Palaeoaplysina is a genus of tabular, calcified fossils that are a component of many Late Palaeozoic reefs.[1] The fossil acted as a baffle to trap sediment. Historically interpreted as a sponge or hydrozoan,[2] recent studies are converging to its classification in the coralline stem group, placing it among the red algae.[1]
Morphology
The thalloid organism had a series of internal canals opening on one side of the body (presumably the upper side), and volcano-like protuberances on that same side inviting comparison to filter-feeding organisms. On the other hand, it seems to have had a calcified cellular make up akin to that of the coralline reds, suggesting that it was either a stem-group coralline or a coralline-encrusted filter feeder.[3]
Distribution
The organism is widespread in the tropical and near-tropical margin of the Laurentian continent (45–15°N), but is not found elsewhere.[4] Its oldest reported occurrence is Middle Pennsylvanian (mid- to late Moscovian)[5] and youngest is the late Sakmarian.[3] It acts as an important reservoir rock for oil deposits.[3]
^Davies, G. R.; Nassichuk, W. W. (1973). "The Hydrozoan? Palaeoaplysina from the Upper Paleozoic of Ellesmere Island, Arctic Canada". Journal of Paleontology. 47 (2): 251–265. JSTOR1302890.
^Vachard, D.; Kabanov, P. (2007). "Palaeoaplysinella gen. Nov. And Likinia Ivanova and Ilkhovskii, 1973 emend., from the type Moscovian (Russia) and the algal affinities of the ancestral palaeoaplysinaceae n. Comb". Geobios. 40 (6): 849–860. doi:10.1016/j.geobios.2007.01.006.
