. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. DENTITION AND TOOTH REPLACEMENT IN TWO BAURIAMORPH REPTILES 239 them. In the right maxilla the even-numbered series consisting of the 8th, 12th and 14th teeth are preserved recently after they erupted. Eruption of the 10th replacement tooth would have lagged slightly behind these teeth as in the case of the nth in the left maxilla. It therefore appears that on the left the odd teeth were erupting whereas on the right the even teeth were erupting. This may indicate that the teeth have been incorrectly
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. DENTITION AND TOOTH REPLACEMENT IN TWO BAURIAMORPH REPTILES 239 them. In the right maxilla the even-numbered series consisting of the 8th, 12th and 14th teeth are preserved recently after they erupted. Eruption of the 10th replacement tooth would have lagged slightly behind these teeth as in the case of the nth in the left maxilla. It therefore appears that on the left the odd teeth were erupting whereas on the right the even teeth were erupting. This may indicate that the teeth have been incorrectly numbered, but not necessarily because a similar phenomenon was encountered by the author in early cynodonts. A small difference in the degree of development of the. Fig. ^.. — Ericiolacerta parva. Diagrammatic representation of the order of replace- ment of the posterior teeth. A, left maxilla; B, right maxilla and C, left dentary. replacing teeth is also preserved in the odd-numbered series. The replacing tooth for the 13th is larger than those for the 9th and 11 th. Except for these minor differences it appears thai alternate teeth developed and erupted simultaneously. Similar results were obtained in Thrinaxodon (Parrington, 1936). This is in contrast to early Cistecephalus zone cynodonts (Crompton, unpublished MS.) and other early therapsids (Romer and Price, 1940), where a wave of replacement passes from back to front along each alternately numbered series. It is difficult to interpret the order of replacement in the mandible. Replacement does not appear to be of the regular alternate type observed in the maxilla. Over certain short distances there is evidence of alternate replace- ment, 10 and 8, while over others there is not. Unfortunately, the right lower dentition could not be studied. Wear of the teeth The wear surfaces indicate that the upper and lower teeth must have occluded crown to crown, and opposing upper and lower teeth did not shear past one another.
Size: 2137px × 1169px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
