Ichnogenus: Planolites Nicholson, 1873

Stratigraphic Occurrences

Geographic Occurrences

Stratigraphic Description

Sequences (Formations)

  • C3 Sequence (Corryville)
  • C5 Sequence (Bull Fork)

Identification in Hand Sample

  • General morphology: Cylindrical or subcylindrical burrows, straight to curved
  • Branching: None
  • Surface ornamentation: May have striations parallel to burrow
  • Fill: Infilled; in the Cincinnatian, traces usually occur as isolated tunnels that have been infilled with host sediment
  • Lining: None
  • Spreiten: None

Paleoenvironmental Parameters

  • Substrate: Soft- to firmground
  • Oxygen content: Low-high
  • Nutrient content: Moderate-high
  • Energy: Low-high


  • Behavior: Deposit feeding, dwelling
  • Tracemaker: Various invertebrates including worms

Potential Environments

  • Shallow to deep marine
  • Continental (alluvial, lacustrine, eolian)

Planolites from the McMillan Formation of Maysville, Kentucky (OUIP 730)

Published Description

Holland (UGA Strat Lab, 2013):

  • Repichnia (Crawling traces) – “Planolites is an unbranching, unlined burrow filled with sediment that is distinctly different from surrounding sediment. It is distinguished from Palaeophycus, another unbranching horizontal burrow, which is lined and is filled with sediment essentially identical to the surrounding sediment.”

Hasiotis (KU, 2013):

  • Description: Simple, unlined, unbranched cylindrical or subcylindrical infilled burrows, straight to gently curved, horizontal to oblique to bedding planes. Burrows may cross-over.
  • Interpretation: Deposit feeding, dwelling; marine to continental. Found in alluvial, lacustrine, and eolian settings; various invertebrate burrowing organisms including worms and insects.
  • Remarks: Often difficult to distinguish between Palaeophycus, a passively filled burrow, from Planolites, a burrow formed by active backfill that may be of similar size, shape, and orientation (Pemberton and Frey, 1982; Buckman, 1995; Keighley and Pickerill, 1995).

Fossils of Ohio (1996):

  • Planolites is a more or less horizontal, straight to curved burrow that does not have any apparent lining. It can be confused with Paleophycus, another horizontal to subhorizontal burrow, which does have a distinct lining. Planolites is rarely branched. In theory, differentiating the two genera is straightforward, but in practice, distinguishing them may require detailed study of the composition of each specimen and the matrix surrounding it. To confuse matters even further, the two forms may occur on the same slab. Planolites is common in Silurian rocks of western Ohio. It is also one of the most common Ohio ichnofossils overall, and may be found in many of the Ordovician, Devonian, Mississippian, and Pennsylvanian rocks of Ohio. This ichnofossil was formed by predacious or filter feeding worms.

Treatise on Invertebrate Paleontology, Part W, Miscellanea Supplement 1 (1975):

  • Description: “Cylindrical or subcylindrical infilled burrows (diameter up to 15 mm), straight to gently curved, nonbranching; usually more or less horizontal or oblique to bedding planes, penetrating sediment in irregular course and direction, may cross one another.” W. Hantzschel 1975
  • Interpretation: Interpreted as filled endichnial burrows (German, “Stopftunnel”); the name Planolites, explicitly established by Nicholson (1873, p. 288) for “burrows filled up with the sand or mud which worm has passed through its alimentary canal”; simple burrows showing transverse annulations (“packing structure,” “back-filling”) have been place in Planolitesby several authors (e.g. Chisholm (1970, p. 24) fir trace fossils from the Carboniferous of Scotland). Planolitesis often difficult to distinguish from morphologically similar PaleophycusHall; for discussion see Osgood (1970, p. 376) (fillings of Paleophycusare generally regarded as apparently not having been passed through the gut of animals); several “species” assigned to Paleophycus, Chondrites, and even Arthrophycus more correctly referable to Planolites; P. rugulosus Reineck, 1955, type species of Scoyenia White; P. opthalmoides Jessen, 1950, type species of Opthalmidium Pfeiffer, 1968 (superfluous name), for discussion of that “species” see Seilacher (1963 p. 84), “guide fossil” for Upper Carboniferous “Augenschiefer” of Westphalia; Precambrian “species” described by Walcott (1899, 1914) were recently interpreted by Cloud (1968 p. 55) as “algal?”