et al (1983) showed that the IHP acts synergistically with the primary jaw-closing muscles. The jaw-closing function of the IHP has been proposed as an adaptation to a fossorial lifestyle (Nussbaum 1983).…”

Section: Introductionmentioning

confidence: 99%

“…However, the studies of the cranial musculature in caecilians (Wiedersheim 1879;Luther 1914;Lawson 1965;Bemis et al 1983;Nussbaum 1983;Iordanski 1996;Wilkinson & Nussbaum 1997;Kleinteich & Haas 2007) show that the fibre orientation of the IHP in most caecilian species is oblique rather than purely anteroposterior; the muscle fibres run in the caudal and ventral directions. A second simplification in the previous model was to ignore the jaw-closing function of the mm.…”

Section: Introductionmentioning

confidence: 99%

Caecilian jaw-closing mechanics: integrating two muscle systems

Kleinteich

Haas

Summers

2008

J. R. Soc. Interface.

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Caecilians (Lissamphibia: Gymnophiona) are unique among vertebrates in having two sets of jaw-closing muscles, one on either side of the jaw joint. Using data from high-resolution X-ray radiation computed tomography scans, we modelled the effect of these two muscle groups (mm. levatores mandibulae and m. interhyoideus posterior) on bite force over a range of gape angles, employing a simplified lever arm mechanism that takes into account muscle crosssectional area and fibre angle. Measurements of lever arm lengths, muscle fibre orientations and physiological cross-sectional area of cranial muscles were available from three caecilian species: Ichthyophis cf. kohtaoensis; Siphonops annulatus; and Typhlonectes natans. The maximal gape of caecilians is restricted by a critical gape angle above which the mm. levatores mandibulae will open the jaw and destabilize the mandibular joint. The presence of destabilizing forces in the caecilian jaw mechanism may be compensated for by a mandibular joint in that the fossa is wrapped around the condyle to resist dislocation. The caecilian skull is streptostylic; the quadrate-squamosal complex moves with respect to the rest of the skull. This increases the leverage of the jaw-closing muscles. We also demonstrate that the unusual jaw joint requires streptostyly because there is a dorsolateral movement of the quadrate-squamosal complex when the jaw closes. The combination of the two jawclosing systems results in high bite forces over a wide range of gape angles, an important advantage for generalist feeders such as caecilians. The relative sizes and leverage mechanics of the two closing systems allow one to exert more force when the other has a poor mechanical advantage. This effect is seen in all three species we examined. In the aquatic T. natans, with its less well-roofed skull, there is a larger contribution of the mm. levatores mandibulae to total bite force than in the terrestrial I. cf. kohtaoensis and S. annulatus.

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Morphology and function of the feeding apparatus in Dermophis mexicanus (Amphibia: Gymnophiona)

Cited by 84 publications

References 20 publications

Rotational feeding in caecilians: putting a spin on the evolution of cranial design

Rotational feeding in caecilians: putting a spin on the evolution of cranial design

Is solid always best? Cranial performance in solid and fenestrated caecilian skulls

Caecilian jaw-closing mechanics: integrating two muscle systems

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