Urumaco and Venezuelan Paleontology: The Fossil Record of the Northern Neotropics

1 Venezuelan Geography and Biodiversity: A Brief Introduction

3 Venezuelan Geography and Biodiversity: A Brief Introduction Cathy Villalba and Marcelo R. Sánchez-Villagra Venezuela is situated in the tropics. The northern coast lies almost entirely between 10 and 11 degrees north latitude, and the southernmost tip of Amazonas State is less than 1 degree north. The total area of Venezuela is a little over 900,000 km2 . Broadly, three regions can be recognized in the topography of Venezuela: deserts and mountains in the north bordering approximately 2813 km of coastline, flat grassland across the middle section, and in the south a wide expanse of rain forest with some savanna areas and a region of flat-topped mountains, the tepuis. In this chapter we provide a general introduction to the main geographical features and to the living biodiversity of Venezuela, the latter serving as contrast to the extinct forms treated in this book. The names of political entities are referred to in several parts of this book (fig. 1.1). Administratively, Venezuela is divided into 23 states (estados ) and the Capital District of Caracas. The islands of Margarita, Coche, and Cubagua collectively form the state Nueva Esparta, and 72 remaining islands are federal dependencies. The states are further divided into 335 municipalities or municipios, an example of which is the Municipio Urumaco in Estado Falcón. The main topographical and geographical features mentioned in this book pertain to the northern half of Venezuela, illustrated in the map in figure 1.2 and plate 1. The Venezuelan territory contains six great physiographic provinces, described below. The Coastal Continental platform, which is located in the northern portion of the country, between the Caribbean Sea and northern spurs of the mountain range of the coast, includes approximately 18% of the continental surface. It includes a coastal strip of low relief, between 0 and 100 meters above sea level, and two important depressions: the Lake Maracaibo and the region of the delta of the Orinoco. This province includes the Venezuelan islands; some parts of the Unare depression in the center-northeastern end, the coastal plains and plains of low relief, and the sedimentary river basins of the gulfs of Venezuela and Cariaco. The Caribbean Mountain system is a structural continuation of the insular arc of the Eastern Region of the Caribbean, between the northcenter -eastern coastal zone and the depression of the plains. It includes Topography 1 Villalba and Sánchez-Villagra 4 3% of the surface of the country and is the most densely populated region. It represents a complex mountainous system of the alpine type, with varied valleys, hills, and low mountains. Extending from the depression of Carora to the west to the peninsulas of Paria and Araya to the east, with a single important interruption, the depression of Unare, this system is divided into the central and the eastern sections by the depression of Unare and the Cariaco basin. Each section is divided into two oriented chains running east to west: the littoral chain and the chain of the interior , between which are important depressions such as Lake Valencia, the Barlovento plain, and Tuy’s Valley. The central section reaches a maximum altitude of 2,765 meters at Pico Naiguatá (the highest peak of the Cordillera de la Costa, Coastal Mountains) in the littoral chain, while in the eastern section the highest summit is Pico Turimiquire (2,595 meters) in the Serranía del Interior (Chain of the Interior). The region of Valleys and Serranías is topographically variable but with low relief, with altitudes between 500 and 1,700 meters. It is located in the northwestern portion of the country and occupies almost entirely the states of Falcón, Lara, and Yaracuy, with an area of approximately 52,000 km2 . Plains of fluvial lacustrine origin also occur in this region, and on the coast of Falcón the Medanos (dunes) de Coro, which constitute an accumulation of sand caused by the continual action of easterly winds. The mountainous system of the Cordillera de los Andes dominates Venezuelan topography. It constitutes a prolongation of the Colombian Andes, which at the Nudo de Pamplona in Colombia branches into two chains: the Sierra de Perijá and the Cordillera de Mérida, or Venezuelan Andes. The Cordillera de Mérida penetrates into Venezuela near the Táchira depression and extends into Lara state. In its central part it is divided by the rivers Chama and Motatán, which run in opposite directions . The highest tip of the country is the Pico Bol...