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University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 48106 A Xerox Education Company Il 72-29,878 ECHOLS, Betty Joan, 1932- BIOSTRATIGRAPHY AND REPTILE FAUNAS OF THE UPPER AUSTIN AND TAYLOR GROUPS (UPPER CRETACEOUS) OF TEXAS, WITH SPECIAL REFERENCE TO HUNT, FANNIN, LAMAR AND DELTA COUNTIES, TEXAS. The University of Oklahoma, Ph.D., 1972 Paleontology University Microfilms, A XERDKCompany, Ann Arbor. Michigan I ' I THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED THE UNIVERSITY OF OKTÆOMA. GRADUATE COLLEGE BIOSTRATIGRAPHY AND REPTILE FAUNAS OF THE UPPER AUSTIN AND TAYLOR GROUPS (UPPER CRETACEOUS) OF TEXAS, WITH SPECIAL REFERENCE TO HUNT, FANNDf, LAMAR AND DELTA COUNTIES, TEXAS A DISSERTATION SUBMITTED TO THE GRADUATE FACULTY in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY BY JOAN ECHOLS Norman, Oklahoma 1972 BIOSTRATIGRAPHY AND REPTILE FAUNAS OF THE UPPER AUSTIN AND TAYLOR GROUPS (UPPER CRETACEOUS) OF TEXAS, WITH SPECIAL REFERENCE TO HUNT, FANNIN, LAMAR AND DELTA COUNTIES, TEXAS APPROVED BY DISSERTATION COMMITTEE PLEASE NOTE: Some pages may have indistinct print. Filmed as received. University Microfilms, A Xerox Education Company BIOSTRATIGRAPHY AND REPTILE FAUNAS OF THE UPPER AUSTIN AND TAYLOR GROUPS (UPPER CRETACEOUS) OF TEXAS, WITH SPECIAL REFERENCE TO HUNT, FANNIN, LAMAR AND DELTA COUNTIES, TEXAS BY Joan Echols Major Professor; Dr. David B. Kitts . Upper Cretaceous rocks in northeast Texas have furnished many vertebrate specimens, some of which occur as concentrations (eight animals at one locality) of fossils in particular lithologies. Explanations for the concentrations involve both biologic and sedimentologic factors. The units studied are, in ascending order, the Roxton Limestone (Upper Austin Group), and the Ozan Formation, Wolfe City Formation, Pecan Gap Formation and Marlbrook Formation (Taylor Group). These rocks are of Campanian age. The Roxton Limestone is a cross-bedded, intensely bioturbated biomicrite containing many vertebrate and invertebrate fossils. The Ozan and Marlbrook marls are gray, calcareous mudrocks with some fossils. A condensed zone in the Ozan Formation is a glauconitic packed biomicrite containing many vertebrate and invertebrate fossils. The Wolfe City Formation is a massive, light brown orthoquartzite that con­ tains few fossils. The Pecan Gap chalks are white to cream sparse bio- micrites, the basal ten feet of which are another condensed zone. All carbonate and mud rocks are texturally immature and poorly sorted, and all show evidence of bioturhation. Condensed zones occur in the Roxton Limestone, the Ozan Formation and at the base of the Pecan Gap Formation. All of these zones contain concentrations of fossils and phosphatic casts and nodules. Some verte­ brate specimens from these zones are disarticulated by currents and burrowers,'encrusted or bored by marine organisms, bitten and reworked. These specimens were exposed on the sea floor for long periods of time, in areas of by-passing where slow sedimentation caused condensed deposits to form. The occurrence of some of these zones around a synchronous 1X1 high, the Preston anticline, provides evidence of at least indirect tectonic control of biofacies as veil as lithofacies. Concentrations of fossils in the Roxton calcarenitic biomicrites may also indicate tectonic control if currents flowing around the Preston anticline washed carcasses into the area and beached them on the shoal areas near the crest. One species of mosasaur, Clidastes propython, is restricted to occurrence in the Roxton Limestone, because members of this species may have preferred to live in shallow water around the Preston anticline. The vertebrate fauna includes remains of many mosasaurs, a few plesiosaurs and turtles, and many fishes and sharks. The fossils may represent the Clidastes propython-Platecarpus ictericus-Tylosaurus proriger zone, which occurs in the Niobrara and Pierre Formations. Tylo- saurus was the most abundant genus of mosasaurs, and Globidens was the rarest. Some specimens of Tylosaurus are estimated to have been more than 50 feet in length. The fossils occur scattered in all lithologies and in all stratigraphie units but they form concentrations in the con­ densed zones. Restrictions of mosasaur species other than Clidastes propython are the result of rarity of the specimens, rather than biologi­ cal, temporal or sedimentological restrictions. During the late Cretaceous, northeastern Texas may have been similar to the Rowley-Sahul Shelf area (northwestern Australia). Both areas had slow carbonate deposition around alternate highs and basins, with condensed zones forming on the highs where currents removed fine particles. Thus the occurrence of lithofacies and biofacies was influ­ enced by tectonic features in the study area. IV ACKNOWLEDGMENTS This study is submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the University of Oklahoma, The problem was suggested by Dr. Roy N. Jervis, Head of Earth Sciences Department, East Texas State University, The work was directed by Dr. David B. Kitts, whose assistance is gratefully acknowledged. Gratitude is due Drs. Harvey Blatt, Charles Harper, Jiri Zidek for checking the manuscript and making helpful suggestions. I want to thank Dr. John T. Thurmond for his assistance in checking the identifi­ cations and systematic paleontology. Special thanks are due Dr. Gideon T. James, Earth Sciences Department, East Texas State University, for his assistance with field and laboratory techniques, photography, and helpful discussions. The writer wishes to thank Drs. Charles Mankin, David Kitts, and Nolan McWhirter (Head of Earth Sciences Department, East Texas State University) for help in obtaining funds for the project. These funds included Geological Society of America grants number 114-5-67 and 1244.-69, and a grant from University of Oklahoma School of Geology funds. Dr. McWhirter's assistance in obtaining work space,tools, student assistants, and travel funds was especially appreciated. Special thanks are due the Southwest Pump Company, Bonham, Texas, for their loan of a portable gasoline jackhammer for work on ET Locality 4-3. V The helpfulness of many paleontologists during study trips was greatly appreciated; Professor Bob Slaughter, Shuler Museum of Paleon­ tology, Southern Methodist University, Dr. Eugene Gaffney, .American Museum of Natural History, Drs. Nicholas Hotton III and Robert Purdy, United States National Museum, Dr. Robert Scott, University of Texas at Arlington, Dr. Bryce 0. Brown, Strecker Museum, Baylor University, and Dr. Wann Langston, University of Texas at Austin were very helpful. Several students have assisted with special techniques, and I want to thank University of Oklahoma students Dah-Gheng Uu. for X-ray analysis of one sample and Kenneth Sargeant for assistance with insoluble residue techniques. East Texas State University art student Gary Panter did the line drawings and Charles Griffith drafted the map and measured sections. Their help is greatly appreciated. My gratitude is expressed to the many students who assisted with laboratory and field work, especially Irene (Mrs. Retus) Beeler, Otha Boozer, Larry Brent, David Butts, Donald Galbraith, Tad Poutinen, Harold Sheppard, David Stroud, Jesse Todd, Jack Tucker and John Wright. Numerous other students,have donated specimens and given locality information; their help is also acknowledged. I want to express special thanks to my parents, Ben Russell Echols and the late Edna Bollinger Echols, for their assistance and encouragement in all phases of the work. VI TABLE OF CONTENTS Page ABSTRACT............................................