Language: English
A new lizard genus and species is described from the Messel pit fossil site (Middle Eocene): Ornatocephalus metzleri. Its taxonomical position and phylogeny within the lizards as well as the reconstruction of the mode of life are subjects of Ornatocephalus metzleri gen. et spec. nov. (Lacertilia, Scincoida): Taxonomy and Paleobiology of a basal Scincoid Lizard from the Messel Formation (Middle Eocene: basal Lutetian, Geiseltalium), Germany. This extinct species is not known from any other fossil site. Remarkable characters are, among others, the relatively large, heavily sculptured head and the extraordinary long tail.
The systematic classification is problematic and it is not possible to clearly attribute the new taxon to any fossil or recent group. Since there are relationships towards the scincids and cordyloids, the new taxon is placed within the scincoidea. The second part of the article concerns the mode of life of the lizard. Among other characters, the long prehensile tail, the strongly curved claws and the limb proportions strongly suggest an arboreal mode of life.
Three specimens still have intestinal contents, mainly plant remains and a few fragments of insect cuticula. Ornatocephalus metzleriwas not an effective and agile predator, but rather a large herbivore and occasional insectivore.
Introduction 2
Aims of this study 2
The Messel Pit Fossil Site 2
Geology 2
Biostratonomy of Messel fossils 4
Eocene Lake Messel and its surroundings 5
History of the Messel Pit Fossil Site 6
Previous work on Messel Lacertilia 6
Taxonomic and phylogenetic position of the new taxon 7
Lacertilian relationships and paleontology 7
Main concepts in lizard taxonomy Historical overview 7
Stratigraphic distribution of lizards 8
Cladistics and numerical taxonomy 8
Previous cladistical work using numerical taxonomy 10
Material and methods 10
Material 10
Preparation 11
Documentation 11
Cladistical methods using numerical taxonomy 12
Terminology 13
Abbreviations 13
Results 13
Systematic Paleontology 13
Intraspecific variation 65
Results of numerical taxonomy 68
Discussion 81
Taxonomic position of Ornatocephalus metzleri based on comparative morphology 81
Phylogenic reconstruction using numerical methods 93
Synthesis of the results obtained by comparative morphology and numerical taxonomy 98
Palaeoecological Reconstruction of Ornatocephalus metzleri 99
Microhabitat Reconstruction 99
Introduction to Functional Morphology of the Postcranium 99
Material and Methods 101
Results 102
Discussion 105
Nutrition 112
Introduction 112
Material and Methods 115
Results 116
Discussion 118
"Synecology" of Messel Lacertilians and arboreal vertebrates 131
Stratigraphic and geographic distribution of the Scincoidea 132
Scincidae 132
Cordyliformes 133
Paramacellodidae 133
Ornatocephalus metzleri 135
Acknowledgements 135
References 136
Appendix 1-11 143