Which of the following developed for the first time in Annelids?
(2) Development of a true coelom
(3) Metameric segmentation
(4) Both 2 and 3
(3) Metamerism is presence of linear series of body segments. These segments are fundamentally similar in structure. All structure may not be exactly alike. This appeared for the first time in Annelids. In Annelida, true coelom also appeared for the first time in the course of evolution.