The skull of STM 13-162 (a) under white light and (b) under laser-stimulated fluorescence and photostacked with two images to improve clarity. The rhamphotheca is preserved as a brown stain near the premaxilla. The dorsal margins of the premaxilla and upper rhamphotheca are separated and subparallel. The upper rhamphotheca is more complete than the lower rhamphotheca and the rounding of both their tips appears to be genuine. The caudal extent of the upper rhamphotheca is obscured (see c). (c) Reconstruction of STM 13-162, with absent skeletal information (dotted lines and lower saturation) filled in from a previous reconstruction3. The pink shape is the in situ position of the rhamphotheca. The red shape is our reconstruction of the in vivo positioning of the rhamphotheca based on aligning the dorsal edge of the upper rhamphotheca with that of the premaxilla and then aligning the tips of the upper and lower rhamphothecae. We interpret the in situ upper rhamphotheca as extending just caudal to the prominent crack, to the point of color transition in the fluorescing area (mid-naris in vivo; anterior naris in situ). (d–g) Line drawings of the rostra and rhamphothecae of (d) BMNHC-PH986 (scale approximate based on STM 13-162, reconstructed by same methods), (e) IVPP V12352 (vertically reflected), (f) IVPP V11977 (vertically reflected), and (g) IVPP V11553 (vertically reflected). All are in lateral view except for the dentary of (f) which is in in ventral view. (d) Is redrawn from6p. 156, (e–g) are redrawn from4. d Dentary, lr lower rhamphotheca, n naris, p premaxilla, pf premaxillary foramina (vascularization), ur upper rhamphotheca.
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