In one of them, free-living, soft-bottom pedunculate colonies of Stylomaeandra sp. Several beds hosting corals are found within the marine members of the Agrio Formation (Lower Cretaceous, Neuquén Basin). Taphonomic analyses of the specimens are necessary to carry out reliable systematic studies for later measurements of richness and evenness. Samples with Tg1 are useful for systematic studies because most of the macrostructural characters are preserved almost in their original condition. This is not useful for systematic studies due to the loss of all diagnostic features. Tg3 is the stage of preservation most frequently seen in the field. Additionally, those specimens with Tg2 and Tg3 suffered a change in their macrostructural features giving rise to apparent morphological details that may lead to wrong assignments. The loss of microstructural features occurs in Tg1–Tg3, preventing assignment at the suprageneric to the specific level. Tg0 is an ideal state with preservation of the microstructure. Four taphonomic grades were defined as Tg0–Tg3, with an increasing degree of taphonomic distortion. New results are based on a taphonomic analysis carried out to recognize the bias introduced in the systematic assignments by different preservational-taphonomic-grades.
A new systematic revision of the previously studied specimens and new material lead to the rejection of the assignments to Garateastrea, Actinastrea, and Thamnasteria, which are now identified as Australoseris, Stelidioseris, and Etallonasteria, respectively, while those originally identified as Australoseris are maintained. In previous reports, four different genera of corals were identified: Actinastrea, Australoseris, Garateastrea, and Thamnasteria.
#Pes 6 parche argentino Patch
The coral patch reef of the La Manga Formation at Bardas Blancas (Mendoza Province) is a good example of this kind of structure for the Upper Jurassic (Oxfordian) of the Neuquén Basin.