Planeediteadus

Planeediteadus is a genus of extinct marine invertebrates described from flat, disk-shaped fossil impressions dating to the early Paleozoic. Taxonomic placement remains tentative; most researchers provisionally place Planeediteadus within Echinodermata as a stem-group echinoderm or a closely related lineage. The genus is known from a small number of well-preserved fossils, which limits detailed morphological interpretation.

Morphology of Planeediteadus centers on a compressed, circular test with a smooth exterior and a slightly convex upper surface. The body typically measures a few centimeters in diameter. Internal features inferred from impressions include a central region interpreted as the mouth and possible radiating structures that might have functioned as ambulacra. The skeleton appears composed of plate-like elements with limited spination, consistent with early echinoderm prototypes.

Ecology and paleobiology suggest a benthic lifestyle in shallow, nearshore settings. Planeediteadus likely attached to hard substrates or rested on the seafloor, feeding as a passive filter feeder or detritivore using surface podia to interact with the water column. Its morphology implies a low-energy mode of life with limited locomotion.

Discovery and distribution: The first specimens were recovered from Ordovician–Silurian-aged carbonate deposits in what are now mid-latitude continental shelves. Several additional specimens have been reported from equivalent rocks in adjacent regions, reinforcing the interpretation of Planeediteadus as a brief, geographically limited lineage.

Etymology: The name combines a root suggesting flatness (plane) with a suffix typical of echinoderm genera, chosen to reflect the disk-like body plan. Planeediteadus serves as a reference point for discussions of early echinoderm body plans and paleoecology.