South American Sauropodomorph Dinosaurs
Año: 2022 p. 582
Foreword (by L. Salgado).Sauropodomorpha Huene 1932 is one of the most successful groups of dinosaurs that includes the most abundant and diverse herbivorous forms with a worldwide record, extending from the Late Triassic to the Late Cretaceous. Sauropodomorphs include early forms (the formerly traditionally called ?prosauropods?) and the iconic sauropods.With more than 150 valid species and a worldwide distribution, Sauropoda Marsh 1878 comprises the dominant herbivorous dinosaurs from the Middle Jurassic to the Late Cretaceous. The sauropodan body plan, characterized by gigantic size, graviportal locomotion, long necks and tails, and a comparatively small skull, made this group of sauropodomorphs part of the popular culture since the late nineteenth century. Worldwide, the current knowledge about sauropods, their classification, anatomical and paleobiological knowledge, is the result of the joint work of numerous researchers, and I could not name some of them without taking the risk of leaving out others. However, abusing a bit of the generosity of Alejandro, José Luis, and Diego, the editors of this book who invited me to preface it, I will recall two that profoundly influenced many of the sauropod specialists of my generation, including myself: Jack McIntosh (1923−2015), Professor at Wesleyan University (Connecticut, USA), and José Bonaparte (1928−2020), for years Head of the Vertebrate Paleontology Section of the Museo Argentino de Ciencias Naturales (at Buenos Aires city, Argentina). Particularly Bonaparte is, to date and without doubts, the greatest exponent of Mesozoic Vertebrate Paleontology in the entire South American continent. This book deals with South American sauropodomorphs, although South America did not exist as a separate continent when sauropodomorphs lived. Actually, for most of the evolutionary history of this group of dinosaurs, South America was integrated to other landmasses, at first to the rest of Gondwana and later to West Gondwana. Beyond this, the geographical demarcation thought for this book is totally justified based on the superlative record of sauropodomorphs in what is today South America, with forms ranging from the Carnian−when they make their appearance in the paleontological record−up to the Maastrichtian−when they became extinct−. During all that long period of time (more than 160 million years), sauropodomorphs experienced important evolutionary events: diversifications and global or local extinctions, modifying their body plans with the acquisition of unique evolutionary novelties, many of which are directly linked to their herbivory and huge sizes. Many of the events that marked the evolution of the Sauropodomorpha can be better studied from the South American record, and several of these extreme evolutionary transformations have excellent examples in sauropodomorphs recorded in this subcontinent; to mention just two, the earliest giant sauropodomorph (the lessemsaurid Ingentia) and the largest sauropods so far recorded (the lognkosaurs Argentinosaurus and Patagotitan) lived in what is now South America. In this way, the first and last steps toward the gigantism are recorded in this subcontinent; it can be said that, in some way, the evolutionary history of sauropodomorphs begins and ends in South America. Among all the forms that integrate the list of South American sauropodomorphs, titanosaurs undoubtedly occupy a central place, to the point that they have deserved several chapters of the book (8−10). Here, I will again abuse the kindness of the editors bringing to mind to a third sauropodologist that laid the foundations of the current knowledge of the South American representatives of this group of macronarians: Jaime Powell (1953−2016), from the Instituto ?Miguel Lillo? at Tucumán, Argentina. Among some of his discoveries, Jimmy was the one who recognized the existence of osteoderms in some titanosaurs, a characteristic unique to this group of huge reptiles. In this book, there are 37 participant contributors. Although there is a majority of Argentinians, many of them are from other countries in South America and from other continents. After all, South American sauropodomorphs have always raised international interest and are not few of the researchers that, year after year, arrive in the region with the purpose of consulting old collections and seeing new materials: new materials that are increasing at an accelerated rate. This book contains 15 chapters, including systematics, covering the main lineages within Sauropodomorpha (Chapters 1 to 10), paleobiology (Chapters 11 to 14), and taphonomy (Chapter 15), a broad approach that accounts the breadth of interests of its authors. Beyond the notably increase in anatomical and systematic knowledge achieved, especially in the last 30 years, new lines of research in sauropodomorph paleontology have been opened with the incorporation of young researchers; among these are paleosteohistology, reproductive biology, and ichnology, which have also been enhanced with the incorporation of new and not so new technologies, now widely used, such as computed tomography, scanning electron microscopy, or photogrammetry. Hopefully, in the coming years, these new lines of investigation will allow us to learn more about these dinosaurs. Sauropodomorphs went extinct along with the rest of the non-avian dinosaurs, but, needless to say, the fascination they still produce has not diminished. Ninety years after the group was recognized, books like this continue to prove it.