Lower Ordovician trilobites of the Kirtonryggen Formation, Spitsbergen

This monograph describes early Ordovician (Ibexian: Tremadocian-early Floian) trilobites from Northern Spitsbergen from the section through the Kirtonryggen Formation adjacent to Hinlopen Strait. The Formation is divided into three Members, each with distinct trilobites collectively representing the fullest known succession from the Bathyurid biofacies of the eastern Laurentian carbonate platform. Previous research on the Ordovician of Spitsbergen is summarised and correlations with similar faunas previously described from Canada, Greenland, western Newfoundland, Vermont-New York State, Oklahoma and Missouri are discussed. Taxonomic problems are discussed in detail leading to the recognition of 53 species, of which 15 are new, belonging to 31 genera including four new. Twenty-four taxa are described under open or tentative nomenclature. The lower Member yields the earliest known occurrences of the Illaenoidea, Proetoidea and Scutelluoidea, supporting the hypotheses relating the origin of new major clades to inshore habitats.

Auteur
Professor Richard Fortey, F.R.S. is Merit Researcher at the Department of Palaeontology, Natural History Museum.

Texte du rabat

This monograph describes early Ordovician (Ibexian:Tremadocianearly Floian) trilobites from Northern Spitsbergen from the section through the Kirtonryggen Formation adjacent to Hinlopen Strait. The Formation is divided into three Members, each with distinct trilobites collectively representing the fullest known succession from the Bathyurid biofacies of the eastern Laurentian carbonate platform. Previous research on the Ordovician of Spitsbergen is summarised and correlations with similar faunas previously described from Canada, Greenland, western Newfoundland, VermontNew York State, Oklahoma and Missouri are discussed. Taxonomic problems are discussed in detail leading to the recognition of 53 species, of which 15 are new, belonging to 31 genera including four new. Twenty-four taxa are described under open or tentative nomenclature. The lower Member yields the earliest known occurrences of the Illaenoidea, Proetoidea and Scutelluoidea, supporting the hypotheses relating the origin of new major clades to inshore habitats.

Résumé

This monograph describes early Ordovician (Ibexian: Tremadocianearly Floian) trilobites from Northern Spitsbergen from the section through the Kirtonryggen Formation adjacent to Hinlopen Strait. The Formation is divided into three Members, each with distinct trilobites collectively representing the fullest known succession from the Bathyurid biofacies of the eastern Laurentian carbonate platform. Previous research on the Ordovician of Spitsbergen is summarised and correlations with similar faunas previously described from Canada, Greenland, western Newfoundland, VermontNew York State, Oklahoma and Missouri are discussed. Taxonomic problems are discussed in detail leading to the recognition of 53 species, of which 15 are new, belonging to 31 genera including four new. Twenty-four taxa are described under open or tentative nomenclature. The lower Member yields the earliest known occurrences of the Illaenoidea, Proetoidea and Scutelluoidea, supporting the hypotheses relating the origin of new major clades to inshore habitats.

Contenu
Introduction 2 Summary of previous research on the Ordovician of Spitsbergen 3

Stratigraphy of the Kirtonryggen Formation 4

Stratigraphic sub-divisions and age 4

TremadocianFloian boundary 9

Correlation with other areas of Ordovician Laurentia 10

Greenland 11

Canada 12

Northwest Scotland 13

USA 13

Occurrence of trilobites in the Kirtonryggen Formation 15

Field occurrence 15

Biofacies and biogeography 15

Peculiarities of the Spitsbergen faunas 16

Eastern and western Laurentia 17

Origin of major trilobite clades 18

Th e family Bathyuridae 19

Th e problem of type species 20

Morphology of Bathyuridae 21

Systematic Palaeontology 23

Order Aulacopleurida Adrain, 2011 23

Family Hystricuridae Hupé, 1953 23

Genus Svalbardicurus ngen 23

Svalbardicurus delicatus nsp 24

Genus Hystricurus Raymond, 1913 26

Hystricurus cfHystricurus spnovB Adrain et al., 2003 26

Hystricurus sp1 27

Order Proetida Fortey & Owens, 1975 28

Family Bathyuridae Walcott, 1886 28

Sub-family Bathyurinae Walcott, 1886 28

Genus Bolbocephalus Whitfi eld, 1890 28

Bolbocephalus gunnari nsp 30

Bolbocephalus convexus (Billings, 1865) 31

Bolbocephalus stclairi Cullison, 1944 33

Bolbocephalus spcfBkindlei Boyce, 1989 35

Genus Catochia Fortey, 1979 35

Catochia hinlopensis nsp 35

Catochia ornata Fortey, 1979 37

Genus Jeffersonia Poulsen, 1927 37

Jeffersonia striagena nsp 38

Jeffersonia viator nsp 42

Jeffersonia timon (Billings, 1865) 44

'Jeffersonia' aff Jgranosa Cullison, 1944 46

Genus Peltabellia Whittington, 1953 46

Peltabellia glabra nsp 47

Genus Petigurus Raymond, 1913 49

Petigurus nero (Billings, 1865) 49

Petigurus groenlandicus Poulsen, 1937 50

Genus Psalikilopsis Ross, 1953 52

Psalikilopsis nspaff Pcuspicaudata Ross, 1953 53

Bathyurine ngennspA 54

Sub-family Bathyurellinae Hupé, 1953 55

Genus Bathyurellus Billings, 1865 55

Bathyurellus abruptus Billings, 1865 56

Bathyurellus diclementsae nsp 57

Genus Benthamaspis Poulsen, 1946 60

Benthamaspis gibberula (Billings, 1865) 60

Benthamaspis conica Fortey, 1979 62

Genus Ceratopeltis Poulsen, 1937 63

Ceratopeltis cfCbatchensis Adrain & Westrop, 2005 63

Genus Chapmanopyge ngen 63

Chapmanopyge cfsp1 (Loch, 2007) 65

Chapmanopyge 'amplimarginiata' (Billings, 1865) 65

Chapmanopyge cfCsanddoelaensis (Adrain & Westrop, 2005) 67

Chapmanopyge nspA 68

Genus Grinnellaspis Poulsen, 1946 68

Grinnellaspis newfoundlandensis Boyce, 1989 68

Genus Harlandaspis ngen 68

Harlandaspis elongata nsp 71

Genus Licnocephala Ross, 1951 74

Licnocephala brevicauda (Poulsen, 1937) 74

Licnocephala nspA 75

Licnocephala nspB 76

Licnocephala? nspC 76

Genus Punka Fortey, 1979 76

Punka latissima nsp 77

Punka fl abelliformis Fortey, 1979 79

Genus Uromystrum Whittington, 1953 80

Uromystrum affi ne (Poulsen, 1937) 81

Uromystrum aff Uaffine (Poulsen, 1937) 84

Uromystrum drepanon nsp 85

Family Dimeropygidae Hupé, 1955 86

Genus Ischyrotoma Raymond, 1925 86

Ischyrotoma parallela (Boyce,1989) 87

Ischyrotoma nspA 89

Family Proetidae Salter, 1864 90

Genus Phaseolops Whittington, 1963 90

Phaseolops? bobowensi nsp 90

Family Telephinidae Marek, 1952 92

Genus Carolinites Kobayashi, 1940 92

Carolinites? nspA 92

Order Corynexochida Kobayashi, 1935 94

Family Illaenidae Hawle & Corda, 1847 94 Genus Illaenus Dalman, 1827 9...