The extinction of Metapolygnathus parvus marks the end of the Carnian, for example, while the start of the Rhaetian is defined by the first appearance of the genus Misikella.

Metapolygnathus parvus 的灭绝标志着 Carnian 的结， 例如，而 Rhaetian 的开始是由 Misikella 属的首定义的。