Large Camborygma isp. in fluvial deposits of the Lower Permian (Asselian) Dunkard Group, southeastern Ohio, U.S.A.

Accepted Manuscript Large Camborygma isp. in fluvial deposits of the Lower Permian (Asselian) Dunkard Group, southeastern Ohio, U.S.A.

Daniel I. Hembree, Emma S. Swaninger PII: DOI: Reference:

S0031-0182(17)30801-5 doi:10.1016/j.palaeo.2017.12.003 PALAEO 8568

To appear in:

Palaeogeography, Palaeoclimatology, Palaeoecology

Received date: Revised date: Accepted date:

1 August 2017 5 December 2017 5 December 2017

Please cite this article as: Daniel I. Hembree, Emma S. Swaninger , Large Camborygma isp. in fluvial deposits of the Lower Permian (Asselian) Dunkard Group, southeastern Ohio, U.S.A.. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Palaeo(2017), doi:10.1016/j.palaeo.2017.12.003

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ACCEPTED MANUSCRIPT Large Camborygma isp. in fluvial deposits of the Lower Permian (Asselian) Dunkard Group, southeastern Ohio, U.S.A.

Department of Geological Sciences, Ohio University, 316 Clippinger Laboratories, Athens,

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Daniel I. Hembree a*, Emma S. Swaninger a

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Ohio, 45701, U.S.A., [email protected]

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*Corresponding author

ACCEPTED MANUSCRIPT ABSTRACT The lower Washington Formation of the Lower Permian (Asselian) Dunkard Group in southeastern Ohio contains large burrows exposed in cross section in a laterally discontinuous sandstone bed. This study examined the morphology of the burrows and their associated

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lithofacies to interpret the environmental conditions under which they were produced as well as

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the behavior and identity of the trace maker. Mudstone facies below and above the burrow-

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bearing sandstone consist of reddish-brown to variegated paleosols containing rhizohaloes, argillans, and large-scale slickensides, as well as thinly laminated, organic-rich shales containing

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plant fossils. The sandstone facies is 94–147 cm thick, thinly bedded to massive, and fine- to

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medium-grained. The lithofacies are interpreted as deposits of crevasse splays, abandoned channels, and proximal to distal floodplains. Sixty burrows consist of vertical, subvertical, J-

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shaped, Y-shaped, and complex networks of branching shafts and tunnels. The burrows range

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from 5–180 cm in length and 0.8–3.6 cm in width. The main shaft’s angles are typically ~90°, although are rarely 30–70°. Branching angles of subvertical and Y-shaped burrows vary from 0–

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90°. Many burrows extend to the top of the sandstone bed, but others turn into or out of the bed.

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The morphology of the burrows is most similar to Camborygma, known from continental deposits of the Permian to recent. While Camborygma has been previously reported from the

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Permian, this is the first occurrence in the Late Paleozoic Appalachian Basin extending its geographic range. The Dunkard burrows are similar to those of modern freshwater decapods, particularly crayfish. Decapod body fossils are not known from the Dunkard Group, yet these burrows are highly suggestive of their presence. Therefore, these fossil burrows contribute to the paleoecological interpretation of the Dunkard Group, helping to fill in gaps of the terrestrial fauna not otherwise preserved in the fossil record. Decapod burrow morphologies are highly

ACCEPTED MANUSCRIPT variable depending on burrow function and environment. The Dunkard burrows are similar to secondary dwellings, with few open water attachments, multiple branches, and shafts likely extending to the water table.

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Keywords: trace fossil; continental; decapod; paleoecology; Paleozoic

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1. Introduction

Paleozoic continental strata are often devoid of abundant body fossils. However, this is

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generally not a result of an absence of life in the environments in which they were deposited.

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Instead the problem is typically a matter of taphonomy. Soft-bodied or small organisms are lost to processes of decay and dissolution in subaerial environments leading to incomplete

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preservation of terrestrial ecosystems (Martin, 1999). Evidence of the diversity of life in

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subaerial environments can instead be found through trace fossils which are more resistant to taphonomic processes.

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Trace fossils are produced by organisms within or on a substrate and are representations

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of behavior (Bromley, 1996). Interactions between organism behaviors and various media are expressed by the physical reworking of the sediment through feeding, dwelling, locomotion,

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reproduction, and predation (Bromley, 1996). Individual organisms can construct different types of traces and simple trace morphologies may be produced by many different types of organisms (Bromley, 1996) However, the morphology of some traces is unique to certain organisms, allowing some trace fossils to be used as proxies for specific organisms (Seilacher, 2007; Hembree, 2016). Details of ancient environments and climates can also be interpreted by comparing assemblages of trace fossils to similar biogenic structures produced by modern trace-

ACCEPTED MANUSCRIPT making organisms under similar environmental conditions (Bromley, 1996; Hasiotis, 2007; Hembree, 2016). The analysis of trace fossils, therefore, is vital to the interpretation of paleoecological, paleoenvironmental, and paleoclimatic conditions. Large burrows in a sandstone bed of the Lower Permian (Asselian) (304–296 Ma) lower

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Dunkard Group (Washington Formation) of southeast Ohio exhibit vertical, subvertical, J-

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shaped, Y-shaped, and complex branching morphologies. This paper presents a detailed

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examination of the morphology of the burrows and their associated lithofacies to interpret the behavior and identity of the trace-making animal as well as the environmental conditions under

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which the burrows were produced. These data add to and improve the paleoenvironmental and

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paleoecological interpretations of the Late Paleozoic Appalachian Basin and highlight the

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importance of trace fossils to understanding ancient terrestrial ecosystems.

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2. Geologic setting

The Dunkard Group crops out over 12,800 km2 across Ohio, West Virginia, and

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Pennsylvania, near the central Appalachians (Fig. 1A) (Martin, 1998). The Dunkard Group is

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generally defined as Late Pennsylvanian to Early Permian in age (Fig. 2A) (Martin, 1998). Fossils from the Dunkard Group have provided some debated biostratigraphic control

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(Beerbower, 1961, 1969; Martin and Henniger, 1969; Martin 1998), but recent evidence from plant, invertebrate, and vertebrate fossils suggests that most, if not all, of the Dunkard is Asselian to Sakmarian in age (Fig. 2A) (Martin, 1998; Tibert et al., 2011; Lucas, 2013; Schneider et al., 2013). At the approximate time of deposition of the Dunkard Group, Ohio was located at a paleolatitude between 7–15° S and to the northwest of the epicenter of the Allegheny orogeny (Opdyke and DiVenere, 1994; Scotese, 1994).

ACCEPTED MANUSCRIPT The Dunkard Group is largely composed of sandstone, gray to green laminated shales, red mudstones, limestone, and coal (Fig. 2B) (Sturgeon, 1958; Martin, 1998; Fedorko and Skema, 2013). Dunkard Group strata are interpreted to be the deposits of a lower and upper fluvial plain with a surrounding fluvial-lacustrine-deltaic plain, freshwater lakes, and swamps

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(Beerbower, 1961; Phillips and Peppers, 1984; Martin, 1998; Cecil, 2013). Thinly bedded,

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lenticular sandstone deposits are interpreted as fluvial channels and levees and are surrounded by

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blocky to platy mudstones interpreted as paleosols (Martin,1998; Hembree and Blair, 2016;

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Hembree and Bowen, 2017). The variation in color of the paleosols, from red to greenish-gray, as well as other pedogenic features such as nodules, slickensides, and cutans is interpreted to be a

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result of changes in environmental and climatic conditions over the time of deposition and

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3. Study area and methodology

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pedogenesis (Martin, 1998; Hembree and Blair, 2016; Hembree and Bowen, 2017).

The fossil burrows occur in an outcrop approximately 36 km southeast of Athens, Ohio,

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near Coolville, Ohio, along U.S. Route 50 (39.212823°, -81.826446°) (Fig. 1B). Preserved in an

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approximately 1-m-thick sandstone bed of the lower Washington Formation, the fossil burrows are dispersed along the length of the outcrop. Sixty burrows were described qualitatively and

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quantitatively through the documentation of their general morphology, orientation, burrow measurements (straight line length, total length, width, and slope), and distribution distances. Complexity and tortuosity were calculated to provide scale-independent metrics in order to compare burrows of different absolute sizes. Complexity is the sum of the number of segments, openings, and chambers present in a burrow (Meadows, 1991). Tortuosity is the total length of a segment divided by the straight-line length between the ends of the segment (Meadows, 1991).

ACCEPTED MANUSCRIPT Each burrow was photographed and sketched in the field. Liquid latex molds of six, wellpreserved burrows of each type were made in the field by brushing multiple coats of liquid latex directly onto the sandstone, allowing them to dry, and then peeling them off of the rock. The molds were used to aid in the description of the burrows using additional qualitative

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ichnotaxobases such as types of internal surficial features.

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Three, approximately 3–4 m thick stratigraphic sections were measured and described,

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centered around the burrow-bearing sandstone to provide an understanding of the environmental settings before, during, and after the burrows were produced. The sections were located in the

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western, central, and eastern portions of the outcrop (Fig. 3A). The three sections were trenched

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to 20–40 cm deep to expose fresh rock surfaces approximately 1 m above and below the burrowbearing sandstone (Fig. 3B-D). Lithologic units in the sections were described based on grain-

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size, color, texture, sedimentary structures, and other internal features. The top and base of the

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burrow-bearing sandstone was then sampled at each section site for petrographic analysis to observe grain size, mineralogy, and structure. The six thin sections were prepared by Texas

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Petrographic (Houston, Texas) then analyzed using a BA300Pol polarizing microscope and

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4. Results

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photographed with a Moticam10.

4.1. Unit descriptions

The different lithologies in the three stratigraphic sections were divided from the base of the measured sections into 11 sedimentary units based on differences in grain size, color, texture, nodules, sedimentary structures, and fossils (Fig. 4). Similar sequences of lithologic units in the

ACCEPTED MANUSCRIPT three contemporaneous sections were used to define three lithofacies zones around and including the burrowed interval.

4.1.1. Lower mudstone facies

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Unit 1 is a 9–28 cm thick mudstone to silty mudstone that is green to gray at the base and

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becomes variegated up section. The mudstone contains abundant, dispersed small (<1 cm)

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argillans and slickensides. Unit 1 is capped by a layer of organic-rich mudstone and has a sharp upper contact.

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Unit 2 is an 8–21 cm thick, blocky to platy, reddish brown mudstone with common,

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green, circular (0.2–0.5 cm) mottles that increase in density up section. Small (<1 cm) argillans and slickensides are evenly distributed throughout the mudstone. Unit 2 has a gradational upper

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contact.

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Unit 3 is a 16–27 cm thick green to gray mudstone with uncommon, dispersed variegated zones. The mudstone contains common amorphous, yellow and red, 0.2–0.5 cm wide mottles and

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small (<1 cm) argillans that lack slickensides. Slickensides are present, but uncommon, near the

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top of the mudstone. Unit 3 has a gradational upper contact. Unit 4 is a 10–37 cm thick, blocky to platy, reddish brown mudstone with common small

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(0.1–0.2 cm wide), green mottles, medium- to large-scale (1–2 cm) argillans, and slickensides dispersed throughout. Unit 4 has a gradational upper contact. Unit 5 is an 8–9 cm thick green to gray, platy mudstone. Complete plant compression fossils and fossil plant debris are concentrated along bedding planes in the upper 2 cm of the mudstone. Unit 5 has a gradational upper contact.

ACCEPTED MANUSCRIPT Unit 6 is a 15 cm thick blocky to platy, reddish brown mudstone with abundant, small (0.1–0.2 cm wide) green mottles and medium-sized (~1 cm) argillans dispersed throughout the unit. Unit 6 has a gradational upper contact. Unit 7 is an 8 cm thick blocky to platy, drab green to gray mudstone that coarsens

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upward. The top of the mudstone is variegated, just below the sharp contact with the overlying

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sandstone bed.

4.1.2. Middle sandstone facies

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Unit 8 is a 94–147 cm thick, fine- to medium-grained sandstone containing large, vertical

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to subvertical burrows (see section 4.2). The sandstone has varying thicknesses along the length of the outcrop, with a general trend of thickening toward the east. The sandstone is moderately

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well-sorted at the top of the bed and less well-sorted at the bottom (Fig. 5). Unit 8 is composed

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of sand-sized grains of quartz, muscovite, and biotite with finer (silt, clay) grains between the clasts; quartz is the dominant component (>80%) (Fig. 5). More angular grains occur toward the

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bottom of the sandstone beds and become more rounded toward the top.

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Unit 9 consists of 22–26 cm of intercalated fine- to medium-grained sandstone and shale. Sandstone beds are 2–5 cm thick and fine upward into 1–2 cm thick layers of shale. Each shale

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layer is sharply overlain by a sandstone bed. Unit 9 has a gradational upper contact. 4.1.3. Upper mudstone facies Unit 10 is a 22–40 cm thick blocky, green to gray sandy shale that fines upward. Small (<1 cm) argillans, slickensides, and sparse to extensive, 0.1–0.5 cm wide, red amorphous mottling increase in density up section. Unit 10 has a gradational upper contact.

ACCEPTED MANUSCRIPT Unit 11 is a 60–87 cm thick blocky, reddish brown calcareous, fining upward mudstone with small (0.1–0.2 cm wide), common green mottling, large (1–2 cm) argillans and slickensides, and small, dispersed calcareous nodules.

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4.2. Burrow morphology

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The burrows (n = 60) are exposed as weathered cross sections along the sandstone bed

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(Unit 8) and exhibit variations in general architecture and total length. The burrows typically occur individually, although some occur in clusters of 2–5 burrows, spaced 2–10 cm apart.

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Rarely, closely spaced burrows have partially overlapping elements. The burrows include

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straight to sinuous, vertical, subvertical, J-shaped, Y-shaped, and complex branching shafts and tunnels (Figs. 6–7, Table 1). The burrows may have multiple branches stemming from different

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sections of the main shaft. Thus, tortuosity and complexity of the burrows varies from 1.0–1.4

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and 1–9, respectively (Table 1). The mean widths of shafts range from 0.8–3.6 cm and the total length of the burrows ranges from 5–180 cm (Table 1). The measured lengths of the burrows are

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underestimates of their true length. Many of the burrows extend to the top of the sandstone bed,

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whereas others turn into or out of the sandstone before reaching the upper surface or are too weathered to determine where the burrow began. The slopes of the main shafts are of most

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burrows are ~90°, but in some burrows the slope ranges from 30–70° (Table 1). The slopes of the branches, however, are more variable ranging from 0–90°. The larger and deeper burrows, with lengths ranging from 38–180 cm, generally have more branches and more commonly exhibit Yshaped or complex architectures than those that are shorter and shallower. Weathered, circular cross sections contain remnants of a fine-grained (mudstone) burrow fill (Fig. 8A). The surficial

ACCEPTED MANUSCRIPT morphology of the burrows consists of a thin, oxidized lining in some specimens and rare horizontal striations along the inside of burrow walls (Fig. 8B, C). Vertical burrows (n = 39) have predominantly 90° slopes, but may be sinuous along the burrow shaft, and range from 5–88 cm in length and 1.0–3.4 cm in width (Table 1). A well-

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preserved vertical burrow (B2) has a slope of 90° with little deviation, a total length of 38 cm,

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and a mean width of 3.4 cm (Fig. 6A, B).

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Subvertical burrows (n = 13) have slopes that vary from 45–85° with occasional curves along the length of the burrow that result in a lower mean slope. Most subvertical burrows vary

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in tortuosity and have lengths between 7–107 cm (Table 1). Shorter subvertical burrows tend to

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consist of a single, straight shaft without branches, but longer specimens possess branches and may curve along the length of the burrow. A well-preserved subvertical burrow (B48) has a

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mean slope of 70°, a total length of 20 cm, and a mean width of 1.2 cm (Fig. 6C, D).

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A single J-shaped burrow (n = 1) is highly weathered and positioned in the center of the sandstone unit turning out of the bed face (Fig. 6E, F). This J-shaped burrow (B25) has a mean

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slope of 60°, a mean width of 1.8 cm, and a total length of 22 cm; the upper portion of the

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burrow is 13 cm long and the lower portion, after the curve, is 9 cm (Table 1). Y-shaped burrows (n = 5) possess two intersecting shafts, one longer than the other, with

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some variation in morphology. In the first group of Y-shaped burrows, each of the two upper shafts comprise less than half the total length of the burrow; the shafts are vertically oriented until they intersect at which point the single lower shaft bends to a more horizontal orientation. For example, the Y-shaped burrow B57 has upper branches that are 25 and 18 cm, a total length of 78 cm, a mean width of 1.5 cm, and a mean slope of 90° (7A, B). The second group of Yshaped burrows have at least one upper shaft that is more than half the total length of the burrow;

ACCEPTED MANUSCRIPT these upper shafts are vertical with some curvature along their length until they intersect at which point the lower shaft is vertically oriented. The Y-shaped burrow B41 has upper branches that are 43 and 20 cm in length, a total length of 63 cm, a mean width of 2.1 cm, and a mean slope of 90° (Fig. 7C, D).

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More complex burrows (n = 2) have multiple branches connected to a main shaft that

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suggest a modified Y-shaped morphology (e.g., B19, B27). The multiple branches intersect one

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another at varying angles and have slopes that range from 0–90° (Table 1). As a result of the number of branches the complex burrows have complexities of 9 and 5, respectively. The larger

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of the two complex burrows (B19) has a total length of 195 cm with shafts that range from 1–4

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cm in width (mean 2.5 cm) (Fig. 7E, F). Both complex branching burrows extend from the top to

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the base of the sandstone.

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5. Discussion 5.1. Paleoenvironmental interpretation

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The lithologies within the studied interval of the lower Dunkard Group, including

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multiple paleosols, plant fossil-bearing shales, and laterally discontinuous sandstones, are indicative of a continental setting (Collinson, 1996; Kraus, 1999; Fedorko and Skema, 2013).

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The shift between mudstone and sandstone facies record changes from floodplain to fluvial channel environments. 5.1.1. Lower mudstone facies This facies zone is composed of a series of reddish brown and greenish gray mudstone beds ranging from blocky to fissile in texture (Units 1–7) (Fig. 4). These mudstone beds are interpreted as a sequence of two to three stacked paleosols due to presence of simple horizons

ACCEPTED MANUSCRIPT (A, Bw, and C) bearing cutans, slickensides, mottles, and rhizohaloes (e.g., Kraus, 1999; Retallack, 2001; Hembree and Bowen, 2017). The upper surfaces of individual paleosol profiles are recognized by: 1) the occurrence of a laminated, organic-rich mudstone (Sections 2 and 3, Unit 1) and a laminated layer containing plant fossils (Sections 1 and 3, Unit 5) defining remnant

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A horizons (Retallack, 2001; Buol et al., 2003; Hembree and Bowen, 2017); and 2) sharp

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contacts between mudstones bearing pedogenic features (truncated Bw horizons) and overlying

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sedimentary units with preserved primary sedimentary structures (C horizons) (Section 1, Units 2 and 3; Section 2, Units 2 and 3) (Fig. 4). The limited pedogenic development and horizonation of

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these paleosols lead to their interpretation as Inceptisols (Buol et al., 2003; Soil Survey Staff,

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2014). The abundance of oxidized iron, blocky texture, and cutans suggests that these Inceptisols were well-drained, although the presence of slickensides and reduced zones in the B horizons

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suggests at least seasonal soil saturation (Joeckel, 1991; Hembree and Bowen, 2017). The

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stacked nature of the paleosols was likely the result of fluvial flooding events in which older soils were buried by sediment which was then pedogenically modified to form a new soil after

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exposure; this series of events produces either compound and composite series of paleosols

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depending on the frequency of the depositional events (e.g., Joeckel, 1991; Kraus, 1999). In this part of the section, a compound stacking pattern is more common. Evidence for repeated

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flooding events, relatively thin and poorly developed soil profiles, and contact with channel sandstones indicate that these paleosols formed in a distal natural levee setting (e.g., Collinson 1996; Kraus 1999; Hembree and Bowen, 2017). 5.1.2. Middle sandstone facies The thick, laterally extensive, medium-grained sandstone of the middle sandstone facies zone (Units 8–9) suggests deposition in or near a fluvial channel as channel fill, point bar, or

ACCEPTED MANUSCRIPT crevasse splay deposits (e.g., Cross and Schemel, 1956; Collinson, 1996; Martin, 1998). In general, sandstones in the Dunkard Group vary from thin, fine-grained units to very thick bedded, medium- to coarse-grained cliff-forming bodies (Martin, 1998). Smaller sandstone units (10s of cm to a few meters thick), like those of the Lower and Upper Marietta sandstones, are

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separated by multiple mudstone and thin sandstone beds and may lack sedimentary structures

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(Martin, 1998). Most architectures, sedimentary structures, and textures of Dunkard Group

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sandstones are suggestive of fluvial channel deposits that experienced lateral migration of the channel (Allen, 1965). Many Dunkard sandstones also contain interbedded siltstones and

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mudstones interpreted as channel-fill deposits (Martin, 1998).

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Paleochannels represented by four sandstone units in northwest West Virginia from the upper Monongahela Group and Waynesburg (Mather) Sandstone of the lower Dunkard Group

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included two channel sizes (Martin, 1998). The first consisted of smaller paleochannels with

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decreasing deposition over time, resulting in thin sandstone beds. The second was a larger channel that was preserved by continuous channel-fill, resulting in thick sandstone beds (Martin,

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1998). Similarly, Berryhill et al. (1971) described Dunkard sandstone bodies in Washington

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County, Pennsylvania with varying degrees of thick and thin sandstone beds interpreted as having been deposited in meandering stream systems with channels of varying size (Berryhill et

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al., 1971; Martin, 1998).

The sandstone beds in this study are most similar to abandoned channel fill deposits. This interpretation is supported by the lateral discontinuity of the sandstone beds, the general absence of sedimentary structures, the consistent grain size across the sandstone bed, and their gradation into overlying thin-bedded siltstone and mudstone units (e.g., Collinson, 1996).

ACCEPTED MANUSCRIPT 5.1.3. Upper mudstone facies This facies zone has a lower, thin layer of green and gray mudstone capped by a thick, blocky, red mudstone (Units 10–11). Sparse rhizoliths in the mudstone indicate that this unit is a paleosol (Retallack, 2001; Kraus and Hasiotis, 2006; Hembree and Bowen, 2017). The mudstone

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lacks primary sedimentary structures and has a blocky texture also suggesting pedoturbation

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(Kraus, 1999). Sporadically distributed, mm–scale, calcareous nodules occur in the red

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mudstone, suggesting a seasonal, wet-dry cycles (Wright, 1982; Prather, 1985; Allen and Collinson, 1986; Joeckel, 1989, 1991). The presence of large-scale slickensides and argillans

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along ped planes of the red mudstone are suggestive of Vertisols (Retallack, 2001; Buol et al.,

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2003; Giles et al., 2013). Vertisols, relatively immature and poorly developed soils, are characterized by shrinking and swelling of expandable clays (smectite) that experience multiple

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wet and dry periods (Giles et al., 2013; Soil Survey Staff, 2014). Vertisols appear at the drier end

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of a wet-dry paleoclimate when the stress on the soils causes shrinking (Buol et al. 2003). The reddish brown color of the overlying mudstone indicates the presence of oxidized iron (hematite)

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produced in well-drained sediment during seasonal wetting and drying (Kraus and Hasiotis,

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2006). The color of the lower greenish and greenish gray reduced zone, however, suggests seasonal flooding and poor drainage, thereby causing anoxic conditions in the lower B horizon

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(Joeckel, 1991).

5.2. Burrow preservation The Dunkard Group burrows were excavated through cohesive sand and likely maintained as open structures. They were passively filled, during or after occupation of the burrows, by overlying sediment that entered through the surface openings, likely during a

ACCEPTED MANUSCRIPT flooding event. Remnants of fine-grained fill material and the generally good preservation of the shafts and tunnels support this interpretation. The relatively consistent width of the burrow elements and the presence of horizontal striations on the inner wall of some shafts suggest that the passive fill did not substantially alter the original burrow shape. The trace fossils are,

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therefore, fair representations of the burrows original features.

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Although trace fossil morphology is largely dependent on the behavior of the trace

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maker, taphonomic processes such as compaction, diagenesis, and erosion are also important (Bromley, 1996; Savrda, 2007). Compaction affects the burrow morphology by altering cross-

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sectional height or width values or by increasing tortuosity (Hembree et al., 2011). Diagenesis

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can alter the size and morphology of burrows through accretion of additional minerals on the outer surface or other surficial changes (Savrda, 2007). Erosion affects preservation by

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truncating or eliminating burrow architectural elements (Savrda, 2007).

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Although some of the burrow tortuosity may be a result of compaction of the sand after burial, the predominantly vertical orientation of the burrows prevents the distortion of the

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burrows’ cross sectional shape and dimensions by this process. There are no apparent changes

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from diagenesis since there is no evidence of post-burial alteration and secondary mineral growth that may have altered the size or the shape of the burrows. The sharp walls of the burrows are

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clearly defined and bioglyphs are preserved. Erosion has the greatest impact on the burrow morphology. The erosive surface across the top of the sandstone truncates the burrows’ total length. In addition, the eroded face of the sandstone bed exposed two-dimensional, vertical cross sections of the burrows, making three-dimensional reconstructions of the burrows difficult due to the loss of burrow elements.

ACCEPTED MANUSCRIPT 5.3. Ichnotaxonomy The Dunkard Group burrows have vertical, subvertical, J-shaped, Y-shaped, and complex branching morphologies. The shafts and tunnels are circular to subcircular in cross section and some possess horizontal striations on the internal walls. The burrows are generally widely spaced

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and rarely intersect one another. Ichnogenera that are similar to the Dunkard burrows include

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Skolithos, Psilonichnus, and Camborygma (Fig. 9). These ichnogenera are described as having

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vertical, Y-shaped, and multi-branching morphologies, respectively (Pemberton et al., 1992). Skolithos is a simple, vertical shaft with a generally uniform, circular to subcircular cross

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section that is generally unbranched (Fig. 9A) (Alpert, 1974; Häntzschel, 1975). Skolithos occurs

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in both marine and terrestrial environments throughout the Phanerozoic (Häntzschel, 1975). Skolithos is interpreted as a permanent dwelling produced by suspension feeding animals or

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passive carnivores (Pemberton et al., 1992).

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Psilonichnus typically has a Y-shaped morphology but may also be J-shaped and possess several small vertical branches (Fig. 9B) (Nesbitt and Campbell, 2006). The shafts are circular to

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subcircular in cross section, can vary length, and are passively filled (Pemberton and

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MacEachern, 1995; Nesbitt and Campbell, 2006). Psilonichnus first appears in the early Eocene in both marginal marine and terrestrial environments (Fürsich, 1981; Carmona et al., 2004).

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Psilonichnus is interpreted as a dwelling burrow because of the complexity of the burrow’s structures as well as the passive fill which suggests that they were kept open (Fürsich, 1981). Modern dwelling burrows of crabs and crayfish have vertically oriented, unlined burrows with Jand Y-shaped morphologies similar to that of Psilonichnus (Fürsich, 1981; Hobbs, 1981; Frey et al., 1984).

ACCEPTED MANUSCRIPT Camborygma vary in morphology from nearly vertical and subvertical shafts to Y-shaped burrows as well as complex burrow systems with multiple branches and connected corridors (Fig. 9C) (Hasiotis and Mitchell, 1993; Hasiotis et al., 1993; Bedatou et al., 2008). Shafts range from 1–14 cm in diameter and can be up to 9 m long (Hasiotis et al., 1993). Camborygma can

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have preserved surficial structures such as scrape marks, scratch marks, mud- and lag-liners,

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knobby and hummocky surfaces, body impressions, pleopod striae, and chimney structures

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(Hasiotis and Mitchell, 1993; Hasiotis et al., 1993; Smith et al., 2008). Camborygma appears during the Permian and continues into the recent. This ichnogenus is exclusively found in

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channel, levee, and floodplain deposits of fluvial environments as well as lacustrine deposits

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(Hasiotis et al., 1993; Smith et al., 2008).

Based on morphological similarity, the Dunkard Group burrows are assigned to the

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ichnogenus Camborygma. Skolithos has features similar to the Dunkard burrows like simple

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vertical shafts with circular to subcircular cross sections, but the vertical shafts of the Dunkard burrows are too sinuous for Skolithos. In addition, the morphology of Skolithos does not account

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for the larger more complex burrows. Similarly, Psilonichnus has a relatively simple Y-shaped

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morphology without complex branching forms and lacks enlarged chambers. Camborygma, however, has a variety of morphologies ranging from simple, sinuous shafts to complex

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branching systems similar to the Dunkard burrows (Bedatou et al., 2008). Like Camborygma, the more complex Dunkard burrows all share similar, architural elements with the simpler forms (Hasiotis and Mitchell, 1993). Each is composed of a different number of the same type of shafts and tunnels allowing them all to be included in the same ichnogenus.

ACCEPTED MANUSCRIPT 5.4. Trace maker interpretation Determination of the trace maker of the Dunkard burrows cannot be definitive because body fossils were not found within the burrows or in the sandstone. The general architecture and surficial morphology of the burrow can assist in the interpretation, but the size of the trace fossil

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may be misleading (Hembree, 2016). Organisms can produce burrows of equal or larger size

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than their body, which may lead to misconceptions of the trace maker (Hembree, 2016). Given

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the paleoenvironmental setting and geologic age of the burrow-bearing sandstone, potential producers of these trace fossils include arachnids such as spiders and scorpions, amphibians,

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reptiles, or decapods. Determining which is the most likely trace maker requires understanding

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the types of burrows each of these groups produce in the modern. Extant spiders produce a variety of burrow morphologies, from simple vertical shafts

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with or without expanded terminal chambers to burrows with multiple, interconnected shafts and

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tunnels (Fig. 10A) (Kotzman, 1990; Pérez-Miles et al., 2005; Machkour M’Rabet et al., 2007; Hils and Hembree, 2015). Burrow elements have circular cross sections and often possess

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multiple set of parallel scratch marks. Scorpions produce even more burrow morphologies

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including subvertical ramps, U-shaped burrows, helical burrows, and mazeworks with multiple surface openings (Fig. 10B) (Koch, 1978; Shorthouse and Marples, 1980; Polis et al., 1986;

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Hembree et al., 2012; Hembree, 2014). Burrow elements have elliptical cross sections and laterally expanded chambers. Amphibians such as salamanders produce subvertical tunnels, J-, U-, and Y-shaped burrows with elliptical cross sections (Fig. 10C) (Fernandez et al., 2013; Dzenowski and Hembree, 2014). The morphology of the burrows of salamanders and similar limbed amphibians is affected by the animals use of their sprawling fore and hind limbs in excavation which creates

ACCEPTED MANUSCRIPT significantly broader, less uniform burrow morphologies than those described in this study. Vertical elements of salamander burrows also tend to be relatively short (Dzenowski and Hembree, 2014). Extant lizards produce many different burrow morphologies including simple subhorizontal tunnels, helix-shaped burrows, and deep, mucus-lined tunnels (Fig. 10D) (Hasiotis

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et al., 2007; Catena and Hembree, 2014; Doody et al., 2014). The methods of construction of

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these burrows is similar to that of salamanders also resulting in burrow elements with varying

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widths and an elliptical cross section.

Extant freshwater decapod crustaceans including crabs and crayfish construct simple

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vertical burrows, burrows with multiple branches and chambers, and burrows with multiple

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branching tunnels with circular to elliptical cross sections (Fig. 10E, F) (Hasiotis and Mitchell, 1993; Genise, 2017). Architectural morphologies for freshwater decapods are categorized as

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Type I, II, and III, where the burrows have high complexity with many chambers, moderate

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complexity and some chamber development, or simple architectures with terminating, somewhat wider burrow ends, respectively (Hasiotis and Mitchell, 1993). Burrows of freshwater decapods

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tend to extend to the water table so that living chambers will be flooded. As a result, these

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burrows can be quite deep; in some cases, up to several meters (Hasiotis, 2007; Genise, 2017). The most likely tracemakers of the fossil burrows described here, therefore, were

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freshwater decapods based on the general architecture of the burrows, the morphology of the different burrow elements, and the interpreted depositional environment based on the associated lithofacies.

ACCEPTED MANUSCRIPT 5.5. Paleoecological and paleoenvironmental significance Freshwater decapods are aquatic crustaceans that typically live in close proximity to permanent to ephemeral bodies of water, although some are entirely terrestrial (Hobbs, 1981; Welch and Eversole, 2006; Williner et al., 2014). Many freshwater decapods produce burrows

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that serve as dwellings to protect the decapod from desiccation and predation, especially during

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periods of molting (Hobbs, 1981; Horwitz and Knott, 1983; Horwitz et al., 1985). The burrows

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vary from simple shafts to highly complex networks with multiple entrances, shafts, and chambers (Hasiotis and Mitchell, 1993; Carmona et al., 2004). Some freshwater decapods

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construct their burrows at the water front near drainage areas, river banks, or wetland areas,

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whereas others burrow away from direct water and excavate their burrows to the water table, either slightly above or below (Bedatou et al., 2008; Genise, 2017). There are even some

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freshwater decapods that do not associate with the water table at all, but instead rely on rainwater

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for survival (e.g., Horwitz and Richardson, 1986). Decapod burrows have a high preservation potential because of their depth and size

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(Hasiotis, 2002). Burrows attributed to freshwater decapods in the fossil record have been

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described from fluvial deposits as old as the Early Permian to Late Pennsylvanian (Hasiotis and Mitchell, 1993). These interpretations have been based on similarities in burrow architectures,

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branch morphologies, and chimney development between the fossil burrows and burrows of extant freshwater decapods. Burrowing freshwater decapods are divided into three categories, primary, secondary, and tertiary, based on the amount of time spent within the burrow, the burrows connectivity to the open water, and burrow architecture (Hobbs, 1981; Hasiotis and Mitchell, 1993). Primary burrowers typically construct highly complicated burrows away from open water, and seldom

ACCEPTED MANUSCRIPT leave their burrows for the majority of their lives. Secondary burrowers construct less open water attached architectures than primary burrowers, with some additional branching and chambers within the burrow. These decapods often leave their burrow. Tertiary burrowers build burrows for means of reproduction and temporary protection from desiccation, but live most of their lives

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in open water. Decapods, therefore, construct these shelters as temporary, semi-permanent and

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permanent dwellings. Individual components of decapod burrows have additional functions such

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as food, pellet and garbage storage, gardening, feeding, commensalism, breeding, and escape (e.g., Grow, 1981; Frey et al., 1984; Horwitz and Richardson, 1986; Bird and Poore, 1999;

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Fitzsimons and Antos, 2011). Burrower category, as well as the environmental conditions, can,

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therefore, be inferred from the burrow morphology. The burrows of the Dunkard Group are most similar to those of secondary burrowers, varying from relatively simple, but elongate, shafts to

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more complex branching burrows. This morphology suggests that the burrows were constructed

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in close proximity to the water source and the decapods left their burrows regularly. Freshwater decapods have a wide trophic spectrum that ranges from algae, plants, plant

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remains, insect larvae, and sometimes even vertebrates (Collins et al., 2006; Williner et al.,

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2014). Therefore, decapods can play the role of shredder, herbivore, and predator (Williner et al., 2014). Decapods generally rely on organic debris that falls into and on the sediment surface

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around their burrow (Suter and Richardson, 1977; Growns and Richardson, 1988; Sherman, 2003; Alcorlo et al., 2004; Nordhaus et al., 2006). More water-dependent decapods may utilize deposit feeding techniques and feed on nutrients that are transported from local water sources during flooding events (Hobbs, 1981). Decapods also depend on the plants and roots that surround their burrow. Decapod burrows located underneath plants have additional protection from surface conditions (e.g., Lake and Newcombe, 1975; Suter and Richardson, 1977). Plants

ACCEPTED MANUSCRIPT and roots may also be found within the burrow or as lining of the walls, and are consumed as food (Growns and Richardson, 1988; Rudolph, 1997). There is no clear indication what the Dunkard decapods fed on, but as secondary burrowers they likely relied on resources outside of their burrows including detritus, plant material, and other animals. Decapods also contribute to

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ecosystems by being the prey of many vertebrates such as fish, amphibians, reptiles, birds, and

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Beltzer, 1993; Bianchini and Delupi, 1993; Williner et al., 2014).

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mammals (Bonetto et al., 1963; Beltzer, 1983; Beltzer and Paporello, 1984; Lajmanovich and

Based on the requirements of extant decapods, the presence of decapods in this Dunkard

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Group outcrop suggests a diversity of plants and animals in this near-channel paleoenvironment.

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To accommodate this population of infaunal decapods, it is also inferred that this substrate and subsurface environment had high levels of nutrients and oxygen available for use. The nutrient

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and oxygen content of the substrate are heavily influenced by bioturbation and bioirrigation,

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respectively (Bromley, 1996; Bird and Poore, 1999). Bioturbation, such as the construction of elongate, vertical shafts by decapods, leads to increased organic content of sediment through

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surficial burial. Bioirrigation introduces oxygen to deep into the sediment assisting in aerobic

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decomposition in usually anoxic sediments. As a result, subsurface microhabitats thrive and promote the activity of microorganisms, plants, and animals. Freshwater decapods, therefore, fall

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into the category of ecosystem engineers due to their ability to alter their environment (e.g., Jones et al., 1994).

Due to their physiological sensitivities, most terrestrial decapods, both modern and ancient, tend to live at or below the water table by constructing burrows that reach the phreatic zone (Hasiotis, 2002). Smaller and simpler burrows are found closer to the water source than the deeper and more complex burrows that continue down to the water table (Hasiotis and Mitchell,

ACCEPTED MANUSCRIPT 1993). As a result, the depth and complexity of fossil decapod burrows helps to decipher the ancient water table level and its fluctuations (Hasiotis and Mitchell, 1993; Hasiotis and Honey, 2000; Retallack, 2001; Hasiotis, 2002; Smith et al., 2008). Since decapods excavate their burrow to the top or slightly below the water table, even the deepest burrows in the Dunkard sandstone

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unit suggest a relatively shallow water table (generally <1 m) in the area at the time of

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deposition.

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In near-channel subenvironments, decapods tend to be secondary burrowers (Hasiotis, 2002). The closer the decapod is to the channel margin, the greater the diversity of organisms

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and nutrient availability (Hasiotis, 2002). Therefore, by constructing their dwellings near the

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channel, decapods limit their subaerial exposure and maximize potential resources. Burrow complexity likely increased during periods without significant flooding and sediment deposition

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which would normally disturb and cause destruction to near-channel burrows (Miller et al., 1981;

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Hasiotis, 2002).

Water surplus or deficit can indicate seasonal variations in precipitation and temperature

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as well as changes in autogenic processes that shape the landscape (e.g., Brady and Weil, 2002).

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These processes result in variations in substrate type and consistency as well as organism behavior. The morphology and surficial structures of the burrows of a single type of organism

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may be altered because of these changes (Hembree et al., 2011). Variation in the morphology of the burrows across the outcrop, from simple vertical shafts to complex branching systems, are likely the result of these changes in water availability and landscape stability across the Dunkard landscape and over time.

ACCEPTED MANUSCRIPT 6. Conclusions This study documented and analyzed a series of large, vertical burrows in a laterally discontinuous sandstone bed of the Lower Permian (Asselian) Dunkard Group in southeastern Ohio. The burrows vary in morphological complexity, number of branches, and total length. The

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burrows consist of vertical, subvertical, J-shaped, Y-shaped, and complex branching shafts

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assigned to the ichnogenus Camborygma. Some of the burrows possessed series of horizontal

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striations on the inside of the burrow walls and remnants of the fine-grained passive fill along the shaft walls. While the burrow morphology was not impacted greatly by compaction or

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diagenesis, erosion did influence the completeness of some burrows. These burrows are

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preserved within a sequence of multiple reddish brown and greenish gray paleosols, plant fossilbearing, fissile shales, and sandstones interpreted as deposits of floodplains, fluvial channels, and

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slickensides suggest a seasonal climate.

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crevasse splays. Features within the paleosols including pedogenic carbonate nodules and

Although the absence of body fossils of a tracemaker makes their identification difficult,

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the architecture and surficial features of the trace fossils are most similar to burrows constructed

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by modern freshwater decapods. Based on their size, depth, and branching patterns, decapods used these burrows as permanent dwellings close to a water source. These burrows would have

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extended to the water table to provide a water-filled living chamber and likely served additional functions such as food, pellet and garbage storage, gardening, and breeding. These trace fossils further contribute to the complex Paleozoic history of trace makers and behaviors associated with Camborygma. While this ichnogenus is known from Permian deposits, this is the first occurrence in the Late Paleozoic Appalachian Basin extending the geographic range. These fossil burrows contribute to the paleoecological interpretation of the

ACCEPTED MANUSCRIPT Dunkard Group, helping to fill in gaps of the terrestrial fauna not otherwise preserved in the fossil record. Through the combination of data on body fossils and trace fossils, a more complete understanding of the composition of ancient terrestrial ecosystems can be obtained.

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ACKNOWLEDGMENTS

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We would like to thank Dr. Alycia Stigall and Dr. Doug Green for comments on an

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earlier version of this manuscript. This research would not have been possible without funding

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from the American Chemical Society Petroleum Research Fund (52708-UR8) (to DIH).

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Meadows, P.S., 1991. The environmental impact of burrows and burrowing animals – conclusions and a model. In: Meadows, P. S. and Meadows A., eds., The Environmental

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Nordhaus, I., Wolff, M., Diele, K., 2006. Litter processing and population food intake of the mangrove crab Ucides cordatus in high intertidal forest in Brazil. Estuarine, Coastal and

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Sinclair, I.K., 2001. Ichnology and sedimentology of shallow to marginal marine

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distribution of ostracodes across the Pennsylvanian–Permian boundary interval in eastern

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crab Trichodactylus kensleyi (Decapods: Brachyura: Trichodactylidae) at La Plata basin. Zoological Studies 53(1), 1–9.

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Wright, V.P., 1982. Calcrete paleosols from the lower Carboniferous Llanelly Formation, South

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ACCEPTED MANUSCRIPT FIGURE CAPTIONS Fig. 1. A) Location of the Dunkard (green) and Monongahela (orange) groups in the Appalachian Basin and the location of the study area, Athens County (blue), in southeast Ohio, U.S.A. B) Map of Athens County in southeastern Ohio and the location of the burrow-bearing

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outcrop (modified from Hembree and Bowen, 2017).

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Fig. 2. Biostratigraphic timescale and general stratigraphic columns of the Dunkard Group from Pennsylvania and Ohio. A) Inferred ages of Monongahela and Dunkard Group deposits based on

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recent fossil data (after Hembree and Bowen, 2017). B) General stratigraphic column of the

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upper Monongahela Group in southeastern Ohio (Sturgeon, 1958; Hembree et al., 2011; Hembree and Bowen, 2017) and the Dunkard Group of northern West Virginia and southwestern

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Pennsylvania (Fedorko and Skema, 2011; Hembree and Bowen, 2017). C) General stratigraphic

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column of Dunkard Group deposits near Marietta, Ohio (Martin, 1998; Hembree and Bowen,

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2017) in the approximate correlative position with section B.

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Fig. 3. A) Studied outcrop on Route 50 near Coolville, Ohio. Position of the burrow-bearing sandstone is marked by the arrow. The locations of the three described sections are indicated by

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S1-S3. B) Red and green mudstones approximately 1 m below the burrow-bearing sandstone; Unit 1–7. C) Red mudstone approximately 1 m above the sandstone; Units 9–11. D) Sandstone bed with large burrows; Unit 8.

ACCEPTED MANUSCRIPT Fig. 4. Measured sections 1-3 centered on the burrow-bearing sandstone bed. Dashed lines indicate approximate interpreted landscape surfaces. Interpreted paleosol horizons are labeled on the left side of each column.

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Fig. 5. Thin sections from the top and base of the burrow-bearing sandstone bed. Magnification

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at 4x. A, B) Section 1, top and bottom of bed. C, D) Section 2, top and bottom of bed. E, F)

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Section 3, top and bottom of bed.

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Fig. 6. In situ burrows and latex molds. A, B) Vertical shaft (B2). C, D) Subvertical burrow

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(B48). E, F) J-shaped burrow (B25).

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(B41). E, F) Complex burrow (B19).

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Fig. 7. In situ burrows and latex molds. A, B) Y-shaped burrow (B57). C, D) Y-shaped burrow

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Fig. 8. Architectural features of the Dunkard burrows. A) Oblique view of burrow (at arrow)

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extending into the sandstone bed showing the circular cross section and mudstone fill. B) Side view of a Y-shaped burrow with an oxidized lining (at arrows) around one branch. C) Side view

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of a Y-shaped burrow with a series of parallel striations (between arrows) along the inside of the burrow wall.

Fig. 9. Examples of A) Skolithos, B) Psilonichnus, and C) Camborygma.

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burrow, E, F) Modern crayfish (Cambarus) burrows.

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Figure 3

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Figure 6

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Figure 7

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Figure 8

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Figure 9

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Figure 10

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Total Lengthb

Min Width

Max Width

Mean Width

Tortuo sity

Morphol ogyc

(cm)

(cm)

(cm)

(cm)

(cm)

B1

48.0

49.0

2.0

3.0

B2

38.0

38.0

2.0

4.5

1

1.02

V

3.4

90

1

1.00

V

B3

24.0

24.0

2.0

2.5

2.3

90

1

1.00

V

B4

11.0

11.0

1.0

1.0

1.0

90

1

1.00

V

B5

40.0

B6

41.0

58.5

1.0

3.0

1.6

90

3

1.46

Y

41.0

2.0

3.0

2.6

90

3

1.00

Y

B7

69.0

71.0

1.5

2.5

1.9

90

1

1.03

V

B8

28.0

30.0

3.5

5.0

4.2

90

1

1.07

V

B9 B1 0 B1 1 B1 2 B1 3 B1 4 B1 5 B1 6 B1 7 B1 8 B1 9 B2 0 B2 1 B2 2 B2 3 B2 4 B2 5 B2 6 B2 7 B2 8

47.0

48.0

2.5

4.0

3.4

90

1

1.02

V

11.0

11.0

2.0

2.0

90

1

1.00

V

NA

NA

1.0

1.2

45

1

NA

SV

7.5

7.5

1.0

1.0

45

1

1.00

SV

5.0

5.3

0.5

1.0

85

1

1.06

SV

34.0

35.0

2.5

4.0

80

1

1.03

SV

37.0

39.0

0.5

80

3

1.05

Y

72.0

77.0

90

1

1.07

V

43.0

45.0

90

1

1.05

V

38.0

39.0

1.5

2.0

85

1

1.03

V

180.0

195.0

1.0

4.0

73

9

1.08

CB

25.0

2.0

3.0

90

1

1.00

V

57.0

1.5

2.0

90

1

1.06

V

15.0

16.0

2.0

2.0

75

1

1.07

SV

38.0

44.0

1.5

2.5

78

1

1.16

SV

9.0

10.0

1.5

2.0

90

1

1.11

V

18.0

22.0

1.0

2.5

60

1

1.22

J

47.0

52.0

2.0

3.5

90

1

1.11

V

76.0

82.0

1.0

4.0

72

5

1.03

CB

45.0

48.0

1.0

1.5

90

1

1.07

V

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ED

2.5

2.0

5.0

2.0

2.0

PT

AC

54.0

CE

25.0

2.0

CR

Straight Line Lengtha

1.0 0.8 3.1 1.8 2.3 2.0 1.8 2.5 2.5 1.9 2.0 2.0 1.8 1.8 2.8 2.4 1.2

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Comple xity

2.4

Mean Slope (degree s) 90

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Table 1. Burrow data table.

29.0

30.0

1.5

2.0

7.0

10.0

1.5

1.5

35.0

39.0

2.0

4.5

41.0

46.0

2.0

4.0

13.0

13.0

2.0

2.0

10.0

11.0

2.0

2.0

7.0

8.0

1.5

2.0

39.0

42.0

2.5

3.0

41.0

50.0

3.0

3.5

7.0

7.0

2.5

2.5

41.0

43.0

2.5

3.5

38.0

63.0

1.5

3.0

20.0

21.0

1.5

2.0

18.0

19.0

1.0

33.0

33.0

23.0

23.0

49.0

49.0

1.0

2.0

107.0

111.0

1.0

2.0

20.0

1.0

1.5

62.0

1.0

3.0

84.0

88.0

1.5

3.0

14.0

14.0

1.5

1.5

17.0

18.0

1.5

1.5

30.0

30.0

2.0

3.5

8.0

8.0

1.5

1.5

26.0

30.0

1.5

2.0

42.0

42.0

2.0

4.0

60.0

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ED 2.0

3.0

1.0

2.0

PT

CE

20.0

1.5

90

1

1.04

V

90

1

1.03

V

70

1

1.43

SV

90

1

1.11

V

90

2

1.12

V

85

1

1.00

SV

1

1.10

SV

1

1.14

V

90

1

1.08

V

75

1

1.22

SV

90

1

1.00

V

90

1

1.05

V

90

3

1.07

Y

90

1

1.05

V

90

1

1.06

V

90

1

1.00

V

90

1

1.00

V

90

1

1.02

V

73

1

1.04

SV

70

1

1.00

V

90

1

1.03

V

90

1

1.08

V

90

1

1.00

V

90

1

1.06

V

90

1

1.00

V

90

1

1.00

V

80

1

1.15

SV

90

1

1.00

V

2.7 1.8 1.5 3.4 2.5 2.0

85

2.0 1.8 2.7 3.3

90

2.5 3.0 2.1 1.8 1.3 2.5 1.4 1.4 1.3 1.2 1.8 2.1 1.5 1.5 2.8 1.5 1.8 3.0

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3.0

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2.5

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27.0

AN

26.0

AC

B2 9 B3 0 B3 1 B3 2 B3 3 B3 4 B3 5 B3 6 B3 7 B3 8 B3 9 B4 0 B4 1 B4 2 B4 3 B4 4 B4 5 B4 6 B4 7 B4 8 B4 9 B5 0 B5 1 B5 2 B5 3 B5 4 B5 5 B5 6

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B5 58.0 78.0 1.0 2.5 90 3 1.02 Y 1.5 7 B5 21.0 21.0 1.0 1.5 90 1 1.00 V 1.4 8 B5 52.0 64.0 3.0 4.0 77 1 1.23 SV 3.6 9 B6 41.0 43.0 2.5 4.0 90 1 1.05 V 3.0 0 a Straight line length is measured from the highest end point to the lowest. b Total length is the sum of the length of all shafts following all curves. c V= vertical burrow; SV = subvertical burrow; J = J-shaped burrow; Y = Y-shaped burrow; CB = complex branching burrow.

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Highlights  Large, vertical burrows occur the Lower Permian (Asselian) Dunkard Group in southeastern Ohio.  Burrows include vertical, subvertical, J-shaped, Y-shaped, and complex burrows assigned to the ichnogenus Camborygma.  Architecture and surficial features of the trace fossils are similar to burrows constructed by modern freshwater decapods.  These burrows contribute fill in gaps of the terrestrial fauna not otherwise preserved in the fossil record.