Biostratigraphic precision of the Cruziana rugosa group: a study from the Ordovician succession of southern and central Bolivia

Abstract

-Cruziana ichnospecies have been repeatedly reported to have biostratigraphic significance. This study presents a re-evaluation of the arthropod ichnotaxa of the Cruziana rugosa Group from bio-and/or lithostratigraphically well-defined Lower to Upper Ordovician siliciclastic sections of southern and central Bolivia. With the exception of Cruziana rouaulti, the ichnofaunas contain all the members of the Cruziana rugosa Group throughout the Ordovician (Arenig to Caradoc) successions in Bolivia. The Bolivian material therefore indicates that these arthropod ichnofossil assemblages are suitable for recognizing Ordovician strata in Bolivia. These findings cast doubt on their use as reliable indicators for a global intra-Ordovician (Arenig to Caradoc) biozonation of Peri-Gondwanan sedimentary successions.

Lower Ordovician (Arenig) shallow-marine trace fossils of the Pochico Formation, southern Spain: palaeoenvironmental and palaeogeographic implications at the Gondwanan and peri-Gondwanan realm

“…However, many authors ascribed it to Cruziana ďOrbigny (e.g., Neto de Carvalho, 2006;Seilacher, 2007). This is supported by the presence of scratches in well preserved specimens (Egenhoff et al, 2007). The strongly developed side ridges suggest a carapace of an arthropod.…”

“…Therefore, Mángano and Buatois (2003) regarded C. furcifera, C. goldfussi and C. rugosa as subichnospecies of C. rugosa (respectively: C. rugosa furcifera, C. rugosa goldfussi and C. rugosa rugosa). However, many other authors retain them at the ichnospecies level (e.g., Aceñolaza and Milana, 2005;Neto de Carvalho, 2006) regarding that all the three ichnotaxa display distinctive morphological features (e.g., Egenhoff et al, 2007). Cruziana is interpreted as the feeding trace of trilobites and/or other arthropods such as aglaspids, limulids or phyllopods, whereas C. rugosa is attributed exclusively to trilobites (e.g., Seilacher, 1970Seilacher, , 2007.…”

Archetypally Siluro-Devonian ichnofauna in the Cowie Formation, Scotland: implications for the myriapod fossil record and Highland Boundary Fault Movement

“…Beyond ichnogeneric level it is often extremely challenging to distinguish between trace fossils, as morphological differences are often subtle and the quality of specimens highly variable (Egenhoff et al, 2007). However, the bulk ichnofauna of a succession may be more indicative of age as it indirectly records the suite of organisms and ethological styles active in the depositional environment.…”

Trace fossils and depositional environments in the Hawaz Formation, Middle Ordovician, western Libya

“…There has been a remarkable amount of studies published on Ordovician trace fossil assemblages occurring in South America (Mángano et al, 1996(Mángano et al, , 2001(Mángano et al, , 2002a(Mángano et al, , 2005Aceñolaza and Aceñolaza, 2002;Buatois and Mángano, 2003;Aceñolaza and Milana, 2005;Egenhoff et al, 2007) but only a handful of papers deal with localities in Australia (Webby, 1983;Droser et al, 1994), Arabic Peninsula (El-Khayal and Romano, 1988) or Antarctica (Weber and Braddy, 2004). In Africa, Seilacher and Alidou (1988) reported briefly on some Upper Ordovician trilobite traces from the Kandi Formation in Benin, while Kumpulainen et al (2006) studied the ichnoassemblage recorded in the Upper Ordovician Adigrat Sandstone of Eritrea and Le Heron (2010) described some trace fossils related with a Late Ordovician glacial erosional surface in Algeria.…”