THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS ARTICLE 52 (CRETACEOUS 1) PALEOECOLOGY AND PALEONTOLOGY OF THE LOWER CRETACEOUS KIOWA FORMATION, KANSAS ROBERT W. SCOTT Department of Geology, University of Kansas, Lawrence Present address: Waynesburg College, Waynesburg, Pennsylvania The University of Kansas Paleontological Institute THE UNIVERSITY OF KANSAS PUBLICATIONS JANUARY 15, 1970 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS Article 52 (Cretaceous 1), 94 pages, 21 Figures, 7 Plates, 7 Tables PALEOECOLOGY AND PALEONTOLOGY OF THE LOWER CRETACEOUS KIOWA FORMATION, KANSAS ROBERT W. SCOTT Department of Geology, University of Kansas, Lawrence Present address: Waynesburg College, Waynesburg, Pennsylvania CONTENTS PAGE ABSTRACT 5 Interspecific relationships 48 INTRODUCTION 5 Predation 49 Location and geologic setting 5 Competition 50 Previous work 7 Commensalism 50 Approaches and study objectives 7 DEPOSITIONAL ENVIRONMENT AND Vertebrate paleontology 8 PALEOECOLOGIC SYNTHESIS 50 Paleobotany 8 Climate and paleogeography 50 Stratigraphy and correlation 8 Succession of the ancient communities 51 Acknowledgments 12 Summary of other environmental factors 52 KIOWA FOSSIL ASSEMBLAGES AND ASSOCIATIONS 13 CONCLUSIONS 52 Modes of occurrence of Kiowa fossil assemblages 13 SYSTEMATIC DESCRIPTIONS AND Texture, structure, and shape of sedimentary body 13 PALEOECOLOGIC DISCUSSIONS 54 Dispersion of fossils 13 Introduction 54 Density of fossils 13 Phylum Porifera 54 Orientation of fossils 13 Phylum Coelenterata 55 Dissociation of hard parts 13 Phylum Bryozoa 55 Fragmentation of remains 14 Phylum Brachiopoda 57 Size-sorting of abundant species 14 Phylum Annelida 58 Faunal composition 14 Phylum Mollusca 58 Modes of origin of Kiowa fossil assemblages 16 Class Bivalvia 58 Definition of Kiowa fossil associations 16 Subclass Palaeotaxodonta 58 Lithofacies and fossil associations 29 Subclass Pteriomorphia 59 Dark-gray shale lithofacies 29 Subclass Palaeoheterodonta 70 Mudstone lithofacies 30 Subclass Heterodonta 71 Thin-laminated sandstone lithofacies 31 Subclass Anomalodesmata 77 Thin-bedded sandstone lithofacies 34 Class Scaphopoda 78 Mottled-sandstone lithofacies 35 Class Gastropoda 78 Shell-conglomerate lithofacies 36 Subclass Streptoneura 78 Geographic and stratigraphic variations 39 Subclass Euthyneura 82 Comparison of Kiowa fossil associations with Class Cephalopoda 83 analogous marine communities 39 Phylum Arthropoda 84 Introduction 39 Phylum Echinodermata 86 Nuculana association 45 Trace fossils 86 Corbulid-breviarcid association 45 APPENDIX A—METHODS OF STUDY 88 Trachycardium-Turritella association 46 Field methods Pteriid-mytilid association 46 88 Laboratory methods Gryphaea association 47 88 Cypritneria association 47 Simpson's diversity coefficient 90 Crassostrea association 48 Jaccard coefficient 90 Brachidontes association 48 APPENDIX B—DESCRIPTIONS OF LOCALITIES 90 Trace fossil association 48 REFERENCES 91 ILLUSTRATIONS FIGURE PAGE 1. Outcrop of the Kiowa Formation in parts of cen- 14. Histograms showing average relative abundance tral and southern Kansas and location of studied of species in each feeding-habit category in the sections 6 various fossil association and frequency of each 2. Generalized columnar sections and stratigraphic fossil association with each lithofacies 44 nomenclature of Lower Cretaceous rocks in 15. Graph showing the number of species in each Kansas 9 feeding habit and probable trophic level 49 3. Faunal zones and correlation of Kiowa with the 16. Measured parameters of Brachidontes nonbi- Texas Lower Cretaceous section 12 furcus Scott, n. sp. 61 4. Circular histograms showing apical orientations 17. Measured parameters of Ostrea arcuata Scott, of Turritella 15 n. sp., and of O. rugosa Scott, n. sp. 65 Sketch of 5. Dendrogram of Kiowa taxa found at more than 18. Crassatellina oblonga Meek, 1871 71 three localities 17 19. Sketches of Cytheridea? amygdaloides (Cornuel, 1846) 85 6. Dendrogram of taxa, lithofacies, and mode or 20. Sketch of Ophiura sp. indet. 86 origin of fossil assemblages 28 21. Graphs showing variation in relative abundance 7. Maps showing distribution and diversity of of taxa and in number of new species as number Brachidontes, corbulid-breviarcid, and Nuculana of specimens increases 89 associations 31 8. Maps showing distribution and diversity of PLATE FACING PAGE pteriid-mytilid, Trachycardium-Turritella, and 1. Brachiopoda, Bryozoa, and Bivalvia 66 trace fossil associations 33 2. Bivalvia 67 9. Maps showing distribution and diversity of 3. Bivalvia 74 Crassostrea, Gryphaea, Cyprimeria, and Lop/la 4. Bivalvia and trace fossil 75 associations 37 5. Bivalvia 78 10-13. Stratigraphic cross sections of Lower Cre- 6. Gastropoda 79 taceous rocks in central and southern Kansas ....40-43 7. Crustacea and trace fossils 86 TABLES TABLE PAGE 1. Species of Vertebrata reported from the Kiowa 4. Summary of lithologic and paleontologic prop- Formation 10 erties of the Kiowa lithofacies 30 2. Modes of occurrence and origin of fossil assem- 5. Species reported from the Kiowa Formation but not found blages in the Kiowa Formation and their de- or recognized in this study 56 6. Measurements of Brachidon tes nonbifurcus Scott, scriptive criteria 14 n. sp. 61 3. Distribution of the more common taxa of the 7. Measurements of specimens of Ostrea arcuata Kiowa fauna 18 Scott, n. sp., and rugosa Scott, n. sp. 66 Introduction 5 ABSTRACT The Lower Cretaceous (Comanchean) Kiowa Formation at most places in central and southern Kansas overlies Permian rocks unconformably, and underlies the Dakota Formation with apparent unconformity. Four fossil zones—Venezolicenas kiotvanum Zone, Adkinsites bravoensis Zone, lnoceramus comancheanus Zone, and lnoceramus bellvuensis Zone—verify correlation of the lower Kiowa with the Goodland through Denison Formations in Texas. Six lithofacies contain fossils: dark-gray shale; tan mud- stone; thin-laminated sandstone; thin-bedded sandstone; mottled sandstone; and shell conglomerate. Kiowa fossil assemblages are preserved 1) in place or in the neighborhood where the fossils lived or 2) as transported assemblages. Mixed assemblages contain species repre- senting several substrates. Relative abundance data, accurate stratigraphic and geographic distribution data, and the Jaccard coefficient define ten recurring associations of abundant or unique species. The fossil associations are named: Nuculana; corbulid-breviarcid; Trachycardium-Tur- ritella; pteriid-mytilid; Gryphaea; Cyprimeria; Crassostrea; Lopho quadriplicata; Brachi- dontes; and trace fossil associations. Each comprises species distinguished by similar feeding and dwelling habits and substrate preferences. Because the assemblages have paleoecologic consistency, they represent parts of ancient communities and can be com- pared with modern marine benthic communities. Interspecific relationships of predation, trophic levels, competition, and commensalism were not unlike those of present-day marine communities. The climate during transgression and regression of the Kiowa sea was humid, tropical to subtropical. The sea in the nearshore, central Kansas area was shallower and less saline than in the offshore southern Kansas region. INTRODUCTION LOCATION AND GEOLOGIC SETTING In southern Kansas the Kiowa Formation is more than 250 feet thick in drill holes (LATTA, 1946). But The Kiowa Formation, of Early Cretaceous (Coman- exposures consist only of partial sections. Dominant southern Kansas chean) age, crops out in central and lithologies are dark-gray shale with intercalated, thin, Plains physio- on the eastern edge of the Dissected High shell conglomerates and sandstones. The upper part of outcrop areas are graphic province. Two extensive the sequence consists of brown sandstone. In Kiowa Quaternary deposits that con- separated by 80 miles of County, the type area, the Kiowa is generally conform- is dis- ceal the unit. The larger one, in central Kansas, able on the underlying Cheyenne Sandstone; and in continuous and trends northeast-southwest; several out- Clark and Comanche counties it is disconformable over trends liers lie to the east. The southern Kansas belt Permian rocks. The relation between the Kiowa and east-west (Fig. 1). the overlying Dakota is not clear because the contact 125 feet In central Kansas the Kiowa is 100 to is known only from one locality in Kiowa County. In and thick, and dominant lithologies are dark-gray shale most places Tertiary or Pleistocene rocks disconformably overlies brown sandstone. The Kiowa disconformably overlie the eroded Kiowa. Permian rocks and at least locally is disconformable The formation records an onlap-offlap sequence. beneath the Dakota Formation. Northward the outcrop The Early Cretaceous sea advanced from south to narrows and in Washington County the Kiowa is over- north, progressively overlapping older Permian rocks. At lapped by the Dakota. a very thin silty or sandy basal zone Shale generally underlies hummocky, grassy slopes, many localities marks the initial Cretaceous deposition. Retreat of the and sandstone forms more resistant ledges that cap part sea is indicated by development of sublittoral, nearshore of the Smoky Hills region. Good exposures generally sandstones and claystones in the upper part of the sec- are incomplete and widely separated. Only one com- tion. The continental Dakota Formation overlies the plete section of the Kiowa was found in central Kansas. Outcrops at some localities consist of float from re- Kiowa with apparent unconformity. sistant