[Palaeontology, Vol. 54, Part 6, 2011, pp. 1223–1242]

PROBLEMATIC MEGAFOSSILS IN PALAEOSOLS OF SOUTH AUSTRALIA by GREGORY J. RETALLACK Department of Geological Sciences, University of Oregon, Eugene, OR 97403, USA; e-mail: [email protected]

Typescript received 13 February 2009; accepted in revised form 20 August 2009

Abstract: Red calcareous Middle Cambrian palaeosols from Other axial structures (Prasinema nodosum and P. adunatum the upper Moodlatana Formation in the eastern Flinders gen. et spp. nov.) are larger and show distinctive surface Ranges of South Australia formed in well-drained subhumid irregularities (short protuberances and irregular striations, floodplains and include a variety of problematic . The respectively). The size and form of these filaments are most fossils are preserved like trace endichnia but do not like rhizines of soil-crust lichens. Other evidence of life on appear to be traces of burrows or other movement. land includes quilted spheroids (Erytholus globosus gen. et sp. They are here regarded as remains of sessile organisms, com- nov.) and thallose impressions (Farghera sp. indet.), which parable with fungi or living in place, and are formally may have been slime moulds and lichens, respectively. These named as palaeobotanical form genera under provisions of distinctive fossils in Cambrian palaeosols represent commu- the International Code of Botanical Nomenclature. Most nities comparable with modern biological soil crusts. common are slender (0.5–2 mm) branching filaments flanked by green-grey reduction haloes within the red matrix of pal- Key words: Cambrian, South Australia, palaeosol, fungus, aeosol surface horizons (Prasinema gracile gen. et sp. nov.). slime mould, lichen.

B iological soil crusts in the distant geological past Ranges, South Australia (Text-figs 1–3). The Cambrian have long been suspected because of dispersed spores palaeosols described here predate the of land (Gray 1981; Strother 2000), abundance of pedogenic clay plants but nevertheless contain three distinct kinds of (Kennedy et al. 2006), unusually deeply weathered com- enigmatic megafossils: (1) drab-haloed filament traces position of Cambrian sandstones (Dott 2003), carbon iso- (Prasinema gen. nov.), (2) quilted spheroids (Erytholus topic composition of palaeosols (Watanabe et al. 2000) gen. nov) and (3) thalloid impressions (Farghera sp. in- and microbially textured bedding planes (Prave 2002). det.). Although the biological affinities of these fossils Middle Cambrian microbial filaments (Southgate 1986) remain uncertain, they provide new guides to the appear- and lichen-like fossils (Fleming and Rigby 1972; Mu¨ller ance of Cambrian life on land. and Hinz 1992; Retallack 1994) from phosphorites of Formal naming of fossils aids future investigation and western Queensland are in sedimentary facies with evi- wide recognition, as demonstrated by other problematic dence of exposure within tidal flats and rock platforms fossils. For example, Vendobionta were informally noted (Southgate 1986), but such marine-influenced communi- by Mawson (1938, p. 259) as ‘fossil impressions resem- ties are not directly comparable with biological soil crusts bling brachiopod or bivalve form’, but formal description of modern deserts. Unlike grey marine cherts and phos- of five by Sprigg (1947) was needed before their phorites with permineralized fossils or grey shales with global distribution and importance as fossils carbonaceous compressions, to Quaternary red could be appreciated (Fedonkin et al. 2007). The various oxidized palaeosols seldom preserve cellular detail of car- fossils in Cambrian palaeosols formally named here are bonaceous fossils, so efficient is recycling in well-drained preserved as bedding disruptions comparable with some soils (Retallack 1998). Nevertheless, post-Silurian oxidized kinds of trace fossil (endichnia of Martinsson 1970) but palaeosols commonly preserve impressions of , lack backfills, sequential prints or shapes recording move- stems and roots, often with drab mottling from biochemi- ment or behaviour of motile organisms. Each of the dif- cal reduction of buried organic matter (Retallack 1997c). ferent fossil genera described here is preserved in a Problematic megafossil traces of life on dry land now different way, but all appear to have been remains of come from numerous green-red-mottled palaeosols in the sessile organisms such as fungi, lichens, algae or plants in Middle Cambrian, Moodlatana Formation of the Flinders place of growth. Thus, the nomenclatural system

ª The Palaeontological Association doi: 10.1111/j.1475-4983.2011.01099.x 1223 1224 PALAEONTOLOGY, VOLUME 54

TEXT-FIG. 1. Geological map and fossil locality on Ten Mile Creek, South Australia.

appropriate to these fossils is not that of ichnofossils in GEOLOGICAL SETTING the International Code of Zoological Nomenclature (Ha¨ntzschel 1975; Ride et al. 1999) but rather of palaeo- All fossils reported here were collected from a large expo- botanical form genera in the International Code of Botan- sure of the upper Moodlatana and lower Balcoracana For- ical Nomenclature (McNeill et al. 2006). Form genera mation, within a prominent anticline, north of the big such as Thallites (Walton 1923) and Algites (Seward bend in Ten Mile Creek, six miles west of the road to 1894), for example, are used for fossils with the distinctive Martins Wells, on Wirrealpa Station, South Australia dichotomizing form of algal, liverwort or lichen thalli, but (3125¢N, 13894¢E). These palaeosols are early Middle whose exact systematic affinities are uncertain, because Cambrian in age, immediately above upper Moodlatana histological and reproductive structures are not preserved. Formation grey shales with the trilobite Onaraspis rubra

stromatolitic limestone

Mindi palaeosol

Natala palaeosol Viparri palaeosol

A hammer B

TEXT-FIG. 2. Selected fossiliferous palaeosols (A) and distinctive features (B) of the fossil locality in the uppermost Moodlatana Formation in cliffs flanking Ten Mile Creek, South Australia. The stromatolitic limestone marker here is the base of the Balcoracana Formation. For other palaeosols, see Retallack (2008). RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1225

TEXT-FIG. 3. Field sketch of three successive palaeosols, including those yielding fossils described here (upper two only), Middle Cambrian, uppermost Moodlatana Formation, Ten Mile Creek, South Australia. The palaeosols are at 3602 m in Ten Mile Creek section and measured palaeochannels from 3557 and 3561 m, in the next outcrop to the south and west.

(Jago et al. 2006), equivalent to the Oryctocephalus indicus in contrast have extensively disrupted bedding and subsur- zone (Gradstein et al. 2004). At 3602 m in the composite face caliche nodules (Text-fig. 3) of floodplain soils. The section in Ten Mile Creek, these palaeosols are 508.8 Ma Mindi pedotype is intermediate between these extremes, old in the age model of Retallack (2008). with small subsurface gypsum crystals and some persistent Unlike thin marine dolomites and shales of the Moodla- bedding, and is interpreted as a high supratidal palaeosol tana and overlying Balcoracana Formations (Moore 1990), (by Retallack 2008). All the fossils described here are from the fossiliferous palaeosols represent dry land in terms of only three (Mindi, Natala and Viparri) of seven pedotypes both soil drainage and palaeoclimate (Table 1). Pervasive known in the upper Moodlatana Formation (Table 1). cracking, haematite, loess-like grain-size distribution and Both Natala and Viparri pedotypes have a calcic horizon low FeO content of red parts of the palaeosols (Table 2) deeper than usual for the Moodlatana Formation and rep- are evidence of well-drained soils of floodplains and supra- resent a time of subhumid, rather than semi-arid climate, tidal flats. Crack orientation orthogonal to fluvial palaeo- immediately before marine transgression of the basal Balc- channels (Text-fig. 3) is characteristic of gilgai microrelief oracana Formation (Retallack 2008). of Vertisols (Paton 1974). Nodules of gypsum and micrit- The fossils described here are surprisingly large and ic, low magnesium calcite at shallow depths within the pal- plentiful for what would be expected in Cambrian palaeo- aeosols are evidence of semiarid to subhumid Middle sols (Retallack 2008), and the question may be raised Cambrian palaeoclimate. Different kinds of palaeosols whether they represent biological activity after the Cam- (pedotypes) have been interpreted to represent different brian. They do not appear to be products of modern local conditions (Retallack 2008), ranging from intertidal weathering, Cenozoic lateritization or glacial to fluvial (Table 1). The Irkili pedotype for example has landscapes because found in deep boreholes: Prasinema is much relict bedding, including flaser and linsen bedding, common at 1493–1504 feet, Farghera at 1498–1500 feet in and prominent calcite geodes after gypsum crystals, as in Lake Frome no. 2 core and Prasinema at 2089–2090 feet in soils of supratidal flats. The Natala and Viparri pedotypes Lake Frome no. 3 cores archived in the Primary Industries 1226 PALAEONTOLOGY, VOLUME 54

and Resources South Australia (PIRSA) core library at Glenside, a suburb of Adelaide. In outcrop, these fossils can be found more than a metre back from the surface within rock that has organic matter reflectance and clay- mineral illitization of lower greenschist facies of regional 5–10 years 5–10 years 10–200 years 500–2000 years 500–2000 years metamorphism (Retallack 2008). All the fossils are in strata-concordant, dipping layers, traceable laterally for about 50 m and at an angle to modern soils and land- scapes. The red palaeosols with fossils are also interbedded with unweathered black shales and stromatolitic lime- stones (Text-fig. 2). These fossils are an integral part of Cambrian soil structures and horizons (Retallack 2008). mud flat and floodplain mud flat point bar and floodplain Supratidal-alluvial Low alluvial terrace Supratidal mud flat 5–10 years Supratidal and alluvial Alluvial levee and Low alluvial terrace , , , Supratidal sand flat 500–1000 years MATERIALS AND METHODS

Fieldwork in South Australia in 2003, 2006 and 2007 , , included measurement of stratigraphic sections, azimuths and

, from trough cross-beds and palaeosol crack orientations Prasinema gracilis Prasinema gracilis Prasinema gracilis using a Brunton compass, spacing of fossils using a P. fascicularis , milliners tape and dimensions of fossils using a digital sp. indet. sp. indet. callipers. Samples were thin-sectioned for petrographic Prasinema gracilis Prasinema gracilis observations and analysed for major element composition with P. nodulosa Erytholus rotundus Farghera with Farghera Prasinema gracilis and iron valence state using XRF and potassium dichro- Intertidal microbial mat, Polsterland, with mate titration (respectively), by ALS Chemex of Vancou- ver (Canada), against Canada granodioritic stream gravel standard SDMS-2. Fossil specimens are housed in collec- tions of the South Australian Museum, Adelaide.

SYSTEMATIC PALAEONTOLOGY

Kingdom INCERTAE SEDIS high evapotranspiration with marked dry season Not relevant Fluvial microbial mat, Arid (100–300 MAP), Subhumid (500–800 mm MAP) Polsterland, with Subhumid (500–800 mm MAP), Not relevant Polsterland, with Form PRASINEMA gen. nov. Text-figures 4D–F, 5B, C, 6A–D, 8B–F

Type species. Prasinema gracile sp. nov.

Derivation of name. Elided from Greek prasinos (green) and nema (neuter, thread).

Diagnosis. Network of fine (<2 mm diameter) filamen- tous green-grey, sediment-filled, irregular tubes, radiating and decreasing in abundance downward from a sedimen- tary surface, clear grey-green reduction haloes around in red shale with chalcedony geodes (By) sandy layers over deepcalcareous (>50 nodules cm) (Bk) calcareous nodules (Bk) (<50 cm) calcareous nodules (Bk)

Diagnosis Palaeoclimate Former biotathe filaments Palaeotopography contrast Time for formation with red sedimentary matrix; unbranched or branching at irregular intervals and angles, without distinct orders of branch thickness. Palaeosol pedotypes in the Middle Cambrian, Moodlatana Formation, Ten Mile Creek, South Australia.

Adnamatna meaning Taphonomy. Networks of drab-haloed filaments are common at the surface of both Mindi and Natala pedotype palaeosols (Text- figs 2A, 3), which were probably Aquepts and Calcids, respec- tively (Retallack 2008) in the US soil (Soil Survey Pedotype name Imba Ash Thin green mottles (A) TABLE 1. Irkili Salt Green mottles (A) over red shale Viparri Thick Red siltstone (A) with pseudo-anticlinal Natala Big Red siltstone (A) over deep (>50 cm) Mindi Net Grey-red-mottled siltstone (A) Not relevant Polsterland, with Wandara SandWarru Ferruginized Red clay sandstone (A) Red clayey siltstone (A) over shallow Not relevant Polsterland, with RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1227

TABLE 2. XRF chemical analyses of red and green samples (weight per cent).

Pedotype Hue Hoz Spem SiO2 Al2O3 Fe2O3 FeO CaO MgO Na2OK2O TiO2 MnO P2O5 SrO BaO LOI Total

Natala Green A R3315 54.12 12.97 3.57 1.60 4.64 5.6 1.16 4.07 0.68 0.06 0.16 0.01 0.05 10.1 98.8 Natala Red Bw R3316 52.37 12.78 3.68 1.67 5.19 6.06 1.05 4.06 0.68 0.06 0.14 0.01 0.05 11.1 98.91 Mindi Green A R3333 48.51 12.26 2.87 1.73 6.94 7.33 0.85 3.9 0.56 0.07 0.12 0.01 0.05 13.95 99.16 Mindi Red C R3334 41.19 10.25 2.41 1.47 10.51 8.91 0.75 3.27 0.48 0.09 0.11 0.01 0.04 18.6 98.1 Error 2.705 0.825 0.395 n.d. 0.22 0.175 0.105 0.125 0.06 0.025 0.035 n.d. n.d. 0.353

Error is from 10 analyses in same laboratory (ALS-Chemex, Vancouver, BC, Canada) and standard (BC Canada granodioritic stream gravel SDMS-2).

Staff 2000). These palaeosols also include green-grey horizons amentous structures of comparable size (Text-fig. 4D) represent and planar features coating soil structure (Text-fig. 5B), but organisms that died and decayed within the oxidizing environ- Prasinema is only applied to tubular, ellipsoidal or elongate ment of the original soil. structures of irregular form (Text-figs 4D, 6A). Drab-haloed fila- ment traces are especially clear in horizons between the entirely Comparisons. The palaeobotanical form genus Radicites (Potonie drab surface and red subsurface horizons. These structures grew 1893) includes root traces of tracheophytes (Arafiev and Nau- through the soil, dilating and disrupting primary bedding under golnykh 1998; Yakimenko et al. 2004) and differs from Prasinema low (not deep burial) confining pressures (Text-fig. 6C). A cen- in larger size and branches of distinct orders of thickness. tral filament <2 mm in diameter is filled with yellow-green clay- Drab-haloed root traces such as Radicites erraticus (Text-fig. 7) stone with sharp contacts to green-grey matrix extending are much more widespread than indicated by Arafiev and outwards to a diffuse contact with red matrix (Text-figs 4C, 5B, Naugolnykh (1998) and Yakimenko et al. (2004) and have a con- 6A–D). Both green-grey halo and red matrix have the same silty tinuous fossil record in Silurian and younger palaeosols (Table 3). petrographic texture, but the filament fill is slightly more silty Radiculites (Lignier 1906) is a fossil root with permineralized (Text-fig. 6A–D). Furthermore, the green-grey claystone is not xylem and Rhadix (Fritsch 1908) a dubiofossil (Arafiev and much different in total iron content than the red claystone, Naugolnykh 1998), both much stouter than Prasinema. though richer in ferrous iron (Table 2), unlike comparable re- Also generally similar to Prasinema are drab filaments from doximorphic features in Mesoproterozoic (Driese et al. 1995) palaeosols of the 1.8 Ga Lochness Formation, near Mt Isa, and Cenozoic gleyed palaeosols (Retallack 1983; Retallack et al. Queensland (Driese et al. 1995), which differ in having much 2000). The green-grey matrix is thus a chemically reduced alter- less total iron in the drab than red palaeosol matrix, and haloes ation halo, produced largely during closed-system diagenesis, of local iron enrichment. Comparable Cenozoic drab-haloed pe- rather than during open-system gleization in a waterlogged soil, dotubles with iron–manganese bands have been interpreted as or during introduction of contrasting material before burial root traces of plants adapted to seasonally waterlogged palaeo- (Retallack 2001a). Alteration during burial also is supported by sols, which lost ferrous iron to groundwater (Retallack 1983). correlation of central filament diameter with halo diameter, gen- Unnamed tubular Precambrian fossils with green-grey haloes in erally similar to that known from drab-haloed root traces of red quartzites from the 2.0 Ga Medicine Peak Quartzite of Wyo- trees in and younger palaeosols (Table 3; Retallack ming are described as stouter and more bluntly ending than 1997a). Filament traces are more like fine root traces than large Prasinema (by Kauffman and Steidtmann 1981). woody large root traces in scaling closer to surface area (2prin 2 two dimensions of cross sections measured) than to volume (pr Biological affinities. Prasinema was a large organism for Cam- also in cross section: Text-fig. 7). brian palaeosols, with filaments extending as much as 30 cm Cambrian drab haloes are very similar to Devonian and youn- down into palaeosols and interconnected into larger networks. ger root traces, referable to the form species Radicites erraticus Thin sections (Text-fig. 6) betray no evidence for biomineraliza- (Arafiev and Naugolnykh 1998), and thought to have formed tion in Prasinema. The taphonomic model for these and other through gleization of iron oxides and hydroxides by dysaerobic drab-haloed tubular structures (Retallack et al. 2000) proposes microbes consuming remnant soil organic matter shortly after that the filaments were made of organic carbon compounds, burial (Retallack et al. 2000). The drab-haloed filaments have later consumed as fuel for biological reducing power to create top-down gleization like that of surface-water gley, rather than the drab haloes. Furthermore, the log-normal (negatively bottom-up gleization of groundwater gley (Retallack 2001a). skewed) size distribution of both Prasinema and Radicites diame- Surface-water gley is unlikely because grain-size distributions of ters is evidence of indeterminate growth, as has been argued for Cambrian palaeosols failed to detect any fine-grained or cemen- other fossils comparable with colonial , plants and fungi ted impermeable horizon (Retallack 2008) that would perch (Peterson et al. 2003). water table. The most likely explanation is formation of gleyed Biological soil crusts contain a variety of unskeletonized haloes during microbial consumption of organic matter immedi- organisms comparable in size, structure and growth with Prasi- ately after burial of the palaeosol and relative rise of water table nema: adventitious roots of grasses and other herbaceous in a subsiding floodplain. By this view, drab-haloed filaments tracheophytes, rhizoids of liverworts or mosses, bundles of fila- represent the last crop of the palaeosol before burial, but red fil- mentous cyanobacteria (Microcoleus), fungal hyphal bundles or 1228 PALAEONTOLOGY, VOLUME 54

A

B

C

F

E

D

G

H J I

TEXT-FIG. 4. Interpretative sketches of problematic fossils from palaeosols of the Middle Cambrian upper Moodlatana Formation, Ten Mile Creek, South Australia. RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1229

red green

A horizon green

C 1 cm

C horizon red

1 cm

A D E 1 cm

green

yellow red

F B 1 cm 1 cm

TEXT-FIG. 5. A, Problematic megafossils from a Mindi palaeosol (see also Text-fig. 2A). B, Prasinema gracile gen. et sp. nov., holotype, South Australian Museum, specimen number P42257. C, Prasinema nodosum gen et sp. nov., South Australian Museum, specimen number P42340a. D–F. Erytholus globosus gen. et sp. nov. South Australian Museum, in slab (D, specimen number P42255), exposed exterior (E, specimen number P42256) and naturally broken open (F, specimen number P42255). lichen rhizines (Belnap and Lange 2003). Roots or rhizoids are and rhizines of Ascolichens and Basidolichens, especially placoid unlikely because longer and shorter, respectively, and also form- forms (Vogel 1955; Poelt and Baumga¨rtner 1964). These two ing a sharper boundary with soil matrix than apparent in thin alternatives cannot be distinguished on morphological grounds, section (Text-fig. 6A–D). Incorporation of soil matrix within the although primary productivity of Cambrian palaeosols lacking central tubular hole within the drab halo is more like bundles of embryophytic plants would be unlikely to support such abun- cyanobacteria and fungal hyphae. A hyphal origin is most likely dant hyphae of non-lichenized fungi. considering the deep reach (30 cm) of these structures within the palaeosols, well beyond the surficial zone of light penetra- tion, because taphonomic evidence for burial gleization dis- Prasinema gracile sp. nov. cussed above is an indication that drab-haloed Prasinema is the Text-figures 4D, 5B, 6A, B, 8D, E current crop of organic structures, as in comparable drab-haloed root traces (Retallack et al. 2001). Very similar structures to Holotype. Near-vertical specimen, concertina-shaped from burial Prasinema are hyphal bundles of non-lichenized fungi, such as compaction in the centre of the saw slab (P42257; left-hand side; the bootstrap fungus (Armillaria mellea: Mihail and Bruhn 2005) Text-fig. 4D; right-hand side; Text-fig. 5B), from the type Mindi 1230 PALAEONTOLOGY, VOLUME 54

A B 0.5 mm 0.5 mm

D C 0.5 mm 0.5 mm

E F 0.5 mm 0.5 mm

TEXT-FIG. 6. Petrographic thin sections all cut vertical to bedding. A, B, Prasinema gracile gen. et sp. nov. from type Mindi palaeosol. C, D, P. nodosum sp. nov. from type Mindi palaeosol. E, Farghera sp. indet. from the type Natala palaeosol. F, Erytholus globosus gen. et sp. nov. from the type Mindi palaeosol. palaeosol, upper Moodlatana Formation, at the big bend in Ten drillcore of the Parachilna, Billy Creek, Moodlatana and Balcora- Mile Creek, South Australia (3125¢N, 13894¢E). cana Formations, and in some outcrops of the Pantapinna and Grindstone Range Sandstones. Prasinema gracile thus ranges in Other localities. This is the most abundant fossil in Cambrian pal- geological age from earliest Cambrian perhaps to Early aeosols of South Australia and is found in almost all outcrops and in the Flinders Ranges of South Australia (Retallack 2008). RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1231

TABLE 3. Additional occurrences of Radicites erraticus (drab-haloed root traces).

Location Formation Age Ma References

Dominion Range, Antarctica Meyer Desert Formation Pliocene 3.5 Retallack et al. (2001) Khaur, Pakistan Dhok Pathan Formation Late Miocene 8 Retallack (1991) Khaur, Pakistan Chinji Formation Late Miocene 12 Retallack (1991) Nyakach, Kenya Nyakach Formation Middle Miocene 14 Wynn and Retallack (2001) Khaur, Pakistan Kamlial Formation Early Miocene 15 Retallack (1991, 1997b) Majiwa, Kenya Maboko Formation Middle Miocene 15 Retallack et al. (2002) Khaur, Pakistan Murree Formation Early Miocene 17 Retallack (1991) Rusinga Island, Kenya Hiwegi Formation Early Miocene 18 Retallack et al. (1995) Puente Centenario, Panama Cucharacha Formation Early Miocene 18 Retallack and Kirby (2007) Rusinga Island, Kenya Kiahera Formation Early Miocene 19 Bestland and Retallack (1993) Songhor, Kenya Kapurtay Agglomerate Early Miocene 20 Retallack (1991) Koru, Kenya Koru Formation Early Miocene 20 Retallack (1991) Painted Hills, OR, USA John Day Formation Early Oligocene 33 Retallack et al. (2000) Badlands NP, SD, USA Chadron Formation Late Eocene 35 Retallack (1983) Clarno, OR, USA John Day Formation Late Eocene 43 Retallack et al. (2000) Clarno, OR, USA Clarno Formation Late Eocene 45 Retallack et al. (2000) Landslide Butte, MT, USA Two Medicine Formation Late 72 Retallack (1997d) Russell, Kansas, USA Dakota Formation Late Cretaceous 94 Retallack and Dilcher (1981) Kanapolis, KS, USA Dakota Formation Late Cretaceous 96 Retallack (1997c) Dinosaur, CO, USA Morrison Formation Late 150 Retallack (1997d) Petrified Forest NP, AZ, USA Petrified Forest Formation Late 216 Retallack (1997d) Long Reef, NSW, Australia Bald Hill Claystone Early Triassic 245 Retallack (1997a) Mt Rosenwald, Antarctica Fremouw Formation Early Triassic 246 Retallack and Krull (1999) Mt Boyd, Antarctica Fremouw Formation Early Triassic 246 Retallack and Krull (1999) Bethulie, South Africa Katberg Formation Early Triassic 251 Retallack et al. (2003) Lootsberg Pass, South Africa Katberg Formation Early Triassic 251 Retallack et al. (2003) Bethulie, South Africa Balfour Formation Late Permian 253 Retallack et al. (2003) Lootsberg Pass, South Africa Balfour Formation Late Permian 253 Retallack et al. (2003) Tekloof Pass, South Africa Tekloof Formation Late Permian 254 Retallack (2005) Kiama, NSW, Australia Gerringong Volcanics Middle Permian 261 Retallack (1999) Loyal, OK, USA Flowerpot Shale Middle Permian 264 Retallack (2005) Beaufort West, South Africa Abrahamskraal Formation Middle Permian 266 Retallack (2005) Purcell, OK, USA Hennessey Formation Middle Permian 268 Retallack (2005) Seymour, TX, USA Clear Fork Group Early Permian 277 Retallack (2005) Manitou, OK, USA Garber Formation Early Permian 280 Retallack (2005) Lake Kemp, TX, USA Waggoner Ranch Format. Early Permian 282 Retallack (2005) Kadane Corners, TX, USA Petrolia Formation Early Permian 285 Retallack (2005) Byars, OK, USA Stillwater Formation Early Permian 290 Retallack (2005) Nocona, TX, USA Nocona Formation Early Permian 291 Retallack (2005) Manhatten, KS, USA Blue Rapids Shale Early Permian 296 Retallack (1997a) Archer City, TX, USA Archer City Formation Early Permian 296 Retallack (2005) Gateway, CO, USA Cutler Formation Early Permian 297 Retallack (1997a) Marietta, OH, USA Marietta Sandstone Early Permian 298 Retallack (1997a) Drake, MO, USA Cheltenham Formation Pennsylvanian 308 Retallack and Germa´n-Heins (1994) Unadilla, NY, USA Oneonta Formation Late Devonian 376 Retallack (1997a) Mt Crean, Antarctica Azrtec Silstone Middle Devonian 387 Retallack (1997a) Caldey Island, Wales, UK Moor Cliffs Formation Early Devonian 414 Retallack (1997a) Palmerton, PA, USA Bloomsburg Formation Late Silurian 419 Retallack (1992) Danville, PA, USA Bloomsburg Formation Late Silurian 421 Retallack (1992)

Derivation of name. Latin gracilis meaning slender. ously bent; branching irregularly and sparsely, without orders of branching; permeating rock matrix and destroy- Diagnosis. Prasinema with fine (<1 mm) filaments, ing primary sedimentary structures with no clear pre- flanked by a drab halo extending a comparable thickness ferred orientation. outward into reddish matrix; slender, striated and flexu- 1232 PALAEONTOLOGY, VOLUME 54

TEXT-FIG. 7. Size distributions and AC scaling relationships in Prasinema gracilis gen. et sp. nov. in Cambrian palaeosols, Moodlatana Formation, South Australia (A–D, K–O), compared with post- Cambrian drab-haloed root traces (E–J). Halo widths are larger than filament or root widths at their centre but show BD close relationship. Size distributions are skewed from normal (dashed lines calculated for same mean and standard deviation as the measurements). A–D, drab-haloed filament traces in Cambrian Mindi and Natala paleosols. E, F, drab- haloed root traces in Devonian, Bucktail palaeosol in Oneonta Formation, near Unadilla, New York, USA (Retallack 1997a). G, H, drab-haloed root traces in EGI Triassic, Long Reef palaeosol in Bald Hill Claystone, Long Reef, New South Wales (Retallack 1997a, c). I, J, drab- haloed root traces in Luca palaeosol, Eocene, John Day Formation, Clarno, Oregon, USA (Retallack et al. 2000).

FHJ

Dimensions. Mean diameters (±standard deviation, range) of Diagnosis. Prasinema with fine (<1 mm) filaments den- 237 filaments from the Mindi palaeosol were 0.56 (±0.29, 0.03– sely invested with outwardly directed emergences, varying 1.58) mm, and their haloes were 1.73 (±0.78, 0.43–5.80) mm from globose to spinose in shape, and narrow green-grey (Text-fig. 7). Comparable diameters of 430 filaments in the Nat- halo into red matrix; unbranched and straight; subvertical ala palaeosol were 0.50 (±0.25, 0.12–2.13) mm, and their haloes preferred orientation. were 1.46 (±0.69, 0.47–7.12) mm. Description. These fossils are rare, and their relationship with Comparisons. These conspicuously drab-haloed tubular features the slender filaments is unclear. The spacing of emergences are relatively nondescript compared with other species of Prasi- ranges from tightly clustered (Text-fig. 4F) to well spaced (Text- nema with stouter (>2 mm) and less flexuous filaments (P. ad- fig. 6D), so that it is conceivable that these are fertile or special- unatum) and lateral thickenings (P. nodusum). Sparse and ized segments of Prasinema gracile. Unlike P. gracile, which runs irregular branching of Prasinema gracile, ramifying in all in all directions in the rock, P. nodosum was only found near directions through the rock, obscures primary sedimentary struc- vertical to bedding planes defining the tops and bottoms of tures, which are prominent in beds abruptly overlying the palae- enclosing palaeosols. In thin section, they include drab-coloured osol, and also lower in the palaeosol where Prasinema is sparse matrix comparable in texture with the red matrix, and so these (Text-fig. 5A). are interpreted as organisms in place of growth within the soil, rather than parts of organisms protruding from and then on- Prasinema nodosum sp. nov. lapped by upbuilding soil. Text-figures 4F, 5C, 6C–D, 8B, F Dimensions. Mean (±standard deviation, range, number of Holotype. Left-hand example illustrated (Text-figs 4F, 8B) in measurements) include central filament diameter of 0.95 mm specimen P42310 from Natala palaeosol in Ten Mile Creek. (±0.05, 0.91–0.99, 2), external diameter of 2.51 mm (±0.56, 2.11–2.90, 2) mm and external thickening diameter of 0.72 mm Derivation of name. Latin nodosus meaning knotty. (±0.08, 0.61–0.91, 11) mm. RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1233

Comparisons. Middle Cambrian unnamed phosphatized tubes appears to be the result of numerous subparallel filaments of with sharp lateral extensions from the Beetle Creek Formation at comparable form. Cambrian marine algae such as Yuknessia sim- Mt Murray, Queensland (Fleming and Rigby 1972), differ in plex (Gunther and Gunther 1981) differ in showing dichoto- mode of preservation, are hollow with crushing indicative of mous branching, cellular margins and preservation as organic horizontal preservation and about twice the size of P. nodosum. compression within bedding planes. Nevertheless, both fossils have a striated or filamentous con- struction and lateral spines, which may reflect comparable bio- logical affinities. Form genus ERYTHOLUS gen. nov. Less similar to Prasinema nodosum are other congeneric spe- Text-figures 4G–I, 5D–F, 6F cies, which either lack the outer thickenings (P. gracile) or are much thicker (P. adunatum). Prasinema nodosum has a superfi- Type species. Erytholus globosus sp. nov. cial resemblance to a spinose , such as the fossil moss Mu- scites guelescini (Anderson and Anderson 1985), the zosterophyll Derivation of name. Elided from Greek erythros (red) and tholos Sawdonia ornata (Gensel 1991), or the putative alga Margaretia (masculine, dome). dorus (Gunther and Gunther 1981), but unlike these does not appear to have a finished cellular epidermis or cuticle. This same objection also distinguishes Prasinema from problematica that Diagnosis. Spheroidal sandy and silty structures, with have been regarded as mosses or lycopsids, such as the Cam- median vertical column and glide symmetry of 4–12 sub- brian ‘Aldanophyton’ (probably junior synonym of Margaretia horizontal internal partitions; a thin axial thread within according to Rozanov and Zhuravlev 1992), and Ordovician Ak- the central column extends vertically above and below the dalophyton (Snigirevskaya et al. 1992) and Boiophyton (Obhrel spheroid. 1959). Like Prasinema, Mesoproterozoic Horodyskia moniliformis is also found as grey-green markings within purple-red siltstones Taphonomy. These distinctive quilted spheroids within the type (Fedonkin and Yochelson 2002; Martin 2004; Fedonkin et al. Mindi palaeosol are comparable with trace fossil endichnia (of 2007, p. 33) but has the appearance of beads loosely strung on a Martinsson 1970), yet there is no evidence of animal movement. thread, rather than the clustered thickenings of Prasinema nodo- They are entirely oxidized. Although surrounded and penetrated sum. by drab-haloed filaments of Prasinema gracile, there is no thick- ening, curvature or other accommodation of drab filaments sug- gestive of relationship between P. gracile and Erytholus globosus. Prasinema adunatum sp. nov. An axial thread seen in many specimens of E. globosus is always Text-figures 4E, 8C red (Text-fig. 4G–J), never grey-green like Prasinema. Erytholus can be observed in outcrop on vertical faces, and by cracking Holotype. Single thick axis on specimen P42313 (Text-fig. 8C); open rock. Most specimens shatter through the middle to reveal from the type Natala palaeosol in Ten Mile Creek. subhorizontal chambers (Text-figs 4G, I, 5F); very few expose the strongly curved, thick walled, outer surface (Text-figs 4J, Derivation of name. Latin adunatus meaning united. 5E). Internal quilting was not a bedded cavity fill or internal mould (colloform illuviation argillan, of Retallack et al. 2000, Diagnosis. Prasinema of stout (2 mm) filaments, with a fig. 88), burrow backfill (Retallack 2001b) or internal chamber- striated appearance and irregular swellings and thinnings; ing or backfill of a sediment-ingesting organism (Seilacher 1992; unbranched and subhorizontal in orientation. Savazzi 2007), because it cannot have been moved within the whole structure, as revealed by the following observations. In one vertical face, two Erytholus were exposed by breaking open Description. This axis runs oblique to relict bedding planes but the rock vertically and recording former orientation (Text- is closer to horizontal than vertical within the bounding surfaces fig. 5F). The upper smaller Erytholus has a more sandy upper of the type Natala palaeosol. Branching of the axis was not seen, than lower zone, and the lower large one has a more clayey cen- nor is there any clear connection with closely associated fila- tral zone, with sandy upper and lower portions. These lithologi- ments of Prasinema gracile. Like P. gracile, P. adunatum has a cal differences are seen also as beds in the immediately flanking similar sedimentary texture in both drab-coloured material and surrounding matrix. Thus, the internal organic quilt grew within surrounding red matrix. the sediment or was a hollow structure filled with sediment increments, without moving sediment far from original layering, Dimensions. The single specimen found ranged from 2.10 to as has been suggested for some Ediacaran fossils (Grazhdankin 2.45 mm wide (mean 2.32 mm, standard deviation 0.18 mm). and Seilacher 2002; Grazhdankin 2005). The taphonomic mode of Erytholus can be interpreted in two distinct ways: (1) internal Comparisons. Middle Cambrian phosphatized tubes (unnamed) mould or (2) sand skeleton. By the sand skeleton interpretation, from the Beetle Creek Formation at Mt Murray, Queensland the organism grew within the sediment, but by the internal (Fleming and Rigby 1972), are similar to P. adunatum in size, mould interpretation, the chambered organism lived (and died?) longitudinal striation and sub-horizontal preservation but differ at the surface and was later infiltrated by increments of local in their prominent lateral spines. Prasinema adunatum differs sediment. from both P. gracile and P. nodusm in larger diameter, which 1234 PALAEONTOLOGY, VOLUME 54

Comparison. When first discovered, Erytholus specimens were lateral threads and thick wall, but differs from Erytholus in its suspected to be enrolled trilobites or aglaspids. However, thin distinct trigonal vertical divisions and is also larger (up to 6 cm sections and sawn slabs (Text-figs 5D, 6F) revealed no exoskele- diameter and 12 cm long; Fedonkin and Ivantsov 2007). tal remains, doublure, axial fold or limb impressions. The axial However, Ventogyrus is preserved with central thread and column column runs vertically through the middle of the structure and vertical to bedding in red-mottled fine sandstones (Fedonkin is not curved around the periphery, as in an enrolled trilobite. et al. 2007, pp. 142–145; D. Grazhdankin, pers. comm. 2008), Other similar ovoid structures in red beds are Ediacaran fossils comparable with Erytholus in the Mindi palaeosol. These similari- with comparable gliding plane symmetry and quilting (Tojo ties of preservation and internal structure suggest that Erytholus et al. 2007), such as Ernietta, Pambikalbae and Ventogyrus. Erni- may be grouped with Pambikalbae and Ventogyrus within the etta is hollow, rather than a three-dimensional internally layered problematic group Vendobionta (Seilacher 1992, 2007). structure, with internal column and threads, and this hollow is filled with white quartz sandstone distinct from the red siltstone Biological affinities. Fedonkin and Ivantsov (2007) regarded the matrix (Dzik 1999). Pambikalbae has a central column and lat- comparable vendobiont Ventogyrus as a siphonophore cnidarian eral chambers but is much larger (>29 cm long) and more elon- (comparable with the ‘bluebottle’, Physalia physalis), and Dzik gate than Erytholus (Jenkins and Nedin 2007). Like Erytholus, (2003) compares Ventogyrus with ctenophore cnidarians (‘comb Pambikalbae is preserved in three dimensions within red sand- jellies’, such as Cestum veneris). Ctenophores are known as flat- stones. Ventogyrus is ovoid, with a central column and thread, tened impressions back at least as old as Early Cambrian, in the

1 cm

A horizon

red B Bw horizon green C D 1 cm Natala palaeosol

Bk horizon

surface cracks E 1 cm

G 1 cm 1 cm F

Viparri palaeosol A horizon

Bk horizon

A hammer H 1 cm I 1 cm

TEXT-FIG. 8. A, problematic megafossils from Natala and Viparri palaeosols. B, Prasinema nodosum gen. et sp. nov., holotype; South Australian Museum, specimen number P42310. C, P. adunatum gen et sp. nov., holotype; South Australian Museum, specimen number P42313. D, E, P. gracile sp. nov. from a Natala palaeosol; South Australian Museum, specimen numbers P42311 (D) and P42312 (E). F, Prasinema nodosum gen. et sp. nov.; South Australian Museum, specimen number P42317. G–I, Farghera sp. indet. from a Viparri palaeosol; South Australian Museum, specimen numbers 42315 (G), P42314 (H) and P42315 (I). RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1235

Chengjiang fauna of China (Hou et al. 2004), so their fossil (as ‘myxomycetes’), but now regarded as more closely allied to record does not rest entirely on interpretation of controversial Amoebozoa (of Baldauf 2003). These creatures are generally dis- vendobionts. Neither of these groups of hollow, flimsy, marine persed in the soil as flagellated or amoeboid cells or as an irregu- organisms is a suitable explanation for fully inflated and little- larly shaped multinucleate plasmodium (Stephenson and Stempen deformed specimens of Erytholus in a palaeosol, filled with sedi- 1994), but the stalked sporangia have a variety of internal struc- ment preserving exterior bedding. tures similar to Erytholus. A reproductive rather than vegetative In contrast, Seilacher (2007; Seilacher et al. 2005) regards organ is suggested by the near-normal distribution of sizes (Text- vendobionts such as Dickinsonia and Palaeopascichnus as xeno- fig. 9), unlike the skewed distribution of Prasinema (Text-fig. 7) phyophores, comparable with the giant (up to 25 cm) Stanno- and other fossils of indeterminate growth (Peterson et al. 2003). phyllum zonarium of deep marine sediments. An appealing aspect In the slime mould Physarum crateriforme, for example, the stalk of this interpretation is the included sediment (xenophyae), fae- of the continues up within the spheroidal mass of ces (stercomare) and exudates (barite) within xenophyophores sporangia as a columella, which gives off a network of lateral fila- (Levin 1994), comparable with observations of Erytholus in thin ments (capillitium) defining crude chambers within an outer thick section (Text-fig. 6F). However, xenophyophores have irregular wall (peridium: Martin et al. 1983). Such structures release spores or meandrine chambers and lack internal organization of central into the air above the ground and, for Erytholus, would imply thread within a vertical column, and flanking chambers seen in growth from the soil surface, with later covering and infiltration Erytholus. No xenophyophores are known in soil or nonmarine by increments of aeolian or waterlain silt. Such a gap in time for settings. The fossil record of xenophyophores, other than contro- decay of organic matter is compatible with the lack of drab haloes versial Vendobionta, is equally controversial: trace fossils around Erytholus, in contrast to the taphonomy of what are here (Palaeodictyon and other graphoglyphid traces) no older than interpreted as freshly buried Prasinema. Putative slime mould Early Cambrian, and calcareous skeletonized forms (so called compression microfossils have been reported from the 1.025 Ga ‘phylloid algae’) no older than (Levin 1994). Lakhanda Group of Siberia (Hermann and Podkovryov 2006), Other plausible biological models for the whorled filamentous and problematic trails of about the same age from the Chorhat construction of Erytholus are green algae, particularly Charales Sandstone of India may have been created by slime moulds (Con- known back to Early Devonian (Feist and Feist 1997), or Dasy- way Morris 2000), so neither Erytholus nor comparable Ediacaran cladales such as Chaetocladus known back to Middle Ordovician Ernietta, Ventogyrus,orPambikalbae would be the oldest fossil (Kenrick and Vinther 2006). Such algae are aquatic and not record of such organisms. Differences between Erytholus and slime known from palaeosols but could conceivably have been a part mould sporangia include an order of magnitude larger size and of the aquatic parent material of the Mindi palaeosol, as in an continuation of the axial thread out the top of the structure. enigmatic calcite-filled axis from Ordovician red beds of the Ju- niata Formation in Pennsylvania (Retallack 2001b). This enig- matic fossil from Pennsylvania, like Charales and Dasycadales, Erytholus globosus sp. nov. was a system of dichotomously branching tubes arranged in Text-figures 4G–I, 5D–F, 6F whorls. In contrast, Erytholus is not constructed as a whorled scaffolding but quilted from planar to filamentous partitions Holotype. Large lower example of specimen P42255 (Text- without true whorling, and a glide symmetry of offset laterals. fig. 5D, F); from the type Mindi palaeosol in Ten Mile Creek Another possible biological model for Erytholus is a truffle, (top of specimen was marked by a black circle coplanar with the meant here in the general sense of underground fungus, rather ancient land surface). than implying the commercial extant species Tuber melanospo- rum (Pezizales, Ascomycota). Truffle growth form evolved inde- Derivation of name. Latin globosus meaning spherical. pendently in several fungal lineages: Zygomycotina (pea truffles), Ascomycota (true truffles), Basidiomycota (false truffles) and Diagnosis. Erytholus 5–20 mm in diameter, with 4–12 Deuteromycota (anamorphous fungi: Bruns et al. 1989; Pegler stacked internal layers divided by a wide (4–6 mm) verti- et al. 1993). Truffles have internal chambers in a variety of cal column. patterns: radial, alveolar and spongy. Radial–bilateral chambers most like Erytholus are known from Elaphomyces muricatus Description. Erytholus spheroids are smooth or sparsely ridged (Elaphomycetales, Ascomycota: Pegler et al. 1993), but this lacks when cracked out of the rock in exterior view, but, in cross sec- a central column or thread. There is a possible Precambrian tion, show an irregular system of subhorizontal chambers filled fossil record of Ascomycota (Retallack 1994, 2007), ‘higher with red claystone and white sandstone. The chambers have the fungi’ (Ascomycota + Basidiomycota: Butterfield 2005) and general appearance of bilateral symmetry around a central col- Glomeromycota (Yuan et al. 2005), so that these Cambrian fos- umn but, in detail, are not entirely symmetrical, with horizontal sils would not be unusually old fungi. Nevertheless, all truffles quilting at slightly different levels and chamber margins turning exclude sediment from their interior, and although it could infil- either up or down at the margins (Text-fig. 4). The chambers trate chambers of decayed examples, the abundant included sedi- are also ill-defined by ferruginized claystone (Text-fig. 6F). The ment continuous with exterior grain-size variation makes truffles chamber floors are deflected where they meet the central col- an unlikely explanation for Erytholus. umn, but a narrow tubular structure within that extends both A final possibility for Erytholus is a sporangium of a slime above and below the structure for an undetermined distance. mould (Myxomycota), traditionally regarded as related to fungi 1236 PALAEONTOLOGY, VOLUME 54

The size distribution of Erytholus, and the number and size of Form genus FARGHERA Retallack, 2009 its chambers are near normal (Text-fig. 9A–D). Burial compac- tion has rendered them slightly oblate, on average, so that width Farghera sp. indet. is generally greater than height (Text-fig. 9E). Chamber thickness Text-figures 4A–C, 6E, 8G–I does not vary with overall width except in the smallest specimens, but this relationship does not have the statistical significance Description. Viparri palaeosols have disrupted surficial sandy expected of growth relationships of metazoans (Text-fig. 9F). layers and deep cracks oriented orthogonal to palaeochannel The distribution of Erytholus within the type Mindi palaeosol direction (Text-fig. 3) like those of modern swelling clay soils, or is highly variable, from barely a centimetre apart (Text-fig. 5F) Vertisols (Soil Survey Staff 2000). These light-coloured sandstone to more than a metre. Average spacing of 78 specimens seen in stringers give good contrast between thin structures filled with outcrop along 62 m strike length of the Mindi palaeosol was red clay and with regular dichotomous branches radiating from a 1.19 ⁄ m. All were in the upper 20 cm of the palaeosol, which has centre, spreading upward at low angles to relict bedding (Text- relict bedding indicative of a cumulic A horizon (Retallack figs 4A–C, 6E, 8G–I). These specimens were examined under an 2008), and thus supportive of a taphonomic model of a surface environmental scanning electron microscope (FEI QANTA capa- hollow structure filled by increments of sediment. ble of forming an image without coating), and only clay was seen, with no histological details. Thin section examination confirms Dimensions. Mean (±standard deviation, range) of 145 speci- that these are impressions filled with clayey sediment and have mens of Erytholus globosus include horizontal diameter (coplanar shelf-like or tubular extensions (Text-fig. 6E). with bedding) of 13.09 mm (±4.82, 3.36–34.77), vertical dia meter 10.25 mm (±3.65, 2.85–24.18), chamber height 1.53 mm Dimensions. Mean width (±standard deviation, range) of 500 (±0.43, 0.46–2.57) and number of chambers 7.45 (±1.10, 5–12). specimens of Farghera sp. indet. is 1.78 mm (±0.58, 0.53–3.68, see Text-fig. 10). Localities. Most of the fossils of Erytholus globosus were found in the type Mindi palaeosol in the uppermost Moodlatana Forma- Taphonomy. The preservational style of these dichotomizing tion at 3602 m in the composite section in both Ten Mile fossils is identical with plant impressions preserved in red (3125¢S, 13894¢E) and Balcoracana Creeks (3118¢S, 13890¢E), palaeosols in growth position, such as leaves of Evolsonia from but others were seen at the Ten Mile Creek locality in the Irkili the Permian of (Mamay 1989) and Sanmiguelia from the palaeosol of the lower Balcoracana Formation at 3611 m. Triassic of Colorado (Tidwell et al. 1977). Lack of histological details rules out the taphonomic model of Spicer (1977) in Comparisons. Only one species of Erytholus is currently recog- which a replica of the surface is made by predepositional nized. ferric oxide coatings fuelled by microbial decay. This latter

TEXT-FIG. 9. Measurements of Erytholus globosus gen. et sp. nov. in a Mindi palaeosol, showing width in plane of bedding (A), thickness vertical to bedding (B), chamber thickness vertical to bedding (C), number of chambers in vertical stack (D), isometric growth in width to thickness relationship (E), and indeterminate growth relationship of chamber addition (F). RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1237

irregular branching (Retallack 2009). The only species of Farghera known so far is F. robusta, which has rounded thallus termina- tions about half the width of these specimens from the Viparri palaeosol. Viparri specimens are more fragmented and also repre- sent a larger thallus of more wrinkled form. The broad thallus may be an indication of a more mesophytic form than F. robusta known from sandy Entisol palaeosols (Upi pedotype associated with Adla and Matarra Aridosols) of drier climate than Vertisols (Viparri of Retallack 2008). This material is a different species than Farghera robusta, but detailed characterization will have to wait discovery of more complete and informative material. TEXT-FIG. 10. Width measurements of 500 Farghera sp. indet. in a Viparri palaeosol. The dashed line is a computed Biological affinities. Comparable dichotomizing thalli are found normal curve with the same mean and standard deviation as the in liverworts such as Marchantia (Smith 1990) and algae such as measurements: the data are normally distributed. Fucus and Dictyota (Graham and Wilcox 2000), but these lack the rhizine-like extensions characteristic of Farghera (Retallack 2009). The Viparri thalli are comparable with foliose lichens model applies best to Cretaceous Araliaephyllum leaves from such as Xanthoparmelia reptans and Physcia caesia (Text- swales of seasonally waterlogged palaeosols in sandy levees in the fig. 11B). Small lichens of ground-hugging rosette growth habit Dakota Formation of Kansas (Retallack and Dilcher 1981). Vi- are common in biological soil crusts of modern deserts (Belknap parri palaeosols in contrast show cracking patterns and orienta- and Lange 2003). Farghera would not be the oldest known tions suggestive of well-drained soils (Text-fig. 3). lichen, because putative permineralized lichens are known from the 0.6 Ga Doushantuo Formation of China (Paramecia among Comparisons. Impressions and compressions of dichotomously others, as interpreted by Retallack 1994; unnamed crustose form branching thalli are commonly assigned to the form genera Thal- of Yuan et al. 2005) and also the 2.6 Ga Carbon Leader of the lites (Walton, 1923) and Algites (Seward, 1894), but Farghera dif- Witwatersrand Group of South Africa (Thucomyces of Hallbauer fers from both form genera in its rhizine-like structures scattered and Van Warmelo 1974; Hallbauer et al. 1977). Other fossil along the margins of the thallus, and occasional monopodial and lichens include Devonian crustose (Taylor et al. 2004) and foli-

1 cm

A 0.5 mm B

hammer

D C 1 mm 1 mm E

TEXT-FIG. 11. Modern organisms comparable with problematic Cambrian palaeosol megafossils: A, exterior and cutaway view of the internally chambered sporangium of a slime mould (Myxomycota), Physarum crateriforme, Iowa, USA. B, crustose-thallose lichen (Ascomycota) Physcia caesia, Painted Hills, Oregon, USA. C, placoid lichen with rhizomorphs (Ascomycota) Toninia sedifolia from the Austrian alps. D, placoid lichen with rhizines (Basidiomycota) Endocarpon sp. indet., from the Namibian desert. E, biological soil crust, 2 km west of fossil site in Billy Creek, South Australia. A is after Martin et al. (1983); C is after Poelt and Baumga¨rtner (1964); D is after Vogel (1955): others original. 1238 PALAEONTOLOGY, VOLUME 54

TEXT-FIG. 12. Reconstructed soil biota and coastal-fluvial landscapes of the Moodlatana Formation.

ose forms (Jurina and Krassilov 2002), Eocene microscopic cal soil crusts thus includes (1) microbial earths, recog- epiphyllous forms (Sherwood-Pike 1985) and Oligocene frag- nized by stromatolitic and other microbial textures, (2) ments in amber (Poinar 1992). polsterlands, recognized by discrete megascopic nonvascu- lar forms, and (3) brakelands, recognized by megascopic herbaceous vascular plants other than grasses (Retallack CONCLUSIONS 1992). Cambrian polsterlands are thus indicated by this paper, which reports three problematic kinds of mega- Biological soil crust is a term introduced by Belnap and scopic remains comparable with those of lichen thalli and Lange (2003) because such desert vegetation includes rhizines, and slime mould fruiting bodies from Cambrian microbes (cyanobacteria and algae), microbial fruiting palaeosols (Text-fig. 11). Weathering, carbon sequestra- bodies (mushrooms and slime moulds), vascular tion and landscape stabilization under modern polster- cryptogams (lycopsids and ) and nonvascular plants lands are modest compared with those under vascular (mosses and liverworts). Such wide definition of biologi- RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1239 land plants, but far from negligible (Retallack 1992), as BALDAUF, S. L. 2003. The deep roots of eukaryotes. Science, indicated also by petrographic and geochemical study of 300, 1703–1706. Cambrian palaeosols (Retallack 2008). BELNAP, J. and LANGE, O. L. (eds) 2003. Biological soil Lack of water, heat and essential nutrients is an impor- crusts: structure, function and management. Springer, Berlin, tant limit to productivity of modern biological soil crusts 503 pp. BESTLAND, E. A. and RETALLACK, G. J. 1993. Volcani- in deserts, but they thrive also in warm-wet regions until cally influenced calcareous paleosols from the Kiahera Forma- outcompeted by other plant communities (Belnap and tion, Rusinga Island, Kenya. Journal of the Geological Society of Lange 2003), such as brakelands dating only back to Early London, 150, 293–310. Silurian and woodlands dating back to Middle Devonian BRUNS, T. D., FOGEL, R., WHITE, T. J. and PALMER, J. (Retallack 1992). An important limit to life on land on the D. 1989. Accelerated evolution of a false-truffle from a mush- early Earth was ultraviolet light, especially before about room ancestor. Nature, 339, 140–142. 2 Ga when oxygen levels were less than 0.1 times modern BUTTERFIELD, N. J. 2005. Probable Proterozoic fungi. level, too low to create a significant ozone layer (Kasting Paleobiology, 31, 165–181. 1987). Drab-haloed filament traces in red oxidized soils CONWAY MORRIS, S. 2000. The Cambrian ‘explosion’: comparable with those reported here have been described slow-fuse or megatonnage? Proceedings of the National Acad- (though not interpreted as biological soil crusts) from the emy of Sciences of USA, 97, 4426–4429. DOTT, R. H. 2003. The importance of eolian abrasion in su- 1.8 Ga Lochness Formation of western Queensland (Driese permature quartz sandstones and the paradox of weathering et al. 1995). Even with significant ultraviolet radiation, life on vegetation-free landscapes. Journal of Geology, 111, 387– could survive within soil at levels where hard radiation was 405. filtered by overlying transparent grains (Sagan and Pollack DRIESE, S. G., SIMPSON, E. and ERICKSSON, K. A. 1974), so that the antiquity of drab-haloed root traces or 1995. Redoximorphic paleosols in alluvial and lacustrine other evidence of life in palaeosols may not be a reliable deposits, 1.8 Ga Lochness Formation, Mt Isa: pedogenic pro- guide to past variation in Earth-surface ultraviolet radiation. cesses and implications for paleoclimate. Journal of Sedimen- In summary, a long suspected fossil record of polster- tary Research, A66, 58–70. lands in pre-Devonian rocks now includes a variety of DZIK, J. 1999. Organic membranous skeleton of the Precam- megafossils in surface horizons of moderately developed brian metazoans from Namibia. Geology, 27, 519–522. Cambrian palaeosols representing stable land surfaces —— 2003. Anatomical information content in Ediacaran fossils and their possible biological affinities. Integrative and Compar- of floodplains and supratidal flats (Text-fig. 12). These ative Biology, 43, 114–126. megafossils include drab haloes around filamentous struc- FEDONKIN, M. A. and IVANTSOV, Y. A. 2007. Ventogy- tures, chambered spheroids and thalloid impressions. rus, a possible siphonophore-like trilobozoan coelenterate Comparable structures may be widely overlooked in pre- from the Vendian sequence (Late Neoproterozoic), Russia. Devonian red beds, and this account provides search 187–194. In VICKERS-RICH, P. and KOMAROWER, P. images, a taxonomic framework and an introduction to (eds). The rise and fall of the . Geological Society their interpretation. of London Special Publications, 286, 470 pp. —— and YOCHELSON, E. L. 2002. Middle Proterozoic Acknowledgements. Pauline Coulthard offered advice on aborigi- (1.5 Ga) Horodyskia moniliformis Yochelson and Fedonkin, the nal sacred sites, and Barbara and Warren Fargher graciously gave oldest known tissue-grade colonial eucaryote. Smithsonian permissions for fieldwork on Wirrealpa Station. Research was Contributions to Paleobiology, 94, 29 pp. funded by the Petroleum Research Fund of the American Chem- —— GEHLING, J. G., GREY, K., NARBONNE, G. M. and ical Society, and fieldwork aided by Christine Metzger. VICKERS-RICH, P. 2007. The rise of animals. Johns Hop- kins University Press, Baltimore, 326 pp. Editor. Lyall Anderson FEIST, M. and FEIST, R. 1997. Oldest record of a bisexual plant. Nature, 385, 401. FLEMING, P. J. G. and RIGBY, J. K. 1972. Possible land REFERENCES plants from the Middle Cambrian, Queensland. Nature, 238, 266. FRITSCH, A. 1908. Problematica Silurica. Syste`me Silurien du ANDERSON, J. M. and ANDERSON, H. M. 1985. Palaeofl- Centre de la Bohe`me, 1908, 1–28, 12 pls. ora of southern Africa. Prodromus of South African megafloras, GENSEL, P. G. 1991. Notes on the cuticular morphology of Devonian to Lower Cretaceous. A.A. Balkema, Rotterdam, 423 Sawdonia acanthotheca, particularly in regard to emergences. pp. Neues Jahrbuch fu¨r Geologie und Pala¨ontologie, Abhandlungen, ARAFIEV, M. P. and NAUGOLNYKH, S. V. 1998. Fossil 183, 49–59. roots from the upper Tatarian deposits in the basin of the GRADSTEIN, F. M., OGG, J. G. and SMITH, A. G. 2004. A Sukhona and Malaya Severnaya Dvina Rivers: stratigraphy, Geologic Time Scale 2004. Cambridge University Press, Cam- taxonomy and orientation paleoecology. Paleontological Jour- bridge, 589 pp. nal, 32, 82–96. 1240 PALAEONTOLOGY, VOLUME 54

GRAHAM, L. E. and WILCOX, L. W. 2000. Algae. Prentice- Ska˚ne, Sweden. Review of Palaeobotany and Palynology, 142, Hall, Upper Saddle River, 616 pp. 153–160. GRAY, J. 1981. The microfossil record of early land plants: LEVIN, L. A. 1994. Paleoecology and ecology of xenophyo- advances in understanding of early terrestrialization, 1970– phores. Palaios, 9, 32–41. 1984. Royal Society of London Philosophical Transactions, A309, LIGNIER, O. 1906. Radiculites reticulatus, radicelle fossile de 167–185. Sequoinee. Societe´ Botanique du France Bulletin, 6, 193–201. GRAZHDANKIN, D. 2005. A re-examination of the Nama- MAMAY, S. H. 1989. Evolsonia, a new genus of Gigantopterid- type Vendian organism Rangea schneiderhoehni. Geological aceae from the Lower Permian Vale Formation, north-central Magazine, 142, 571–582. Texas. American Journal of Botany, 76, 1299–1311. —— and SEILACHER, A. 2002. Underground Vendobionta MARTIN, D. B. 2004. Depositional environment and taphon- from Namibia. Palaeontology, 45, 57–78. omy of the ‘strings of beads’; Mesoproterozoic multicellular GUNTHER, L. F. and GUNTHER, V. G. 1981. Some Middle fossils in the Bangemall Supergroup, Western Australia. Cambrian fossils of Utah. Brigham Young University Geology Australian Journal of Earth Sciences, 51, 555–561. Studies, 28, 1–87. MARTIN, G. W., ALEXOPOULOS, C. J. and FARR, M. L. HALLBAUER, D. K. and VAN WARMELO, K. T. 1974. 1983. The genera of Myxomycetes. University of Iowa Press, Fossilized plants in thucolite from Precambrian rocks of the Iowa City, 561 pp. Witwatersrand, South Africa. Precambrian Research, 1, 193– MARTINSSON, A. 1970. Toponomy of trace fossils. Geologi- 212. cal Journal, Special Issue, 3, 323–330. —— JAHNS, H. M. and BELTMANN, H. A. 1977. Morpho- MAWSON, D. 1938. Cambrian and sub-Cambrian formations logical and anatomical observations on some Precambrian at Parachilna Gorge. Royal Society of South Australia Tranasac- plants from the Witwatersrand, South Africa. Geologische tions, 62, 255–262. Rundschau, 66, 477–491. MCNEILL, J., BARRIE, F. R, BURDET, H. M., et al. (eds) HA¨ NTZSCHEL, W. 1975. Treatise on invertebrate paleontol- 2006. International code of botanical nomenclature (Vienna ogy. Part. W. Miscellanea. Supplement 1. Trace fossils and prob- Code) adopted by the seventeenth International Botanical Con- lematica. Geological Society of America, Boulder, Colorado gress, Vienna, Australia, July 2005. A.R.G. Ganter, Ko¨nigstein, and University of Kansas Press, Lawrence, Kansas, 269 pp. 568 pp. HERMANN, T. N. and PODKOVRYOV, V. N. 2006. Fun- MIHAIL, J. D. and BRUHN, J. N. 2005. Foraging behaviour gal remains from the Late Riphean. Paleontological Journal, 40, of Armillaria rhizomorph systems. Mycological Research, 109, 207–214. 1195–1207. HOU, X-G., ALDRIDGE, R. G., BERGSTRO¨ M, J., SI- MOORE, P. S. 1990. Origin of redbeds and variegated sedi- VETER, D. J., SIVERTER, D. J. and FENG, X.-H. 2004. ments, Cambrian, Adelaide Geosyncline, South Australia. Geo- The Cambrian fossils of Chengjiang, China. Blackwell, Malden, logical Society of Australia Special Publication, 16, 334–350. 233 pp. MU¨ LLER, K. J. and HINZ, I. 1992. Cambrogeorginidae fam. JAGO, J. B., ZANG, W. L., SUN, X. L., BROCK, G. A., nov., soft-integumented problematica from the Middle Cam- PATERSON, J. R. and SKOVSTED, C. B. 2006. Correla- brian of Australia. Alcheringa, 16, 333–335. tion within early Palaeozoic basins of eastern South Australia. OBHREL, J. 1959. Ein Landpflanzenfund im mittelbo¨hmischen Palaeoworld, 15, 406–423. Ordovizium. Geologie, 8, 535–541. JENKINS, R. J. F. and NEDIN, C. 2007. The provenance and PATON, T. R. 1974. Origin and terminology for gilgai in Aus- paleobiology of a new multivaned chambered frondose organ- tralia. Geoderma, 11, 221–242. ism from the Ediacaran (later Proterozoic) of South Australia. PEGLER, D. N., SPOONER, B. M. and YOUNG, T. W. K. 195–222. In VICKERS-RICH, P. and KOMAROWER, P. 1993. British truffles. Royal Botanic Gardens, Kew, 216 pp. (eds). The rise and fall of the Ediacaran biota. Geological Society PETERSON, K. J., WAGGONER, B. and HAGADORN, J. of London Special Publications, 286, 470 pp. W. 2003. A fungal analog for Newfoundland Ediacaran fossils? JURINA, A. L. and KRASSILOV, V. A. 2002. Lichenlike fos- Integrative and Comparative Biology, 43, 127–136. sils from the Givetian of central Kazakhstan. Paleontological POELT, J. and BAUMGA¨ RTNER, H. 1964. U¨ ber Rhi- Journal, 36, 541–547. zinenstra¨nge bei placodialen Flechten. O¨ sterreich Botanische KASTING, J. F. 1987. Theoretical constraints on oxygen and Zeitschrift, 111, 1–18. carbon dioxide concentrations in the Precambrian atmosphere. POINAR, G. O. 1992. Life in amber. Stanford University Press, Precambrian Research, 34, 205–229. Stanford, 350 pp. KAUFFMAN, E. G. and STEIDTMANN, J. R. 1981. Are POTONIE, H. 1893. Die Flora des Rotliegenden von Thu¨rin- these the oldest metazoan trace fossils? Journal of , gen. Preussische Geologische Landesanstalt Ahandlerung, 9, 55, 923–927. 1–298. KENNEDY, M., DROSER, M., MAYER, L. M., PEVEAR, PRAVE, A. R. 2002. Life on land in the Proterozoic: evidence D. and MROFKA, D. 2006. Late Precambrian oxygenata- from the Torridonian rocks of northwest Scotland. Geology, ion: inception of the clay mineral factory. Science, 311, 1446– 30, 811–814. 1449. RETALLACK, G. J. 1983. Late Eocene and Oligocene paleosols KENRICK, P. and VINTHER, J. 2006. Chaetocladus gracilis from Badlands National Park, South Dakota. Geological Society n. sp., a non-calcified Dasycladales from the Upper Silurian of of America Special Publication, 193, 82 pp. RETALLACK: CAMBRIAN PALAEOSOL FOSSILS 1241

—— 1991. Miocene paleosols and ape habitats of Pakistan and Antarctica. Journal of the Geological Society of London, 158, Kenya. Oxford University Press, New York, 346 pp. 925–935. —— 1992. What to call early plant formations on land. Palaios, —— WYNN, J. G., BENEFIT, B. R. and MCCROSSIN, M. 7, 508–520. L. 2002. Paleosols and paleoenvironments of the middle Mio- —— 1994. Were the Ediacaran fossils lichens? Paleobiology, 20, cene, Maboko Formation, Kenya. Journal of Human Evolution, 523–544. 42, 659–703. —— 1997a. A colour guide to paleosols. Wiley, Chichester, 346 —— SMITH, R. M. H. and WARD, P. D. 2003. Vertebrate pp. extinction across the Permian-Triassic boundary in the Karoo —— 1997b. Early forest soils and their role in Devonian global Basin of South Africa. Bulletin of the Geological Society of change. Science, 276, 583–585. America, 115, 1133–1152. —— 1997c. Palaeosols in the upper Narrabeen Group of New RIDE, W. D. L., COGGER, H. G., DUPUIS, C., et al. (eds) South Wales as evidence of Early Triassic palaeoenvironments 1999. International Code of Zoological Nomenclature. Interna- without exact modern analogues. Australian Journal of Earth tional Trust for Zoological Nomenclature, London, 306 pp. Sciences, 44, 185–201. ROZANOV, A. Y. and ZHURAVLEV, A. Y. 1992. The —— 1997d. Dinosaurs and dirt. 345–359. In WOLBERG, D. Lower Cambrian fossil record in the Soviet Union. 205–282. L., STUMP, E. and ROSENBERG, G. D. (eds). Dinofest In LIPPS, J. H. and SIGNOR, P. W. (eds). Origin and early International. Academy of Natural Sciences, Philadelphia, 602 evolution of the Metazoa. Plenum, New York, 578 pp. pp. SAGAN, C. and POLLACK, J. B. 1974. Differential transmis- —— 1998. Fossil soils and completeness of the rock and fossil sion of sunlight on Mars: biological implications. Icarus, 21, record. 133–163. In DONOVAN, S. K. and PAUL, C. R. C. 490–495. (eds). The adequacy of the fossil record. John Wiley, Chichester, SAVAZZI, E. 2007. A new reconstruction of Protolyellia (Early 312 pp. Cambrian psammocoral). 339–353. In VICKERS-RICH, P. —— 1999. Permafrost palaeoclimate of Permian palaeosols in and KOMAROWER, P. (eds). The rise and fall of the Ediac- the Gerringong volcanics of New South Wales. Australian aran biota. Geological Society of London Special Publications, Journal of Earth Sciences, 46, 11–22. 286, 470 pp. ——2001a. Soils of the past. Blackwell, Oxford, 404 pp. SEILACHER, A. 1992. Vendobionta and Psammocorallia: lost —— 2001b. Scoyenia burrows from Ordovician palaeosols of the constructions of Precambrian evolution. Journal of the Geologi- Juniata Formation in Pennsylvania. Palaeontology, 44, 209– cal Society, 149, 607–613. 235. —— 2007. The nature of Vendobionts. 387–397. In VICKERS- —— 2005. Permian greenhouse crises. In LUCAS, S. G. and RICH, P. and KOMAROWER, P. (eds). The rise and fall of ZIEGLER, K. E. (ed.). The nonmarine Permian. Bulletin New the Ediacaran biota. Geological Society of London Special Publi- Mexico Museum of Natural History and Science, 30, 256–269. cations, 286, 470 pp. —— 2007. Growth, decay and burial compaction of Dickinsonia, —— BUATOIS, L. A. and MANGANO, M. G. 2005. Trace an iconic Ediacaran fossil. Alcheringa, 31, 215–240. fossils in the Ediacaran-Cambrian transition: behavioral —— 2008. Cambrian paleosols and landscapes of South Austra- diversification, ecological turnover and paleoenvironmental lia. Australian Journal of Earth Sciences, 55, 1083–1106. shifts. Palaeogeography Palaeoclimatology Palaeoecology, 227, —— 2009. Cambrian-Ordovician non-marine fossils from South 323–356. Australia. Alcheringa, 33, 355–391. SEWARD, A. C. 1894. Catalogue of the Mesozoic plants in the —— and DILCHER, D. L. 1981. Early angiosperm reproduc- Department of Geology, British Museum. The Wealden flora pt tion: Prisca reynoldsii gen. et sp. nov. from mid-Cretaceous 1. British Museum (Natural History), London, 252 pp. coastal deposits in Kansas, U.S.A. Palaeontographica, 179, 103– SHERWOOD-PIKE, M. A. 1985. Pelicothallus Dilcher, an 137. overlooked fossil lichen. Lichenologist, 17, 114–115. —— and GERMA´ N-HEINS, J. 1994. Evidence from paleo- SMITH, A. J. E. 1990. The liverworts of Britain and Ireland. sols for the geological antiquity of rain forest. Science, 265, Cambridge University Press, Cambridge, 372 pp. 499–502. SNIGIREVSKAYA, N. S., POPOV, L. E. and ZDEBSAK, —— and KIRBY, M. X. 2007. Middle Miocene global change D. 1992. Novie nakhodki ostatkov drevnishchikh vishchikh and paleogeography of Panama. Palaios, 22, 667–679. rastenii v srednem ordovike yuzhnogo kazakhstana (New —— and KRULL, E. S. 1999. Landscape ecological shift at the findings of the oldest higher plant remains in the Middle Permian-Triassic boundary in Antarctica. Australian Journal of Ordovician of south Kazakhstan). Botanicheskii Zhurnal, 77, Earth Sciences, 46, 786–812. 1–8. —— BESTLAND, E. A. and DUGAS, D. P. 1995. Miocene SOIL SURVEY STAFF 2000. Keys to soil taxonomy. Poca- paleosols and habitats of Proconsul in Rusinga Island, Kenya. hontas Press, Blacksburg, 600 pp. Journal of Human Evolution, 29, 53–91. SOUTHGATE, P. N 1986. Cambrian phoscrete profiles, —— —— and FREMD, T. J. 2000. Eocene and Oligocene pa- coated grains and microbial processes in phosphogenesis, leosols of central Oregon. Geological Society of America Special Georgina Basin, Australia. Journal of Sedimentary Petrology, 56, Paper, 344, 192 pp. 429–441. —— KRULL, E. S. and BOCKHEIM, J. G. 2001. New SPICER, R. A. 1977. The pre-depositional formation of some grounds for reassessing palaeoclimate of the Sirius Group, leaf impressions. Palaeontology, 20, 907–912. 1242 PALAEONTOLOGY, VOLUME 54

SPRIGG, R. C. 1947. Early Cambrian (?) jellyfishes from the VOGEL, S. 1955. Niedere ‘‘Fensterpflanzen: in der su¨dafrikanis- Flinders Ranges, South Australia. Royal Society of South Aus- chen Wu¨ste. Beitrage Biologie Pflanzen, 31, 45–135. tralia Transactions, 71, 212–224. WALTON, J. 1923. On a new method of investigating fossil STEPHENSON, S. L. and STEMPEN, H. 1994. Myxomyce- plant impressions or incrustations. Annals of Botany, 37, 379– tes: a handbook of clime molds. Timber Press, Portland, 183 391. pp. WATANABE, Y., MARTINI, J. E. J. and OHMOTO, H. STROTHER, P. K. 2000. Cryptospores: the origin and early 2000. Geochemical evidence for terrestrial ecosystems 2.6 bil- evolution of the terrestrial flora. In GASTALDO, R. A. and lion years ago. Nature, 408, 574–578. DIMICHELE, W. A. (eds). Phanerozoic terrestrial ecosys- WYNN, J. G. and RETALLACK, G. J. 2001. Paleoenviron- tems. Paleontological Society Special Papers, 6, 3–17. mental reconstruction of middle Miocene paleosols bearing TAYLOR, T. N., KLAVINS, S. D., KRINGS, M., TAY- Kenyapithecus and Victoriapithecus, Nyakach Formation, LOR, E. L., KERP, H. and HASS, H. 2004. Fungi from the southwestern Kenya. Journal of Human Evolution, 40, 263– Rhynie Chert; a view from the dark side. Royal Society of Edin- 288. burgh Earth Sciences Transactions, 94, 457–473. YAKIMENKO, E., INOSEMTSEV, S. and NAU- TIDWELL, W. D., SIMPER, A. D. and THAYN, G. F. 1977. GOLNYKH, S. 2004. Upper Permian paleosols (Salarevskian Additional information concerning the controversial Triassic Formation) in the central part of the Russian Platform: paleo- plant; Sanmiguelia. Palaeontographica, B163, 143–151. ecology and paleoenvironment. Revista Mexicana de Ciencias TOJO, B., SIATO, R., KAWAKAMI, S. and OHNO, T. Geologicas, 21, 111–119. 2007. Theoretical morphology of quilt structures in Ediacaran YUAN, X-L., XIAO, S.-H. and TAYLOR, T. N. 2005. fossils. 399–404. In VICKERS-RICH, P. and KOMA- Lichen-like symbiosis 600 million years ago. Science, 308, ROWER, P. (eds). The rise and fall of the Ediacaran biota. 1017–1020. Geological Society of London Special Publications, 286, 470 pp.