Andean Geology ISSN: 0718-7092 [email protected] Servicio Nacional de Geología y Minería

Le Roux, Jacobus P.; Nielsen, Sven N.; Henríquez, Álvaro Depositional environment of Stelloglyphus llicoensis isp. nov.: a new radial from the Ranquil Formation, south- Andean Geology, vol. 35, núm. 2, julio, 2008, pp. 307-319 Servicio Nacional de Geología y Minería Santiago, Chile

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Depositional environment of Stelloglyphus llicoensis isp. nov.: a new radial trace fossil from the Neogene Ranquil Formation, south-central Chile

Jacobus P. Le Roux1, Sven N. Nielsen2, Álvaro Henríquez1

1 Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 13518, Correo 21, Santiago, Chile. [email protected]; [email protected] 2 Institut für Geowissenschaften, Christian-Albrechts-Universität, Ludewig-Meyn-Str.10, 24118 Kiel, Germany. [email protected]

ABSTRACT. Stelloglyphus llicoensis isp. nov. is a large radial, discoidal to ellipsoidal trace fossil with a central shaft and single to bifurcating branches radiating from different levels. A 30 m thick measured section of the Ranquil For- mation at Punta Litre contains an associated trace fossil assemblage including Zoophycos, , Phycosiphon, Nereites missouriensis, Lockeia siliquaria, Psammichnites(?), Parataenidium, Ophiomorpha, and Rhizocorallium, some of which reworked the Stelloglyphus traces. The sedimentology, together with micro- and macrofossils and the associated trace fossil assemblage, suggest that the succession was deposited in an outer continental shelf to slope environment in subtropical to tropical waters.

Keywords: Continental shelf, Slope, Radial trace fossil, Ichnofacies, Stelloglyphus, Dactyloidites.

RESUMEN. Ambiente depositacional de Stelloglyphus llicoensis isp. nov.: una nueva traza fósil radial de la For- mación Ranquil (Neógena), centro-sur de Chile. Stelloglyphus llicoensis isp. nov. es una traza fósil grande, radial, y discoidal a elipsoidal con una asta central y ramas sencillas a bifurcadas que radian desde diferentes niveles. Un perfil estratigráfico de 30 m medido en la Formación Ranquil en Punta Litre contiene una asociación de trazas fósiles asocia- das que incluye Zoophycos, Chondrites, Phycosiphon, Nereites missouriensis, Lockeia siliquaria, Psammichnites(?), Parataenidium, Ophiomorpha, y Rhizocorallium, algunas de las cuales retrabajaron las trazas de Stelloglyphus. La sedi- mentología, junto con los micro- y macrofósiles y la asociación de trazas fósiles, indican que la sucesión fue depositada en la parte exterior de la plataforma continental hasta el talud continental en aguas subtropicales a tropicales.

Palabras claves: Plataforma continental, Talud, Traza fósil radial, Ichnofacies, Stelloglyphus, Dactyloidites.

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1. Introduction between Punta Millongue (73º38’W-37º33’S) in the south and Punta Pichicui (73º27’W-37º12’S) The Ranquil Formation, south of Concepción, in the north (Fig. 1). Tavera (1942) proposed a is equivalent to the of central age for this formation on the basis of Chile in sedimentology, faunal content, age, echinoderm fossils. Groves and Nielsen (2003), and depositional history (Finger et al., 2007), based on unpublished foraminiferal data of M. but well separated geographically. It consists of Marchant (personal communication to SNN, 2001) fine conglomerates, , siltstones and and supported by molluscan faunal similarities with mudstones (García, 1968) reflecting different the Navidad Formation in the coastal sector west environments (Nielsen et al., 2004; Nielsen and of Santiago, suggested a age for this Frassinetti, 2007a; Finger et al., 2007). Besides formation. Finger et al. (2007) recorded the presence the well known mollusk fauna, trace fossils are of the planktonic foraminifers Neogloboquadrina also ubiquitous and, although less studied, are continuosa (N4b-N16), Globoquadrina dehiscens common in both the Navidad (Encinas et al., 2006) (N4b-N17), Globigerinella obesa s.l. (since and Ranquil Formations. Since trace fossils are P22), Globoturborotalia apertura (N16-N21), known to be an excellent tool for reconstructing Neogloboquadrina acostaensis (N16-N23), paleoenvironments, they are employed here as an Globorotalia spheriomiozea (N18-N19a), and additional means to determine the paleobathymetry, Globorotalia puncticulata (N19a-N21) from the supplementing the microfossil data from nearby Ranquil Formation at Punta El Fraile (their locality outcrops provided by Finger et al. (2007). FRA), 5 km east of the beach where the trace fossils Trace fossils are generally visible only on were subsequently discovered. The overlapping bedding planes or in cross sections, so that they range of these confirms a age can normally be examined in two dimensions (N19a) of 4.4 to 4.6 Ma, which we accept. Benthic only. Three-dimensional studies are sometimes foraminifers include Bulimina spicata, Pullenia possible due to the removal of softer, surrounding bulloides, Ammodiscus discoideus, Ehrenbergina deposits, for example where sand-filled galleries of fyfei, Pyrgo murrhina, Sphaeroidina bulloides, Ophiomorpha or Thalassinoides within mudrocks Bathysiphon spp., and Melonis pompilioides, which are accentuated by of the latter. Here suggest downslope mixing of shelf and bathyal we describe a new radial trace fossil, perfectly species (Finger et al., 2007). The presence of the preserved in calcareous concretions that were gastropods Zonaria frassinetti and Solatisonax eroded from their sedimentary host rocks and bieleri in nearby outcrops of similar age indicates washed up on a beach east of Llico, south-central subtropical to tropical water temperatures (Groves Chile. This provides a unique opportunity to study and Nielsen, 2003; Nielsen and Frassinetti, the morphology of this new ichnospecies in 3 2007b). This is supported by the occurrence of the dimensions. foraminifer Pulleniatina primalis (Kennett and Srinivasan, 1983). However, deep-water gastropod 2. Geological Setting genera living today off the Chilean coast, e.g., Bathybembix, have also been reported from Punta The radial trace fossil occurs in the Ranquil El Fraile (Nielsen et al., 2004). Formation of the , which forms part At the base of the Ranquil Formation, a of a series of basins developed along the Chilean unit consisting of intercalated shale and fine- continental margin (Aguirre, 1985; Le Roux grained , overlain by paraconglomerates and Elgueta, 1997). The basin is filled by Upper containing fine-grained sandstone and siltstone to deposits represented clasts within a clayey to silty matrix, can be by the , the distinguished. It is followed by grey mudstones Lebu Group, the Neogene Ranquil, intercalated with fine-grained, calcareous, well- Tubul and Albarrada formations, and younger, laminated sandstones containing abundant plant unconsolidated Holocene (Pineda, material and calcareous concretions, as well as fluid 1986). escape structures. Hummocky cross-lamination was The Ranquil Formation, as originally defined observed at some localities. This unit fines upward by García (1968), crops out locally along the coast into poorly exposed mudrocks with calcareous

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Fig. 1. Location map showing distribution of the Ranquil Formation on the Arauco Peninsula and localities mentioned in text. Star marks the type locality of Stelloglyphus llicoensis isp. nov.

concretions (containing the trace fossils described penetrating the mudrocks from above are common here), which are locally interbedded with mudstone at these localities (Le Roux and Vargas, 2005; Le breccias. In some areas (for example, Ranquil and Roux et al., 2008). Punta El Fraile) the mudrocks are deeply eroded by The greatest concentration of trace fossil- channels filled with medium- to very coarse-grained bearing concretions occurs on the beach between sandstone containing abundant mudstone clasts, Estero Pajonal and Punta Litre (37º11’43.80”S- interpreted by Le Roux et al. (2008) as resulting 37º11’57.02”S; 73º33’38.49”W-73º32’46.24”W; from a tsunami backwash which eroded coastal Fig. 1). At this locality, there is a beach cliff compo- beach sand and dunes and redistributed them over sed of mudrocks with in situ calcareous concretions the continental shelf and slope. Sandstone dykes (Fig. 2), some of which contain the radial trace fos-

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Fig. 2. Measured section of the Ranquil Formation between Punta Litre and Estero Pajonal.

sils (Fig. 3). It is very unlikely that these concretions Zoophycos, Chondrites, Phycosiphon, Nereites could have been reworked from older beds, because missouriensis, Lockeia siliquaria, Parataenidium, the mudstones in which they occur represent a very Ophiomorpha, Rhizocorallium and Psammich- low-energy environment where currents would nites(?). Because the last ichnogenus is known only have been incapable of transporting them. from the , the traces could alternatively The beds in this section dip gently westward, represent Scolicia. so that the measured section at Punta Litre (Fig. 2) The Zoophycos ichnofacies seems to best depicts the immediately underlying succession of represent the trace fossil assemblage mentioned intercalated mudstones and fine- to very fine-grai- above. In Seilacher’s (1964, 2007) original model, ned sandstones. The latter show parallel lamination, this ichnofacies occurs between the Cruziana and current and wave ripple lamination, small-scale Nereites ichnofacies on the external shelf to up- trough cross-lamination, as well as flute, slump and per continental slope. The Zoophycos ichnofacies fluid escape structures. is dominated by Zoophycos, Phycosiphon, and Trace fossils are fairly common in the inter- Chondrites, although Nereites missouriensis, Pla- bedded sandstone-mudstone unit and include nolites, Thalassinoides, and Cladichnus may also

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Fig. 3. A. In situ calcareous concretions containing radial trace fossils (Stelloglyphus llicoensis isp. nov.); B, C. In situ ellipsoidal concretion showing B, top surface with radial downward-curving tunnels and C, (turned around) bottom surface with tunnels in cross-section.

be present. In general, the presence of Zoophycos 3. Systematic Ichnology and Chondrites indicates sediments poor in oxygen, especially where occasional turbidity currents oc- Ichnogenus: Stelloglyphus Vialov, 1964. cur (Buatois and Mángano, 1992) or where there Type ichnospecies: Stelloglyphus turkomanicus is a high input of nutrients (Buatois and López Vialov, 1964; Late Cretaceous (Turonian), Turk- Angriman, 1991). However, in higher diversity menistan assemblages such as the one described here, these Stelloglyphus llicoensis isp. nov. Figs. 4A-C traces usually occupy deeper tiers where and 5A-C. could be poor in oxygen, whereas the shallow tier Type material: Holotype SGO.PI.6424 (Fig. 4A) and the sea floor may be well oxygenated (J.M. de and four paratypes SGO.PI.6425 (Figs. 4B and 5A- Gibert, personal communication, 2007). C). Two further paratypes SMF XXX 849 and SMF Ophiomorpha, Lockeia, and Rhizocorallium are XXX 850. SGO.PI is the collection prefix related more typical of the Cruziana ichnofacies (Buatois to the Sección Paleontología, Museo Nacional de et al., 2002), which represents the lower shoreface Historia Natural, Santiago, Chile; SMF refers to the to shelf environment. The observed trace fossil as- Naturmuseum Senckenberg, Frankfurt am Main, semblage thus indicates a shelf to upper continental Germany. slope environment, which agrees with the benthic Other material examined: One specimen cut for foraminiferal data. The presence of hummocky examination (SGO.PI). Many more specimens, all cross-lamination and (storm?) wave ripples in some from the area east of Llico, were observed at the beds supports an environment just above the storm type locality. wave base, i.e., the lower shoreface to continental Derivation of the name: After the fishing village shelf. The fining-upward sandstones and flute marks of Llico located just west of the ichnofossil type at the base of some beds, however, also indicate oc- locality. casional turbidity currents, which are more typical of Type locality: The Pacific coast near the fishing the continental slope. village of Llico; Ranquil Formation, about 5 km The mudrocks containing the radial trace fossils west of the succession at Punta El Fraile, which has form part of a generally fining-upward succession, been dated as late Miocene to early in age so that they probably indicate deeper water than by Finger et al. (2007). that represented by the underlying sandstone- Occurrence: Concretions containing trace fossils mudstone unit described above. A continental slope of the new ichnospecies Stelloglyphus llicoensis environment is therefore envisaged. The brecciated were washed up on beaches east of Llico, bet- mudstones within this unit were probably deposited ween Estero Pajonal (73º33’25’’W) and La Cal by debris flows triggered by storms or earthquakes (73º31’05’’W). In situ occurrences were found at on the steeper slopes. 73°33’00’’W (Figs. 2, 3).

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Fig. 4. Stelloglyphus llicoensis isp. nov. A1, A2. Discoidal concretion with holotype SGO.PI.6424, showing downward-curved radial tunnels. Note meniscate shapes (arrow) in some tunnels. A1, top, and A2, bottom views; B1, B2. Ellipsoidal concretion with paratype SGO.PI.6425a, showing central shaft and radial, downward-curving tunnels. Note double-ring structure and outward- widening radial tunnels with smooth walls. Both rings of central shaft in some cases have a hard, protruding layer on their outside, possibly of organic origin. B1, top, and B2, bottom views; C. Lateral view of ring structure formed by fused radial tunnels about halfway from the base. This concretion was not recovered.

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Diagnosis: Multi-level, meniscate, rarely branched 5C) to ellipsoidal (Figs. 2, 4B, 5A) and flattened tunnels normally radiating and curving downward along the bedding. The tops of the concretions from a central shaft, but bottom tunnels in some cases are slightly cone- or dome-shaped, with flatter, also curve upward. Filling of tunnels different from less curved bases. The shapes of these concretions surrounding sediment. Central shaft well developed, have clearly been controlled by the traces, because less than 10 mm in diameter, with distinct inner and their outlines follow the curvature of the tunnels. outer rings sometimes separated by a hard, protruding Fifty-six measured concretions had long diameters

layer. (Dl) ranging in size from 150-400 mm, compared

Description: The concretions containing Stello- to 140-310 mm for the intermediate diameters (Di) glyphus llicoensis are generally discoidal (Figs. 4A, and 80-180 mm for the short (vertical) diameters

Fig. 5. Stelloglyphus llicoensis isp. nov. A1, A2. Paratype SGO.PI.6425b, two specimens of Stelloglyphus llicoensis, with interpenetra- ting radial elements displaying distinctly segmented or meniscate structures. A2, top, and A1, bottom views; B1, B2. Paratype SGO.PI.6425c showing cross-sections of tunnels and central shaft. B1, bottom, and B2, top views; C1, C2. Paratype SGO. PI.6425d, showing rare case of elements radiating upward from central shaft and surrounded by vertical tunnels penetrating from the top of the structure. C1, top, and C2, bottom views.

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(Ds), with means of 265(±53.6) mm, 225(±40.2) are distinctly segmented or meniscate (Fig. 5A), mm and 123(±24.5) mm, respectively. The mean but in general they become wider away from the

Di/Dl ratio is 0.86(±0.10) with a range of 0.65-1.00, shaft. On the domed upper surface of the concre-

whereas the Ds/Dl ratio is 0.47(±0.10) with a range tions, 20 to 40, partly overlapping stellate burrows of 0.32-0.73. Although this discoidal to ellipsoidal may be preserved, curving downward along the form is due to concretion-formation processes, it surface but in some cases also laterally. About one- was clearly controlled by the burrow systems and third to halfway from the top of the concretions, thus reflects the actual geometry of the latter. many stellate burrows fuse to form an irregular, The trace fossil consists of a central shaft from ring-shaped structure around the perimeter (Fig. which radiate single and occasionally branched, un- 4C). The lower part of the concretions generally walled tubes (Fig. 4A2) with common constrictions displays the tunnels in cross-section (Figs. 2, 5C2). and menisci, filled with light pinkish brown, very However, in some cases the lowermost tunnels fine- to fine-grained, calcareous sandstone or lime- branch horizontally from the central shaft and stone within a buff, muddy, calcareous matrix con- curve upward, so that the basal and top sections taining scattered sand grains. The central, vertical to may be similar in appearance (Fig. 4B). oblique shaft measures less than 10 mm in diameter Stelloglyphus llicoensis is associated with and in and has an inner and an outer ring (Figs. 4B2, 5A2, some cases reworked by Zoophycos, which reaches 5C1) separated by a groove, both rings being formed more than 500 mm in diameter and displays whorls by micritic mud. This probably represents a lining or with spreiten in cross-section, up to 3 storeys deep. reinforcement of the shaft (J.M. de Gibert, personal Minute to mm-scale Chondrites also commonly communication, 2007). The two ring structures are occurs at the top of the Stelloglyphus llicoensis occasionally separated by a hard, protruding layer up concretions, where they are locally associated with to 2 mm thick, with a similar layer lining the outside large, horizontal gastropod-produced trails. of the outer ring. The shafts penetrate to the base of A thin section of one of the concretions shows the structures, although in some cases they cannot a very fine, unlaminated, micritic mudstone with be distinguished from radial tunnels that become spherical to slightly oval, calcareous framboidal sub-vertical towards the base. In rare cases, there structures 0.l-0.35 mm across, probably formed are two or more shafts within the same concretion, by microbes under reducing conditions. This sup- with their radial tunnels interpenetrating (Fig. 5A2). ports the oxygen-poor environment (at least in the This does not necessarily mean that the two tunnel subsurface) suggested by the occurrence of the systems were formed simultaneously, however. A Zoophycos ichnofacies trace fossils in areas sub- longitudinal section cut through one shaft shows a ject to occasional turbidity currents (Buatois and segmented structure, with the inner ring broken into Mángano, 1992). These framboidal structures are fragments 2-5 mm long and arranged in an en echelon surrounded and partially to completely replaced manner. This possibly resulted from compaction by calcite crystals somewhat larger than the after the structure had been formed. The outer ring matrix. Small, spherical carbon grains less than is vague in longitudinal section, being hardly discern- 0.01 mm across as well as larger, irregular flakes ible from the matrix. probably representing or fragments are The trace fossils are visible in the concretions also common. All of these are partly replaced by only because of chemical and physical weathering calcite, which also forms veinlets up to 0.4 mm enhancing their external features. Natural cracks wide, consisting of larger crystals. An unbroken, exposing the interior of in situ concretions show delicate tests preserved within the thin only a very homogeneous mass of fine-grained section consists of slightly larger calcite crystals sandy limestone, which is also the case with a largely destroyed during polishing. laboratory-cut concretion containing clear Stello- Remarks: Star-shaped or radial trace fossils may glyphus llicoensis on its external surface. be caused by different behaviors - including res- The tubes radiating from the central shaft are in ting traces, farming structures, feeding structures a stellate pattern, each with a diameter of 10 to 20 and possible nests - and have been described from mm and circular to oval in cross-section. Their lon- a wide variety of environments (Grubić, 1970; gitudinal shapes vary widely, from almost smooth to Häntzschel, 1970; Bromley, 1990; Seilacher, regularly pinching and swelling, and in some cases 2007). These include ichnotaxa without a cen-

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tral shaft, such as Asteriacites Schlotheim, 1820 The type ichnospecies of Dactyloidites, Dac- (Mángano et al., 1999), Asterosoma Otto, 1854 tyloidites bulbosus Hall, 1886 [=Dactyloidites (Pervesler and Uchman, 2004), and Lorenzinia asterioides (Fitch, 1850)] from the Early Gabelli, 1900 (Uchman, 1998), as well as ichnotaxa of New York State, and other ichnospecies such as in which a central shaft or knob is present. Among Dactyloidites cabanasi, which is a stellate form the latter are Arenituba Stanley and Pickerill, 1995, with 4-6 broad, leaf-shaped radial tunnels around a Asterichnus Bandel, 1967, Atollites Maas, 1902, central shaft (Vintaned et al., 2006), are restricted Capodistria Vialov, 1964 (Vialov, 1968), Dac- to one bedding plane. Some of the better known tyloidites Hall, 1886 (Fürsich and Bromley, 1985), ichnospecies like D. ottoi and D. peniculus do not Estrellichnus Uchman and Wetzel, 2001, Gloc- occur only in a single plane, but are multitiered and kerichnus Pickerill, 1982 (Książkiewicz, 1977), resemble our new ichnospecies to a certain extent. Gyrophyllites Glocker, 1841 (Fischer-Ooster, 1858; However, because of their differences from the Fürsich, 1974), Maiakarichnus Verde and Martínez, type ichnospecies, it is doubtful whether these two 2004, Phoebichnus Bromley and Asgaard, 1972, forms really belong within the ichnogenus Dac- Sphaerichnus Fürsich, 1998 and Stelloglyphus tyloidites. Dactyloidites ottoi Geinitz, 1849 is the Vialov, 1964 (Häntzschel, 1975). type ichnospecies of Haentzschelinia Vialov, 1964, Of those traces radiating from a central shaft, a placement regarded as appropriate by Seilacher all except Dactyloidites, Maiakarichnus, Phoebich- (2007) and followed here, and we regard D. penicu- nus, Sphaerichnus and Stelloglyphus have tunnels, lus as being closer to Stelloglyphus llicoensis than lobes, ridges or grooves developed essentially to Dactyloidites asterioides. However, a revision of along the same horizontal plane, or curving upward the ichnogenus Dactyloidites is beyond the scope towards the surface only at their extremities. The of this work. burrows described here do not form a ring struc- Stelloglyphus llicoensis differs widely from ture on bedding surfaces, which is distinct from, Haentzschelinia ottoi, which is characterized by for example, Estrellichnus jacaensis Uchman and protrusive spreiten (Gibert et al., 1995). Although Wetzel, 2001 or Capodistria vettersi Vialov, 1968 it superficially resembles Dactyloidites peniculus (Uchman and Wetzel, 2001). D’Alessandro and Bromley, 1986, from the Pleisto- Among those traces with multi-level radiating cene of southern Italy (D’Alessandro and Bromley, tunnels, only Dactyloidites and Stelloglyphus have 1986; Uchman and Pervesler, 2007), it differs from characteristics similar to the new traces found at the latter through better defined lateral tunnels Llico, as discussed below. Maiakarichnus currani (some of which bifurcate in contrast to those of D. Verde and Martínez, 2004, recently described from peniculus), in having non-symmetrical tunnels, and the Late Miocene of Uruguay by these authors, is in that its tunnels generally do not curve upwards preserved in full relief as a subspherical chamber after reaching the distal part and thus do not produce with numerous thin shafts radiating upward from a concave centre at the base. The latter feature was its upper part and sides. It has been interpreted as not observed in any of the more than 60 specimens a callianassid brood structure. Phoebichnus, with examined by us. The tunnels are also much wider its type ichnospecies P. trochoides (Bromley and (10-20 mm) than those of D. peniculus (5-6 mm). Asgaard, 1972), has been described from the Ju- Stelloglyphus llicoensis also resembles some rassic of Greenland and its occurrence elsewhere is ichnospecies of Gyrophyllites (e.g., Fürsich, 1974; restricted to a few other successions. It Fu, 1991) but differs from these in being tridi- has a large central disc and double-walled tunnels mensional (Fig. 6). That is, while ichnospecies of radiating horizontally at different levels, containing Gyrophyllites are star-shaped planar constructions, bi-directional back-fill menisci. Related forms in- specimens of Stelloglyphus llicoensis radiate in clude Phoebichnus bosoensis Kotake, 2003, which three dimensions. According to Fürsich (1974), derives from the Neogene, and Phoebichnus minor Gyrophyllites may have several storeys, but each that occurs in the Cambrian (Li and Yuan, 1999). storey is restricted to a single bedding surface. The monotypic ichnogenus Sphaerichnus, describ- However, individual branches of Gyrophyllites are ed from the of India ‘lacks any internal leaf-shaped and contrast strongly with the tubes structure such as spreiten’ (Fürsich, 1998). of S. llicoensis. Especially Gyrophyllites isp. from

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Fig. 6. Schematic reconstruction of Stelloglyphus llicoensis isp. nov. in a discoidal concretion. A. Vertical cross section through the axis of the trace fossil; B. Lateral view; C. Bottom view; D. Top view.

the Miocene flysch of Langun, Borneo (Fu, 1991, i.e., backfilled burrow-systems of stationary- de pl. 6 figs. A, B) looks similar. However, it seems posit-feeding organisms, and were grouped as to be the same specimen that was later figured as ‘gyrophyllitids’ by Seilacher (2007). Consequen- Stelloglyphus by Seilacher (2007, pl. 47). Some ich- tly, Stelloglyphus llicoensis is here interpreted as nospecies of Stelloglyphus (see Häntzschel, 1975, a feeding burrow system. Fodinichnia commonly fig. 69) seem to be restricted to individual bedding display active filling due to food processing and planes, but published figures are rather poor. Others, typically have unwalled burrows, which fit in with like one example from the Miocene of Borneo our observations (Buatois et al., 2002). (Seilacher, 2007, pl. 47 upper left) are very similar to the here described Stelloglyphus llicoensis in 4. Conclusions being multitiered but not restricted to individual bedding planes. Because of this we classify our new The radial trace fossil Stelloglyphus llicoensis ichnospecies within the ichnogenus Stelloglyphus, occurs in an early Pliocene sedimentary succession although the tridimensional morphology can only rich in organic material, deposited in subtropical to be guessed at for the type ichnospecies (Häntzschel, tropical waters in an outer shelf to upper continental 1975, fig. 69). slope environment, in contrast to similar ichnos- The ichnogenera Stelloglyphus, Gyrophyllites, pecies that occur in shallow water environments, and Dactyloidites are interpreted as fodinichnia, e.g., Dactyloidites peniculus (D’Alessandro and

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Bromley, 1986), D. cabanasi (Vintaned et al., trazas fósiles, Formación Kotick Point, Cretácico de 2006) and Haentzschelinia ottoi (Gibert et al., Antártida. Ameghiniana 29: 69-84. 1995; Agirrezabala and Gibert, 2004). Turbidity Buatois, L.A.; López Angriman, A.O. 1991. Ichnología currents occasionally disturbed the generally calm de la Formación Whiskey Bay (Cretácico, Isla James Ross, Antártida): Implicancias paleoecológicas y environment. The sediment pore-water was proba- paleoambientales. Ameghiniana 28: 75-88. bly poor in oxygen, at least in the subsurface, as Buatois, L.A.; Mángano, M.G.; Aceñolaza, F.G. 2002. indicated by calcareous framboidal structures and Trazas Fósiles: Señales de Comportamiento en el preserved plant fragments. The trace fossil consists Registro Estratigráfico. Museo Paleontológico Egidio of a central, double-ringed shaft with single to Feruglio, Chubut, Argentina: 382 p. branched, smooth to meniscate tunnels radiating D’Alessandro, A.; Bromley, R.G. 1986. Trace fossils in downward from different levels. Only in rare cases Pleistocene sandy deposits from Gravina area, southern Italy. Rivista Italiana di Paleontologia e Stratigrafia do the basal radial elements curve slightly upward. 92: 67-102. Stelloglyphus llicoensis is interpreted as a backfi- Encinas, A.; Le Roux, J.P.; Buatois, L.A.; Nielsen, S.N.; lled burrow-system of a stationary deposit-feeding Finger, K.L.; Fourtanier, E.; Lavenu, A. 2006. Nuevo organism. The ichnofossil is associated with the esquema estratigráfico para los depósitos mio-plioce- Zoophycos ichnofacies, although it may also have nos del área de Navidad (33°00’-34°30’S), Chile cen- some affinity with the Cruziana ichnofacies. tral. Revista Geológica de Chile 33 (2): 221-246. Finger, K.L.; Nielsen, S.N.; DeVries, T.J.; Encinas, A.; Peterson, D.E. 2007. Paleontologic evidence for Acknowledgements sedimentary displacement in Neogene forearc basins M. Dziggel (GeoForschungsZentrum Potsdam, of central Chile. Palaios 22: 3-16. Germany) produced the final version of figure 6. This Fischer-Ooster, C.V. 1858. Die fossilen Fucoiden der project was funded by Fondecyt 1010691 and Deuts- Schweizer Alpen, nebst Erörterungen über deren che Forschungsgemeinschaft grants Ni699/4-1, which geologisches Alter. Huber: 72 p. Bern. is gratefully acknowledged. The study was completed Fitch, A. 1850. A historical, topographical and agricultural while JPLR held a fellowship at the Hanse Institute for survey of the County of Washington. Transactions of Advanced Study in Delmenhorst, Germany and SNN was the New York State Agricultural Society 9 (1849): at GFZ Potsdam; the logistical and financial support of 753-944. both institutions is greatly appreciated. Reviews by J. de Fu, S. 1991. Funktion, Verhalten und Einteilung fucoider Gibert, S. Palma, V. Pineda, L. Spalletti and an anony- und lophocteniider Lebensspuren. Courier Forschungs- mous reviewer helped to improve the manuscript. institut Senckenberg 135: 1-79. Fürsich, F.T. 1974. Corallian (Upper Jurassic) trace fossils References from England and Normandy. Stuttgarter Beiträge zur Naturkunde B13: 1-51. Agirrezabala, L.M.; Gibert, J.M. de, 2004. Paleodepth Fürsich, F.T. 1998. Environmental distribution of trace and paleoenvironment of Dactyloidites ottoi (Geinitz, fossils in the Jurassic of Kachch (western India). 1849) from the Lower Cretaceous deltaic deposits Facies 39: 46-53. (Basque-Cantabrian basin, west Pyrenees). Palaios Fürsich, F.T.; Bromley, R.G. 1985. Behavioural interpre- 19: 276-291. tation of a rosetted spreite trace fossil: Dactyloidites Aguirre, L. 1985. The southern Andes. In The Ocean ottoi (Geinitz). Lethaia 18: 199-207. Basins and Margins (Nairn, A.E.M.; Stehli, F.G.; Gabelli, L. 1900. Sopra un interessante impronta medu- Uyeda, S.; editors). The Pacific Ocean. Plenum Press soide. Il Pensiero Aristotelico nella Scienza Moderna, 7a: 265-376. New York. anno I°, fascicolo II°: 75-79. Bandel, K. 1967. Trace fossils from two Upper Penn­ García, F. 1968. Estratigrafía del Terciario de Chile cen- sylvanian sandstones in Kansas. The University of tral. In Symposio Terciario de Chile, Zona Central Kansas, Paleontological Contributions 18: 1-13. (Cecioni, G.; editor). Editorial Andrés Bello: 25-58. Bromley, R.G. 1990. Trace fossils: biology and taphonomy. Santiago. Special Topics in Palaeontology 3: 280 p. Geinitz, H.B. 1849. Das Quadersandsteingebirge oder Bromley, R.G.; Asgaard, U. 1972. Notes on Greenland Kreidegebirge in Deutschland. Graz and Gerlach, trace fossils. III. A large radiating burrow-system Freiberg: 292 p. in Jurassic micaceous sandstones of Jameson Land, Gibert, J.M. de; Martinell, J.; Doménech, R. 1995. The east Greenland. Gronlands Geologiske Undersogelse rosetted feeding trace fossil Dactyloidites ottoi Rapport 49: 23-30. (Geinitz) from the Miocene of Catalonia. Geobios Buatois, L.A.; Mángano, M.G. 1992. La oxigenación como 28: 769-776. factor de control en la distribución de asociaciones de Glocker, F.E. 1841. Über die kalkführende Sandsteinfor-

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mation auf beiden Seiten der mittleren March, in der Nielsen, S.N.; Frassinetti, D. 2007b. The Miocene Archi- Gegend zwischen Kwassitz und Kremsier. Academia tectonicidae () of Chile. Paläontologische Caesarea Leopoldino-Carolina Germanica Naturae Zeitschrift 81: 291-303. Curiosorum 19 (Supplement 2): 309-334. Nielsen, S.N.; Frassinetti, D.; Bandel, K. 2004. Miocene Groves, L.T.; Nielsen, S.N. 2003. A new Late Miocene Vetigastropoda and Neritimorpha (Mollusca, Gastro- Zonaria (Gastropoda: Cypraeidae) from central Chile. poda) of Central Chile. Journal of South American The Veliger 46: 351-354. Earth Sciences 7: 73-88. Grubić, A. 1970. Rosetted trace fossils: a short review. Otto, E. von. 1854. Additamente zur Flora des Quaderge- In Trace fossils (Crimes, T.P.; Harper, J.C.; editors). birges in Sachsen. Part 2. G. Mayer, Leipzig: 53 p. Geological Journal, Special Issue 3: 185-188. Pervesler, P.; Uchman, A. 2004. Ichnofossils from the Hall, J. 1886. Note on some obscure organisms in the type area of the Grund Formation (Miocene, Lower roofing slate of Washington County, New York. New Badenian) in northern Lower Austria (Molasse basin). York State Museum of Natural History, Annual Report Geologica Carpathica 55: 103-110. 39: p. 160, pl. 11. Pickerill, R.K. 1982. Glockerichnus, a new name for the Häntzschel, W. 1970. Star-like trace fossils. In Trace fos- trace fossil ichnogenus Glockeria Książkiewicz, 1968. sils (Crimes, T.P.; Harper, J.C.; editors). Geological Journal of 56: 816. Journal, Special Issue 3: 201-214. Pineda, V. 1986. Evolución paleogeográfica de la cuenca Häntzschel, W. 1975. Trace fossils and problematica. sedimentaria cretácico-terciaria de Arauco. In Geología In Treatise on Invertebrate Paleontology, Part W y recursos minerales de Chile (Frutos, J.; Oyarzún, R.; Supplement 1 (Teichert, C.; editor). Geological Pincheira, M.; editors). Editorial de la Universidad de Society of America and University of Kansas Press, Concepción 1: 375-390. Lawrence: 269 p. Schlotheim, E.F. von. 1820. Die Petrefactenkunde auf Kennett, J.P.; Srinivasan, M.S. 1983. Neogene Planktonic ihrem jetzigen Standpunkte durch die Beschreibung : a Phylogenetic Atlas. Hutchinson Ross, seiner Sammlung versteinerter und fossiler Überreste Stroudsburg: 265 p. des Thier und Pflanzenreiches der Vorwelt erläutert. Kotake, N. 2003. Ethologic and ecologic interpretation Becker, Gotha: 437 p., 15 pl. of complex stellate structures in Pleistocene deep- Seilacher, A. 1964. Sedimentological classification and sea sediments (Otadai Formation), Boso Peninsula, nomenclature of trace fossils. Sedimentology 3: central Japan. , Palaeoclimatology, 256-263. Palaeoecology 192: 143-155. Seilacher, A. 2007. Trace Fossil Analysis. Springer Verlag, Książkiewicz, M. 1977. Trace fossils in the flysch of Berlin Heidelberg New York: 226 p. the Polish Carpathians. Palaeontologia Polonica 36: Stanley, D.C.A.; Pickerill, R.K. 1995. Arenituba, a 1-208. new name for the trace fossil ichnogenus Micatuba Le Roux, J.P.; Elgueta, S. 1997. Paralic parasequences Chamberlain, 1971. Journal of Paleontology 69: associated with sea-level oscillations in an ac- 612-614. tive margin setting: Trihueco Formation of the Arauco Tavera, J. 1942. Contribución al estudio de la estratigrafía Basin, Chile. Sedimentary Geology 110: 257-276. y paleontología del Terciaro de Arauco. Anales del Le Roux, J.P.; Nielsen, S.N.; Kemnitz, H.; Henríquez, A. Congreso Panamericano de Ingeniería de Minas y 2008. A Pliocene mega-tsunami deposit and associated Geología No. 1, 2: 580-632. Santiago. features in the Ranquil Formation, southern Chile. Uchman, A. 1998. Taxonomy and ethology of flysch Sedimentary Geology 203: 164-180. trace fossils: A revision of the Marian Książkiewicz Le Roux, J.P.; Vargas, G. 2005. Hydraulic behavior of collection and studies of complementary material. tsunami backflows: Insights from their modern and Annales Societatis Geologorum Poloniae 68: 105- ancient deposits. Environmental Geology 49: 65-75. 218. Li, Y.; Yuan, J.L. 1999. Lower Cambrian trace fossils Uchman, A.; Pervesler, P. 2007. Palaeobiological and from the Mantou Formation of Huainan, Anhui. Acta palaeoenvironmental significance of the Pliocene trace Paleontologica Sinica 38: 114-124. fossil Dactyloidites peniculus. Acta Palaeontologica Maas, O. 1902. Über Medusen aus dem Solenhofer Schiefer Polonica 52: 799-808. und der unteren Kreide der Karpathen. Palaeontogra- Uchman, A.; Wetzel, A. 2001. Estrellichnus jacaensis nov. phica 48: 297-322. igen., nov. isp.-A large radial trace fossil from Eocene Mángano, M.G.; Buatois, L.A.; West, R.R.; Maples, C.G. flysch (Hecho Group, northern Spain). Geobios 34: 1999. The origin and paleoecologic significance of 357-361. the trace fossil Asteriacites in the Pennsylvanian of Verde, M.; Martínez, S. 2004. A new ichnogenus for crus- Kansas and Missouri. Lethaia 32: 17-30. tacean trace fossils from the Upper Miocene Camacho Nielsen, S.N.; Frassinetti, D. 2007a. The Miocene Formation of Uruguay. Palaeontology 47: 39-49. Volutidae (Gastropoda: Neogastropoda) from the Vialov, O.S. 1964. Zvezdchatye ieroglify iz Triasa seve- Pacific coast of Chile. Journal of Paleontology 81: rovostoka Sibiri [Star-shaped hieroglyphs from the 82-102. of northeastern Siberia]. Akademija Nauk

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SSSR, Geologii i Geofiziki, Sibirskoe Otdelenie 5: Vintaned, J.A.G.; Liñán, E.; Mayoral, E.; Dies, M.E.; Goza- 112-115. lo, R.; Muñiz, F. 2006. Trace and soft body fossils from Vialov, O.S. 1968. On star-shaped problematica (In the Pedroche Formation (Ovetian, Lower Cambrian Russian, English title). Ezheegodnik Vsesoyuznogo of the Sierra de Córdoba, S. Spain) and their relation Paleontologiches-kiyego Obshchestva 18: 326-340. to the Pedroche event. Geobios 39: 443-468.

Manuscript received: July 27, 2007; accepted: February 26, 2008.

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