Morphology, Phylogeny and Taxonomy of Osteolepiform Fish

A discussion and description of prehistoric fish within an international series Material of six osteolepiform genera is described in Morphology, Phylogeny and Taxonomy of Osteolepiform Fish. This publication is Number 61 within the Fossils and Strata series. The international Fossils and Strata series features monographs in palaeontology and biostratigraphy with taxonomic descriptions. The series is owned by and published on behalf of The Lethaia Foundation in cooperation with the Scandinavian countries.

Auteur

Ulf J. Borgen is the editor of Morphology, Phylogeny and Taxonomy of Osteolepiform Fish, published by Wiley.

Hans A. Nakrem is the editor of Morphology, Phylogeny and Taxonomy of Osteolepiform Fish, published by Wiley.

Contenu
Introduction 1 General taxonomy 2

'Crossoptgerygii' and 'Rhipidistia' 2

Osteolepiform subdivisions 3

Terminology 4

Cranial roof 4

Endocranium 13

Dermal bones in mouth roof 13

Lower jaw 14

Operculo-gular bones 15

Upper Palaeozoic fossil locality in the Oslo Region 16

Stratigraphy 16

Descriptions 18

Material, methods and repository 18

Genus Askerichthys n gen 20

Askerichthys heintzi n sp 20

Genus Megalichthys Agassiz, 1835 62

Megalichthys cf M hibberti Agassiz, 1835 62

Megalichthys pygmaeus Tranquair, 1879 97

Megalichthys syndentolaminaris n sp 99

Genus Latvius Jarvik, 1948 100

Latvius grewingki (Gross, 1933) 101

Latvius deckerti Jensen, 1966 114

Latvius sp Jensen, 1966 121

Latvius cf L niger Jensen, 1973 128

Genus Osteolepis Agassiz, 1835 130

Osteolepis macrolepidotus Agassiz, 1835 131

Genus Gyroptychius McCoy, 1848 131

Gyroptychius milleri (Jarvik, 1948) 131

Gyroptychius groenlandicus Jarvik, 1950a 141

Morphologic comparisons and discussions 160

Fronto-ethmoidal shield 160

General shape 160

Interpremaxilla 162

Composition of naso-rostro-premaxillary complex 162

Shape of upper mouth margin 165

Anterior palatal (premaxillary and rostral) teeth and palatal processes 166

Defi nitions and occurrences of morphotypes of anterior palatal teeth 166

Tooth replacement and evolutionary relationship between the anterior palatal dental morphotypes 167

Number of premaxillary teeth 169

Systematic significance of anterior palatal teeth 170

Anterior palatal processes 171

Postrostrals 172

Variation and trends in postrostral pattern 172

Taxonomic significance of postrostral pattern 176

Nasals 178

Number of nasal bones 178

Positions of the bones in the nasal series 178

Circumnarial dermal bones and supraorbitals 180

Variation in eusthenopterids 180

Reconstructing the circumnarial pattern in Osteolepis macrolepidotus 186

Reconstructing the pattern of supraorbitals in Osteolepis macrolepidotus 188

Circumnarial and supraorbital pattern in other Devonian osteolepiforms 189

Homologizations of circumnarial bones in Megalichthys hibberti, Ectosteorhachis, Askerichthys and Cladarosymblema 191

Supraorbito-tectal series of panderichthyids 196

Frontals and dermosphenotics 197

Shape and composition of frontals 197

Shape, positions and extension of dermosphenotic bones 199

Fenestrae 199

Position of nasal fenestra 199

Shape of nasal fenestra 200

Processus dermintermedius 201

Tubercles in nasal fenestra 202

Presence or absence of pineal openings 202

Position of pineal foramen 203

Shape of pineal openings 204

Size of pineal fenestra and presence of pineal plates 204

Sensory canals 204

Pitlines 205

Parietal shield 206

Relative lengths of fronto-ethmoidal and parietal shields 206

Shape of parietal shield 207

Proportions 207

Protruding posterior margin 209

Position of spiracular incision 212

Relative length of the spiracular incision 213

Parietals 214

Shape of parietals 214

Parietal structures 214

Intertemporals 215

Shape of interpemporal 215

Anterior intertemporal margin and process in post-Devonian taxa 216

Anterior intertemporal processes in Devonian forms 222

On the function of the intracranial joint 223

Lateral shelf of intertemporal 223

Ventral surface of intertemporal 224

Supratemporals 228

Shape 228

Ventral surface and lateral margin 228 Spiracular structures 231</p&g...