Amblypoda
Encyclopedia
Amblypoda is a taxonomic hypothesis uniting a group of extinct, herbivorous mammal
s. They were considered a suborder of the primitive ungulate
mammals and have since been shown to represent a polyphyletic group.
es. These animals were, in fact, descendants of the small ancestral ungulates that retained all the primitive characteristics of the latter, accompanied by a huge increase in body size.
The Amblypoda were confined to the Paleocene
and Eocene
periods and occurred in North America
, Asia
(especially Mongolia
) and Europe
. The cheek teeth were short-crowned (brachyodont), with the tubercles more-or-less completely fused into transverse ridges, or cross-crests (lophodont type), and the total number of teeth was in one case the typical 44, but in another was fewer. The vertebra of the neck unite on nearly flat surfaces, the humerus
had lost the foramen, or perforation, at the lower end, and the third trochanter to the femur
may have also been wanting. In the forelimb, the upper and lower series of carpal (finger) bones scarcely alternated, but in the hind foot, the astragalus overlapped the cuboid, while the fibula, which was quite distinct from the tibia
(as was the radius
from the ulna
in the forelimb), articulated with both astragalus and calcaneum.
, representing the family Coryphodontidae, from the lower Eocene of Europe and North America, in which there were 44 teeth and no horn-like excrescences on the long skull, while the femur had a third trochanter. The canines were somewhat elongated and were followed by a short gap in each jaw, and the cheek-teeth were adapted for succulent food. The length of the body reached about six feet in some cases.
In the middle Eocene formations of North America occurred the more specialized Uintatherium
(or Dinoceras), typifying the family Uintatheriidae
. Uintatheres were huge creatures with long narrow skulls, of which the elongated facial portion carried three pairs of bony horn-cores, probably covered with short horns in life, the hind-pair having been much the largest. The dental formula was i. 0/3, c. 1/1, p. 3/3·4, m. 3/3, the upper canines having been long sabre-like weapons, protected by a descending flange on each side of the lower front jaw.
In the basal Eocene of North America, the Amblypoda were represented by extremely primitive, five-toed, small ungulates such as Periptychus and Pantolambda
, each of these typifying a family. The full typical series of 44 teeth was developed in each, but whereas in the Periptychidae
, the upper molars were bunodont and tritubercular, in the Pantolambdidae, they had assumed a selenodont structure. Creodont
characters were displayed in the skeleton.
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. They were considered a suborder of the primitive ungulate
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...
mammals and have since been shown to represent a polyphyletic group.
Characteristics
The Amblypoda take their name from their short and stumpy feet, which were furnished with five toes each and supported massive pillar-like limbs. The brain cavity was extremely small and insignificant in comparison to the bodily mass, which was equal to that of the largest rhinocerosRhinoceros
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. These animals were, in fact, descendants of the small ancestral ungulates that retained all the primitive characteristics of the latter, accompanied by a huge increase in body size.
The Amblypoda were confined to 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...
and 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...
periods and occurred in 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...
, 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...
(especially Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
) and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. The cheek teeth were short-crowned (brachyodont), with the tubercles more-or-less completely fused into transverse ridges, or cross-crests (lophodont type), and the total number of teeth was in one case the typical 44, but in another was fewer. The vertebra of the neck unite on nearly flat surfaces, the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
had lost the foramen, or perforation, at the lower end, and the third trochanter to the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
may have also been wanting. In the forelimb, the upper and lower series of carpal (finger) bones scarcely alternated, but in the hind foot, the astragalus overlapped the cuboid, while the fibula, which was quite distinct from the tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
(as was the radius
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...
from the ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
in the forelimb), articulated with both astragalus and calcaneum.
Types of amblypods
The most generalized type was CoryphodonCoryphodon
Coryphodon is an extinct genus of mammal. It was widespread in North America between 59 and 51 million years ago. It is regarded as the ancestor of the genus Hypercoryphodon of Mid Eocene Mongolia....
, representing the family Coryphodontidae, from the lower Eocene of Europe and North America, in which there were 44 teeth and no horn-like excrescences on the long skull, while the femur had a third trochanter. The canines were somewhat elongated and were followed by a short gap in each jaw, and the cheek-teeth were adapted for succulent food. The length of the body reached about six feet in some cases.
In the middle Eocene formations of North America occurred the more specialized 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...
(or Dinoceras), typifying the family Uintatheriidae
Uintatheriidae
The 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....
. Uintatheres were huge creatures with long narrow skulls, of which the elongated facial portion carried three pairs of bony horn-cores, probably covered with short horns in life, the hind-pair having been much the largest. The dental formula was i. 0/3, c. 1/1, p. 3/3·4, m. 3/3, the upper canines having been long sabre-like weapons, protected by a descending flange on each side of the lower front jaw.
In the basal Eocene of North America, the Amblypoda were represented by extremely primitive, five-toed, small ungulates such as Periptychus and Pantolambda
Pantolambda
Pantolambda is an extinct genus of Paleocene pantodont mammal. Pantolambda lived during the middle Paleocene, and has been found both in Asia and North America. A generalized early mammal, it had a vaguely cat-like body, heavy head, long tail, and five-toed plantigrade feet ending in blunt nails...
, each of these typifying a family. The full typical series of 44 teeth was developed in each, but whereas in the Periptychidae
Periptychidae
Periptychidae is a family of Paleocene placental mammals, known definitively only from North America. The family is part of a radiation of early herbivorous and omnivorous mammals classified in the extinct order Condylarthra, which may be related to some or all living ungulates...
, the upper molars were bunodont and tritubercular, in the Pantolambdidae, they had assumed a selenodont structure. Creodont
Creodonta
The creodonts are an extinct order of mammals that lived from the Paleocene to the Miocene epochs. They shared a common ancestor with the Carnivora....
characters were displayed in the skeleton.
Current taxonomy of animals once classified in Amblypoda
Few authorities recognize Amblypoda in modern classifications. The following mammals were once considered part of this group:- Order Pholidota (pangolinPangolinA pangolin , also scaly anteater or Trenggiling, is a mammal of the order Pholidota. There is only one extant family and one genus of pangolins, comprising eight species. There are also a number of extinct taxa. Pangolins have large keratin scales covering their skin and are the only mammals with...
s) - Order PantodontaPantodontaThe Pantodonta are an order of now extinct placental mammals.Pantodonts are well known from the Paleocene of North America and Asia, and one early genus Alcidedorbignya, that was found in the Paleocene of South America...
- Family Wangliidae
- Family Harpyodidae
- Family Bemalambdidae
- Family Pastoralodontidae
- Family Titanoideidae
- Family Pantolambdidae (including PantolambdaPantolambdaPantolambda is an extinct genus of Paleocene pantodont mammal. Pantolambda lived during the middle Paleocene, and has been found both in Asia and North America. A generalized early mammal, it had a vaguely cat-like body, heavy head, long tail, and five-toed plantigrade feet ending in blunt nails...
) - Family Barylambdidae
- Family Cyriacotheriidae
- Family Pantolambdodontidae
- Family Coryphodontidae (including CoryphodonCoryphodonCoryphodon is an extinct genus of mammal. It was widespread in North America between 59 and 51 million years ago. It is regarded as the ancestor of the genus Hypercoryphodon of Mid Eocene Mongolia....
)
- Order DinocerataDinocerataDinocerata mammals are an extinct order of plant-eating, rhinoceros-like hoofed creatures famous for their paired horns and tusk-like canine teeth...
- 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....
(includes 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...
, Eobasileus, Tetheopsis, etc. 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...
is sometimes placed in its own family.)
- Family Uintatheriidae
- Order Condylarthra
- Family HyopsodontidaeHyopsodontidaeHyopsodontidae is an extinct family of unspecialized, primitive mammals from the Condylarthra order, living from the Paleocene to the Eocene in North America and EurasiaThey were generally small insectivorous animals. The most common genus is Hyopsodus....
- Family Mioclaenidae
- Family PhenacodontidaePhenacodontidaeAn extinct family of large herbivorous mammals in the order Condylarthra.Dentition shows that species like Pleuraspidotherium and its relatives were probably browsers....
- Family PeriptychidaePeriptychidaePeriptychidae is a family of Paleocene placental mammals, known definitively only from North America. The family is part of a radiation of early herbivorous and omnivorous mammals classified in the extinct order Condylarthra, which may be related to some or all living ungulates...
(including Periptychus) - Family Peligrotheriidae
- Family Didolodontidae
- Family Hyopsodontidae