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Loops, circles, spirals and the appearance of guided behaviors from the Ediacaran-Cambrian of Brittany, NW France

  • October 2019
  • Conference: International Meeting on the Ediacaran system and the Ediacaran-Cambrian Transition
  • At: Guadalupe, Spain
Authors:
Romain Gougeon at University of Saskatchewan
Romain Gougeon
Didier Néraudeau at Université de Rennes 1
Didier Néraudeau
Marc Poujol at Université de Rennes 1
Marc Poujol
Alfredo Loi at Università degli studi di Cagliari
Alfredo Loi
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Abstract and Figures

The Ediacaran-Cambrian transition is the place of striking changes in Earth ecosystems, with a diversification of life recorded by a complexification in animal behaviors. In a series of classic papers, Crimes (1974, 1987, 1992a, b) compiled worldwide data on trace fossil distribution from that time period, evaluating their potential as biomarkers and deciphering evolutionary processes. He suspected that many trace fossils typical of Phanerozoic deep-water settings originated in shallower environments. Spiraling is a strategy developed by organisms to survive in environments depleted in nutrient, exemplified by the farming open-burrow system Spirorhaphe (Seilacher, 1977). On the other hand, simple horizontal spirals of deposit-feeders are represented by many ichnogenera, common forms being Spirodesmos and Spirophycus (Buatois et al., 2017). Spiral trace fossils are poorly reported from the Ediacaran-Cambrian transition and remain problematic (e.g. Jensen, 2003; Carbone & Narbonne, 2014). Conversely, simple looping horizontal trails, fully circling (i.e. Circulichnis) or self-overcrossing (i.e. Gordia) are easily and abundantly identified. Crimes (1992a) suspected spiral trace fossils to appear stratigraphically higher than simple looping trails, at the same level of treptichnids (n.b. it is interesting to note that the two spiralling traces at issue, Planispiralichnus and Protospiralichnus, are omitted in another list in Crimes, 1992b; these Russian forms are now suspected to represent circular treptichnids by Marusin, 2011). The Brioverian from central Brittany, NW France, is a thick siliciclastic sedimentary succession that have been intensely deformed due to the successive Cadomian and Variscan orogenetic events. Hence, its stratigraphy, basin architecture and fossil content have been poorly understood, and the position of its uppermost limit within the Ediacaran or the Cambrian is still a pending question. However, recent investigations reported insights of life in the form of simple trace and body fossils in shallow-marine, tidally influenced settings (Gougeon et al., 2018; Néraudeau et al., 2018). Following up this promising start, new investigations were conducted and new ichnofossils were reported from outcrops in Saint-Gonlay, Montfort-sur-Meu (estearn Brittany) and Crozon (western Brittany; Fig. 1). From these, abundant horizontal looping, fully circling and pseudo- to perfect-spiraling trails are found associated with microbially stabilized surfaces. Although the two first forms can be identified as Gordia and Circulichnis respectively, the ichnotaxonomic position of the latest ones is more uncertain. Regardless of their actual name, spiral trails are not uncommon in the section and show that more complex programs (i.e. phobotaxis and thigmotaxis) were already acquired by their tracemakers. An Ediacaran double spiral from Australia closely relates in shape and size to the holotype of Spirorhaphe involute (Jensen, 2003). This trace fossil is transitional with unguided meanders, and the preservation as a trail or burrow is unknown; an affinity with a farming open-burrow system is then difficult to conceive. Beside that report, the oldest true Spirorhaphe is coming from the Ordovician (Pickerill, 1980; Lehane & Ekdale, 2016). Regarding simple deposit-feeder spirals, they are reported from the Ediacaran-Cambrian transition in both shallow- (this study) and deep-marine settings (Carbone & Narbonne, 2014). Microbially stabilized surfaces were pervasive at that time and may have been a wealthy medium for the nutrition of trail producers. Increasing sediment processing by penetrative animals during the Cambrian resulted in the progressive retreat of microbial mats in deep-marine settings (Crimes, 1992a, b; Buatois et al., 2011). After their disappearance by the Ordovician, eventually, organisms adapted their simple spirals of deposit-feeders to these nutrient-poor environments by developing more complex, farming open-burrow systems.
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Loops, circles, spirals and the appearance of guided behaviors from the Ediacaran-
Cambrian of Brittany, NW France
Gougeon, R.1,2,*, Néraudeau, D.2, Poujol, M.2 & Loi, A.3
1Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2,
Canada
2Univ Rennes, CNRS, Géosciences Rennes - UMR 6118, F-35000 Rennes, France
3Dipartimento di Scienze Chimiche e Geologiche, Università di Cagliari, Cittadella
Universitaria, 09042 Monserrato, Italy
*gougeon.romain@gmail.com
The Ediacaran-Cambrian transition is the place of striking changes in Earth ecosystems,
with a diversification of life recorded by a complexification in animal behaviors. In a series of
classic papers, Crimes (1974, 1987, 1992a, b) compiled worldwide data on trace fossil
distribution from that time period, evaluating their potential as biomarkers and deciphering
evolutionary processes. He suspected that many trace fossils typical of Phanerozoic deep-water
settings originated in shallower environments. Spiraling is a strategy developed by organisms
to survive in environments depleted in nutrient, exemplified by the farming open-burrow
system Spirorhaphe (Seilacher, 1977). On the other hand, simple horizontal spirals of deposit-
feeders are represented by many ichnogenera, common forms being Spirodesmos and
Spirophycus (Buatois et al., 2017).
Spiral trace fossils are poorly reported from the Ediacaran-Cambrian transition and
remain problematic (e.g. Jensen, 2003; Carbone & Narbonne, 2014). Conversely, simple
looping horizontal trails, fully circling (i.e. Circulichnis) or self-overcrossing (i.e. Gordia) are
easily and abundantly identified. Crimes (1992a) suspected spiral trace fossils to appear
stratigraphically higher than simple looping trails, at the same level of treptichnids (n.b. it is
interesting to note that the two spiralling traces at issue, Planispiralichnus and
Protospiralichnus, are omitted in another list in Crimes, 1992b; these Russian forms are now
suspected to represent circular treptichnids by Marusin, 2011).
The Brioverian from central Brittany, NW France, is a thick siliciclastic sedimentary
succession that have been intensely deformed due to the successive Cadomian and Variscan
orogenetic events. Hence, its stratigraphy, basin architecture and fossil content have been
poorly understood, and the position of its uppermost limit within the Ediacaran or the Cambrian
is still a pending question. However, recent investigations reported insights of life in the form
of simple trace and body fossils in shallow-marine, tidally influenced settings (Gougeon et al.,
2018; Néraudeau et al., 2018). Following up this promising start, new investigations were
conducted and new ichnofossils were reported from outcrops in Saint-Gonlay, Montfort-sur-
Meu (estearn Brittany) and Crozon (western Brittany; Fig. 1). From these, abundant horizontal
looping, fully circling and pseudo- to perfect-spiraling trails are found associated with
microbially stabilized surfaces. Although the two first forms can be identified as Gordia and
Circulichnis respectively, the ichnotaxonomic position of the latest ones is more uncertain.
Regardless of their actual name, spiral trails are not uncommon in the section and show that
more complex programs (i.e. phobotaxis and thigmotaxis) were already acquired by their
tracemakers.
An Ediacaran double spiral from Australia closely relates in shape and size to the
holotype of Spirorhaphe involute (Jensen, 2003). This trace fossil is transitional with unguided
meanders, and the preservation as a trail or burrow is unknown; an affinity with a farming open-
burrow system is then difficult to conceive. Beside that report, the oldest true Spirorhaphe is
coming from the Ordovician (Pickerill, 1980; Lehane & Ekdale, 2016). Regarding simple
deposit-feeder spirals, they are reported from the Ediacaran-Cambrian transition in both
shallow- (this study) and deep-marine settings (Carbone & Narbonne, 2014). Microbially
stabilized surfaces were pervasive at that time and may have been a wealthy medium for the
nutrition of trail producers. Increasing sediment processing by penetrative animals during the
Cambrian resulted in the progressive retreat of microbial mats in deep-marine settings (Crimes,
1992a, b; Buatois et al., 2011). After their disappearance by the Ordovician, eventually,
organisms adapted their simple spirals of deposit-feeders to these nutrient-poor environments
by developing more complex, farming open-burrow systems.
References:
Buatois, L.A.; Mángano, M.G.; Noffke, N. & Chafetz, H. (2011). The trace-fossil record of
organism-matground interactions in space and time. SEPM Special Publication, 101: 15-28.
Buatois, L.A.; Wisshak, M.; Wilson, M.A. & Mángano, M.G. (2017). Categories of
architectural designs in trace fossils: a measure of ichnodisparity. Earth-Science Reviews,
164: 102-181.
Carbone, C. & Narbonne, G.M. (2014). When life got smart: the evolution of behavioral
complexity through the Ediacaran and Early Cambrian of NW Canada. Journal of
Paleontology, 88: 309-330.
Crimes, T.P. (1974). Colonisation of the early ocean floor. Nature, 248: 328-330.
Crimes, T.P. (1987). Trace fossils and correlation of late Precambrian and early Cambrian
strata. Geological Magazine, 124: 97-119.
Crimes, T.P. (1992a). Changes in the trace fossil biota across the Proterozoic-Phanerozoic
boundary. Journal of the Geological Society, 149: 637-646.
Crimes, T.P. (1992b). The record of trace fossils across the Proterozoic-Cambrian boundary.
In: Origin and early evolution of the Metazoa (Lipps, J.H. & Signor, P.H., Eds.), Springer,
Boston, MA, 177-202.
Gougeon, R.; Néraudeau, D.; Dabard, M.P.; Pierson-Wickmann, A.C.; Polette, F.; Poujol, M.
& Saint-Martin, J.P. (2018). Trace fossils from the Brioverian (Ediacaran–Fortunian) in
Brittany (NW France). Ichnos, 25: 11-24.
Jensen, S. (2003). The Proterozoic and earliest Cambrian trace fossil record; patterns, problems
and perspectives. Integrative and Comparative Biology, 43: 219-228.
Lehane, J.R. & Ekdale, A.A. (2016). Morphometric analysis of graphoglyptid trace fossils in
two dimensions: implications for behavioral evolution in the deep sea. Paleobiology, 42:
317-334.
Marusin, V.V. (2011). Evolution of organism-sediment interaction in transition to Phanerozoic
biosphere. In: Neoproterozoic sedimentary basins: stratigraphy, geodynamics and petroleum
potential. Procedings of the International conference, Novosibirsk, 61-62.
Néraudeau, D.; Dabard, M.P.; El Albani, A.; Gougeon, R.; Mazurier, A.; Pierson‐Wickmann,
A.C.; Poujol, M.; Saint Martin, J.P. & Saint Martin, S. (2018). First evidence of Ediacaran–
Fortunian elliptical body fossils in the Brioverian series of Brittany, NW France. Lethaia,
51: 513-522.
Pickerill, R.K. (1980). Phanerozoic flysch trace fossil diversity - observations based on an
Ordovician flysch ichnofauna from the Aroostook-Matapedia Carbonate Belt of northern
New Brunswick. Canadian Journal of Earth Sciences, 17: 1259-1270.
Seilacher, A. (1977). Evolution of trace fossil communities. In: Developments in Palaeontology
and Stratigraphy (Hallam, A., Ed.), Elsevier, 359-376.
Figure 1 (next page). Looping, circling and spiraling trace fossils from the Brioverian. Scale
bars are 1 cm. 1. Gordia with numerous self-overcrossings. Montfort-sur-Meu (les Grippeaux).
2. Circular Gordia with one self-overcrossing (arrow). Saint-Gonlay (la Lammerais). 3. Tiny
Circulichnis on a microbially stabilized surface. Note that the trail starts (or ends) outside of
the circle (arrow). Saint-Gonlay (la Lammerais). 4. Perfect tiny Circulichnis (top right)
associated with horizontal trails (left) and a pit of indistinct affinity (bottom right). Saint-Gonlay
(la Lammerais). 5. Pseudo-spiraling Gordia with a self-overcrossing (arrow) and an unguided
course. Montfort-sur-Meu (le Bois-du-Buisson). 6. Spiral trail with an uncertain guided course.
Montfort-sur-Meu (le Bois-du-Buisson). 7, 8. Perfect spiral trails with guided courses.
Montfort-sur-Meu (les Grippeaux; 7) and Crozon (8).
... The present materials resemble ring-like trace fossils Circulichnis montanus Vialov, 1971 and "Phycodes" coronatum Crimes and Anderson, 1985. Circulichnis montanus was originally reported from the Upper Triassic and can be convincingly traced back to the Ordovician (Pickerill and Keppie, 1981;Fillion and Pickerill, 1984) and further to the basal Cambrian (Gougeon et al., 2019). Our specimens are similar to the holotype of Circulichnis montanus in tunnel width and diameter for the ring-like portion. ...
... Our specimens are similar to the holotype of Circulichnis montanus in tunnel width and diameter for the ring-like portion. Circulichnis montanus with short branches has also been noted in previous reports (Pickerill and Keppie, 1981;Gougeon et al., 2019). "Phycodes" coronatum shows regularly spaced vertical shafts (a total of 20 ideally) on a ring-like burrow and has only been reported from the lowest Cambrian (Crimes and Anderson, 1985). ...
... Motor control evolution as evidenced by trace fossils may thus provide additional information about evolutionary ecology of benthic faunas. Spiralling/looping and guided movement patterns arose during the Ediacaran-Cambrian transition as shown by the conspicuous appearance of loops, circles, and spirals in the trace fossil record (Marusin, 2011;Gougeon et al., 2019). The lowest Cambrian witnesses the prominent occurrence of several morphologically complex, guided burrows in the shallow-marine environment, such as the systematicprobing Treptichnus pedum that takes curved to strongly looping routes (Jensen, 1997;Wilson et al., 2012), perfect circular galleries with equidistant vertical shafts "Phycodes" coronatum (Crimes and Anderson, 1985), and multi-level helicoidal trace Gyrolithes (Laing et al., 2018). ...
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... Despite the report of fossils since the 19th century, the age of its uppermost beds (Ediacaran or early Cambrian) is a long-standing conundrum. Recently, new investigations unravelled a unique assemblage of trace and body fossils in the vicinity of Rennes (Néraudeau et al. 2016Gougeon et al. 2018bGougeon et al. , 2019. Trace fossils are dominantly simple, horizontal and associated with microbially stabilized surfaces; of these, planispirals represent a surprising discovery. ...
... Ichnofossils were first discovered in the late 19th century (Lebesconte, 1886), but did not draw the attention of the scientific community for a long time. Recently, new investigations in the vicinity of Rennes (Fig. 1b) have unravelled an assemblage dominated by simple horizontal grazing trails (Circulichnis, Gordia, Helminthoidichnites, Helminthopsis), passively filled horizontal burrows (Palaeophycus) and horizontal spiral trace fossils (Spirodesmos; Néraudeau et al. 2016;Gougeon et al. 2018bGougeon et al. , 2019. In addition, microbially textured surfaces (MISS of Noffke et al. 2001) are common both in fossiliferous and azoic intervals (Lebesconte, 1886;Gougeon et al. 2018b). ...
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In northwestern France, the Brioverian series is a thick siliciclastic succession deposited during the Cadomian cycle (c. 750–540 Ma). In the uppermost Brioverian beds, previous studies unravelled an assemblage dominated by simple horizontal trace fossils associated with microbially stabilized surfaces. Here, we report Spirodesmos trace fossils – one-way, irregular and regular horizontal spirals – from Crozon (Finistère, Brittany), Montfort-sur-Meu and St-Gonlay (Ille-et-Vilaine, Brittany). After reviewing the literature on horizontal spiral trace fossils, an Ediacaran–Fortunian Spirodesmos pool is identified from marginal-marine to shelf settings, while an Ordovician–Recent trend formed in the deep-marine realm. These results suggest that an onshore–offshore migration in Spirodesmos took place during Ediacaran–Fortunian to Ordovician time, similar to what happened in graphoglyptids. In addition, the age of the uppermost Brioverian beds (Ediacaran or early Cambrian) is still a pending question. Here, we report two new U–Pb detrital zircon datings from sandstone samples in St-Gonlay, giving maximum deposition ages of 551 ± 7 Ma and 540 ± 5 Ma. Although these results do not discard an Ediacaran age for the uppermost Brioverian beds, a Fortunian age is envisioned because the new dating corroborates previous dating from Brittany, Mayenne and Normandy. However, the intervals of error of the radiometric dating, and the dominance of non-penetrative trace fossils associated with matgrounds (an ecology more typical of the Ediacaran Period), do not allow definitive conclusions on the age of the uppermost Brioverian beds.
... Circulichnis first occurs in the Fortunian (Mángano and Buatois, 2014) and becomes common in Ordovician deep-sea deposits (Pickerill and Keppie, 1981;Pickerill et al., 1988). Circulichnis with short branches has also been noted in previous reports (e.g., Pickerill and Keppie, 1981;Gougeon et al., 2019). Recently, more irregular ring-like trace was included in Circulichnis (Uchman and Rattazzi, 2019). ...
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Full-text available
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Graphoglyptids are deep-marine trace fossils, often found preserved as casts in positive relief on the base of turbidites. Previous analyses of the behavioral evolution of graphoglyptids suggested they were slowly diversifying, becoming optimized, and getting smaller over time until the Late Cretaceous, when a sudden increase in diversification occurred. This current study quantifies the morphology of approximately 400 different graphoglyptid specimens, ranging in age from the Cambrian to the present, in order to evaluate the behavioral evolutionary interpretations made previously. Results from this study indicate that although some general evolutionary patterns can be discerned, they are not as straightforward as previously reported. Different topological categories of trace fossils represent organisms’ responses to evolutionary pressures in unique ways. While burrow widths of meandering traces were becoming smaller over time, as predicted by previous workers, the burrow widths of the network traces were becoming smaller only until the Late Cretaceous, when they started to get larger again. The times of significant evolutionary changes in behavior were not consistent among various topological categories, with some morphological features being affected in the Late Cretaceous and others during the beginning of the Eocene. It is likely that the behavioral evolution of graphoglyptids was influenced by deep-marine global influences linked to climate change, glaciation, and deep-ocean warming. These influences affected each topological group uniquely, suggesting that different species or genera of trace makers were creating each of the topological categories. This is contrary to the hypothesis that all graphoglyptids were created by closely related species.
The Record of Trace Fossils across the Proterozoic—Cambrian Boundary
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  • Jan 1992
Numerous studies have shown that there is a dramatic increase in the abundance and diversity of trace fossils at about the base of the Cambrian (Seilacher, 1956; Daily, 1972; Crimes, 1975, 1987; Alpert, 1977; Fedonkin, 1980a,b; Brasier, 1982; Urbanek and Rozanov, 1983; Crimes and Anderson, 1985; Fritz and Crimes, 1985; Nowlan et al., 1985; Paczesna, 1986; Narbonne et al., 1987). Accordingly, the possibility of using trace fossils to define or correlate the base of the Cambrian System has been widely discussed (Daily 1972; Alpert, 1977; Fedonkin, 1980a; Crimes and Anderson, 1985; Crimes, 1987; Narbonne et al., 1987).
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  • Mar 2014
Ediacaran and early Cambrian strata in NW Canada contain abundant trace fossils that record the progressive development of complex behavior in early animal evolution. Five feeding groups can be recognized: microbial grazing, deposit-feeding, deposit-feeding/predatory, filter-feeding/predatory, and arthropod tracks and trails. The lower Blueflower Formation (ca. 560-550 Ma) contains abundant burrows that completely cover bedding surfaces with small (similar to 1 mm diameter) cylindrical burrows that were strictly restricted to microbial bedding surfaces and exhibited only primitive and inconsistent avoidance strategies. The upper Blueflower contains three-dimensional avoidance burrows and rare filter-feeding or possibly predatory burrows, suggesting increased behavioral responses in food gathering that marked the beginning of the agronomic revolution in substrate utilization. Cambrian strata of the Ingta Formation contain systematically meandering burrows and more diverse feeding strategies, including the onset of treptichnid probing burrows that may reflect predation. These observations imply that Ediacaran burrowers were largely characterized by crude, two-dimensional avoidance meanders that represented simple behavioral responses of individual burrowers to sensory information, and that the subsequent development of more diverse and complex feeding patterns with genetically programmed search pathways occurred during the earliest stages of the Cambrian explosion. These observations further imply that changes occurred in both the food source and substrate during the ecological transition from Proterozoic matgrounds to Phanerozoic mixgrounds.
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Article
Trace fossils became relatively diverse in shallow-water clastic seas in the late Proterozoic (Vendian), with a further significant increase in abundance, diversity and complexity in the Tommotian and Atdabanian. Little change followed in the remainder of the Lower Palaeozoic. Traces typical of deeper-water facies evolved in shallow water during the Vendian and early Cambrian, and may have slowly migrated into the deep ocean during the remainder of the Lower Palaeozoic. There are a limited number of short-ranging ichnogenera which may be useful for correlation but the first appearance of ichnogenera may be a more satisfactory method. Three trace fossil zones covering the ranges Redkino and Kotlin, Rovno and Tommotian-lower Atdabanian are recognized and may be useful for world-wide correlation. -Author
Phanerozoic flysch trace fossil diversity -observations based on an Ordovidan flysch ichnofauna from the Aroostook-Matapedia Carbonate Belt of northern New Brunswick
Article
An Ordovician flysch trace fossil assemblage from the Aroostook–Matapedia Carbonate Belt, northern New Brunswick, consists of the following identifiable ichnogenera: Alcyonidiopsis, Asteriacites, Asterosoma, Belorhaphe, Bifasciculus, Buthotrephis, Chondrites, Cochlichnus, Cosmorhaphe, Diplichnites, Fucusopsis, Glockeria, Gyrochorte, Helminthoida, Helminthopsis, Neonereites, Paleodictyon, Planolites, Protopaleodictyon, Scalarituba, Spirodesmos, Spirorhaphe, and Taenidium. The stratigraphic range of six ichnogenera, viz. Glockeria, Gyrochorte, Helminthoida, Spirodesmos, Spirorhaphe, and Taenidium, is, therefore, now extended to rocks of Ordovician age.The diversity exhibited by the assemblage is inconsistent with currently proposed models of Phanerozoic flysch trace fossil diversity. It is suggested that existing models suffer from an inadequacy of sampling and systematic effort per period of geological time, as reflected by the limited number of post-Cambrian/pre-Cretaceous, particularly post-Carboniferous/pre-Cretaceous, adequately documented flysch ichnoassemblages. The assemblage described here clearly illustrates a significant radiation of deep-sea behavioural diversity in the Ordovician. This is possibly related to the development during the Ordovician of a sufficient oxygen concentration and supply of organic detritus in the deep sea or colonization of deeper-water habitats concomitant with the significant diversification of Ordovician shelf benthic communities.