The Urumaco Formation is a

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

that includes deposits from the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

. It is the site of several "giant forms": the

turtles Turtles are an order (biology), order of reptiles known as Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) an ...

crocodiles Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant memb ...

sloths Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their l ...

and

rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are nat ...

of Urumaco are among the largest of their groups.

Location

The Urumaco formation is located in the

Urumaco Urumaco is a town in Falcón State in Venezuela. It is of interest to paleontologists due to its rich fossil history. The arid climate of the region means that the fossils are not hidden by vegetation. The fossils were first made known to scienc ...

region in the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

coastal

Falcón ) , anthem = , image_map = Falcon in Venezuela.svg , map_alt = , map_caption = Location within Venezuela , pushpin_map = , pushpin_map_alt = , pushpin_mapsiz ...

state. The deposits date from 10 to 5.3 million years ago and the Urumaco formation was deposited in an area with large

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...

s and shallow coastal

seas This is a list of seas of the World Ocean, including marginal seas, areas of water, various gulfs, bights, bays, and straits. Terminology * Ocean – the four to seven largest named bodies of water in the World Ocean, all of which have "Ocean ...

. These conditions in the Late Miocene contrast strongly with the current dry environment in the area today.

Fauna

Cartilaginous fish

There are 21 known species of cartilaginous fishes from the Urumaco Formation, belonging to the orders

Lamniformes The Lamniformes (, from Greek ''lamna'' "fish of prey") are an order (biology), order of sharks commonly known as mackerel sharks (which may also refer specifically to the family Lamnidae). It includes some of the most familiar species of sharks, ...

Carcharhiniformes Carcharhiniformes , the ground sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and the sandbar shark. Members of this order are characterized by the presen ...

Myliobatiformes Myliobatiformes () is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown the myliobatiforms to be a monophyletic grou ...

and

Rajiformes Rajiformes is one of the four orders in the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head ...

. ''

Carcharhinus caquetius ''Carcharhinus'' is the type genus of the family Carcharhinidae, the requiem sharks. One of 12 genera in its family, it contains over half of the species therein. It contains 35 extant and eight extinct species to date, with likely more species y ...

'' is an

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

species of predator shark from Urumaco. A large number of well-preserved

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of the

sawfish Sawfish, also known as carpenter sharks, are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish wi ...

Pristis rostra ''Pristis'' is a genus of sawfish of the family Pristidae. These large fish are found worldwide in tropical and subtropical regions in coastal marine waters, estuaries, and freshwater lakes and rivers. Sawfish have declined drastically and al ...

'' have been found in the deposits. The

megalodon Megalodon (''Otodus megalodon''), meaning "big tooth", is an extinct species of mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. It was formerly thought to be a membe ...

is also known from the Urumaco Formation. The coastal seas of Urumaco were further inhabited by species that still live in the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

today, such as the

spotted eagle ray The spotted eagle ray (''Aetobatus narinari'') is a cartilaginous fish of the eagle ray family, Myliobatidae. As traditionally recognized, it is found globally in tropical regions, including the Atlantic, Pacific and Indian Oceans. Recent auth ...

smooth hammerhead shark The smooth hammerhead (''Sphyrna zygaena'') is a species of hammerhead shark, and part of the family Sphyrnidae. This species is named "smooth hammerhead" because of the distinctive shape of the head, which is flattened and laterally extended int ...

tiger shark The tiger shark (''Galeocerdo cuvier'') is a species of requiem shark and the last extant member of the family Galeocerdonidae. It is a large macropredator, capable of attaining a length over . Populations are found in many tropical and tempera ...

and

bull shark The bull shark (''Carcharhinus leucas''), also known as the Zambezi shark (informally zambi) in Africa and Lake Nicaragua shark in Nicaragua, is a species of requiem shark commonly found worldwide in warm, shallow waters along coasts and in riv ...

Bonefish

The bony fishes from the Urumaco Formation include

groupers Groupers are fish of any of a number of genera in the subfamily Epinephelinae of the family Serranidae, in the order Perciformes. Not all serranids are called "groupers"; the family also includes the sea basses. The common name "grouper" i ...

, piranha-like fish such as

pacas A paca is a member of the genus ''Cuniculus'' of ground-dwelling, herbivorous rodents in South and Central America. It is the only genus in the family Cuniculidae. Pacas are large rodents with dots and stripes on their sides, short ears, and ...

cuttlefish Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of ...

, thorny catfish and red-tailed catfish.

Reptiles

The Urumaco Formation has a great diversity of crocodilians with twelve known species. Seven species of

caimans A caiman (also cayman as a variant spelling) is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico, Central and South America fr ...

have been described: '' Caiman brevirostris'', '' C. latirostris'', ''

Globidentosuchus brachyrostris ''Globidentosuchus'' is an extinct genus of basal caimanine crocodylian known from the late Middle to Late Miocene of the Middle and the Upper Members of the Urumaco Formation at Urumaco, Venezuela. Its skull was very short and robust, with l ...

'', '' Melanosuchus fisheri'', '' Mourasuchus arendsi'', '' M. nativus'' and '' Purussaurus mirandai'', '' Gryposuchus croizati'', '' G. jessei'', '' Hesperogavialis cruxenti'' and '' Ikanogavialis gameroi'' are the

gavials The gharial (''Gavialis gangeticus''), also known as gavial or fish-eating crocodile, is a crocodilian in the family Gavialidae and among the longest of all living crocodilians. Mature females are long, and males . Adult males have a distinct ...

of Urumaco, a group that is no longer found in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

today. The kinship of '' Charactosuchus mendesi'' with the other crocodilians is considered unclear. Multiple species of crocodilians were able to live together because they focused on specific niches, making it limited competition between species. For example, ''Mourasuchus arendsi'' had a duck-like beak with which it caught

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

, the 10-foot-long, fish-eating ''Gryposuchus croizati'' lived particularly in estuaries, and the 11.5-foot-long ''Purussaurus mirandai'' hunted a wide range of prey animals. '' Stupendemys geographicus'' is the best-known turtle species from the Urumaco formation. This animal from the American necked turtles family was one of the largest turtles ever with a shell 3.3 meters long. Other turtles from Urumaco include several species of '' Bairdemys, ''the ''

mata mata Matamata () is a town in Waikato, New Zealand. It is located near the base of the Kaimai Ranges, and is a thriving farming area known for Thoroughbred horse breeding and training pursuits. It is part of the Matamata-Piako District, which takes ...

Chelus lewisi'' and softshell turtles. In addition to the multiple crocodilians and turtles, vertebra of a

boa Kwon Bo-ah (; born November 5, 1986), known professionally as BoA, is a South Korean singer, songwriter, dancer, record producer and actress. One of the most successful and influential Korean entertainers, she has been dubbed the " Queen of K- ...

have also been found in the Urumaco Formation.

Mammals

Phoberomys pattersoni ''Phoberomys pattersoni'' is an extinct rodent that lived in the ancient Orinoco River delta around 8 million years ago. It was the second-largest of the roughly seven species of its genus. Like many other rodents, ''Phoberomys'' was a herbivore ...

'' is one of the largest known rodents ever. This three-meter-long relative of today's

pacarana The pacarana (''Dinomys branickii'') is a rare and slow-moving Hystricognathi, hystricognath rodent indigenous to South America. Native Tupian languages, Tupi people call it the ''pacarana'' (false paca) because it is superficially similar to the ...

had a lifestyle similar to that of the capybara. Several species of

xenarthra Xenarthra (; from Ancient Greek ξένος, xénos, "foreign, alien" + ἄρθρον, árthron, "joint") is a major clade of placental mammals native to the Americas. There are 31 living species: the anteaters, tree sloths, and armadillos. Ex ...

ns are known from the Urumaco Formation. '' Urumaquia robusta'' was a

ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbe ...

from the

Megatheriidae Megatheriidae is a family of extinct ground sloths that lived from approximately 23 mya—11,000 years ago. Megatheriids appeared during the Late Oligocene (Deseadan in the SALMA classification), some 29 million years ago, in South America ...

weighing four tons. Others ground sloths from Urumaco are '' Bolivartherium urumaquensis'', '' Urumacotherium garciai'', '' Eionaletherium tanycnemius'', and '' Pseudoprepotherium venezuelanum'' belonging to the

Mylodontidae Mylodontidae is a family of extinct South American and North American ground sloths within the suborder Folivora of order Pilosa The order Pilosa is a clade of xenarthran placental mammals, native to the Americas. It includes the anteaters a ...

.'' Urumacocnus urbani'' and '' Pattersonocnus diazgameroi'' are ground sloths from the

Megalonychidae Megalonychidae is an extinct family of sloths including the extinct ''Megalonyx''. Megalonychids first appeared in the early Oligocene, about 35 million years (Ma) ago, in southern Argentina (Patagonia). There is actually one possible find datin ...

. '' Boreostemma pliocena'' is a

glyptodont Glyptodonts are an extinct subfamily of large, heavily armoured armadillos. They arose in South America around 48 million years ago and spread to southern North America after the continents became connected several million years ago. The best-kn ...

. '' Bounodus enigmaticus'' (

Proterotheriidae Proterotheriidae is an extinction, extinct family of fossil ungulates from the Cenozoic era that displays toe reduction. Despite resembling primitive, small horses, they were only distantly related to them, and instead belonged to the native Sou ...

Litopterna Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of South American ungulates that were endemic to the continent, until the G ...

) and ''

Gyrinodon ''Gyrinodon'' is an extinct genus of toxodontid notoungulate that lived from the Late Miocene and Early Pliocene in what is now Brazil and Colombia. Description This animal was approximately the size of a modern rhinoceros, and they were sim ...

'' (

Toxodontidae Toxodontidae is an extinct family of notoungulate mammals, known from the Oligocene to the Holocene (11,000 BP) of South America, with one genus, ''Mixotoxodon'', also known from the Pleistocene of Central America and southwestern North America ...

Notoungulata Notoungulata is an extinct order of mammalian ungulates that inhabited South America from the early Paleocene to the Holocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resemb ...

) are the South American ungulates of the Urumaco formation. In the waters of Urumaco lived the freshwater dolphins '' Ischyrorhynchus vanbenedeni'' and '' Saurodelphis'' and the

dugongs The dugong (; ''Dugong dugon'') is a marine mammal. It is one of four living species of the order Sirenia, which also includes three species of manatees. It is the only living representative of the once-diverse family Dugongidae; its closest m ...

'' Nanosiren sanchezi'' and possibly ''

Metaxytherium ''Metaxytherium'' is an extinct genus of dugong that lived from the Oligocene until the end of the Pliocene. Fossil remains have been found in Africa, Europe, North America and South America. Generally marine seagrass specialists, they inhabite ...

''. Fossil Sirenia of the West Atlantic and Caribbean region. VIII. ''Nanosiren garciae'', gen. et sp. nov. and ''Nanosiren sanchezi'', sp. nov. DP Domning & OA Aguilera. Journal of Vertebrate Paleontology (2008).

References

{{Reflist Geologic formations of Venezuela Neogene Venezuela Miocene Series of South America Laventan Mayoan Chasicoan Lagerstätten Fossiliferous stratigraphic units of South America Paleontology in Venezuela