The converging results of microstructural analysis and molecular phylogeny: Consequence for the overall evolutionary scheme of post-Paleozoic corals and the concept of Scleractinia

During the last three decades, a series of paleontological and biological results have brought considerable changes to the long-standing question of a possible relationship between the Paleozoic and modern corals. Microstructural descriptions of samples from the alpine outcrops (Salzkammergut and Dolomites) along with new specimens from Turkey have shown first that the classical Wells’ scheme have to be re-examined. Accordingly, several investigations based on molecular phylogeny have repeatedly led to the conclusion that, at the family level, the taxonomy inherited from Vaughan and Wells cannot be maintained. From an overall evolutionary viewpoint, agreement also exists between microstructural analysis and molecular phylogeny. A recently discovered Triassic family, the Pachythecalids, exhibits highly unexpected skeletal features and microstructures in both septa and walls. Additionally, structural relationships between walls and septa demonstrate a particular mode of growth, with ontogenic priority to the theca. Comparison of the corallite microstructures suggests that most of the Triassic fauna can be derived from this unique family by an evolutionary process during which the septal system became progressively prevalent upon the wall. This monophyly of the modern corals is also well supported by molecular phylogeny. esent concept of Scleractinia has to be re-examined because it cannot include neither Pachythecalids, probably related to the Late Permian Polycoelids, nor some other post-Paleozoic corals, including extant Guyniidae, with long recognized specific structural patterns.