Taxonomy and paleobiology of a basal scincoid lizard (Lacertilia, Scincomorpha: gen. et spec. nov.) from the Messel formation (middle eocene: basal Lutetian, Geiseltalium), Germany [Elektronische Ressource] / von Sinje Weber

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Taxonomy and Paleobiology of a basal Scincoid Lizard (Lacertilia, Scincomorpha: gen. et spec. nov.) from the Messe1 Formation Taxonomy and Paleobiology of a basal Scincoid Lizard (Lacertilia, Scincomorpha: gen. et spec. nov.) from the Messel Formation (Middle Eocene: basal Lutetian, Geiseltalium), Germany Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften vorgelegt beim Fachbereich Biologie der Johann Wolfgang Goethe-Universität in Frankfurt am Main von Sinje Weber aus Frankfurt am Main Frankfurt 2001 (DF1) vom Fachbereich Biologie der Johann Wo1 fgang Goethe-Universität in Frankfurt als Dissertation angenommen. Dekan: Prof. Dr. B. Streit 1. Gutachter: Dr. Ch. Winter Prof. Dr. F.F. Steininger 2. Datum der Disputation: 09.04.2002 Contents I Introduction ................... ..... ............... ............................................................................ 5 1.1 Aims of this study .................................................................................................................. 5 1.2 The Messe1 Pit Fossil Site ..................................................................................................... 5 1.2.1 Geology ........................................................................................................................................... 5 1.2.2 Biostratonomy of Messe1 fossils ..................................................................................................

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Taxonomy and Paleobiology of a basal Scincoid Lizard
(Lacertilia, Scincomorpha: gen. et spec. nov.)
from the Messe1 Formation Taxonomy and Paleobiology of a basal Scincoid Lizard
(Lacertilia, Scincomorpha: gen. et spec. nov.)
from the Messel Formation
(Middle Eocene: basal Lutetian, Geiseltalium), Germany
Dissertation
zur Erlangung des Doktorgrades
der Naturwissenschaften
vorgelegt beim Fachbereich Biologie
der Johann Wolfgang Goethe-Universität
in Frankfurt am Main
von
Sinje Weber
aus Frankfurt am Main
Frankfurt 2001
(DF1) vom Fachbereich Biologie der
Johann Wo1 fgang Goethe-Universität in Frankfurt als Dissertation angenommen.
Dekan: Prof. Dr. B. Streit
1. Gutachter: Dr. Ch. Winter
Prof. Dr. F.F. Steininger 2.
Datum der Disputation: 09.04.2002 Contents
I Introduction ................... ..... ............... ............................................................................ 5
1.1 Aims of this study .................................................................................................................. 5
1.2 The Messe1 Pit Fossil Site ..................................................................................................... 5
1.2.1 Geology ........................................................................................................................................... 5
1.2.2 Biostratonomy of Messe1 fossils ...................................................................................................... 6
....................................................................................... 8 1.2.3 Eocene Lake Messe1 and its surroundings
1.2.4 History of the Pit Fossil Site ............................................................................................... 9
.............................................................................................. 10 1.2.5 Previous work on Messe1 Lacertilia
2 Tawonomic and phylogenetic position of the new tavon ................... .. .................. I I
2.1 Lacertilian relationships and paleontology ....................................................................... 11
2.1.1 Main concepts in lizard taxonomy - Historical overview ............................................................. 11 14 2.1.2 Stratigraphic distribution of lizards
2.1.3 Cladistics and numerical taxonomy 14
2.1.4 Previous cladistical work using numerical taxonomy .................................................................... 17
2.2 Material and methods ......................... ..... 18
2.2.1 ......................................................................................................................................... 18
.................................................................................................................................... 2.2.2 Preparation 19
.............................................................................................................................. 2.2.3 Documentation 20
............................................................................ 21 2.2.4 Cladistical methods using numerical taxonomy
2.2.5 Terminology ................................................................................................................................. 23
2.2.6 Abbreviations ................................................................................................................................ 27
2.3 Results .................................................................................................................................. 27
2.3.1 Systematic Paleontology ................................................................................................................ 27
2.3.1 . 1 Diagnosis 28
........................................................................................................................... 2.3.1.2 Description 29
2.3.1.2.1 Specimen SMF ME 35 16, designated holotype ............................................................. 29
2.3.1.2.2 SMF ME 475a+b, paratype ........................................................... 39
2.3.1.2.3 Specimen WDC-C-MG 12211 23, designated paratype ................................................... 48
2.3.1.2.4 SMNK-PAL 38 13, ......................................................... 63
2.3.1.2.5 Specimen SMF ME 1249a+b, additional material .......................................................... 71
2.3.1.2.6 SMNK-Me 930a, .............................................................. 86
2.3.1.2.7 Cast fiom the Fossilien- und Heimatmuseum Messel, additional material ...................... 86
.................................................................................................................... 2.3.2 Intraspecific variation 98
2.3.3 Results of numerical taxonomy ..................................................................................................... 98
2.3.3.1 Cornplete matrices .................................................................................................................. 98
2.3.3.1.1 ESTES et al . (1988) ........................... .. ......................................................................... 98
2.3.3.1 . 1. 1 Matrix excluding the new genus and species ............................................................ 98
2.3.3.1.1.2 including the new and .......................................................... 101
2.3.3.1.2 EVANS & CHURE (1998) ................................................................................................ 101
2.3.3.1.2.1 Matrix excluding the new genus and species 10 1
2.3.3.1.2.2 including the new and 103
2.3.3.1.3 LEE (1998) ..................................................................................................................... 103
2.3.3.1.3.1 Matrix excluding the new genus and species 103
2.3.3.1.3.2 including the new and 103
2.3.3.1.4 CALDWELL (1999) .......................................................................................................... 105
2.3.3.1.4.1 Matrix excluding the new genus and species .......................................................... 105
2.3.3.1.4.2 including the new and 105
2.3.3.2 Matrices limited to osteological characters .......................................................................... 105
107 2.3.3.2.1 Reduced matrix of ESTES et al . (1 988) 107 2.3.3.2.1.1 Matrix excluding the new genus and species
2.3.3.2.1.2 including the new and 107
2.3.3.2.2 Reduced matrix of EVANS & CHURE (1 998) .................................................................. 109
.......................................................... 109 2.3.3.2.2.1 Matrix excluding the new genus and species
2.3.3.2.2.2 including the new and 109 2.3.3.2.3 LEE (1998) ................... .. ........................................................................................... 109
2.3.3.3 Matrix limited to characters visible in the new genus and species ....................................... 109
2.3.3.3.1 Reduced matrix of ESTES et al . (1 988) .......................................................................... 109
2.3.3.3.1.1 Matrix excluding the new genus and species .......................................................... 109
......................................................... 2.3.3.3.1.2 including the new and 111
.................................................................. 2.3.3.3.2 Reduced matrix of EVANS & CHURE (1 998) 111 111 2.3.3.3.2.1 Matrix excluding the new genus and species
2.3.3.3.2.2 including the new and 111
2.3.3.3.3 Reduced matrix of LEE (1 998) ....................................................................................... 111
2.3.3.3.3.1 Matrix excluding the new genus and species 111
2.3.3.3.3.2 including the genus and species 113
2.3.3.4 Taxa limited to Scincomorpha .............................................................................................. 113
.......................................................................... 2.3.3.4.1 Reduced matrix of ESTES et al . (1 988) 113
2.3.3.4.1.1 Matrix without characters of the new genus and species ........................................ 113
2.3.3.4.1.2 including of the new genus and ..................................... 113
.................................................................. 2.3.3.4.2 Reduced matrix of EVANS & CHURE (1998) 115
2.3.3.4.2.1 Matrix excluding the new genus and species .......................................................... 115
2.3 .3.4.2.2 including character states of the new genus and species ............................. 115
.................................................................................. 2.3.3.4.3 Reduced matrix fiom LEE (1998) 115
2.3.3.4.3.1 Matrix without character states of the new genus and species ................................ 115
2.3.3.4.3.2 including states of the new genus and 115
2.4 Discussion ........................................................................................................................... 116
2.4.1 Taxonomic position of the new genus and species based on comparative morphology .............. 116
2.4.1.1 Key characters of the new and ....................................................................... 116
2.4.1.2 Taxonomic relationship of the new genus and species to higher taxa .................................. 121
.......................................................................................................................... 2.4.1.3 Conclusions 134
2.4.2 Phylogenic reconstruction using numerical methods ................................................................... 135
.......................................................................... 2.4.2.1 General comrnents on numerical taxonomy 135
2.4.2.2 Complete matrices ................................................................................................................ 137
2.4.2.3 Matrices reduced to osteological characters ......................................................................... 138
2.4.2.4 Matrices to characters visible in the new genus and species ................................... 139
...................................................................................... 2.4.2.5 reduced to Scincomorpha 140
2.4.3 Synthesis of the results obtained by comparative morphology and numerical taxonomy ............ 141
3 Microhabitat Reconstruction of the new genus and species ................................... I43
3.1 Introduction ....................................................................................................................... 143
3.1.1 Palaeoecological Reconstructions ............................................................................................... 143
3.1.2 Functional Morphology of the Postcranium ................................................................................ 144
3.1.2.1 Limb Span proportions .......................................................................................................... 144
3.1.2.2 Femur and tibia ..................................................................................................................... 145
...................................................................................................................... 3.1.2.3 Manus and pes 145
................................................................................................................... 3.1.2.4 Tail morphology 145
3.1.2.4.1 Tail length 146
............................................................................................................... 3.1.2.4.2 Prehensile tails 146
3.1.3 Aims of the present study ......................................................................................................... 146
3.2 Material and Methods ............ ... ................................................................................... 146
3.3 Results ................................................................................................................................ 148
3.3.1 Limb Span proportions ................................................................................................................. 148
...................................................................................................... 3.3.2 Proportion of femur and tibia 151 3.3.3 Length of tail vertebrae 152
3.3.4 Structure of manus and pes .......................................................................................................... 154 3.4 Discussion ..................... ; ..................................................................................................... 157
3.4.1 Microhabitat reconstruction for the new genus and species ........................................................ 157
3.4.1.1 Function of the tail ............................................................................................................... 157
3.4.1.2 Limb proportions and habitat ............................................................................................... 159
................................................................................... 3.4.1.3 Advantages of a relatively short tibia 161
................................................................................................................. 3.4.1.4 Tal1 neural spines 161
3.4.1.5 Moving in a three-dimensional habitat ................................................................................. 162
4 Nutrition ......................................... ........................................................................... I63
4.1 Introduction ....................................................................................................................... 163
............................................................................... 4.1.1 Nutritional remains from Messe1 vertebrates 163
............................................................................................................................. 4.1.2 Teeth and diet 164
............................................................................................................ 4.1.3 Lacertilian cranial kinesis 165
4.2 Material and Methods ....................................................................................................... 167
4.3 Results 168
........................................................................................................................ 4.3.1 Intestinal contents 168
4.3.1.1 Plant remains 168
4.3.1.2 Rernains of arthropod exoskeletons ...................................................................................... 188
4.3.2 Estimated weight of the new genus and species .......................................................................... 196
4.3.3 Tooth morphology in the new genus and ........................................................................ 197
4.3.4 Cranial kinesis in the new genus and species .............................................................................. 197
4.4 Discussion ........................................................................................................................... 198
4.4.1 Tentative diet reconstruction for the new genus and species ....................................................... 198
..................................................................................................................... 4.4.2 Herbivory in lizards 199
............................................................................................................................. 4.4.3 Jaw mechanics 199 4.4.4 Digestive abilities 201
4.5 "Synecology" of Messe1 Lacertilians and arboreal vertebrates ............................. 203
5 Stratigraphie und geographic distribution of the Scincoidea ................................ 206
5.1 Scincidae 206
5.2 Cordyliformes ................................................................................................................... 206
5.3 Paramacellodidae .............................................................................................................. 207
5.4 Gen . et . spec . nov ............................................................................................................... 207
6 Acknowledgements ................................ .................................................................... 209
.................................................................................... 7 Index o f Figures and Tables 211
7.1 Figures ................................................................................................................................ 211
7.2 Tables .................................................................................................................................. 215
................................................................................................................ 8 Referen ces 216
9 Appendix 1-7: Line drawings of the specimens of the new genus and species ....... 230 Taxonomy and Paleobiology of a basal Scincoid Lizard
(Lacertilia, Scincomorpha: gen. et spec. nov.)
from the Messel Formation
(Middle Eocene: basal Lutetian, Geiseltalium), Germany
Abstract. - A new lizard genus and species is descnbed from the World Hentage
Messel Pit Fossil Site (Middle Eocene: basal Lutetian, Geiseltalium) near Darmstadt,
Germany. It is placed within the Scincoidea (Scincidae, Cordyliformes +
Paramacellodidae), but no attribution to a distinct family can be made. Its phylogenetic
position is problematic as it probably represents the descendant of a stem group taxon of
the Scincoidea or an interesting „link" between Scincidae and Cordyliformes. Extensive
phylogenetic analyses using numerical taxonomy are undertaken. Unaltered and
modified matnces from different authors are analysed in order to generate a vanety of hypotheses. These are discussed with the results of comparative anatomy,
the latter having a higher impact on the final classification. Key characters of the new
taxon are as follows: The dorsal aspect of the skull is covered with a characteristic
osteodermal pattem, the jugal has a huge posterior process, the retroaricular process and
teeth show a typical scincoid morphology. Six well preserved specimens can safely be
attributed to the new species which is not yet known from any other fossil site. The very
long prehensile tail of the new genus and species, its curved claws, limb proportions and
missing body osteodems strongly suggest an arboreal mode of life. The long tail could
secure support by grabbing branches, but probably was too fragile to hold the entire
body weight. The locomotion and microhabitat exploitation of the new taxon can best be
compared to the arboreal emerald monitors Varanus prasinus and Varanus beccarii
with their long tails and strongly curved claws. In three of the fossil specimens intestinal
contents are still preserved. They contain plant remains and a few fiagments of insect
cuticula. Due to its Cover of osteoderms, the skull was largely akinetic, suggesting the
new taxon not to be an effective and agile predator, but a rather large herbivore and
occasional insectivore, which was probably capable of strenuous biting. Its presence in
the Lower Middle Eocene of Messel neither supports nor contradicts the current
opinions of Scincoid Paleobiogeography.
Keywords: Lacertilia, Scincomorpha, Scincoidea, Numencal Taxonomy, Cladistics,
Palaeobiology, Intestinal Contents, Eocene, Messel Chapter 1 : Introduction - 5
1 lntroduction
7.7 Aims of this study
A lizard of uncertain taxonomical position from the Messel Pit Fossil Site, which is
unknown from the fossil record and from extant specimens, will be described. The
taxonomical position and phylogeny of the new taxon will be discussed by comparing
morphological information with the results of numerical taxonomy. A palaeobiological
reconstruction of the appearance, mode of life and feeding habits of the new taxon will
base on comparative morphology, morphometry and on gut content analysis. The
paleobiogeography of the new taxon will be discussed in context with related taxa.
7.2 The Messel Pit Fossil Site
1.2.1 Geology
The Messel Pit Fossil Site is situated 8 km Northeast of Darmstadt and 20 km Southeast
of Frankfurt (Fig. 1). The pit has an extent of 700 by 1000 meters (Fig. 2), a central
depth of 70 meters and is surrounded by a ridge called Sprendlinger Horst. The latter
represents the northem extension of the so-called cristalline Odenwald. The central core
of the ndge contains rocks of Palaeozoic age and is covered by sediments and vulcanites
from the Lower Permian (Rotliegend). To date it is unclear how the depression was
formed which allowed the accumulation of water, representing the Eocene lake Messel.
In Eocene times, the Upper Rhine Graben sank down over 2000 meters and
simultaneously the Sprendlinger Horst shield shifted upwards. A plausible model
connects these tectonic events with the origin of the depression that later formed Lake
Messel (e.g. WAGNER 1950, MA~ESS 1966, HARMS 2001). In total, six oil shale
localities in vicinity of Messel are situated on a rough line running from Southwest to
Northeast (SCHAAL 1992). This would be consistent with the appearance of a Graben
structure during these strong tectonic events that took place during the Early Eocene
(MATTHESS 1966, JACOBY 1997). Another widely discussed model shapes Lake Messel
as a crater that originated from a crater lake explosion (RIETSCHEL 1994). An unlikely,
but not yet falsified explanation for the depressions on the Sprendlinger Horst is asteroid
impact (M~LLER, M. 1995, PIRRUNG 1998). It is also possible that tectonic and volcanic
processes both contributed to the genesis of the depression (HARMS 2001). To further
investigate this question a Messel Drilling Projekt is currently camed out.
Dunng the Lower Middle Eocene (Lutetium or better Geiseltalium afler FRANZEN &
HAUBOLD 1985) a freshwater lake produced sediments which today represent the Messel
Formation. In the centre of the pit, the so called oil shale rock is still more than 200 m in
thickness and the deposition period was estimated to about one million (GOTH 1990) to
two million (MON 1977) years. Both authors calculated a sedimentation rate of 0.1 to
0.15 rnm 1 year, a measurement which is consistent with modern tropical lakes.
However, &ION (1 977) points out that these measurements were taken from the central,
well laminated sediments only. Other members of the formation are less well laminated
and may therefore have been sedimented in much shorter periods of time. The
depositional period of the Messel Lake is a topic of current research (Messel Drilling
Project 2001). The age of the Messel sediments has been estimated to +I- 49 Mill. years,
which corresponds to the MPl 1 Zone and is based on volcanic material (LIPPOLT et al.
1975, WEBER & ZIMMERLE 1985) and mammal biostratigraphy (HAUPT 19 1 1, TOBIEN