Urumaco Formation

Last updated
Urumaco Formation
Stratigraphic range: Late Miocene
Type Geological formation
Location
Country Venezuela

The Urumaco Formation is a formation in Venezuela that includes deposits from the Late Miocene. It is the site of several "giant forms": the turtles, crocodiles, sloths and rodents of Urumaco are among the largest of their groups.

Contents

Location

The Urumaco formation is located in the Urumaco region in the Caribbean coastal Falcón state. The deposits date from 10 to 5.3 million years ago and the Urumaco formation was deposited in an area with large rivers, swamps, estuaries, lagoons and shallow coastal seas. 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, Carcharhiniformes, Myliobatiformes and Rajiformes. [1] Carcharhinus caquetius is an endemic species of predator shark from Urumaco. A large number of well-preserved fossils of the sawfish Pristis rostra have been found in the deposits. The megalodon is also known from the Urumaco Formation. The coastal seas of Urumaco were further inhabited by species that still live in the Caribbean Sea today, such as the spotted eagle ray, smooth hammerhead shark, tiger shark and bull shark.

Bonefish

The bony fishes from the Urumaco Formation include groupers, piranha-like fish such as pacas, cuttlefish, thorny catfish and red-tailed catfish. [2]

Reptiles

The Urumaco Formation has a great diversity of crocodilians with twelve known species. [3] Seven species of caimans have been described: Caiman brevirostris , C. latirostris , Globidentosuchus brachyrostris , Melanosuchus fisheri , Mourasuchus arendsi , M. nativus and Purussaurus mirandai , Gryposuchus croizati , G. jessei , Hesperogavialis cruxenti and Ikanogavialis gameroi are the gavials of Urumaco, a group that is no longer found in South America 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, limiting infraspecific competition. For example, the 4.3–5.5 metres (14–18 ft)Mourasuchus arendsi [4] had a duck-like beak with which it caught crustaceans, the fish-eating Gryposuchus croizati, 10 metres (33 ft) in length, [5] lived particularly in estuaries, and Purussaurus mirandai, 10 metres (33 ft) in length, [6] 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 2.4–3 metres (7.9–9.8 ft) long. [7] Other turtles from Urumaco include several species of Bairdemys , [8] the mata mata Chelus lewisi and softshell turtles.

In addition to the multiple crocodilians and turtles, vertebra of a boa have also been found in the Urumaco Formation. [9]

Mammals

Phoberomys pattersoni is one of the largest known rodents ever. [10] This three-meter-long relative of today's pacarana had a lifestyle similar to that of the capybara. Several species of xenarthrans are known from the Urumaco Formation. Urumaquia robusta was a ground sloth from the Megatheriidae weighing four tons. Others ground sloths from Urumaco are Bolivartherium urumaquensis , Urumacotherium garciai , Eionaletherium tanycnemius , and Pseudoprepotherium venezuelanum belonging to the Mylodontidae. [11] Urumacocnus urbani and Pattersonocnus diazgameroi are ground sloths from the Megalonychidae. [12] Boreostemma pliocena is a glyptodont. Bounodus enigmaticus (Proterotheriidae, Litopterna) and Gyrinodon (Toxodontidae, Notoungulata) are the South American ungulates of the Urumaco formation. [13] In the waters of Urumaco lived the freshwater dolphins Ischyrorhynchus vanbenedeni and Saurodelphis and the dugongs Nanosiren sanchezi and possibly Metaxytherium . [14] [15]

Related Research Articles

<i>Purussaurus</i> Extinct genus of reptiles

Purussaurus is an extinct genus of giant caiman that lived in South America during the Miocene epoch, from the Friasian to the Huayquerian in the SALMA classification. It is known from skull material found in the Brazilian and Peruvian Amazon, Colombian Villavieja Formation, Panamanian Culebra Formation, Urumaco and Socorro Formations of northern Venezuela.

<i>Stupendemys</i> Extinct genus of turtles

Stupendemys is an extinct genus of freshwater side-necked turtle, belonging to the family Podocnemididae. It is the largest freshwater turtle known to have existed, with a carapace over 2 meters long. Its fossils have been found in northern South America, in rocks dating from the Middle Miocene to the very start of the Pliocene, about 13 to 5 million years ago. Male specimens are known to have possessed bony horns growing from the front edges of the shell and the discovery of the fossil of a young adult shows that the carapace of these turtles flattens with age. A fossil skull described in 2021 indicates that Stupendemys was a generalist feeder.

<i>Mourasuchus</i> Extinct genus of reptiles

Mourasuchus is an extinct genus of giant, aberrant caiman from the Miocene of South America. Its skull has been described as duck-like, being broad, flat, and very elongate, superficially resembling Stomatosuchus from the Late Cretaceous.

<i>Gryposuchus</i> Extinct genus of gavialoid crocodilian

Gryposuchus is an extinct genus of gavialid crocodilian. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the Miocene epoch. One recently described species, G. croizati, grew to an estimated length of 10 metres (33 ft). Gryposuchus is the type genus of the subfamily Gryposuchinae, although a 2018 study indicates that Gryposuchinae and Gryposuchus might be paraphyletic and rather an evolutionary grade towards the gharial.

Hesperogavialis is an extinct genus of gryposuchine gavialid. Fossils have been found from Venezuela and Brazil that date back to the Middle to Late Miocene. Although Hesperogavialis is one of the best known gavialoids from South America, the posterior portion of the skull is still unknown, making any attempts at classification within the family somewhat more difficult than other gavialoids in which much of the skull is present. The genus possibly comprises three species. The type species, H. cruxenti, has been found in the Urumaco Formation in Venezuela. A second possible species, named H. bocquentini, has been described from the Solimões Formation in Acre, Brazil, and can be distinguished from H. cruxenti by the asymmetry seen in the anterior portion of the nasals and the small distance between alveoli. A third species can be recognized from the same locality in Acre, although a formal name has yet to be given to it.

Ikanogavialis is an extinct genus of gavialid crocodilian. Fossils have been found in the Urumaco Formation in Urumaco, Venezuela and the Solimões Formation of Brazil. The strata from which remains are found are late Miocene in age, rather than Pliocene as was once thought. A possible member of this genus survived into the Late Holocene on Muyua or Woodlark Island in Papua New Guinea.

<span class="mw-page-title-main">Castillo Formation, Venezuela</span>

The Castillo Formation is an Early Miocene geologic formation in the Falcón Basin of Venezuela. The formation unconformably overlies the Matatere, Misoa, El Paují and Jarillal Formations. The Castillo Formation is overlain by Quaternary alluvium and in places by the Capadare Formation. The formation, deposited in a calm near-shore lagoonal brackish environment, with possibly fluvial influence, has provided a rich assemblage of fossil crocodylians, turtles, giant sloths and various types of fish.

Gryposuchinae is an extinct subfamily of gavialid crocodylians. Gryposuchines lived mainly in the Miocene of South America. However, "Ikanogavialis" papuensis may have survived more recently, into the Late Pleistocene/Holocene. Most were long-snouted coastal forms. The group was named in 2007 and includes genera such as Gryposuchus and Aktiogavialis, although a 2018 study indicates that the group might be paraphyletic and rather an evolutionary grade towards the gharial.

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 large units of spherical teeth used to break the shells of molluscs as part of its durophagus diet. It is thought to be one of the most basal Caimanines, even sharing some traits with alligatorids.

<i>Eionaletherium</i> Possibly marine ground sloth from Venezuela

Eionaletherium is an extinct genus of ground sloth from the Late Miocene coasts of Venezuela containing one species: E. tanycnemius.

<i>Caiman wannlangstoni</i> Extinct species of reptile

Caiman wannlangstoni is an extinct species of caiman that lived in what is now the Amazon Basin and surrounding areas during the Middle and Late Miocene. Fossils of C. wannlangstoni have been found in the Pebas Formation near Iquitos in Peru and include partial skulls and isolated skull bones. Other fossils were uncovered from the Urumaco Formation in Venezuela and the Laventan Honda Group of Colombia. The species was first described in 2015. Features that in combination distinguish C. wannlangstoni from other caimans include a deep snout, a wavy upper jaw margin, a large and upward-directed narial opening, and blunt teeth at the back of the jaws. Based on the sizes of the skulls, its estimated body length is about 211 to 227 centimetres.

<i>Gnatusuchus</i> Extinct genus of reptiles

Gnatusuchus is an extinct genus of caiman represented by the type species Gnatusuchus pebasensis from the Middle Miocene Pebas Formation of Peru. Gnatusuchus lived about 13 million years ago (Ma) in a large wetland system called the Pebas mega-wetlands that covered over one million square kilometers of what is now the Amazon Basin.

Bairdemys is an extinct genus of side-necked turtles in the family Podocnemididae. The genus existed from the Late Oligocene to Late Miocene and its fossils have been found in South Carolina, Puerto Rico, Panama and Venezuela. The genus was described in 2002 by Gaffney & Wood and the type species is B. hartsteini.

Caiman brevirostris is an extinct species of caiman that lived during the Late Miocene, around 11.6 million years ago, to the end of the Miocene 5.3 million years ago in Acre and Amazonas, Brazil as well as Urumaco, Venezuela. Several specimens have been referred to the species, but only 3 of them are confidently placed in the species. C. brevirostris was originally named in 1987 on the basis of a single, incomplete rostrum with an associated mandibular ramus that had been found in Acre, Brazil. C. brevirostris is very distinct among Caiman species and caimaninae overall in that it preserves a characteristically short and robust skull that bears blunt posterior teeth that were built to break down harder foods. This was an adaption for durophagy, likely to crush shells of mollusks and clams which were common in the wetlands that C. brevirostris resided in.

<span class="mw-page-title-main">San Gregorio Formation, Venezuela</span>

The San Gregorio Formation is a lithostratigraphic unit dating back to the Pliocene to Pleistocene of Venezuela. The formation is split into three members, the older Vergel Member, the Cocuiza Member (Pleistocene) and the Río Seco Member. During this time the region is thought to have been covered by a mixed environment of open grassland and forested areas surrounding a permanent freshwater system. The diverse fauna of the San Gregorio Formation, including a variety of freshwater fish, crocodilians, turtles and snakes, also includes many mammals interpreted to have been part of the first major wave of the Great American Interchange in addition to native clades such as glyptodonts, ground sloths and caviomorph rodents.

<i>Pseudoprepotherium</i> Extinct genus of ground sloths

Pseudoprepotherium is an extinct genus of sloths of the family Mylodontidae. It was widespread across northern South America during the Early to Late Miocene epoch around 21 to 5.3 million years ago. Fossils of the animal have been found in Brazil, Venezuela, and Peru. Pseudoprepotherium lived in a tropical climate with a water-rich environment. Their known remains are limited to limb bones, except for a few skulls and teeth. Based on these remains, they were most likely medium to large-sized mylodontid. The genus was described in 1961 and currently contains three species, which were originally assigned to the genus Prepotherium.

<i>Proeremotherium</i> Extinct genus of mammals

Proeremotherium is an extinct genus of megatheriine ground sloths in the family Megatheriidae. It lived during the Late Miocene and Early Pliocene of what is now Venezuela. So far, two largely complete skulls have been recovered in the Falcón Basin in Venezuela. The finds identify the animals as medium-sized representatives of the Megatheriidae. In the cranial anatomy, Proeremotherium resembles the later and giant Eremotherium. It is therefore assumed that the two ground sloths are directly related to each other.

Caiman australis is an extinct species of caiman described in 1858 on the basis of a left maxilla that was collected from the Upper Miocene age Ituzaingó Formation of Entre Rios, Argentina.

Bolivartherium is an extinct genus of mylodontine mylodontid sloth that lived during the Late Miocene and Late Pliocene in what is now Venezuela. Fossils have been found in the Codore and Urumaco Formations of Venezuela.

<i>Magdalenabradys</i> Extinct genus of ground sloths

Magdalenabradys is an extinct genus of mylodontid ground sloths that lived during the Middle Miocene and Early Pliocene of what is now Colombia and Venezuela. Fossils have been found in the Villavieja Formation of the Honda Group in Colombia, and the Codore and Urumaco Formations of Venezuela.

References

  1. ↑ Sawfishes and other elasmobranch assemblages from the Mio-Pliocene of the South Caribbean (Urumaco Sequence, northwestern Venezuela). JD Carrillo Briceño et al.. PLOS One (2015).
  2. ↑ Neogene vertebrates from Urumaco, Falcón State, Venezuela: Diversity and significance. MR Sánchez Villagra & OA Aguilera. Journal of Systematic Palaeontology (2010).
  3. ↑ Crocodylian diversity peak and extinction in the late Cenozoic of the northern Neotropics. TM Scheyer et al.. Nature Communications (2013).
  4. ↑ Paiva, Ana Laura S.; Godoy, Pedro L.; Souza, Ray B. B.; Klein, Wilfried; Hsiou, Annie S. (2022-10-01). "Body size estimation of Caimaninae specimens from the Miocene of South America". Journal of South American Earth Sciences. 118: 103970. doi: 10.1016/j.jsames.2022.103970 . ISSN   0895-9811.
  5. ↑ Riff, Douglas; Aguilera, Orangel A. (2008-06-01). "The world's largest gharialsGryposuchus: description ofG. croizati n. sp. (Crocodylia, Gavialidae) from the Upper Miocene Urumaco Formation, Venezuela". Paläontologische Zeitschrift. 82 (2): 178–195. doi:10.1007/BF02988408. eISSN   1867-6812. ISSN   0031-0220.
  6. ↑ "Giant prehistoric caiman had extra hip bone to carry its weight". BBC News. 2019-12-17. Retrieved 2023-03-06.
  7. ↑ Zurich, University of. "Extinct giant turtle had horned shell of up to three meters". phys.org. Retrieved 2023-03-06.
  8. ↑ Two new species of the side necked turtle genus, Bairdemys (Pleurodira, Podocnemididae), from the Miocene of Venezuela. ES Gaffney et al.. Paläontologische Zeitschrift (2008).
  9. ↑ Fossil snakes from the Neogene of Venezuela (Falcón state). JJ Head, MR Sánchez Villagra & OA Aguillera. Journal of Systematic Palaeontology (2006).
  10. ↑ Fossil rodents from the Late Miocene Urumaco and Middle Miocene Cumaca Formations, Venezuela. J. Horovitz et al.. In: Urumaco & Venezuelan Paleontology. MR Sánchez Villagra, OA Aguillera & AA Carlini. Indiana University Press (2010).
  11. ↑ Rincón, A. D.; McDonald, H. G.; Solórzano, A.; Flores, M. N.; Ruiz-Ramoni, D. (2015). "A new enigmatic Late Miocene mylodontoid sloth from northern South America". Royal Society Open Science. 2 (2). doi:10.1098/rsos.140256. PMC   4448802 . PMID   26064594.
  12. ↑ Two new megalonychid sloths (Mammalia: Xenarthra) from the Urumaco Formation (late Miocene), and their phylogenetic affinities. AD Rincón, A Solórzano, HG McDonald & M Montellano-Ballesteros. Journal of Systematic Palaeontology (2018).
  13. ↑ A new Megadolodinae (Mammalia, Litopterna, Protherotheriidae) from the Urumaco Formation (Late Miocene) of Venezuela. AA Carlini, JN Gelfo & R Sánchez. Journal of Systematic Palaeontology (2006).
  14. ↑ Fossil cetaceans (Mammalia, Cetacea) from the Neogene of Colombia and Venezuela. G Aguirre Fernández et al. Journal of Mammalian Evolution (2016).
  15. ↑ 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).
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.