ABSTRACT

"Tadpole nests" are a true biogenic sedimentary structure known only from the Recent. All known occurrences of supposed fossil forms have been disputed and are considered to be interference ripple marks of inorganic rather than of organic origin. Silurian, Carboniferous, and Triassic "tadpole nest"-like structures could not have been produced by tadpoles because frogs did not appear until the Jurassic Period. A new occurrence of Recent "tadpole nests" from New York indicates that tadpoles produce nests with their tails while feeding from bottom sediments and that their delicate nature severely limits their chances of preservation in the fossil record.

The term "tadpole holes" (Dionne, 1969) is unnecessary because the term it was meant to replace, "tadpole nests," is correct by definition. Although Benjaminichnus Boekschoten, 1964, was proposed for Recent "tadpole nests" and was also intended for any fossil forms that may some day be found, it is an objective synonym of Batrachiodes Hitchcock, 1858 (non Lacepede, 1800), an inorganic sedimentary structure (interference ripple marks).

We recommend strongly that Recent biogenic sedimentary structures, and other potential trace fossils with known producers, not be given formal taxonomic names. Instead, the taxonomic (or colloquial) name of the organisms responsible for a structure should be used for reference. The possibility of such a structure being found as a trace fossil is insufficient justification for giving it a taxonomic name.