Dinocerata
Encyclopedia
Dinocerata mammals are an extinct order of plant-eating
, rhinoceros
-like hoofed creatures famous for their paired horns and tusk
-like canine teeth. The earliest dinoceratan, Prodinoceras
, first appeared in Asia
during the Paleocene
, but nearly all later types are from North America
(dinoceratans must have crossed the Bering land bridge, which may have been exposed during Paleocene-Eocene times). They lived alongside another group of large plant-eaters of the Eocene
, the brontotheres. The most famous dinoceratan is Uintatherium
.
How dinoceratans are related to other mammals is in dispute. They are probably part of the hoofed mammal (ungulate
) group and have similarities with some South American hoofed mammals
, namely, the primitive Carodnia
of Paleocene South America
. Another idea is that dinoceratans are closely related to pantodonts and tillodonts. A more controversial view is that dinoceratans descend from the anagalids, a small group of rabbit
-like mammals. But they may be related to an ungulatomorph group called zhelestidae. Many dinoceratans are large, but they have one of the smaller brain
s among the mammal
s (the smallest brains of the mammal class belong to pantodonts), distinctly smaller than those of later ungulates (hoofed mammals) and other mammals.
Although dinoceratans have traditionally been placed in the superorder Ungulatomorpha, this clade is now considered to be polyphyletic. This is the result of recent genetic and molecular research, which is rewriting the story of mammalian classification. The various members of the Ungulatomorpha are now placed in two very different lineages of placental mammals (Afrotheria
and Laurasiatheria
). In the case of the dinoceratans, it's now believed they are related to "true" ungulates after all, so they should be considered members of Laurasiatheria. They are suspected of being closely related to the true ungulate orders Perissodactyla and Artiodactyla. It is, however, entirely possible that one of the earlier viewpoints may turn out to be correct: that the dinoceratans are related to the pantodonts and tillodonts and should be treated among the Cimolesta
. This would still make them members of Laurasiatheria. As it is impossible to extract genetic material from fossils this old, the phylogenetic position of dinoceratans may well shift again in the future.
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
, 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....
-like hoofed creatures famous for their paired horns and tusk
Tusk
Tusks are elongated, continuously growing front teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canines, as with warthogs, wild boar, and walruses, or, in the case of elephants and narwhals, elongated incisors...
-like canine teeth. The earliest dinoceratan, Prodinoceras
Prodinoceras
Prodinoceras was the earliest known uintathere genus, which lived in the late Paleocene of Mongolia. It is also regarded as the basal uintathere, as, although it had the characteristic fang-like tusks, it had yet to evolve the characteristic knob-like horns.It is very similar to its North...
, first appeared in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
during the Paleocene
Paleocene
The 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...
, but nearly all later types are from North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
(dinoceratans must have crossed the Bering land bridge, which may have been exposed during Paleocene-Eocene times). They lived alongside another group of large plant-eaters of 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...
, the brontotheres. The most famous dinoceratan is Uintatherium
Uintatherium
Uintatherium, is an extinct genus of herbivorous mammal that lived during the Eocene epoch, which includes a single species currently recognized, U. anceps. They were similar to today's rhinoceros both in size and in shape, although they are not closely related...
.
Classification
Ungulate
Ungulates are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. They make up several orders of mammals, of which six to eight survive...
) group and have similarities with some South American hoofed mammals
Meridiungulata
Meridiungulata is an extinct clade with the rank of cohort or super-order, containing the South-American ungulates: Pyrotheria , Astrapotheria, Notoungulata and Litopterna...
, namely, the primitive Carodnia
Carodnia
Carodnia vieirai is an extinct meridiungulate mammal from the Paleocene of South America. It is related to, and possibly gave rise to the order Pyrotheria, into which some experts also place Carodnia....
of Paleocene 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...
. Another idea is that dinoceratans are closely related to pantodonts and tillodonts. A more controversial view is that dinoceratans descend from the anagalids, a small group of rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
-like mammals. But they may be related to an ungulatomorph group called zhelestidae. Many dinoceratans are large, but they have one of the smaller brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
s among the mammal
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 (the smallest brains of the mammal class belong to pantodonts), distinctly smaller than those of later ungulates (hoofed mammals) and other mammals.
Although dinoceratans have traditionally been placed in the superorder Ungulatomorpha, this clade is now considered to be polyphyletic. This is the result of recent genetic and molecular research, which is rewriting the story of mammalian classification. The various members of the Ungulatomorpha are now placed in two very different lineages of placental mammals (Afrotheria
Afrotheria
Afrotheria is a clade of mammals, the living members of which belong to groups from Africa or of African origin: golden moles, sengis , tenrecs, aardvarks, hyraxes, elephants and sea cows. The common ancestry of these animals was not recognized until the late 1990s...
and Laurasiatheria
Laurasiatheria
Laurasiatheria is a large group of placental mammals believed to have originated on the northern supercontinent of Laurasia. It includes shrews, hedgehogs, pangolins, bats, whales, most hoofed mammals, and carnivorans, among others....
). In the case of the dinoceratans, it's now believed they are related to "true" ungulates after all, so they should be considered members of Laurasiatheria. They are suspected of being closely related to the true ungulate orders Perissodactyla and Artiodactyla. It is, however, entirely possible that one of the earlier viewpoints may turn out to be correct: that the dinoceratans are related to the pantodonts and tillodonts and should be treated among the Cimolesta
Cimolesta
Cimolesta is an extinct order of mammals. A few experts place the pangolins within Cimolesta, though most other experts prefer to place the pangolins within their own order, Pholidota....
. This would still make them members of Laurasiatheria. As it is impossible to extract genetic material from fossils this old, the phylogenetic position of dinoceratans may well shift again in the future.
Taxonomy and Phylogeny
Most experts place all of the known genera of Dinocerata within one family, Uintatheriidae, and split it into two subfamilies, Uintatheriinae and Gobiatheriinae. Some experts prefer to split Uintatheriidae into three families, with Gobiatherium in Gobiatheriidae, the other Eocene genera into Uintatheriidae proper, and place the Paleocene genera, Prodinoceras and Probathyopsis into the family "Prodinoceratidae."- LaurasiatheriaLaurasiatheriaLaurasiatheria is a large group of placental mammals believed to have originated on the northern supercontinent of Laurasia. It includes shrews, hedgehogs, pangolins, bats, whales, most hoofed mammals, and carnivorans, among others....
- Ungulatomorpha?
- Order Dinocerata
- Family UintatheriidaeUintatheriidaeThe Uintatheriidae is a family of extinct mammals that includes Uintatherium. They belong to the order Dinocerata, one of several extinct orders of primitive mammals that are sometimes united in the Condylarthra....
- Subfamily Gobiatheriinae
- GobiatheriumGobiatheriumGobiatherium was one of the last Uintatheres, from the Mid Eocene of Mongolia. Unlike its North American cousins, Uintatherium or Eobasileus, Gobiatherium lacked knob-like horns, or even fang-like tusks...
- Gobiatherium
- Subfamily Uintatheriinae
- ProdinocerasProdinocerasProdinoceras was the earliest known uintathere genus, which lived in the late Paleocene of Mongolia. It is also regarded as the basal uintathere, as, although it had the characteristic fang-like tusks, it had yet to evolve the characteristic knob-like horns.It is very similar to its North...
- ProbathyopsisProbathyopsisProbathyopsis is an extinct genus of Uintatheriidae.It was similar to Prodinoceras.Probathyopsis lived in the United States in the Paleocene epoch.Its name means "Before Bathyopsis"....
- Dinoceras
- BathyopsisBathyopsisBathyopsis is an extinct genus of uintathere.-References:*Lucas, S.G. and R.M. Schoch. 1998. Dinocerata. pp.284-291 in C.M. Janis, K.M. Scott, and L.L. Jacobs Evolution of Tertiary Mammals of North America Cambridge University Press, Cambridge.* The Beginning of the Age of Mammals by Kenneth D. Rose...
- UintatheriumUintatheriumUintatherium, is an extinct genus of herbivorous mammal that lived during the Eocene epoch, which includes a single species currently recognized, U. anceps. They were similar to today's rhinoceros both in size and in shape, although they are not closely related...
- EobasileusEobasileusEobasileus cornutus is an extinct species of dinocerate mammal.Eobasileus was long and stood tall at the shoulder. It looked very similar to the related Uintatherium. Like Uintatherium, it had three pairs of blunt horns on its skull, possibly covered with skin like the ossicones of a giraffe...
or Uintacolotherium - TetheopsisTetheopsisTetheopsis is an extinct genus of Uintatheriidae....
- DitetradonDitetradonDitetradon is an extinct genus of Uintatheriidae....
- Jiaoluotherium
- Prodinoceras
- Subfamily Gobiatheriinae
- Family Uintatheriidae