A total of 407 samples from Holes 1129C, 1131A, and 1132B were examined in this study (Table T1). These samples contained common to abundant bryozoan skeletons. More than 60 genera were present. About 80% of the genera were assigned to cheilostomes. Although the cyclostomes were not so diverse, they were volumetrically important constituents. The bryozoan fauna was dominated by delicate branching cyclostomes and flat robust branching, articulated branching, and fenestrate cheilostomes. Large fragments of nodular/arborescent cheilostomes were rare but, when present, comprised >50% of the total bryozoan skeletal weight. Articulated branching cyclostomes and articulated zooidal cheilostomes were found in most samples, but they were minor components. The dominant genera included Adeonellopsis, Cellaria, Phidoloporidae gen. indet., Nevianipora, Idmidronea, Hornera, and Crisia. Surface features of the bryozoan skeletons were well preserved, although the zoaria were broken and fragmented. Some skeletons were abraded and/or cemented.
We studied three genera of bryozoans (Idmidronea spp., Nevianipora sp., and Adeonellopsis spp.) because they were abundant in many samples (Fig. F5). Their characteristic features were as follows:
- Nevianipora sp. is a delicate branching cyclostome, the colonies are branched dichotomously, the transverse shape of the branch is oval with flattened back, the autozooid opening is limited to one side of the branch, and peristomes are projected alternately (Fig. F5A).
- Idmidronea spp. are also a delicate branching cyclostomes but differ from Nevianipora sp. by forming more delicate and fragile colonies (Fig. F5B).
- Adeonellopsis spp. are flat robust branching cheilostome. Their colonies are more robust than the other genera (Fig. F5C).