Molar dentition of the docodontan Haldanodon (Mammaliaformes) as functional analog to tribosphenic teeth DISSERTATION zur Erlangung des Doktorgrades (Dr. rer. nat.) der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn vorgelegt von JANKA J. BRINKKÖTTER aus Berlin Bonn 2018 I Angefertigt mit Genehmigung der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn 1. Gutachter: Prof. Dr. Thomas Martin 2. Gutachter: Prof. Dr. P. Martin Sander Tag der Promotion: 14. Dezember 2018 Erscheinungsjahr: 2019 II List of abbreviations d – deciduous tooth M – upper molar m – lower molar P – upper premolar p – lower premolar m – mesial buc – buccal dex – dextral sin – sinistral L – length W – width fr. – fragment III List of contents Abstract .................................................................................................................................. 01 Kurzfassung ........................................................................................................................... 02 1 Aim of study ........................................................................................................................ 04 2 Introduction ........................................................................................................................ 06 2.1 Systematical position of the Docodonta ............................................................................ 06 2.2 Definitions of terms ........................................................................................................... 11 2.2.1 Abrasion and Attrition ............................................................................................... 11 2.2.2 Wear facets ................................................................................................................ 12 2.2.3 Mastication functions ................................................................................................ 13 2.2.3.1 Shear-cutting ...................................................................................................... 13 2.2.3.2 Crushing ............................................................................................................. 13 2.2.3.3 Grinding ............................................................................................................. 14 2.3 Morphology of “pseudotribosphenic“ molars ................................................................... 14 2.3.1 Convergent development of crushing basins on the lower molars in mammalian history ........................................................................................................................ 14 2.3.2 “Pseudotalonid basin”, “pseudoprotocone”, and “pseudotrigon basin” on docodont molars ........................................................................................................................ 17 3 Material ............................................................................................................................... 19 3.1 Docodonta ......................................................................................................................... 19 3.1.1 Haldanodon exspectatus K ÜHNE AND KRUSAT 1972 ................................................ 19 3.2 Marsupialia ........................................................................................................................ 20 3.2.1 Didelphis L INNAEUS 1758 ......................................................................................... 20 3.2.2 Monodelphis B URNETT 1829 ..................................................................................... 21 4 Methods ............................................................................................................................... 23 4.1 Terminology ...................................................................................................................... 23 4.1.1 Cusps and crests ........................................................................................................ 23 4.1.1.1 Docodonta .......................................................................................................... 23 4.1.1.2 Didelphis and Monodelphis ............................................................................... 24 4.1.2 Wear facets ................................................................................................................ 25 4.1.2.1 Docodonta .......................................................................................................... 25 4.1.2.2 Didelphis and Monodelphis ............................................................................... 27 IV 4.2 Measurements ................................................................................................................... 27 4.3 Recording of striations with scanning electron microscope (SEM) .................................. 28 4.4 CT scans, reconstruction, and printing of 3D-models ....................................................... 29 4.5 Occlusal Fingerprint Analyser (OFA) ............................................................................... 30 5 Results ................................................................................................................................. 32 5.1 Haldanodon molars ........................................................................................................... 32 5.1.1 Determination of position for isolated molars ........................................................... 32 5.1.2 Abrasion patterns of molar rows ............................................................................... 39 5.1.2.1 Definition of wear stages ................................................................................... 39 5.1.2.2 Wear pattern ...................................................................................................... 43 5.1.3 Position of facets ....................................................................................................... 45 5.1.4 Striation patterns and trailing edges .......................................................................... 47 5.2 Tooth-tooth-contact diagrams ........................................................................................... 59 5.2.1 Haldanodon ............................................................................................................... 59 5.2.2 Didelphis .................................................................................................................... 60 5.2.3 Monodelphis .............................................................................................................. 61 6 Discussion ............................................................................................................................ 65 6.1 Location of basins and “pseudoprotocone“ on docodont molars ...................................... 65 6.1.1 Location of basins on the lower molars ..................................................................... 65 6.1.2 Location of “pseudotrigon basin“ and “pseudoprotocone“ on the upper molars ...... 66 6.2 Determination of position for isolated Haldanodon molars ............................................. 67 6.3 Wear patterns of Haldanodon molar rows ........................................................................ 70 6.4 Reconstruction of the mastication cycle of Haldanodon .................................................. 73 6.4.1 Previous studies on various docodont taxa ................................................................ 73 6.4.2 Position of facets on molars ...................................................................................... 77 6.4.3 Occlusion of molar dentition ..................................................................................... 81 6.4.4 Striation patterns on molars ....................................................................................... 85 6.4.5 Mastication movement .............................................................................................. 92 6.4.6 Functions performed by molars ................................................................................. 97 6.4.7 Relevance of the results for the Haldanodon molar dentition for other docodont taxa .......................................................................................................................... 102 6.5 Comparison of tribosphenic and docodont “pseudotribosphenic“ tooth morphology .... 111 6.5.1 Comparison of molar functions in Didelphis and Haldanodon .............................. 111 6.5.2 Comparison of molar functions in Monodelphis and Haldanodon ......................... 116 V 6.5.3 Disparities of molar functions in between tribosphenids and docodonts ................ 121 7 Summary ........................................................................................................................... 126 8 Acknowledgments ............................................................................................................ 130 9 References ......................................................................................................................... 131 Appendix .............................................................................................................................. 144 List of specimens List of measurements taken from Haldanodon molar rows List of highest, lowest, and mean values of measurements