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Simon Clabby 2006
Please note that these are the names of the trace fossil, not the trace maker, as this can be impossible to determine

Beaconites

Ophiomorpha

Planolites

Skolithos

Simon Clabby 2006
   

Ancorichnus Heinberg, 1974
Pronounced
ANN-corr-ICK-nuss
Meaning
Type of Trace
Domichnia (Living trace)
Stratigraphy
Material
Cylindrical, weakly sinuous, sub- to horizontal burrow containing a central meniscate fill and a structured mantle. Unwalled.
Remarks
Made by unknown animals.
Simon Clabby 2006
   

Beaconites Vialov, 1962
Pronounced
BEE-con-eye-TEEZ
Meaning
xxx
Type of Trace
Domichnia (Living trace)
Stratigraphy
Material
Small, cylindrical, unbranched, walled, meniscate burrow. Straight or sinuous, horizontal (rarely incluined or vertical) Weakly to strongly meniscate packets or segments enclosed by distinct, smooth and unornamented burrow linings.
Remarks
Made by unknown animals, these are frequently found in heavily bioturbated layers.
Simon Clabby 2006
   

Ophiomorpha Lundgren, 1891
Pronounced
OAF-ee-oh-MOR-fa
Meaning
Type of Trace
Domichnia (Habitation trace)
Stratigraphy
Material

Vertical and horizontal three dimensional burrow systems of cylindrical tunnels 5-50 mm in diameter, with acute angled Y-shaped or T-shaped branching. At or near the points of branching the tunnels are swollen. The walls of the tunnels usually have elongate or discoidal pellets pushed into them. They are typically smoothed-off internally but exhibit a nodular mamillated, tuberculate appearance externally. The pellets are sometimes elongated parallel to the length of the tunnel and may be between 5 mm and 10 mm long.
Some burrows show longitudinal ridges on the outer surface or have an oval cross section. There may also be interconnecting tunnels that are smooth rather than nodular. The system can be over 1 m in depth and cover a wide area.

Remarks
Ophiomorpha is currently interpreted as burrows of decapod crustaceans particularly of callianassids. This interpretation is supported by the presence of Ophiomorpha-like burrows in modern sediments that are known to have been produced by callianassids. Further, fossil catlianassid claws have been found in the same rocks as Ophiomorpha. The swellings of tunnels may be turning structures, and the ridges scratch marks made by the producers perhaps during production of the burrow. Smooth tunnels were likely to have been infrequently used or constructed in relatively firm substrates and did not require the reinforcement given by pellets.
Not uncommonly, Ophiomorpha may be transitional to Thalassinoides, the two burrow morphologies occurring in close association and presumably excavated by the same organisms.
Simon Clabby 2006
   

Planolites Nicholson, 1897
Pronounced
PLAN-oh-LIE-tees
Meaning
Type of Trace
Fodinichnia (Feeding trace)
Stratigraphy
Material
These are infilled burrows up to l6mm diameter. Uniformly cylindrical or sub-cylindrical and sometimes branching. They are horizontal or gently inclined to the bedding plane, straight or gently curved and may also cross one another. The burrow fill differs from the surrounding matrix
Remarks
The interpretation of Planolites is sediment that has been passed through the gut of a worm like organism, with the infilling sediment having a different character from that of the surrounding matrix. The burrow is not lined, indicating that the organism was passing through the sediment (and vice verse) rather then living within it.

Palaeophycus has been confused with Planolites but is distinguished by identical burrow fill and matrix, indicating that the organism was using the burrow as a domicile (living trace).

Simon Clabby 2006
   

Skolithos Haldemann, 1840
Pronounced
SKOLL-ith-oss
Meaning
Type of Trace
Domichnia (Habitation trace)
Stratigraphy
Material
Parallel, vertical, sub-cylindrical, unbranched tubes between 1 mm and 15 mm in diameter, remaining constant for each tube. Tube lengths vary from 300 mm to a maximum of 1 metre. Inner walls may have fine rings around them but are otherwise unlined - The trace is most frequent in arenaceous sediments and may either be closely crowded together or more widely spaced. In bedding surface view the trace maybe preserved as pimples on the bottom of a bed
Remarks
Skolithos was interpreted originally as a plant. Other historic interpretations include the product of brachiopod pedicles or gas bubbles rising from below in the sediment. Currently the favoured trace
producers are phoronid worms.
Simon Clabby 2006
   

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