Late Hirnantian and early Rhuddanian shelly faunas dominated by brachiopods are well developed in the clastic facies succeeding the cool and deep-water, very-low-diversity Hirnantia fauna in Zhejiang and Jiangxi provinces, south-east China; elsewhere in the world, during this interval, brachiopod assemblages are generally rare. The Cathaysiorthis brachiopod fauna, occurring within the Normalograptus persculptus to Akidograptus ascensus biozones, straddling the Ordovician and Silurian boundary, is systematically described herein. Comparison of the fauna with the preceding Hirnantia fauna in South China shows some major contrasts, but similarities in the dominance of orthides and strophomenides, the rarity of pentamerides and atrypides, and the lack of trimerellides. Virtually all the genera recorded are ‘hold-over’ genera from the diverse latest Katian fauna and have long ranges and wide geographical distributions except for some endemics. A major faunal change in the brachiopod fauna occurred within the N. persculptus Biozone, beneath the Ordovician–Silurian boundary. The end of the second episode of the Ordovician extinction event of brachiopods may have extended from the middle N. persculptus Biozone, prior to the start of the Silurian, coincident with N. persculptus Biozone – bearing beds generally overlying the Hirnantia fauna and a striking positive carbonate isotope excursion, present in many places in the world. The end Ordovician extinction is substantially different from the end Permian mass extinctions characterized by a sharp decline at all taxonomic levels with high extinction rates, the absence of ‘hold-overs’, Lazarus and progenitor taxa, prevalent miniaturization of shell size and a much slower recovery rate during the Triassic. This sharp contrast was enhanced by the relative intensity of both extinctions with widely different causes, patterns and consequences and by the relatively weak ecosystem disturbances through the Ordovician–Silurian transition rather than the ecosystem collapse during the early Triassic. A new family, Cathaysiorthidae, and five new genera or subgenera, Aegiromena (Aegiromenella), Eopholidostrophia (Megapholidostrophia), Chunanella, Yuhangella and Eospirifer (Protospirifer), are established, as well as fourteen new species: Anisopleurella asiatica, Chunanella chunanensis, Deliella delicatula, Dolerorthis (D.) multicostellata, Epitomyonia subquadrata, Eopholidostrophia (Megapholidostrophia) magnifica, Eoplectodonta (E.) boucoti, Eospirifer (E.) eosinensis, Fardenia (F.) flexa, Hesperorthis orientalis, Katastrophomena zheganensis, Mendacella mutabilis, Sulcatospira simplex and Yuhangella yui.
Abstract 5
Introduction 5
Geological setting 6
Material 9
Age of the fauna 14
Faunal analysis 16
Ecological differentiation 18
Faunal comparison 20
With the Hirnantia fauna 20
With other related faunas 20
Concluding remarks 21
Systematic palaeontology 22
Order Lingulida Waagen, 1885 22
Superfamily Linguloidea Menke, 1828 22
Family Pseudolingulidae Holmer, 1991 22
Genus Pseudolingula Mickwitz, 1909 22
Order Craniopsida Gorjansky and Popov, 1985 24
Superfamily Craniopsoidea Williams, 1963 24
Family Craniopsidae Williams, 1963 24
Genus Paracraniops Williams, 1963 24
Order Craniida Waagen, 1885 26
Superfamily Cranioidea Menke, 1828 26
Family Craniidae Menke, 1828 26
Genus Deliella Halamski, 2004 26
Genus Pseudocrania McCoy, 1851 29
Order Strophomenida Öpik, 1934 29
Superfamily Strophomenoidea King, 1846 29
Family Strophomenidae King, 1846 29
Genus Katastrophomena Cocks, 1968 29
Strophomenid gen. et sp. indet. 31
Family Rafinesquinidae Schuchert, 1893 33
Genus Leptaena Dalman, 1828 33
Genus Kiaeromena Spjeldnaes, 1957 35
Family Leptostrophiidae Caster, 1939 37
Genus Eomegastrophia Cocks, 1967 37
Family Eopholidostrophiidae Rong and Cocks, 1994 38
Genus Eopholidostrophia Harper, C. W. J., Johnson and Boucot, 1967 38
Subgenus Megapholidostrophia nov. 39
Superfamily Plectambonitoidea Jones, *1928 42
Family Leptestiidae Öpik, 1933 42
Genus Leangella Öpik, 1933 42
Family Xenambonitidae Cooper, 1956 45
Genus Aegiromena Havlíček, 1961 45
Subgenus Aegiromenella nov. 45
Family Sowerbyellidae Öpik, 1930 49
Genus Anisopleurella Cooper, 1956 49
Genus Eoplectodonta Kozlowski, 1929 51
Order Orthotetida Waagen, 1884 54
Superfamily Chilidiopsoidea Boucot, 1959 54
Family Chilidiopsidae Boucot, 1959 54
Genus Fardenia Lamont, 1935 54
Superfamily Triplesioidea Schuchert, 1913 57
Family Triplesiidae Schuchert, 1913 57
Genus Triplesia Hall, 1859 57
Order Protorthida Schuchert and Cooper, 1931 59
Superfamily Skenidioidea Kozlowski, 1929 59
Family Skenidiidae Kozlowski, 1929 59
Genus Skenidioides Schuchert and Cooper, 1931 59
Order Orthida Schuchert and Cooper, 1932 62
Superfamily Orthoidea Woodward, 1852 62
Family Glyptorthidae Schuchert and Cooper, 1931 62
Genus Glyptorthis Foerste, 1914 62
Family Hesperorthidae Schuchert and Cooper, 1931 64
Genus Hesperorthis Schuchert and Cooper, 1931 64
Genus Dolerorthis Schuchert and Cooper, 1931 69
Family Cathaysiorthidae nov. 70
Genus Cathaysiorthis Rong, Huang, Zhan and Harper, 2008 71
Cathaysiorthid gen. et sp. indet. 1 74
Cathaysiorthid gen. et sp. indet. 2 76
Superfamily Plectorthoidea Schuchert and LeVene, 1929 76
Family Plectorthidae Schuchert and LeVene, 1929 76
Genus Plectorthis Hall and Clarke, 1892 76
Plectorthid gen. et sp. indet. 78
Superfamily Dalmanelloidea Schuchert, 1913 78
Family Dalmanellidae Schuchert, 1913 78
Genus Yuhangella nov. 78
Genus Levenea Schuchert and Cooper, 1931 79
Genus Templeella Rozman and Rong, 1993 85
Family Dicoelosiidae Cloud, 1948 89
Genus Epitomyonia Wright, 1968b 89
Family Rhipidomellidae Schuchert, 1913 93
Genus Mendacella Cooper, 1930 93
Superfamily Enteletoidea Waagen, 1884 99
Family Draboviidae Havlíček, 1950 99
Genus Chunanella nov. 99
Genus Salopina Boucot, 1960 102
Order Pentamerida Schuchert and Cooper, 1931 102
Superfamily Pentameroidea McCoy, 1844 102
Family Virgianidae Boucot and Amsden, 1963 102
Genus Brevilamnulella Amsden, 1974 102
Order Rhynchonellida Kuhn, 1949 111
Superfamily Rhynchotrematoidea Schuchert, 1913 111
Family Trigonirhynchiidae McLaren, 1965 111
Genus Rostricellula Ulrich and Cooper, 1942 111
Genus Thebesia Amsden, 1974 113
Order Atrypida Rzhonsnitskaya, 1960 114
Superfamily Atrypoidea Gill, 1871 114
Family Atrypidae Gill, 1871 114
Genus Alispira Nikiforova, 1961 114
Genus Eospirigerina Boucot and Johnson, 1967 115
Genus Sulcatospira Xu, 1979 118
Order Athyridida Boucot, Johnson and Staton, 1964 121
Superfamily Meristelloidea Waagen, 1883 121
Family Meristellidae Waagen, 1883 121
Genus Hindella Davidson, 1882 121
Genus Whitfieldella Hall and Clarke, 1894 123
Order Spiriferida Waagen, 1883 125
Superfamily Cyrtioidea Frederiks, 1924 125
Family Cyrtiidae Frederiks, 1924 125
Genus Eospirifer Schuchert, 1913 125
Subgenus Protospirifer nov. 125
Subgenus Eospirifer Schuchert, 1913 127
Acknowledgements 131
References 131