Shahkarami et al.—Ediacaran–Cambrian ichnostratigraphy
Dam, 1990; P. circinatum Richter, 1853; P. coronatum Crimes and Anderson, 1985; P. curvipalmatum Pollard, 1981; P. flabellum (Miller and Dyer, 1878); P. fusiforme Seilacher, 2000; P. templus Han and Pickerill, 1994; P. parallelum Seilacher, 2000; P. reniforme Hofmann, 1979; P. ungulatus Fillion and Pickerill, 1990; and P. wabanensis Fillion and Pickerill, 1990. Some forms of Phycodes consist of a few main branches showing a spreite-like structure, which distally give rise to numerous free branches. In other forms, the spreite are lacking, and branches tend to be more random (Osgood, 1970). Phycodes reflects a variety of behavioral activities by the tra- cemaker (Han and Pickerill, 1994), but two basic interpretations are a feeding trace (fodinichnion) produced by an organism that systematically mines a nutrient-rich layer along a silt-mud surface, most likely annelids (Seilacher, 1955), or a structure produced by an organism that burrowed outwards from a single point and then withdrew to a ‘home-case’ only to re-burrow outwards again through the previously excavated tunnel (Marintsch and Finks, 1982; Singh et al., 2008). Phycodes ranges in age from Cambrian (Crimes and Anderson, 1985) to Miocene (Bradley, 1981). Phycodes has been reported from shallow-marine, deep-marine (Crimes et al., 1977; Bradley, 1981; Narbonne, 1984), and brackish-water (Hakes, 1985) environments. Non-marine examples are in need of re- evaluation (Pollard, 1985). Although the Soltanieh specimen supports placement in Phycodes, poor preservation prevents an ichnospecific assessment.
Occurrence.—Upper Shale Member.
Ichnogenus Planolites Nicholson, 1873 Planolites montanus Richter, 1937 Figure 4.3
Materials.—Five slabs (P3311.8, P3311.11, P3311.17, P3311.19, P3313.8) containing thirteen specimens.
Description.—Horizontal, unbranched, straight to slightly curved, unornamented, cylindrical burrows. Burrow-fill similar to the host rock. Width is 0.6–2.8mm; maximum preserved length is 47.1mm. Preserved as positive and negative hyporelief.
Remarks.—Four ichnospecies of Planolites are currently recognized based on size, curvature, and wall characteristics: P. beverleyensis (Billings, 1862); P. annularis Walcott, 1890; P. montanus Richter, 1937; and P. constriannulatus Stanley and Pickerill, 1994. Planolites montanus comprises small, curved to tortuous burrows. Planolites beverleyensis comprises large, straight to gently curved burrows. Planolites annularis consists of transversely annulated burrows, and Planolites constriannulatus is comprised of a burrow with both long- itudinal striations and transverse annulation. Planolites is interpreted as feeding burrows (fodinichnia) of deposit-feeders (Pemberton and Frey, 1982), and ranges in age from Cambrian to Holocene (Häntzschel, 1975; Mángano and Buatois, 2014). Planolites is found in almost every depositional environment (Pemberton and Frey, 1982).
Occurrence.—Upper Shale Member.
Ichnogenus Psammichnites Torell, 1870 Psammichnites gigas (Torell, 1868) Figure 4.1
Materials.—Six slabs (P3313.2, P3313.5, P3313.6, P3313.7, P3317.1, P3317.2) containing fifteen specimens.
Description.—Large, unbranched, horizontal, straight to slightly curved bilobate trails. The burrow-fill is finer-grained and darker in color compared to the host sediment. Width is 6.7–20.0mm; maximum length preserved is 148.8mm. Overlap among specimens is locally common. Preserved as negative hyporelief and positive epirelief. Negative hyporeliefs are gently concave, with a median ridge. Positive epireliefs are gently convex with a shallow, straight median groove of vari- able width and depth.
Remarks.—There is general agreement that the ichnogenus Olivellites Fenton and Fenton, 1937 is a junior synonym of Psammichnites (Chamberlain, 1971; D’Alessandro and Brom- ley, 1987; Maples and Suttner, 1990; Seilacher, 1997; Zhu, 1997; Mángano et al., 2002a). The ichnotaxonomic status of the lower Cambrian ichnospecies Taphrhelminthopsis circularis Crimes et al., 1977 is more uncertain. Uchman (1995a) demonstrated that the ichnogenus Taphrhelminthopsis is a preservational variant of Scolicia and, therefore, its junior synonym. Taphrhelminthopsis circularis is most likely a pre- servational variant of Psammichnites (Mángano and Buatois, 2016). Psammichnites is distinguished from Didymaulichnus by lack of median groove on the lower side and by its overall more complex internal structure (Seilacher, 2007). Psammichnites gigas Torell, 1870 is the type ichnospecies of Psammichnites; other ichnospecies include P. plummeri (Fenton and Fenton, 1937); P. grumula (Romano and Meléndez, 1979); P. implexus (Rindsberg, 1994); and P. saltensis (Aceñolaza and Durand, 1973). The Soltanieh specimens are very similar in overall shape and size to Psammichnites gigas, as described and illustrated by Hofmann and Patel (1989) from the lower Cambrian of New Brunswick, Canada. Psammichnites is interpreted as a back-filled structure representing the feeding activities of a subsurface vagile animal using a siphon-like device (Mángano et al., 2002a; Jago and Gatehouse, 2007). The ichnogenus Psammichnites ranges in age from early Cambrian to Permian (Mángano et al., 2002a), and the type ichnospecies, Psammichnites gigas, is of early Cambrian age (Jago and Gatehouse, 2007). Psammichnites gigas was first recorded in the Soltanieh Formation by CiabeGhodsi (2007).
Occurrence.—Upper Shale Member. Ichnogenus Rusophycus Hall, 1852
Rusophycus avalonensis Crimes and Anderson, 1985 Figure 4.2
Materials.—One slab containing one specimen (P3313.9).
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