. Bulletin of the British Museum (Natural History), Geology. 274 EVOLUTION OF THE SNOUT IN ACTINOPTERYGIANS antero-lateral edge of the frontal for a short distance and fits neatly over the anterior extremities of the dermopterotic and the dermosphenotic. Both the postrostral and the nasals curve downwards anteriorly, to give the snout a rounded shape (, ). Ventrally the postrostral joins the rostro-premaxillary. Both the rostro-premaxillary and the antorbital, which meets the rostro-premaxillary posteriorly, bear pointed teeth (, ).. Ang Clav Fig. 4. Mesonichthys a
. Bulletin of the British Museum (Natural History), Geology. 274 EVOLUTION OF THE SNOUT IN ACTINOPTERYGIANS antero-lateral edge of the frontal for a short distance and fits neatly over the anterior extremities of the dermopterotic and the dermosphenotic. Both the postrostral and the nasals curve downwards anteriorly, to give the snout a rounded shape (, ). Ventrally the postrostral joins the rostro-premaxillary. Both the rostro-premaxillary and the antorbital, which meets the rostro-premaxillary posteriorly, bear pointed teeth (, ).. Ang Clav Fig. 4. Mesonichthys aitkeni (Traquair). Reconstruction of the dermal bones of the skull in lateral view. There are only two members of the infraorbital series. The first is a short rectangular bone which joins the antorbital anteriorly and the maxilla ventrally. Posteriorly it is united with the second infraorbital. The second infraorbital forms half of the posterior margin of the orbit and is concave anteriorly. This infraorbital is also concave posteriorly where it fits under the second suborbital bone, whilst ventrally its margin is convex. Dorsally the second infraorbital joins the dermos- phenotic. The dermosphenotic forms the upper posterior quarter of the orbit's margin, and posteriorly it is concave where it fits round the first suborbital. The suborbital series consists of two bones of approximately the same size and which together are oval in outline. The lower suborbital is rounded ventrally while the upper is rounded dorsally, the suture between them is Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
Size: 1861px × 1343px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
