Balanoglossites-burrowed firmgrounds – The most common ichnofabric on earth?

The ichnogenus Balanoglossites Mägdefrau, 1932 is a common constituent of firmground ichnofabrics in shallow-marine carbonates of the Middle Triassic Germanic Basin, from where it has been known for about 220 years. Despite its basin-wide distribution, this characteristic trace fossil only rarely has been recognised elsewhere. Instead, such burrows have been assigned to different ichnotaxa, foremost among them the superficially similar ichnogenus Thalassinoides Ehrenberg, 1944. A rigorous application of ichnotaxobases as defined in their diagnoses and evidenced by their type material, relevant ichnospecies such as Balanoglossites triadicus Mägdefrau, 1932 and B. ramosus Knaust, 2008 can be distinguished from Thalassinoides suevicus (Rieth, 1932) and T. paradoxicus Kennedy, 1967. Balanoglossites is assumed to be produced by polychaetes, whereas Thalassinoides results from the activity of crustaceans. A review of the literature together with new observations from 87 stratigraphic units reveals that Balanoglossites is a very common constituent of mainly monospecific ichnofabrics in carbonates and has a wide distribution in shallow-marine environments from the Ediacaran throughout the Phanerozoic. Its distinction from similar ichnotaxa, such as Thalassinoides, increase its value as facies indicator and for sequence-stratigraphic analysis.