Stupendemys
Encyclopedia
Stupendemys is a prehistoric genus
of freshwater turtle
. Its fossil
s have been found in northern South America
, in rocks dating from the late Miocene
to the very start of the Pliocene
, about 6 to 5 million years ago.
Stupendemyss carapace
measured over 1.8 m (5.9 ft) in length and was also very wide. With an estimated total carapace length of more than 3.3 m (10.8 ft), it was the largest turtle that ever existed, surpassing even Archelon
. The largest freshwater turtle living today is the Arrau Turtle (Podocnemis expansa), a pleurodire closely related to Stupendemys, but the Arrau Turtle measures only 75 centimetres (29.5 in).
Two species have been described to date. Stupendemys geographicus was more robust; it remains have been found in the Urumaco Formation
of Venezuela
. Stupendemys souzai, marginally smaller and more slender, was recovered from the Solimões Formation in Acre State, Brazil
.
Its weight helped Stupendemys stay under water for extended periods of time, grazing on aquatic plant
s. On the other hand, it was probably a very weak swimmer, unable to move its bulk against a swift current, and thus probably avoided smaller streams.
Since S. souzai fossils have been found in sites which yield a rich fossil fauna
, even though little is known with certainty, much can be inferred about the ecology
of these animals. Among the aquatic animals that shared the habitat with S. souzai were fish, including catfish
such as Phractocephalus and Callichthyidae
, characids such as Acregoliath rancii and the Tambaqui
(Colossoma macropomum), the South American Lungfish
(Lepidosiren paradoxa), trahiras (e.g. Paleohoplias assisbrasiliensis) and freshwater rays and shark
s. Crocodilia
ns and other Crurotarsi
were diverse and abundant, among them such taxa as Charactosuchus fisheri
, Gryposuchus
, Mourasuchus
, Nettosuchidae and the giant Purussaurus brasiliensis. Other turtles and tortoise
s found in the same deposits are Chelus columbiana (a prehistoric relative of the Mata mata
) and Chelonoidis (= Geochelone
). Further aquatic vertebrates included river dolphin
s and the large darter
"Anhinga" fraileyi.
Terrestrial mammals were plentiful, and the fauna included many megaherbivores, like the ground sloth
Acremylodon campbelli, Toxodontidae
(e.g. Gyrinodon and Trigodon
), Proterotheriidae
, and caviomorph
rodents, some of them of immense size also (e.g. Kiyutherium, Neoepiblema, Phoberomys burmeisteri, Potamarchus murinus, Telicomys amazonensis and Tetrastylus). Smaller mammals living in that time and place were the ateline monkey
Stirtonia and the bulldog bat
Noctilio lacrimaelunaris.
Altogether, this fauna is massively dominated by large herbivores and generally lacks terrestrial carnivores. It can thus be assumed that the habitat was mostly low-lying rainforest
that was seasonally flooded, as well as floodplain
s and swamp
land. The rivers must have been wide and slow-moving, as the fossil-rich rocks are alluvial deposits and do not show evidence of fast-flowing riverbeds that would have dug into the sediment deeply while depositing little of their own.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of freshwater turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
. Its fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s have been found in northern South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, in rocks dating from the late Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
to the very start of the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
, about 6 to 5 million years ago.
Stupendemyss carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
measured over 1.8 m (5.9 ft) in length and was also very wide. With an estimated total carapace length of more than 3.3 m (10.8 ft), it was the largest turtle that ever existed, surpassing even Archelon
Archelon
Archelon is a genus of extinct sea turtle, the largest that has ever been documented.-Discovery:...
. The largest freshwater turtle living today is the Arrau Turtle (Podocnemis expansa), a pleurodire closely related to Stupendemys, but the Arrau Turtle measures only 75 centimetres (29.5 in).
Two species have been described to date. Stupendemys geographicus was more robust; it remains have been found in the Urumaco Formation
Urumaco
Urumaco is a town in the state of Falcón in Venezuela. It is of world importance for its fossils. The arid climate of the region means that the fossils are not hidden by vegetation. They were first made known to science by geologists who came across them while looking for oil...
of Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
. Stupendemys souzai, marginally smaller and more slender, was recovered from the Solimões Formation in Acre State, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
.
Ecology
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s. On the other hand, it was probably a very weak swimmer, unable to move its bulk against a swift current, and thus probably avoided smaller streams.
Since S. souzai fossils have been found in sites which yield a rich fossil fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
, even though little is known with certainty, much can be inferred about the ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
of these animals. Among the aquatic animals that shared the habitat with S. souzai were fish, including catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...
such as Phractocephalus and Callichthyidae
Callichthyidae
Callichthyidae is a family of catfishes , called armored catfishes due to the two rows of bony plates running down the length of the body. This family contains some of the most popular freshwater aquarium fish, such as the Corydoras.-Taxonomy:The family derives its name from the Greek words kallis...
, characids such as Acregoliath rancii and the Tambaqui
Tambaqui
The tambaqui is a freshwater fish of the subfamily Serrasalminae, family Characidae. It is also known by the names pacu, black pacu, black-finned pacu, giant pacu, cachama and gamitana....
(Colossoma macropomum), the South American Lungfish
South American lungfish
The South American lungfish, Lepidosiren paradoxa, is the single species of lungfish found in swamps and slow-moving waters of the Amazon, Paraguay, and lower Paraná River basins in South America. Notable as an obligate air-breather, it is the sole member of its family Lepidosirenidae...
(Lepidosiren paradoxa), trahiras (e.g. Paleohoplias assisbrasiliensis) and freshwater rays and shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s. Crocodilia
Crocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
ns and other Crurotarsi
Crurotarsi
The Crurotarsi are a group of archosauriformes, represented today by the crocodiles,...
were diverse and abundant, among them such taxa as Charactosuchus fisheri
Charactosuchus
Charactosuchus is an extinct genus of crocodilian. It was assigned to the family Crocodylidae in 1988. Specimens have been found from Colombia, Brazil, Jamaica, and possibly Florida and South Carolina...
, Gryposuchus
Gryposuchus
Gryposuchus is an extinct genus of gavialoid crocodilian. It is the type genus of the subfamily Gryposuchinae. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the early and middle Miocene epoch. One recently described species, G...
, Mourasuchus
Mourasuchus
Mourasuchus is an extinct genus of giant crocodilian from the Miocene of South America. It was similar in length and weight to Rhamphosuchus...
, Nettosuchidae and the giant Purussaurus brasiliensis. Other turtles and tortoise
Tortoise
Tortoises are a family of land-dwelling reptiles of the order of turtles . Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise...
s found in the same deposits are Chelus columbiana (a prehistoric relative of the Mata mata
Mata mata
The mata mata or matamata is a freshwater turtle found in South America, primarily in the Amazon and Orinoco basins.-Taxonomy:...
) and Chelonoidis (= Geochelone
Geochelone
Geochelone is a genus of tortoises.Geochelone tortoises, which are also known as typical tortoises or terrestrial turtles, can be found in Africa and Asia. They primarily eat plants.The genus consists of three extant species:...
). Further aquatic vertebrates included river dolphin
River dolphin
River dolphins are the four living species of dolphin that reside in freshwater rivers and estuaries. River dolphins inhabit areas of Asia and South America. They are classed in the Platanistoidea superfamily of cetaceans. Three species live in fresh water rivers. The fourth species, the La Plata...
s and the large darter
Darter
The darters or snakebirds are mainly tropical waterbirds in the family Anhingidae. There are four living species, three of which are very common and widespread while the fourth is rarer and classified as near-threatened by the IUCN. The term "snakebird" is usually used without any additions to...
"Anhinga" fraileyi.
Terrestrial mammals were plentiful, and the fauna included many megaherbivores, like the ground sloth
Ground sloth
Ground sloths are a diverse group of extinct sloths, in the mammalian superorder Xenarthra. Their most recent survivors lived in the Antilles, where it has been proposed they may have survived until 1550 CE; however, the youngest AMS radiocarbon date reported is 4190 BP, calibrated to c. 4700 BP...
Acremylodon campbelli, Toxodontidae
Toxodontidae
Toxodontidae is an extinct family of notoungulate mammals known from the Oligocene through the Pleistocene of South America, with one genus, Mixotoxodon, also known from the Pleistocene of Central America. They somewhat resembled rhinoceroses, and had teeth with high crowns and open roots,...
(e.g. Gyrinodon and Trigodon
Trigodon
Trigodon gaudryi is an extinct species of the family Toxodontidae, a large bodied notoungulate which inhabited South America during the Miocene living from 11.61—7.25 Ma and existed for approximately ....
), Proterotheriidae
Proterotheriidae
Proterotheriidae is an extinct family of fossil ungulates from the Tertiary period that displays toe reduction. Despite resembling primitive, small horses, they were not related to them, but belonged to the order Litopterna....
, and caviomorph
Caviomorpha
Caviomorpha is the rodent infraorder or parvorder that unites all South American hystricognaths. It is supported by both fossil and molecular evidence.-Origin:...
rodents, some of them of immense size also (e.g. Kiyutherium, Neoepiblema, Phoberomys burmeisteri, Potamarchus murinus, Telicomys amazonensis and Tetrastylus). Smaller mammals living in that time and place were the ateline monkey
Atelinae
Atelinae is a subfamily of New World monkeys in the family Atelidae, and includes the various spider and woolly monkeys. The primary distinguishing feature of the atelines is their long prehensile tail which can support their entire body weight....
Stirtonia and the bulldog bat
Bulldog bat
The Noctilionidae family of bats, commonly known as bulldog bats orfisherman bats, are represented by two species, the Greater Bulldog Bat and the Lesser Bulldog Bat. They are found near water, from Mexico to Argentina...
Noctilio lacrimaelunaris.
Altogether, this fauna is massively dominated by large herbivores and generally lacks terrestrial carnivores. It can thus be assumed that the habitat was mostly low-lying rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
that was seasonally flooded, as well as floodplain
Floodplain
A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...
s and swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
land. The rivers must have been wide and slow-moving, as the fossil-rich rocks are alluvial deposits and do not show evidence of fast-flowing riverbeds that would have dug into the sediment deeply while depositing little of their own.