| 释义 |
serpenticone Palæont.|sɜːˈpɛntɪkəʊn|
[f. serpenti-, comb. form of serpent n. (see -i-) + cone n.1]
An ammonoid in which the whorls are slender and overlap very little, so that the shell resembles a coiled snake.
1923H. H. Swinnerton Outl. Palæont. x. 214 The forms assumed by these derivatives [of cadicones] were determined mainly by modification of the whorl shape in two directions. In the one the venter and dorsum became arched; the outer consequently embraced the inner whorls and the umbilicus became narrower and even disappeared. The shell thus produced was globose in shape and is described as a sphærocone... In the other modification the whorl increased in height..; the effect of this was to produce a shell with a widely open umbilicus and having the appearance of a coiled snake. The descriptive term serpenticone is therefore applied to this type of shell. 1970R. M. Black Elements Palaeont. viii. 87 Dactylioceras..has an evolute shell with a wide, shallow umbilicus; the whorl section is oval. It is a typical serpenticone. |