Heliophycus seilacheri n. isp. and Biformites insolitus Linck, 1949 (trace fossils) from the Late Triassic of the Germanic Basin: their taxonomy and palaeoecological relevance

The star-shaped ichnotaxa Asteriacites Schlotheim, 1820 and Heliophycus Miller & Dyer, 1878 are revised. Due to lack of type material and the introduction of two names for the same structures by Schlotheim, the name Asteriacites Schlotheim, 1820 is considered a nomen dubium and its further use is not recommended. Instead, the well defined name Heliophycus Miller & Dyer, 1878 should be used for star-shaped trace fossils. A re-study of the type material of Biformites insolitus Linck, 1949 reveals that the structures are best explained as being made by asterozoans. This interpretation has significant consequences for the palaeoenvironmental interpretation of the deposits bearing Biformites. It suggests that at least some beds of the Stuttgart Formation (Middle Keuper) were deposited under fully marine conditions. A new name for star-shaped ichnofossil, Heliophycus seilacheri n. isp. is proposed. Recommendations for the wording of trace fossil diagnoses are given.