Potential Evolutionary Significance of Meniscate Trace Fossils (Beaconites/Taenidium), from the Lowville Limestone (Upper Ordovician), Mohawk Valley, New York

Horizontal meniscate burrows assignable to Beaconites (or Taenidium) barretti from the Upper Ordovician Lowville Limestone are exposed at Ingham Mill (East Canada Creek, between Herkimer and Fulton counties) in upstate New York. These specimens are noteworthy for several reasons. 1) They are the oldest known specimens of this taxon; the previously oldest records are Late Silurian; 2) They are the largest known specimens of this taxon, with widths (6-7 cm) more than double typical widths. 3) They may be unique in frequently ending with a circular feature, suggesting an inclined or vertical component, and so deep burrowing behavior. 4) They occur on hummocky surfaces associated with marine tidal channels. Silurian occurrences are also in intertidal carbonates, but this form is best known from Devonian and Carboniferous rocks that formed in terrestrial or lacustrine environments.

Meniscate burrows of this type have been attributed to numerous taxa, most recently myriapods, perhaps arthropleurids. Modern myriapods are not normally marine nor are they active burrowers. The Ingham specimens, therefore, may be one of the earliest known records of relatively large, myriapod or myriapod-like animals, and may indicate that such groups had burrowing habits before they began to make the evolutionary transition to the terrestrial environment.