Sabella bavincourti Vaillant 1909 from the Eocene of northern France is a little-known trace foss... more Sabella bavincourti Vaillant 1909 from the Eocene of northern France is a little-known trace fossil subsequently attributed – as Cteniza bavincourti – to the burrowing activities of a trapdoor spider. It is thus an ichnospecies name and not a body fossil. Its interpretation as the activity of a spider is questionable and its original assignment to a worm burrow seems intuitively more likely. Irrespective of the affinities of the producer, the ICZN also covers ichnotaxa such that classifying these structures under a modern genus name creates a homonym. It is here reassigned as the ichnotaxon Oichnus bavincourti comb. nov. Another problematic name is Theridium columbianum (Scudder 1878) from the Eocene of Canada and the USA, which is based on fossilized spider egg sacs. Under current ICZN rules fossil cocoons fall under the definition of ‘‘work of an animal’’. We propose reassigning them here to Araneaovoidus igen. nov., as Araneaovoidus columbiae (Scudder 1878) comb. nov.; but stress that this is now a trace fossil name. Similar problems underlie fossilized galls attributed (probably correctly) to mites, but assigned to living eriophyid mite genera. Fossil galls are the preserved pathological reactions of plant tissue and are also not ichnotaxa sensu Bertling et al. (2006). We propose that these mite names lie outside the bounds of zoological nomenclature. Within the broader context of arachnid-related trace fossils we briefly review the literature on fossil spider webs, as well as putative arachnid trackways such as Paleohelcura Gilmore 1926 and Octopodichnus Gilmore 1927.
We welcome the comments by Kaiser & Klok (2008) on our article concerning the giant p... more We welcome the comments by Kaiser & Klok (2008) on our article concerning the giant pterygotid chelicerae, although we note that they do not provide a revised size estimate, thus providing an alternative hypothesis to test. As we noted in our original article, the conclusion that ...
Palaeobiodiversity and Palaeoenvironments, Jan 1, 2010
Arthropod trackways from the Early Devonian of Alken an der Mosel are described, assigned to the ... more Arthropod trackways from the Early Devonian of Alken an der Mosel are described, assigned to the ichnospecies Palmichnium pottsae and attributed to medium-sized eurypterids known from the assemblage. Ichnological and sedimentological evidence suggests that several similarly sized animals simultaneously crawled towards, or away from, the shoreline traversing the lower intertidal zone, where conditions for trackway preservation were most favourable. Comparison with modern horseshoe crabs suggests that this synchronized behaviour may have been part of the reproductive cycle of eurypterids, supporting the previously formulated 'massmoult-mate' hypothesis.
Im Gegensatz zu der relativen Kleinwüchsigkeit heutiger Arthropoden (Gliederfüßer) zeigen uns Fos... more Im Gegensatz zu der relativen Kleinwüchsigkeit heutiger Arthropoden (Gliederfüßer) zeigen uns Fossilien, dass einige Repräsentanten dieser Gruppe geradezu gigantische Ausmaße erreichten. In der Eifel wurde nun die Chelicere eines Seeskorpions aus dem Unterdevon gefunden, der vermutlich 2,46 m lang war.
The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic g... more The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic groups concerned. To this aim, trace fossils are rigorously defined with regard to biological taxa and physical sedimentary structures. Potential ichnotaxobases are evaluated, with morphology resulting as the most important criterion. For trace fossils related to bioerosion and herbivory, substrate plays a key role, as well as composition for coprolites. Size, producer, age, facies and preservation are rejected as ichnotaxobases. Separate names for undertracks and other poorly preserved material should gradually be replaced by ichnotaxa based on well-preserved specimens. Recent traces may be identified using established trace fossil taxa but new names can only be based on fossil material, even if the distinction between recent and fossil may frequently remain arbitrary. It is stressed that ichnotaxa must not be incorporated into biological taxa in systematics. Composite trace fossil structures (complex structures made by the combined activity of two or more species) have no chnotaxonomic standing but compound traces (complex structures made by one individual tracemaker) may be named separately under certain provisions. The following emendations are proposed to the International Code of Zoological Nomenclature: The term ‘work of an animal’ should be deleted from the code, and ichnotaxa should be based solely on trace fossils as defined herein.
The aglaspidid arthropod, Australaglaspis stonyensis gen. et sp. nov., is described from the Idam... more The aglaspidid arthropod, Australaglaspis stonyensis gen. et sp. nov., is described from the Idamean (Upper Cambrian) of Stony Point, Montagu, north-western Tasmania. The dorsal exoskeleton comprises a semicircular cephalon with a well-defined marginal rim, acute genal angles, oval eyes, subtriangular glabella area and a subtrapezoidal hypostome. The trunk bears eleven somites with well-developed pleural spines that progressively curve backwards. Paired postventral plates cover the last trunk tergites and the base of the tailspine, which is long and characterized by a medial cleft. Bilobed ventral impressions indicate the pres-ence of homopodous appendages, forming a food groove along the trunk. The fossil assemblage and its mode of preservation suggest that Australaglaspis originally possessed a phosphatic cuticle, but chemical traces of it have been lost because of regional metamorphism and weathering. Australaglaspis appears to be closely related to the North American aglaspidid Chraspedops modesta Raasch, 1939, based on its medially cleft tailspine.
The phylogenetic position of aglaspidids, a problematic group of Lower Palaeozoic arthropods of u... more The phylogenetic position of aglaspidids, a problematic group of Lower Palaeozoic arthropods of undetermined affinities, is re-examined in the context of the major Cambrian and Ordovician lamellipedian arthropod groups. A cladistic analysis of ten genera of aglaspidids sensu stricto, six aglaspidid-like arthropods and 42 Palaeozoic arthropod taxa indicates that Xenopoda, Cheloniellida, Aglaspidida sensu lato and Trilobitomorpha form a clade (Artiopoda Hou and Bergstro¨m, 1997) nested within the mandibulate stem-lineage, thus discarding previous interpretations of these taxa as part 'of the chelicerate stem-group (Arachnomorpha Heider, 1913). The results confirm an aglaspidid identity for several recently described arthropods, including Quasimodaspis brentsae, Tremaglaspis unite, Chlupacaris dubia, Australaglaspis stonyensis and an unnamed Ordovician Chinese arthropod. The problematic Bohemian arthropod Kodymirus vagans was recovered as sister taxon to Beckwithia typa, and both form a small clade that falls outside Aglaspidida sensu stricto, thus discarding eurypterid affinities for the former. The analysis does not support the phylogenetic position of Kwanyinaspis maotianshanensis at the base of Conciliterga as proposed in recent studies, but rather occupies a basal position within Aglaspidida sensu lato. The results indicate a close association of aglaspidid arthropods with xenopods (i.e. Emeraldella and Sidneyia) and cheloniellids (e.g. Cheloniellon, Duslia); the new clade ''Vicissicaudata'' is proposed to encompass these arthropods, which are characterized by a differentiated posterior region. The phylogenetic position of aglaspidid arthropods makes them good outgroup candidates for analysing the internal relationships within the groups that form Trilobitomorpha. This work provides a much clearer picture of the phylogenetic relationships among Lower Palaeozoic lamellipedians.
Sabella bavincourti Vaillant 1909 from the Eocene of northern France is a little-known trace foss... more Sabella bavincourti Vaillant 1909 from the Eocene of northern France is a little-known trace fossil subsequently attributed – as Cteniza bavincourti – to the burrowing activities of a trapdoor spider. It is thus an ichnospecies name and not a body fossil. Its interpretation as the activity of a spider is questionable and its original assignment to a worm burrow seems intuitively more likely. Irrespective of the affinities of the producer, the ICZN also covers ichnotaxa such that classifying these structures under a modern genus name creates a homonym. It is here reassigned as the ichnotaxon Oichnus bavincourti comb. nov. Another problematic name is Theridium columbianum (Scudder 1878) from the Eocene of Canada and the USA, which is based on fossilized spider egg sacs. Under current ICZN rules fossil cocoons fall under the definition of ‘‘work of an animal’’. We propose reassigning them here to Araneaovoidus igen. nov., as Araneaovoidus columbiae (Scudder 1878) comb. nov.; but stress that this is now a trace fossil name. Similar problems underlie fossilized galls attributed (probably correctly) to mites, but assigned to living eriophyid mite genera. Fossil galls are the preserved pathological reactions of plant tissue and are also not ichnotaxa sensu Bertling et al. (2006). We propose that these mite names lie outside the bounds of zoological nomenclature. Within the broader context of arachnid-related trace fossils we briefly review the literature on fossil spider webs, as well as putative arachnid trackways such as Paleohelcura Gilmore 1926 and Octopodichnus Gilmore 1927.
We welcome the comments by Kaiser & Klok (2008) on our article concerning the giant p... more We welcome the comments by Kaiser & Klok (2008) on our article concerning the giant pterygotid chelicerae, although we note that they do not provide a revised size estimate, thus providing an alternative hypothesis to test. As we noted in our original article, the conclusion that ...
Palaeobiodiversity and Palaeoenvironments, Jan 1, 2010
Arthropod trackways from the Early Devonian of Alken an der Mosel are described, assigned to the ... more Arthropod trackways from the Early Devonian of Alken an der Mosel are described, assigned to the ichnospecies Palmichnium pottsae and attributed to medium-sized eurypterids known from the assemblage. Ichnological and sedimentological evidence suggests that several similarly sized animals simultaneously crawled towards, or away from, the shoreline traversing the lower intertidal zone, where conditions for trackway preservation were most favourable. Comparison with modern horseshoe crabs suggests that this synchronized behaviour may have been part of the reproductive cycle of eurypterids, supporting the previously formulated 'massmoult-mate' hypothesis.
Im Gegensatz zu der relativen Kleinwüchsigkeit heutiger Arthropoden (Gliederfüßer) zeigen uns Fos... more Im Gegensatz zu der relativen Kleinwüchsigkeit heutiger Arthropoden (Gliederfüßer) zeigen uns Fossilien, dass einige Repräsentanten dieser Gruppe geradezu gigantische Ausmaße erreichten. In der Eifel wurde nun die Chelicere eines Seeskorpions aus dem Unterdevon gefunden, der vermutlich 2,46 m lang war.
The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic g... more The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic groups concerned. To this aim, trace fossils are rigorously defined with regard to biological taxa and physical sedimentary structures. Potential ichnotaxobases are evaluated, with morphology resulting as the most important criterion. For trace fossils related to bioerosion and herbivory, substrate plays a key role, as well as composition for coprolites. Size, producer, age, facies and preservation are rejected as ichnotaxobases. Separate names for undertracks and other poorly preserved material should gradually be replaced by ichnotaxa based on well-preserved specimens. Recent traces may be identified using established trace fossil taxa but new names can only be based on fossil material, even if the distinction between recent and fossil may frequently remain arbitrary. It is stressed that ichnotaxa must not be incorporated into biological taxa in systematics. Composite trace fossil structures (complex structures made by the combined activity of two or more species) have no chnotaxonomic standing but compound traces (complex structures made by one individual tracemaker) may be named separately under certain provisions. The following emendations are proposed to the International Code of Zoological Nomenclature: The term ‘work of an animal’ should be deleted from the code, and ichnotaxa should be based solely on trace fossils as defined herein.
The aglaspidid arthropod, Australaglaspis stonyensis gen. et sp. nov., is described from the Idam... more The aglaspidid arthropod, Australaglaspis stonyensis gen. et sp. nov., is described from the Idamean (Upper Cambrian) of Stony Point, Montagu, north-western Tasmania. The dorsal exoskeleton comprises a semicircular cephalon with a well-defined marginal rim, acute genal angles, oval eyes, subtriangular glabella area and a subtrapezoidal hypostome. The trunk bears eleven somites with well-developed pleural spines that progressively curve backwards. Paired postventral plates cover the last trunk tergites and the base of the tailspine, which is long and characterized by a medial cleft. Bilobed ventral impressions indicate the pres-ence of homopodous appendages, forming a food groove along the trunk. The fossil assemblage and its mode of preservation suggest that Australaglaspis originally possessed a phosphatic cuticle, but chemical traces of it have been lost because of regional metamorphism and weathering. Australaglaspis appears to be closely related to the North American aglaspidid Chraspedops modesta Raasch, 1939, based on its medially cleft tailspine.
The phylogenetic position of aglaspidids, a problematic group of Lower Palaeozoic arthropods of u... more The phylogenetic position of aglaspidids, a problematic group of Lower Palaeozoic arthropods of undetermined affinities, is re-examined in the context of the major Cambrian and Ordovician lamellipedian arthropod groups. A cladistic analysis of ten genera of aglaspidids sensu stricto, six aglaspidid-like arthropods and 42 Palaeozoic arthropod taxa indicates that Xenopoda, Cheloniellida, Aglaspidida sensu lato and Trilobitomorpha form a clade (Artiopoda Hou and Bergstro¨m, 1997) nested within the mandibulate stem-lineage, thus discarding previous interpretations of these taxa as part 'of the chelicerate stem-group (Arachnomorpha Heider, 1913). The results confirm an aglaspidid identity for several recently described arthropods, including Quasimodaspis brentsae, Tremaglaspis unite, Chlupacaris dubia, Australaglaspis stonyensis and an unnamed Ordovician Chinese arthropod. The problematic Bohemian arthropod Kodymirus vagans was recovered as sister taxon to Beckwithia typa, and both form a small clade that falls outside Aglaspidida sensu stricto, thus discarding eurypterid affinities for the former. The analysis does not support the phylogenetic position of Kwanyinaspis maotianshanensis at the base of Conciliterga as proposed in recent studies, but rather occupies a basal position within Aglaspidida sensu lato. The results indicate a close association of aglaspidid arthropods with xenopods (i.e. Emeraldella and Sidneyia) and cheloniellids (e.g. Cheloniellon, Duslia); the new clade ''Vicissicaudata'' is proposed to encompass these arthropods, which are characterized by a differentiated posterior region. The phylogenetic position of aglaspidid arthropods makes them good outgroup candidates for analysing the internal relationships within the groups that form Trilobitomorpha. This work provides a much clearer picture of the phylogenetic relationships among Lower Palaeozoic lamellipedians.
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