Tabulates, subclass or order Tabulata, are extinct corals of anthozoans. Tabulates, unlike rugosans, were always colonial organisms. They have simple calcareous skeleton, colonies consisting of prismatic or tube-like corallites communicating by mural pores or pore channels or tunnels. Polyps lived inside corallites as chambers with base-like tabulae below and septal spines or laminar septa on sides protruding from the corallite wall. Tabulate corals are taxonomically complicated because of their simplicity. Favositids are characterized by closely packed corallites with mural-pores and their morphology is so variable that it differs even within a colony. Heliolitids are more complicated because of their coenenchymal tissue between corallites, which consists of tiny tubes - tubuli or wavy dissepiments. Halysitids are similar with having often coenenchyme, but their corallites are enclosed into ranks of various shape and size. Syringoporids form fasciculate colonies consisting of tubes having little space around and being connected by pore tunnels. Auloporids are reptant forms encrusting other organisms, as a small horny network.
Tabulate corals occurred in the Ordovician Period of America and Siberia, much earlier than in Baltoscandia. The first appearances of tabulates Lyopora, Eoflecheria, Saffordophyllum and Protaraea in Baltica are known from the level of the Oandu Stage. Estonia is rich in Ordovician and Silurian tabulates, which are easy to find in localities of Hiiumaa, Vormsi and Saaremaa. Quarries in mainland are nice places to observe tabulates in their living position.
Tabulates are large, but their finer taxonomy is observed only from peels and thin-sections. Normally pair of thin-sections is made from transverse and vertical directions of colony growth. Peel is an acetate replica from the polished and etched surface of the colony cut. Thin-sections are thin pieces of colonies, clued to glass and grinded down until 50 microns. Their scanned and photographed images are investigated later by using different software.
Role in geology
Tabulates are sessile organisms which preferred only shallow seas and are not mush useful in stratigraphy. They were spread on ancient oceans sporadically or formed bioherms or biostromes. Together with strtomatoporoids, rugosans and other fossils in the same community, they are informative in palaeoecology. Sedimentological processes are readable also from the shape and growth details of such organisms.
Selection of related publications
- [DOI] . Palaeoecology of corals and stromatoporoids in a late Silurian biostrome in Estonia
- [DOI] . A new microconchid species from the Silurian of Baltica
- [DOI] . Growth characteristics of Protoheliolites norvegicus (Tabulata; Upper Ordovician; Estonia)
- [DOI] . New endobiotic cornulitid and Cornulites sp. aff. Cornulites celatus (Cornulitida, Tentaculita) from the Katian of Vormsi Island, Estonia
- . The oldest heliolitids from the early Katian of the East Baltic region
- [DOI] . Diverse early endobiotic coral symbiont assemblage from the Katian (Late Ordovician) of Baltica
- [DOI] . The worm endosymbionts in tabulate corals from the Silurian of Podolia, Ukraine
- . The earliest endosymbiotic mineralized tubeworms from the Silurian of Podolia, Ukraine
- . 10th International Symposium on Fossil Cnidaria and Porifera. Excursion B2: Lower Paleozoic geology and corals of Estonia. Excursion Guidebook
- [DOI] . Morphological variation of the tabulate coral Paleofavosites cf. collatatus Klaamann, 1961 from the Silurian of the Bagovichka River localities, Podolia (Ukraine)
- . Intraspecific variation in Wenlock tabulate corals from Saaremaa (Estonia) and its taxonomic implications
- . Stromatoporoid response to muddy substrates in Silurian limestones
- . Classification and controls of internal banding in Palaeozoic stromatoporoids and colonial corals
- . Cystihalysites sp. and its significance to biostratigraphy and event stratigraphy in the Ludlow (Late Silurian) of Gotland, Sweden
- . Locality descriptions
- . Tabulate corals from the Lower Silurian of Jämtland (Sweden)
- . Description of the type section, cyclicity, and correlation of the Riksu Formation (Wenlock, Estonia)
- . Environment related morphological variation in Early Silurian tabulate corals from the Baltic area
- . The halysitid coral genera Halysites and Cystihalysites from Gotland, Sweden
- . Heliolitine corals of the upper Douro Formation (upper Silurian), Canadian Arctic Islands.
- . The system of heliolitoids
- . Growth form in Silurian heliolitid corals: the influence of genetics and environment.
- . Heliolitidis in the East Baltic Late Silurian coral communities
- . The Tabulate corals of Jaani and Jaagarahu Stages (Wenlockian, Estonia) and their Biozones