. Breviora. . Fig. I. Ischyrhiza aronicola, AMNH 9330, rostral tooth; o, dorsal, and h, anterior views; Harbicht Hill, Hell Creek Formation, McCone Coun- ty. Montana; X 8. long, which is about maximum size of Lance Formation speci- mens (Estes, 1964. p. 14). They state (1968, p. 237) that their Turonian Eagle Ford Formation specimens are smaller than those from the Lance Formation and the one they figure (1968. fig. 3k;) is about mm long, not significantly smaller than the minimum mm of Lance specimens. Their figure 3k-m, offered as a temporal sequence of size change, thus represents a
. Breviora. . Fig. I. Ischyrhiza aronicola, AMNH 9330, rostral tooth; o, dorsal, and h, anterior views; Harbicht Hill, Hell Creek Formation, McCone Coun- ty. Montana; X 8. long, which is about maximum size of Lance Formation speci- mens (Estes, 1964. p. 14). They state (1968, p. 237) that their Turonian Eagle Ford Formation specimens are smaller than those from the Lance Formation and the one they figure (1968. fig. 3k;) is about mm long, not significantly smaller than the minimum mm of Lance specimens. Their figure 3k-m, offered as a temporal sequence of size change, thus represents approximately the size variation occurring within Lance Formation specimens, although they state (1968, p. 236) that the ". . size of the teeth in the Lance collections is very constant . ." Since they do not give size range for any of their samples, it is difficult to know in what part of the observed range their figured specimens fall. How- ever, the Harbicht Hill specimen is mm in total length, sig- nificantly exceeding the known range of Lance specimens. The crown of the Harbicht Hill specimen is longer relative to the base than in other specimens of this species, but this condition is partly the result of erosion. In other features it does not differ from /. avonicola and can be referred to it without much doubt. A late Paleocene specimen from Wyoming (Shotgun member. Fort Union Formation, specimens collected by Craig Wood) is mm long. This specimen and that from Harbicht Hill may provide substan- tiation for Slaughter and Steiner's suggestion of temporal size in- crease in /. avonicola, and may also strengthen the 'Taleocene aspect" of the Harbicht Hill locality suggested by Sloan and Van Valen (1965).. 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 Harvard University. Museum of
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