Paleoneurology of Amniotes: New Directions in the Study of Fossil Endocasts

Description

This book presents a detailed examination of the current state of knowledge in the field of paleoneurology in the main amniote groups (reptiles, birds and mammals), and advances  resulting from new non-invasive technologies. The study of fossil endocasts is an area of considerable current interest, and has long been central to our understanding of the evolution of the brain, development of senses and behavioral adaptations in diverse vertebrate groups and across vertebrates as a whole. Recent advances in non-invasive imaging have significantly increased the number of fossil taxa for which brain morphology is known, and it may now be possible to quantitatively analyze the relative size of brain regions.  Providing a general overview of current perspectives and problems in evolutionary neuroanatomy, this book is intended for a wide range of readers, including undergraduate and graduate students, teachers, and anyone with a special interest in paleoneurology. It is also useful as supplementary reading for courses in digital anatomy, vertebrate comparative anatomy, computed morphometrics, paleontology, neurology and radiology as well as evolution programs List of Reviewers Contents About the Editors Contributors Chapter 1: Introduction References Chapter 2: The Paleoneurology of Early Reptiles 2.1 Early Evolutionary History and Diversity of Reptiles 2.2 Historical Background 2.2.1 The Fossil Record 2.2.2 Unresolved Issues 2.3 Anatomical Overview 2.3.1 Characterization of Cranial Endocast Morphology 2.3.2 Spaces Associated with Cranial Blood Supply 2.4 Brain Evolution and Paleobiological Inferences 2.4.1 Morphological Brain Diversity 2.4.2 Brain-Size Evolution and Encephalization Quotient 2.4.3 Sensory Perception Hearing and Balance Olfaction 2.5 Outstanding Questions and Perspectives 2.6 Conclusions References Chapter 3: The Paleoneurology of Ichthyopterygia and Sauropterygia: Diverse Endocranial Anatomies of Secondarily Aquatic Diapsids 3.1 Systematics and Phylogenetic Context 3.1.1 Ichthyopterygia Owen, 1860 3.1.2 Sauropterygia Owen, 1860 3.2 Historical Background 3.2.1 The Record of Endocranial Morphologies and Other Paleoneurological Features in Ichthyopterygia and Sauropterygia 3.2.2 Problematics 3.3 Overview of General and Comparative Anatomy 3.3.1 Characterization of Cranial Endocast Morphology Ichthyopterygia Sauropterygia 3.3.2 Voids Associated with Cranial Blood Supply Ichthyopterygia Sauropterygia 3.4 Brain Evolution and Paleobiologic Inferences Based on Endocast Morphology 3.4.1 Morphological Brain Diversity Ichthyopterygia Sauropterygia 3.4.2 Brain-Size Evolution and Encephalization Quotient 3.4.3 Sensory Evolution in Ichthyopterygia and Sauropterygia Ichthyopterygia Sauropterygia 3.5 Future Directions: Outstanding Questions and Perspectives 3.6 Conclusions References Chapter 4: Contrasting Brains and Bones: Neuroanatomical Evolution of Turtles (Testudinata) 4.1 Systematic and Phylogenetic Context 4.2 Historical Background 4.2.1 Summary of Neuroanatomical Research History 4.2.2 Problematics 4.3 Overview of General and Comparative Anatomy 4.3.1 Characterization of Neuroanatomical Structures Brain Morphology of Turtles Cranial Nerves of Turtles Braincase Endocast Morphology of Turtles and Correspondence of Brain and Endocast Shape Ontogeny of the Turtle Brain and Endocast Variation in Adult Braincase Endocast Morphology 4.3.2 Spaces Associated with Cranial Blood Supply Evolution of the Blood Canal System in Turtles Digital Dissection of Major Cranial Blood Vessels in Trachemys scripta 4.4 Brain Evolution and Paleobiologic Inferences Based on Endocast Morphology 4.4.1 Brain-Size Evolution 4.4.2 Sensory Evolution Vestibular Sense Hearing Vision Olfaction 4.5 Future Directions 4.6 Concluding Remarks References Chapter 5: A Look in to the Neurocranium of Living and Extinct Lepidosauria 5.1 Introduction 5.1.1 The Osseous Braincase 5.1.2 The Brain and Cranial Nerves 5.2 Phylogeny and Diversity of Lepidosauria 5.2.1 Early Diverging Lepidosaurian Lineages 5.2.2 Rhynchocephalia Günter, 1867 5.2.3 Squamata Oppel, 1811 The Extinct Mosasauria 5.3 Lepidosaur Braincase Diversity and the Fossil Record 5.3.1 Braincase of Stem-Lepidosaurians 5.3.2 Braincase of Rhynchocephalia Endocranial Features of Stem-Rhynchocephalia 5.3.3 Squamata Braincase of Stem-Squamata Braincase of Dibamidae Braincase of Gekkonomorpha Braincase of Scinciformata Braincase of Laterata Braincase of Toxicofera Braincase of Extinct Snakes and Available Endocranial Features 5.4 Overview of General Comparative Neuroanatomy 5.4.1 Characterization of the Reptilian Central Nervous System 5.4.2 Brain Morphology of Sphenodon 5.4.3 Brain Morphology of the Squamata Brain Morphology of Lizards Endocranial Casts in Lizards Brain Morphology of Snakes 5.5 Paleoneurology 5.5.1 Sources of Data for Paleoneurology and Limitation for the Study 5.5.2 Paleoneurology of Snakes and Mosasauroids: Cranial Endocasts and Other Sources of Information Paleoneuroanatomy of Dinilysia patagonica Paleoneuroanatomy of Mosasauroidea Inner Ear of Extant and Extinct Lepidosaurians 5.6 Future Directions and Conclusions 5.7 Conclusions References Chapter 6: Paleoneurology of the Early Diversification of Triassic Archosauriforms and Pseudosuchians 6.1 Systematic and Phylogenetic Context 6.2 Historical Background 6.2.1 Problematics 6.3 Overview of General and Comparative Anatomy 6.3.1 Non-archosaurian Archosauriforms Proterosuchidae Erythrosuchidae Protopyknosia Euparkeriidae Vanclavea and Litorosuchus Doswelliidae Proterochampsidae 6.3.2 Pseudosuchian Archosaurs Phytosauria Aetosauria Ornithosuchidae Erpetosuchidae Gracilisuchidae Poposauroidea Non-crocodylomorph Loricata 6.4 Brain Evolution and Paleobiological Inferences 6.4.1 Sensory Evolution 6.5 Future Directions 6.6 Concluding Remarks References Chapter 7: An Overview on the Crocodylomorpha Cranial Neuroanatomy: Variability, Morphological Patterns and Paleobiological Implications 7.1 Phylogenetic Context and Introduction to Paleoneurology of Crocodylomorpha 7.2 Overview of General and Comparative Anatomy 7.2.1 Neuroanatomy of Extant Crocodylians Brain Inner Ear Cranial Nerves of Crocodylomorphs 7.2.2 Comparative Anatomy of Crocodylomorph Brain and Inner Ear Non-crocodyliform Crocodylomorphs and Basal Crocodyliforms Thalattosuchia (Teleosauroidea and Metriorhynchoidea) Notosuchia (Uruguaysuchidae, Peirosauridae and Sebecosuchia) Early Eusuchians and Crocodylia 7.2.3 Cranial Nerves of Crocodylomorphs 7.3 Paleobiological Implications of Crocodyliform Neuroanatomy 7.4 Final Remarks References Chapter 8: Paleoneurology of Non-avian Dinosaurs: An Overview 8.1 Phylogenetic Context 8.1.1 Saurischia Seeley 1887 Theropoda Marsh 1881 Sauropodomorpha von Huene 1932 8.1.2 Ornithischia Seeley 1888 Thyreophora Nopcsa 1915 Neornithischia Cooper 1985 8.2 Historical Background 8.2.1 Brief Summary of the History of Dinosaur Paleoneurology Brains vs. Spinal Cord Early Studies and Current State of Knowledge of Dinosaur Paleoneurology 8.2.2 Non-invasive Techniques and Paleoneurology 8.2.3 Problems for the Study of Dinosaur ‘Brains’ 8.2.4 Cranial Endocast Reliability 8.2.5 Brain to Endocranial Cavity Ratio 8.2.6 Ontogeny 8.3 Overview of General and Comparative Brain Anatomy 8.3.1 The Reptilian Central Nervous System 8.3.2 Characterization of Cranial Endocast Morphology in Dinosaurs Generalized Dinosaur Endocast The Cranial Endocast of Theropoda The Endocast of Sauropodomorpha The Cranial Endocast of Ornithischia 8.4 Evolutionary Patterns in Dinosaur Neuroanatomy 8.4.1 Encephalization Quotient 8.4.2 Brain Architecture and Evolution 8.5 Future Directions and Conclusions References Chapter 9: Anatomy and Evolution of Avian Brain and Senses: What Endocasts Can Tell Us 9.1 Systematic and Phylogenetic Context 9.2 Historical Background 9.3 The Bauplan of the Avian Brain 9.4 Avian Brain Disparity 9.5 Cranial Nerves 9.6 Brain Vascularization 9.7 Brain Size 9.8 Senses 9.8.1 Inner Ear 9.8.2 Vision 9.8.3 Olfaction 9.9 The Non-avian Theropod – Aves Brain and Senses Transition 9.10 Concluding Remarks References Chapter 10: Evolution of the Mammalian Neurosensory System: Fossil Evidence and Major Events 10.1 Phylogenetic Context 10.2 Historical Background 10.3 The Ancestral Amniote 10.3.1 The Amniote Skeleton 10.3.2 Peripheral Sensory System Olfactory system Visual System Auditory System Peripheral Somatosensory System The Ancestral Amniote Brain 10.4 Early Pan-Mammalian History 10.4.1 Node 4: Therapsida 10.4.2 Node 9: Cynodontia 10.4.3 Node 11 (Unnamed) 10.4.4 Node 12: Probainognathia 10.4.5 Node 14: Mammaliamorpha 10.4.6 Node 15: Mammaliaformes 10.4.7 Node 16: Unnamed 10.4.8 Node 17: Mammalia Ossified Ethmoid Complex The Mammalian Middle Ear Orofacial Motor Skills Spinal Cord Nocturnality 10.5 Discussion References Chapter 11: Evolution of the Brain and Sensory Structures in Metatherians 11.1 Marsupial Origins, Diversity, and Phylogenetic Relationships 11.1.1 Marsupial Biogeography 11.1.2 Marsupial Diversity 11.1.3 Are Marsupials Representative of a Small-Brained, Primitive Mammalian Ancestor? 11.2 Historical Background 11.2.1 The Record of Endocranial Morphology and any Other Paleoneurological Approaches in the Group Under Study 11.2.2 Problematics 11.3 Overview of General and Comparative Anatomy 11.3.1 Endocast Morphology 11.3.2 Spaces Associated with Cranial Blood Supply 11.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 11.4.1 Morphological Brain Diversity Endocasts and Phylogenetic Traits Functional and/or Behavioral Interpretations of Endocast Morphology 11.4.2 Brain-Size Evolution and Encephalization Quotient Marsupial Brain Size and Behavioral Correlates 11.4.3 Sensory Evolution: Vision, Somatosensory System, Auditory System, Vestibular Sense, Olfaction 11.4.4 Brain Anatomy in Marsupials Versus Placentals 11.5 Future Directions: Outstanding Questions and Perspectives 11.6 Concluding Remarks References Chapter 12: Early Evolution of the Brain in Primates and Their Close Kin 12.1 Systematic and Phylogenetic Context 12.1.1 The Phylogenetic Position of Primates Within Mammalia 12.1.2 Taxonomy and Phylogeny of Primates 12.2 Historical Background 12.2.1 The Record of Endocranial Morphology and Any Other Paleoneurological Approaches in the Group Under Study Pre-CT Post-CT 12.2.2 Problematics 12.3 Overview of General and Comparative Anatomy 12.3.1 Characterization of Cranial Endocast Morphology Plesiadapiformes Adapoids and Omomyoids 12.3.2 Spaces Associated with Cranial Blood Supply 12.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 12.4.1 Morphological Brain Diversity 12.4.2 Brain-Size Evolution and Encephalization Quotient 12.4.3 Sensory Evolution: Vestibular Sense, Vision, Hearing, Olfaction, Taste, etc. 12.4.4 Evolution, Form and Function of Derived Brain Structures 12.5 Future Directions: Outstanding Questions and Perspectives 12.6 Concluding Remarks/Final Considerations References Chapter 13: Paleoneurology of Artiodactyla, an Overview of the Evolution of the Artiodactyl Brain 13.1 Systematic and Phylogenetic Context 13.2 Historical Background 13.2.1 Documentation of Artiodactyl Endocasts in the Fossil Record Endocranial Morphology of Extinct Artiodactyla Clades Endocasts of Modern Artiodactyl Groups 13.2.2 Problematics 13.3 Overview of General and Comparative Anatomy 13.3.1 Characterization of Cranial Endocast Morphology Overview of Modern Artiodactyl Brain Morphology, Primary Identification of Structures Endocranial Morphology of Extinct Artiodactyla Clades Endocranial Morphology of Crown Artiodactyla Clades 13.3.2 Space Associated with Cranial Blood Vessels 13.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 13.4.1 Morphological Brain Diversity: General Picture of Brain Evolution in Artiodactyla Olfactory Bulbs Neopallium Size and Complexity 13.4.2 Brain-Size Evolution and Encephalization Quotient Brain Size in Artiodactyla Brain Size in Non-cetacean Artiodactyls Brain Size in Cetacea 13.5 Future Directions: Outstanding Questions and Perspectives 13.6 Concluding Remarks References Chapter 14: Evolution of the Brain and Sensory Structures in Sirenia 14.1 Sirenian Biogeography, Fossil Record, and Phylogenetic Context 14.2 Historical Background 14.2.1 The Record of Endocranial Morphology and Any Other Paleoneurological Approaches to Sirenia 14.2.2 Problematics 14.3 Overview of General and Comparative Anatomy 14.3.1 Cranial Endocast Morphology 14.3.2 Spaces Associated with Cranial Blood Supply 14.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 14.4.1 Morphological Brain Diversity 14.4.2 Brain-Size Evolution and Encephalization Quotient 14.4.3 Sensory Evolution: Vision, Vestibular Sense, Hearing, Mechanoreception, Olfaction 14.4.4 Evolution and Form of Sirenian Brain Compared to Close Mammalian Relatives 14.5 Future Directions: Outstanding Questions and Perspectives 14.6 Concluding Remarks References Chapter 15: Paleoneurology of the Proboscidea (Mammalia, Afrotheria): Insights from Their Brain Endocast and Labyrinth 15.1 Historical Review and Current Data on the Variations of the Endocranial Cast Across Proboscidean Phylogeny 15.1.1 Introduction 15.2 Evolution of Endocranial Capacity 15.2.1 The Tools to Study the Evolution of Brain Size in Extinct Proboscideans 15.2.2 Patterns of Encephalization Evolution in Proboscideans 15.2.3 The Effect of Insular Dwarfism on Brain Size 15.2.4 Why Did Elephantimorpha Evolve an Enlarged Brain? 15.3 Evolution of Brain Morphology 15.3.1 Neuroanatomy of Modern Elephants 15.3.2 Morphology of the Endocranial Cast in Stem Proboscideans 15.3.3 Morphology of the Endocranial Cast in Elephantiformes Evolution of the Temporal Lobe Frontal Lobes and Olfactory Bulbs The Cerebellum and Evolution of the Trunk Cortical Sulcation and Gyrification 15.4 Evolution of the Bony Labyrinth, Hearing, and Balance 15.4.1 Historical Review 15.4.2 Bony Labyrinth Anatomy of Extant Elephants 15.4.3 Evolution of the Ear Region and Bony Labyrinth in Proboscidea Basal Proboscideans The Evolution of Low-Frequency Hearing Deinotheriidae and Elephantimorpha 15.5 Final Considerations References Chapter 16: Brain Evolution in Fossil Rodents: A Starting Point 16.1 Systematic and Phylogenetic Context 16.2 Historical Background 16.2.1 The Record of Endocranial Morphology and Any Other Paleoneurological Approaches in the Group Under Study 16.2.2 Problematics 16.3 Overview of General and Comparative Anatomy 16.3.1 Characterization of Cranial Endocast Morphology Ischyromyidae Sciuroidea Caviomorpha 16.3.2 Spaces Associated with Cranial Nerves and Blood Supply 16.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 16.4.1 Morphological Brain Diversity 16.4.2 Brain-Size Evolution and Encephalization Quotient 16.4.3 Sensory Evolution: Vestibular Sense, Vision, Hearing, Olfaction, Taste, etc. 16.5 Future Directions: Outstanding Questions and Perspectives 16.6 Concluding Remarks Appendix References Chapter 17: Paleoneurology of Carnivora 17.1 Systematic and Phylogenetic Context 17.2 Historical Background 17.3 Overview of General and Comparative Anatomy 17.3.1 Characterization of Cranial Endocast Morphology of Living Taxa 17.3.2 Sensory Evolution 17.3.3 Cellular Composition 17.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 17.4.1 Morphological Brain Diversity Through Time Eocene Carnivorans Oligocene Carnivorans Early and Middle Miocene Carnivorans Late Miocene and Plio-Pleistocene Carnivorans 17.4.2 The Evolution of Gyrification in Carnivorans 17.4.3 Brain-Size Evolution 17.5 Concluding Remarks References Chapter 18: Paleoneurology of Extinct Cingulates and Insights into Their Inner Ear Anatomy 18.1 Systematic and Phylogenetic Context 18.2 Historical Background 18.2.1 The Record of Endocranial Morphology of Fossil Cingulates 18.2.2 Problematics 18.3 Overview of General and Comparative Anatomy 18.3.1 Characterization of Cranial Endocast Morphology Armadillos Glyptodonts Pampatheres 18.3.2 Inner Ear Endocast Anatomy 18.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 18.4.1 Morphological Brain Diversity 18.4.2 Brain-Size Evolution and Encephalization Quotient 18.4.3 Sensory Evolution: Vestibular Sense 18.5 Future Directions: Outstanding Questions and Perspectives 18.6 Final Considerations References Chapter 19: The Endocranial Cavities of Sloths (Xenarthra, Folivora): Insights from the Brain Endocast, Bony Labyrinth, and Cranial Sinuses 19.1 Systematic and Phylogenetic Context 19.2 Historical Background 19.2.1 The Record of Endocranial Morphology of Fossil Sloths 19.3 Overview of General and Comparative Anatomy 19.3.1 Brain Cavity and Cranial Nerves Brain Cavity Cranial Nerves 19.3.2 Bony Labyrinth 19.3.3 Cranial Sinuses 19.4 Evolutionary Inferences Based on Endocast Morphology 19.4.1 Brain Cavity and Cranial Nerves Brain Cavity Cranial Nerves 19.4.2 Bony Labyrinth 19.4.3 Cranial Sinuses 19.5 Open Problems and Future Directions: Outstanding Questions and Perspectives 19.6 Concluding Remarks References Chapter 20: Endocranial Morphology and Paleoneurology in Notoungulates: Braincast, Auditory Region and Adjacent Intracranial Spaces 20.1 Systematic and Phylogenetic Context 20.1.1 South American Native Ungulates 20.1.2 Notoungulata 20.2 The Study of Notoungulates Braincast and Auditory Region over the Years 20.2.1 Braincast 20.2.2 Auditory Region 20.2.3 Advances in Recent Years 20.3 Overview of the Endocranial Morphology 20.3.1 Characterization of Notoungulate Braincast 20.3.2 Spaces Associated with Intracranial Blood Supply 20.3.3 Spaces Associated with the Middle and Inner Ear 20.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 20.4.1 Morphological Brain Diversity 20.4.2 Relative Brain Size Evolution: A Challenging Task in Notoungulates 20.4.3 Inferred Sensory and Locomotor Capabilities: Olfaction, Hearing and Vestibular Sense 20.5 Final Considerations: Conclusions, Outstanding Questions and Perspectives References Chapter 21: Paleoneurology of Litopterna: Digital and Natural Endocranial Casts of Macraucheniidae 21.1 Systematic and Phylogenetic Context 21.2 Historical Background 21.2.1 The Record of Endocranial Morphology and Any Other Paleoneurological Approaches in Litopterna 21.2.2 Problematics 21.3 Overview of General and Comparative Anatomy 21.3.1 Characterization of Endocranial Cast Morphology CT Scanning and Endocast Acquisition Criteria for Neuromorphological Interpretation Description of the Digital Endocranial Casts and Neuromorphological Interpretation (Figs. 21.1, 21.2, 21.3 and 21.4) Endocranial Spaces Associated with Pneumatization of the Cranial Roof 21.3.2 Natural Endocranial Cast (or Natural Brain Endocast) 21.4 Brain Evolution and Paleobiological Inferences Based on Endocast Morphology 21.4.1 Morphological Endocranial Cast Diversity Comparative Neuromorphology with Extinct South American Native Ungulates and Living and Extinct Euungulata Frontal Sinuses 21.4.2 Brain-Size Evolution and Encephalization Quotient 21.5 Future Directions: Oustanding Questions and Perspectives 21.6 Conclusions References Index