Fig 1.
A-B. Representative biplanar fluoroscopy frames of Gekko gecko biting on a bite force transducer (recorded at 250 frames per seconds).
In each view, the screen coordinates of the implanted radiopaque markers (6 in the snout, 5 in the braincase, 3 in the right lower jaw and 4 in the left lower jaw) are digitized throughout the sequence to calculate the 3D position of the elements of interest (the snout, the braincase and the lower jaw). The snout of the subject is oriented to the right. C-D. Still frames extracted from an XROMM animation of Gekko gecko biting. Mesokinetic angle is calculated as the angle between the anterior-posterior axis of the snout (in gold, defined by 2 landmarks in blue) and the anterior-posterior axis of the braincase (in red, defined by 2 landmarks in grey). A fifth landmark (green) was defined at the tip of the lower jaw to measure gape distance. Note that these are virtual landmarks created in the XROMM animations; i.e., they are different than the markers surgically implanted. XROMM animations allow quantifying the movements of the snout and of the lower jaw relative to the braincase reference system: antero-posterior axis (red axis), dorso-ventral axis (green axis) and medio-lateral axis (blue axis). See S1 File for an example of full XROMM animation.
Table 1.
Variables and terminology used in this study.
Fig 2.
Mesokinesis during gape display in Gekko gecko.
Representative traces show (A) gape (i.e., the distance between the tip of the upper and lower jaw) and (B) the associated mesokinetic displacement over time. Note that the snout flexes dorsally above rest position during gape display, and maximum gape occurs simultaneously with maximum dorsal flexion of the snout relative to the braincase.
Fig 3.
Mesokinesis during defensive biting in Gekko gecko.
Representative traces show (A) bite force measured with a bite force transducer and (B) the associated mesokinetic displacement over time. In the sequence presented, 3 bites were recorded measuring 4.79 N, 6.84 N and 5.50 N, respectively. Note that the snout flexes ventrally below rest position during biting, and maximum bite force occurs simultaneously with maximum ventroflexion of the snout relative to the braincase.
Fig 4.
Mesokinesis during intra-oral transport and puncture crushing cycles in Gekko gecko.
Representative traces show (A) gape and (B) the associated mesokinetic displacement over time. The horizontal dotted line represents the mesokinetic angle at rest position in the individual represented.
Fig 5.
Mesokinesis during intra-oral transport and pharyngeal packing cycles in Gekko gecko.
Representative traces show (A) gape and (B) the associated mesokinetic displacement over time. The horizontal dotted line represents the mesokinetic angle at rest position in the individual represented.
Table 2.
The number of replicates is presented for the complete data set and for each of the five individuals.
Fig 6.
Correlation between maximum gape and dorsal rotation of the snout at the mesokinetic angle at maximum gape during gape display in Gekko gecko.
The correlation is significant across all sequences recorded in this study (bold line), as well as at the individual level for 4 of the 5 individuals studied (continuous lines; see Table 4 for correlation parameters). Symbols represent individuals. Dotted line represents rest position: positive values indicate dorsal rotation of the snout above rest position; negative values indicate ventral rotation of the snout below rest position.
Table 3.
Summary of mesokinetic displacements (mean ± standard error of the mean) observed in Gekko gecko during gape display and defensive biting.
Table 4.
Summary of the correlations between mesokinetic displacements and performance in Gekko gecko during gape display and defensive biting.
Fig 7.
Correlation between ventral rotation of the snout relative to the braincase and maximum bite force performance in Gekko gecko.
The correlation is significant in 4 of the 5 individuals studied (continuous lines; see Table 4 for correlation parameters), but only approaches significance across all individuals (see Table 4). Symbols represent individuals. Dotted line represents rest position: positive values indicate dorsal rotation of the snout above rest position; negative values indicate ventral rotation of the snout below rest position.
Table 5.
Summary of the mesokinetic movements (mean ± standard error of the mean) observed in Gekko gecko during post-ingestion feeding.
Fig 8.
Summary of the contribution of mesokinetic movement to jaw gape distance in Gekko gecko during gape display, intra-oral food transport and processing behaviors in the 5 individuals studied.
Positive values indicate that dorsal rotation of the snout above rest position increases gape opening distance in comparison to a theoretical akinetic skull where gape distance is solely induced by the depression of the lower jaw. Negative values indicate that ventral rotation of the snout below rest position increases gape closing distance without lower jaw elevation. Colors represent individuals, note that no feeding data could be collected for individuals 2 (red) and 3 (blue).