Encyclopedia of Paleoherpetology, Part 3A1: Basal Tetrapoda

About this book

Language: English

The last two decades or so there have witnessed a renaissance of scientific interest in the origin of tetrapods, driven by spectacular discoveries of fish-like sarcopterygians with tetrapod characters and very primitive tetrapods. This research has revolutionized our understanding of the sequence of acquisition of key tetrapod features as well as the timing and circumstances of critical events during this major evolutionary transition. The new finds have not only established the existence of an unexpected diversity of Late Devonian stem tetrapods but are also beginning to fill in a major hiatus in the fossil record, informally known as “Romer’s Gap”, during which tetrapods made the transition from a primarily aquatic to a terrestrial mode of life. The foremost expert in the study of origin and early diversification of tetrapods, Professor Jennifer A. Clack, and a leading expert on late Paleozoic non-amniote tetrapods, Dr. Andrew R. Milner, present here a synopsis of our current knowledge of the anatomy and diversity of Late Devonian and Carboniferous (Mississippian-Pennsylvanian) stem tetrapods. The phylogenetic relationships of many of the taxa included in this review remain unresolved, and thus the title “basal Tetrapoda” was selected faute de mieux. We are well aware that most authors would extend the tetrapod stem-group much farther into fish-like sarcopterygians such as Eusthenopteron. In the absence of suitable formal taxonomic categories, “basal Tetrapoda” is used here in a less inclusive meaning – tetrapodomorph taxa with limbs and digits that cannot be assigned to more derived clades such as Temnospondyli and Amniota or their respective proximate sister taxa.

Contents

Editorial Preface   V
Institutional abbreviations   VII
Abbreviations and conventions used in figures   VIII
Origin of tetrapods   1
Classification and relationships   1
   The relatives of tetrapods   2
   Morphology of the ‘fish’-tetrapod transformation   4
   Ecology of the ‘fish’-tetrapod transformation   5
   Chronology of the ‘fish’-tetrapod transformation   7
Historical Overview   8
   First descriptions (1851-1865)   8
   Carboniferous tetrapod assemblages (1866-1910)   8
   Evolutionary scenarios (1911-1930)   8
   Devonian tetrapods and comprehensive classifications (1930-1966)   9
   Improved preparation and diagnosis (1967-1980)   9
   The information explosion (1981-present)   10
   The next decades   11
Systematic paleontology   12
   Tetrapodomorpha Ahlberg, 1991a   13
   Givetian-Frasnian tetrapodomorphs   13
   Frasnian tetrapodomorphs   13
      Family Elginerpetidae Ahlberg, 1995   13
         Elginerpeton Ahlberg, 1995   13
         Obruchevichthys Vorobyeva, 1977   14
   Famennian tetrapodomorphs   15
      Family Acanthostegidae Jarvik, 1952   15
         Acanthostega Jarvik, 1952   18
      Family Ichthyostegidae Säve-Söderbergh, 1932   21
         Ichthyostega Säve-Söderbergh, 1932   23
         Ymeria Clack, Ahlberg, Blom & Finney 2012   27
         Ichthyostegidae incertae sedis   28
      Family undesignated   28
         Metaxygnathus Campbell & Bell, 1977   28
         Ventastega Ahlberg, Luksevics & Lebedev, 1994   29
         Unnamed skull fragment from the Ketleri Formation of Latvia   29
         Hynerpeton Daeschler et al., 1994   31
         Densignathus Daeschler, 2000   32
         Sinostega Zhu, Ahlberg, Zhao & Jia, 2002   32
         Jakubsonia Lebedev, 2004   32
      Family Tulerpetidae Lebedev & Coates, 1995   33
         Tulerpeton Lebedev, 1984   35
   Mississippian and Pennsylvanian stem-tetrapods   35
      Family Whatcheeriidae Clack, 2002c   35
         Pederpes Clack, 2002c   35
         Whatcheeria Lombard & Bolt, 1995   36
         Occidens Clack & Ahlberg, 2004   38
         Ossinodus Warren & Turner, 2004   41
      Family Crassigyrinidae Huene, 1948   42
         Crassigyrinus Watson, 1929   42
      Family Colosteidae Cope, 1875   44
         Colosteus Cope, 1869   45
         Greererpeton Romer, 1969   45
         Pholidogaster Huxley, 1862   48
         Deltaherpeton Bolt & Lombard 2010   48
         Colosteidae incertae sedis   48
         Ichthyerpeton Wright & Huxley, 1866   48
         Not Colosteidae   49
      Family Caerorhachidae Carroll, 1988   49
         Caerorhachis Holmes & Carroll, 1977   49
      Superfamily Baphetoidea Cope, 1875 sensu A. C. Milner & Lindsay, 1998   52
         Eucritta Clack, 1998a   52
      Family Baphetidae Cope, 1875   54
         Subfamily Baphetinae Cope, 1875   54
            Baphetes Owen, 1854   54
         Subfamily Loxommatinae Lydekker, 1889   56
            Loxomma Huxley, 1862   56
            Megalocephalus Barkas, 1873   58
            Kyrinion Clack, 2003a   60
            Not Baphetidae   61
            ‘Loxomma’   61
      Family Spathicephalidae Beaumont 1977   61
         Spathicephalus Watson, 1929   61
   Stem-Tetrapoda incertae sedis 62
      Doragnathus Smithson, 1980b   62
      Westlothiana Smithson & Rolfe, 1990   62
      Silvanerpeton Clack, 1994a   64
      Eldeceeon Smithson, 1994   66
      Casineria Paton, Smithson & Clack, 1999   66
      Antlerpeton Thomson, Shubin & Poole, 1998   69
      Sigournea Bolt & Lombard, 2006   70
      Kirktonecta Clack, 2011   70
      Material from the Tournaisian of southern Scotland and northern England   71
      Material from the Tournaisian of Horton Bluff, Nova Scotia   71
      Material from the Mississippian of Hancock County, Kentucky   72
      Material from the Mississippian Pomquet Formation, Nova Scotia   74
Paleobiology and ecology of Carboniferous tetrapods   74
Paleobiogeography   76
   Devonian   76
   Carboniferous   77
Literature cited   80
Index of taxa   91

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