Macraucheniidae
Encyclopedia
Macraucheniidae is a family in the Litopterna
order
of extinct South American ungulates
. The recessed nasal bones of their skulls suggest that they may have had a small proboscis
, or trunk. Their hooves were similar to those of rhinoceros
es today, with a simple ankle joint and three digits on each foot. Thus, they may have been capable of rapid directional change when running away from predators, such as large Phorusrhacid
terror birds and Smilodon
saber-toothed cats. Macraucheniids probably lived in large herds to gain protection against these predators, as well as to facilitate finding mates for reproduction.
The family Macraucheniidae includes genera
such as Theosodon
, Xenorhinotherium
, and Macrauchenia
. Macrauchenia is the best-known and most recent macraucheniid. It became extinct during the Pleistocene
Epoch
. It was one of the few litopterns to survive the ecological pressures of the Great American Interchange
between North and South America, which took place after the Isthmus of Panama
rose above sea level some 3 million years ago. It may instead have died out in the aftermath of the invasion of the Americas by human hunters. When Macrauchenia died out, so too did the Macraucheniidae and the entire litoptern order.
Subfamily Macraucheniinae
Subfamily Sparnotheriodontinae
Litopterna
Litopterna is an extinct order of fossil hoofed mammals from the Tertiary period that displays toe reduction. Three-toed, and even a one-toed horselike form developed....
order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of extinct South American ungulates
Meridiungulata
Meridiungulata is an extinct clade with the rank of cohort or super-order, containing the South-American ungulates: Pyrotheria , Astrapotheria, Notoungulata and Litopterna...
. The recessed nasal bones of their skulls suggest that they may have had a small proboscis
Proboscis
A proboscis is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In simpler terms, a proboscis is the straw-like mouth found in several varieties of species.-Etymology:...
, or trunk. Their hooves were similar to those of rhinoceros
Rhinoceros
Rhinoceros , also known as rhino, is a group of five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia....
es today, with a simple ankle joint and three digits on each foot. Thus, they may have been capable of rapid directional change when running away from predators, such as large Phorusrhacid
Phorusrhacidae
Phorusrhacids , colloquially known as "terror birds" as the larger species were apex predators during the Miocene, were a clade of large carnivorous flightless birds that were the dominant predators in South America during the Cenozoic, 62–2 million years ago. They were roughly 1–3 meters tall...
terror birds and Smilodon
Smilodon
Smilodon , often called a saber-toothed cat or saber-toothed tiger, is an extinct genus of machairodonts. This saber-toothed cat was endemic to North America and South America, living from near the beginning through the very end of the Pleistocene epoch .-Etymology:The nickname "saber-tooth" refers...
saber-toothed cats. Macraucheniids probably lived in large herds to gain protection against these predators, as well as to facilitate finding mates for reproduction.
The family Macraucheniidae includes genera
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...
such as Theosodon
Theosodon
Theosodon is an extinct genus of litoptern mammal from the early Miocene of South America.Theosodon bore a superficial resemblance the modern guanaco, and was around in length. It had a long neck and tapir-like, three-toed feet...
, Xenorhinotherium
Xenorhinotherium
Xenorhinotherium , an extinct Brazilian genus in the family Macraucheniidae, was related to Macrauchenia patachonica of Patagonia.-Name:...
, and Macrauchenia
Macrauchenia
Macrauchenia was a long-necked and long-limbed, three-toed South American ungulate mammal, typifying the order Litopterna. The oldest fossils date back to around 7 million years ago, and M...
. Macrauchenia is the best-known and most recent macraucheniid. It became extinct during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
Epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...
. It was one of the few litopterns to survive the ecological pressures of the Great American Interchange
Great American Interchange
The Great American Interchange was an important paleozoogeographic event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents...
between North and South America, which took place after the Isthmus of Panama
Isthmus of Panama
The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal...
rose above sea level some 3 million years ago. It may instead have died out in the aftermath of the invasion of the Americas by human hunters. When Macrauchenia died out, so too did the Macraucheniidae and the entire litoptern order.
Genera
Subfamily Cramaucheniinae- Caliphrium
- Coniopternum
- CramaucheniaCramaucheniaCramauchenia is a member of the litoptern order of South American mammals. Cramauchenia was named by Florentino Ameghino. The name has no literal translation. Instead, it is an anagram of the name of a related genus Macrauchenia....
- Notodiaphorus
- Phoenixauchenia
- Pternoconius
- TheosodonTheosodonTheosodon is an extinct genus of litoptern mammal from the early Miocene of South America.Theosodon bore a superficial resemblance the modern guanaco, and was around in length. It had a long neck and tapir-like, three-toed feet...
Subfamily Macraucheniinae
- Cullinia
- MacraucheniaMacraucheniaMacrauchenia was a long-necked and long-limbed, three-toed South American ungulate mammal, typifying the order Litopterna. The oldest fossils date back to around 7 million years ago, and M...
- MacrauchenidiaMacrauchenidiaMacrauchenidia is an extinct genus of South American litoptern, related to Macrauchenia, and belonging to the same family, Macraucheniidae....
- Oxyodontherium
- Macraucheniopsis (=Macrauchenia?)
- Mesorhinus (=Oxyodontherium?)
- Oxyodontherium
- ParanaucheniaParanaucheniaParanauchenia is an extinct genus of the South American litopterns, related to Macrauchenia, belonging to the same family, Macraucheniidae, and is known only from fossil finds in South America. It possessed three toes and long limbs. The species Paranauchenia denticulata lived in the Miocene epoch...
- Promacrauchenia (=Macrauchenia?)
- Pseudomacrauchenia (=Promacrauchenia?)
- Scalabrinia (=Scalabrinitherium?)
- ScalabrinitheriumScalabrinitheriumScalabrinitherium is an extinct genus of the family Macraucheniidae. Fossils of this animal were found amongst the fossils of prehistoric xenarthrans....
- Windhausenia
- XenorhinotheriumXenorhinotheriumXenorhinotherium , an extinct Brazilian genus in the family Macraucheniidae, was related to Macrauchenia patachonica of Patagonia.-Name:...
Subfamily Sparnotheriodontinae
- Decaconus
- Guilielmofloweria
- Megacrodon
- Oroacrodon
- Periacrodon
- Phoradiadius
- Polymorphis
- VictorlemoineaVictorlemoineaVictorlemoinea is an extinct litoptern genus of the family Macraucheniidae.This animal is considered a member of the Macraucheniidae family, but according to some scientific authorities, could just as easily be from the Sparnotheriodontidae, and is said to share some features with the didolodont...
(=Sparnotheriodon?)