TY - JOUR
T1 - A highly diverse trilobite fauna with Avalonian affinities from the Middle Cambrian Acidusus atavus Zone (Drumian Stage) of Bornholm, Denmark
AU - Weidner, Thomas
AU - Nielsen, Arne Thorshøj
PY - 2014/1/2
Y1 - 2014/1/2
N2 - A newly collected trilobite fauna from the lowermost part of the Alum
Shale Formation at Øleå, Bornholm, Denmark, demonstrates the presence of
a thin but richly fossiliferous Middle Cambrian Acidusus atavus Zone (Paradoxides paradoxissimus Superzone). The lower part of the zone (the Tomagnostus fissus–Ptychagnostus atavus
Zone of older Scandinavian literature) is represented by a
discontinuous limestone bed, up to 20 cm thick, whereas the upper part (Hypagnostus parvifrons
Zone of older literature) is represented by shale, less than 80 cm
thick, containing lenses of bituminous limestone. A total of 39 agnostid
and 21 polymerid species are recorded from the A. atavus Zone
(including 12 taxa treated under open nomenclature). One additional
polymerid species collected from an ice-rafted boulder derived from the
Bornholm area is also treated. The fauna is described and illustrated,
with designation and reillustration of relevant lectotypes. The
abundance of polymerid trilobites in comparison with nearby Scania,
southern Sweden, where 25 agnostid and nine polymerid species have been
reported from equivalent strata, is indicative of a less dysoxic
environment in the Bornholm area, which was probably uplifted. The
trilobite fauna resembles the coeval assemblages described from England,
Wales, eastern Newfoundland and eastern Siberia, sharing several
species not reported previously from Baltica, including Anopolenus sp., Agraulos longicephalus, Bailiella ornata, Clarella impar, Solenopleura? applanata, Acadagnostus aff. bulkurensis and Phalagnostus ovalis. A few faunal elements originally described from Bohemia and Australia are also present, viz. Hydrocephalus aff. carens, Phalagnostus nudus, Skryjagnostus pompeckji, Hypagnostus aff. clipeus, Euagnostus aff. interstrictus and Euagnostus? aff. glandifer.
AB - A newly collected trilobite fauna from the lowermost part of the Alum
Shale Formation at Øleå, Bornholm, Denmark, demonstrates the presence of
a thin but richly fossiliferous Middle Cambrian Acidusus atavus Zone (Paradoxides paradoxissimus Superzone). The lower part of the zone (the Tomagnostus fissus–Ptychagnostus atavus
Zone of older Scandinavian literature) is represented by a
discontinuous limestone bed, up to 20 cm thick, whereas the upper part (Hypagnostus parvifrons
Zone of older literature) is represented by shale, less than 80 cm
thick, containing lenses of bituminous limestone. A total of 39 agnostid
and 21 polymerid species are recorded from the A. atavus Zone
(including 12 taxa treated under open nomenclature). One additional
polymerid species collected from an ice-rafted boulder derived from the
Bornholm area is also treated. The fauna is described and illustrated,
with designation and reillustration of relevant lectotypes. The
abundance of polymerid trilobites in comparison with nearby Scania,
southern Sweden, where 25 agnostid and nine polymerid species have been
reported from equivalent strata, is indicative of a less dysoxic
environment in the Bornholm area, which was probably uplifted. The
trilobite fauna resembles the coeval assemblages described from England,
Wales, eastern Newfoundland and eastern Siberia, sharing several
species not reported previously from Baltica, including Anopolenus sp., Agraulos longicephalus, Bailiella ornata, Clarella impar, Solenopleura? applanata, Acadagnostus aff. bulkurensis and Phalagnostus ovalis. A few faunal elements originally described from Bohemia and Australia are also present, viz. Hydrocephalus aff. carens, Phalagnostus nudus, Skryjagnostus pompeckji, Hypagnostus aff. clipeus, Euagnostus aff. interstrictus and Euagnostus? aff. glandifer.
U2 - 10.1080/14772019.2012.740080
DO - 10.1080/14772019.2012.740080
M3 - Journal article
SN - 1477-2019
VL - 12
SP - 23
EP - 92
JO - Journal of Systematic Palaeontology
JF - Journal of Systematic Palaeontology
IS - 1
ER -