Middle Devonian sea-anemone burrows, Alpertia sanctacrucensis ichnogen. et ichnosp. n., from the Holy Cross Mountains

Abstract

The new ichnotaxa, Alpertia sanctacrucensis ichnogen. et ichnosp. n., are established for the casts of burrows attributable to the life activity of sea-anemones, and occurring within the finegrained clastic deposits of late Middle Devonian (presumably Upper Givetian) age in the Holy Cross Mountains, Central Poland. The sedimentary structures featuring the ichnotope and a comparative study of the life requirements of the present-day burrowing sea-anemones indicate a shallow sublittoral environment in which these coelenterates have gregariously lived. An ichnological analysis shows that the newly established ichnotaxa should be included into the Bergaueria group of the sea-anemone burrows. The taphonomical conditions under which the swarmy populated biotopes of the sea-anemones were suddenly buried had resulted from the deposition of sandy material from storm-agitated waters (i.e., formation of tempestites). It is also suggested that other gregariously occurring sea-anemone burrows display a similar thanatocoenotic character.