Gondwanatheria
Encyclopedia
Gondwanatheria is an extinct group of mammal
s that lived during the Upper Cretaceous
through the Eocene
in the Southern Hemisphere
, including Antarctica. They are known only from isolated teeth and a few lower jaws, and because of this fragmentary knowledge, their placement is not clear.
ns, or "tooth
less" mammals similar to the modern anteater
. This is somewhat ironic, given that they were originally known only from teeth. They were also treated as members of the Multituberculata
.
The latest thinking is apparently returning towards the xenarthran affinities, or something else entirely. Though generally no longer seen as multituberculates, "a few specimens described as ?Ferugliotherium," are Multituberculates (Kielan-Jaworowska & Hurum, 2001, p.411). "These poorly known specimens (not discussed herein) demonstrate that a branch of multituberculates apparently lived during the Late Cretaceous in South America
."
There are two known families
within Gondwanatheria. The family Sudamericidae was named by Scillato-Yané and Pascual in 1984, and includes the genera Sudamerica
, Gondwanatherium
and Lavanify
. The family Ferugliotheriidae was named by José Bonaparte
in 1986, and includes one genus, Ferugliotherium
.
Further fossil
s have come from India
and Antarctica, where gondwanatherids once lived in the lush forest
s of the Eocene.
s:
From the same paper, (p.203):
The Antarctic peninsula
of the "late Early to latest Eocene" seems to have been a lively place.
Represented by the fossil
s and the geological conditions of the La Meseta Formation (dated to about 40 million years ago) suggest a nearby forest populated by a diverse fauna, which had many similarities with the slightly earlier residents of Patagonia
; small, arboreal, fruit
and insect-eating
possum
s, 10 kg sloth
s, middle-to-large sized grazers (sparnotheriodontids and Trigonostylops
), falcon
s, ratite
s (big flightless bird
s like the rhea
) and penguin
s. At the end of the Eocene the climate seems to have become unsuitable.
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s that lived during the Upper Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
through the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
, including Antarctica. They are known only from isolated teeth and a few lower jaws, and because of this fragmentary knowledge, their placement is not clear.
Classification
The affinities of the group are not clear, but gondwanatherians were first interpreted as early xenarthraXenarthra
The superorder Xenarthra is a group of placental mammals , existent today only in the Americas and represented by anteaters, tree sloths, and armadillos. The origins of the order can be traced back as far as the Paleogene in South America...
ns, or "tooth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...
less" mammals similar to the modern anteater
Anteater
Anteaters, also known as antbear, are the four mammal species of the suborder Vermilingua commonly known for eating ants and termites. Together with the sloths, they compose the order Pilosa...
. This is somewhat ironic, given that they were originally known only from teeth. They were also treated as members of the Multituberculata
Multituberculata
The Multituberculata were a group of rodent-like mammals that existed for approximately one hundred and twenty million years—the longest fossil history of any mammal lineage—but were eventually outcompeted by rodents, becoming extinct during the early Oligocene. At least 200 species are...
.
The latest thinking is apparently returning towards the xenarthran affinities, or something else entirely. Though generally no longer seen as multituberculates, "a few specimens described as ?Ferugliotherium," are Multituberculates (Kielan-Jaworowska & Hurum, 2001, p.411). "These poorly known specimens (not discussed herein) demonstrate that a branch of multituberculates apparently lived during the Late Cretaceous in 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...
."
There are two known families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
within Gondwanatheria. The family Sudamericidae was named by Scillato-Yané and Pascual in 1984, and includes the genera Sudamerica
Sudamerica
Sudamerica, literally "South America" in Spanish, is a genus of mammal from the extinct suborder Gondwanatheria that lived in Patagonia, South America during the Paleocene, just after the end of the "Age of Dinosaurs"....
, Gondwanatherium
Gondwanatherium
Gondwanatherium is a genus of mammal from the extinct suborder Gondwanatheria that lived in Patagonia, South America during the "Age of Dinosaurs", specifically the Upper Cretaceous....
and Lavanify
Lavanify
Lavanify is a mammalian genus from the late Cretaceous of Madagascar. The only species, L. miolaka, is known from two isolated teeth, one of which is damaged. The teeth were collected in 1995–1996 and described in 1997...
. The family Ferugliotheriidae was named by José Bonaparte
José Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...
in 1986, and includes one genus, Ferugliotherium
Ferugliotherium
Ferugliotherium is a fossil mammal from the Campanian and/or Maastrichtian of Argentina in the family Ferugliotheriidae. The genus contains a single species, Ferugliotherium windhauseni, which was first described in 1986...
.
Further fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s have come from India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and Antarctica, where gondwanatherids once lived in the lush forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
s of the Eocene.
Antarctica
Antarctica has more to offer than just marsupialMarsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
s:
- "The occurrence on Seymour IslandSeymour IslandSeymour Island is an island in the chain of 16 major islands around the tip of the Graham Land on the Antarctic Peninsula. Graham Land is closer to continental land mass than any other part of that Antarctica. It lies within the section of the island chain that resides off the west side of the...
of sudamericids, that had become extinct in South America in the PaleocenePaleoceneThe Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
, also indicates that isolation may have allowed extended survival of this GondwanaGondwanaIn paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
n group in the Eocene of Antarctica and the factors that caused their extinction did not affect this continent." (Reguero et al., 2002, p.189)
From the same paper, (p.203):
- "For the sudamericids, Koenigswald et al. (1999) inferred a semi-aquaticAquatic animalAn aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
and perhaps a burrowing way of life, similar to that of living beaverBeaverThe beaver is a primarily nocturnal, large, semi-aquatic rodent. Castor includes two extant species, North American Beaver and Eurasian Beaver . Beavers are known for building dams, canals, and lodges . They are the second-largest rodent in the world...
s. Regarding this, the presence of two Antarctic taxa at Seymour Island (Goin, personal communication, 2000) suggests an important paleoecologicalPaleoecologyPaleoecology uses data from fossils and subfossils to reconstruct the ecosystems of the past. It involves the study of fossil organisms and their associated remains, including their life cycle, living interactions, natural environment, and manner of death and burial to reconstruct the...
constraint related to dietary preference of this group.”
The Antarctic peninsula
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....
of the "late Early to latest Eocene" seems to have been a lively place.
Represented by the fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s and the geological conditions of the La Meseta Formation (dated to about 40 million years ago) suggest a nearby forest populated by a diverse fauna, which had many similarities with the slightly earlier residents of Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
; small, arboreal, fruit
Frugivore
A frugivore is a fruit eater. It can be any type of herbivore or omnivore where fruit is a preferred food type. Because approximately 20% of all mammalian herbivores also eat fruit, frugivory is considered to be common among mammals. Since frugivores eat a lot of fruit they are highly dependent...
and insect-eating
Insectivore
An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects....
possum
Possum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...
s, 10 kg sloth
Sloth
Sloths are the six species of medium-sized mammals belonging to the families Megalonychidae and Bradypodidae , part of the order Pilosa and therefore related to armadillos and anteaters, which sport a similar set of specialized claws.They are arboreal residents of the jungles of Central and South...
s, middle-to-large sized grazers (sparnotheriodontids and Trigonostylops
Trigonostylops
Trigonostylops is an extinct genus of South American ungulate, from the late Paleocene to early Eocene of Argentina.A complete skull of the type species, T. wortmani, has been found, and it has been classified as an astrapothere based on its large lower tusks...
), falcon
Falcon
A falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....
s, ratite
Ratite
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...
s (big flightless bird
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...
s like the rhea
Rhea (bird)
The rheas are ratites in the genus Rhea, native to South America. There are two existing species: the Greater or American Rhea and the Lesser or Darwin's Rhea. The genus name was given in 1752 by Paul Möhring and adopted as the English common name. Möhring's reason for choosing this name, from the...
) and penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
s. At the end of the Eocene the climate seems to have become unsuitable.