GARDINERIA - A SCLERACTINIAN LIVING FOSSIL

The basic architecture (Bauplan) and microstructure of the skeleton of Recent Gardineria are noticeably different from those of most other m odern scleractinians. The wall of the Gardineria skeleton is entirely epithecate (non-trabecular). while in the majority of modern Scleracti nia the epitheca is either absent or added to the main wall which usua lly is of trabecular nature. These different patterns of theca formati on reflect significant anatomical differences in the peripheral parts of the polyp. The Bauplan of Gardineria pattern, exceptional in the mo dern scleractinian fauna, was widespread among early Mesozoic corals, particularly among the Triassic protoheterastraeids. Similar skeletons also occur in some late Palaeozoic rugosans (e.g., polycoeliids). Zar dinophyllum zardini, an aberrant Triassic scleractinian coral, with a supposed rugosan septal insertion, supports the hypothesis of the rugo san origin of the Scleractinia.