Perissodactyla
From Palaeos
Contents |
[edit] Introduction
The Perissodactyla or odd-toed ungulates are browsing and grazing mammals distinguished by having an odd number of toes on the hooves (either 1, 3, or 5). Although early forms (Late Paleocene through to early or middle Eocene) were quite small, a number of lineages quickly evolved large to very large size by the middle Eocene. They were the primary mammalian herbivores from the Eocene to the Miocene, at which time they were supplanted by the Artiodactyla. In contrast to the artiodactyls, perissodactyls are hindgut fermentors (that is, they have relatively simple stomachs supplemented by a large caecum to hold and ferment digested food) and a generally large middle toe.
| PERISSODACTYLA | |
| Taxonomy | Phylogeny |
Class: Mammalia
|
o Cetferungulata `--o Perissodactyla |--Tapiromorpha | `==Isectolophidae (grade) | `--+--Ceratomorpha | `--Chalicotheriidae `--o Hippomorpha [Equoidea] |?-o--Lambdotheriidae | `--Brontotheriidae |--Equidae `--+--Hyracotherium `--Palaeotheriidae |
[edit] Information
Author: Owen, 1848
Stratigraphic Range: Late Paleocene to Recent
Ecological role: Terrestrial Browsers and Grazers
- The following sections are slightly modified from Wikipedia:
[edit] Evolutionary History
The odd-toed ungulates arose in what is now North America in the late Paleocene, less than 10 million years after the Cretaceous-Tertiary extinction event, in which the dinosaurs died out. By the start of the Eocene (55 million years ago) they had diversified and spread out to occupy several continents. The horses and tapirs both evolved in North America; the rhinoceroses appear to have developed in Asia from tapir-like animals and then reinvaded the Americas during the middle Eocene (about 45 million years ago). There were 12 families, of which only three survive. These families were very diverse in form and size; they included the enormous brontotheres and the bizarre chalicotheres. The largest perissodactyl, an Asian rhinoceros called Paraceratherium(also known as Indricotherium, and popularly known as Baluchitherium), reached 12 to 15 tons, more than twice the weight of an elephant.
Perissodactyls were the dominant group of large terrestrial browsers right through the Oligocene. However, the rise of grasses in the Miocene (about 20 million years ago) saw a major change: the even-toed ungulates with their more complex stomachs were better able to adapt to a coarse, low-nutrition diet, and soon rose to prominence. Nevertheless, many odd-toed species survived and prospered until the late Pleistocene (about 10,000 years ago) when they faced the pressure of human hunting and habitat change.
[edit] Taxonomy
The members of the order fall into two suborders:
- Hippomorpha are odd-toed ungulates that are fast runners with long legs. This suborder is represented by a few Eocene forms and the large and once diverse family Equidae, which includes only one extant genus, Equus, comprising the horse, zebra, donkey, onager, and allied species. The Eocene family Brontotheriidae (members of which resemble more the Ceratomorpha) is traditionally included here as well, although its exact relationships are uncertain.
- Ceratomorpha are odd-toed ungulates that have several functional toes and are heavier than and move slower than the Hippomorpha species. This suborder has two extant families: Tapiridae (tapirs) and Rhinocerotidae (rhinoceroses)
- the following section is from Palaeos com:
[edit] Character traits
Characters: elongate skulls; complete set of incisors; premolars molariform, often hypsodont & lophodont; horns, if present are unpaired on frontals or nasals & lack bone core; cervical vertebrae opisthocoelous; tall neural spines on thoracic vertebrae; clavicle absent; scapula is long & narrow with small coracoid process; broad, tall ilium with large gluteal (thigh) muscles; forelegs bear most weight, with hind legs providing propulsion; digits 3-4/3 (equids 1/1); "odd-toed" or mesaxonic, i.e. plane of symmetry passes through a large central digit; astragalus is primary weight-bearing tarsal; intestinal fermentation, normally requiring constant foraging, but superior use (compared to artiodactyl ruminants) of proteins and high-quality food materials.
[edit] Phylogeny
[edit] Dendrogram
<==Perissodactyla | i. s.: Helaletes | Lophiodon | Lophiaspis | Symborodon | Orotherium Marsh 1872 | |--O. cristonense Cope 1876 | |--O. laevii | `--O. vintanum Marsh 1872 | Oligotomus | Dolichorhinus | Brontops |--Tapiromorpha | | i. s.: Heptodon tienshanensis | | Eomoropus | | Palaesyops | | Lambdotherium | |--Orientolophus | `--+--+--Cymbalophus Hooker 1984 | | | `--*C. cuniculus (Owen 1842) [=Hyracotherium cuniculus] | | `--Systemodon Cope 1881 | | |--*S. tapirinus (Cope 1875) (see below for synonymy) | | `--S. etsagicus (Cope 1884) [=Hyracotherium angustidens etsagicum] | `--+--Cardiolophus | `--+--Homogalax protapirinus [=Systemodon protapirinus] | `--+--Isectolophus | `--+--Ceratomorpha | `--Chalicotheriidae `--Hippomorpha [Equoidea] | i. s.: Brontotheriidae [Brontotherioidea] | |--Metatelmatheriinae | | |--Qufutitan Wang & Wang 1997 | | | `--*Q. zhoui Wang & Wang 1997 | | |--Metatelmatherium | | | |--M. cristatum | | | `--M. ultimum | | |--Desmatotitan | | |--Hyotitan | | |--Acrotitan | | `--Arctotitan | |--Rhinotitan [Epimanteoceratinae] | | `--R. mongoliensis | `--Embolotheriinae |--Equidae `--+--Hallensia mathewsi `--+--Hyracotherium Owen 1841 | |--*H. leporinum Owen 1841 | |--H. agile (Marsh 1873) [=Orohippus agilis] | |--H. procyoninum (Cope 1872) [=Helotherium procyoninum] | |--H. siderolithicum | `--H. sylvaticum `--Palaeotheriidae | i. s.: Propachynolophus | Anchilophus | Plagiolophus |--+--Palaeotherium | `--Propalaeotherium `--Pachynolophus |--P. lavocati `--P. livinerensis
Systemodon tapirinus (Cope 1875) [=Hyracotherium tapirinum, Orohippus tapirinus; incl. H. cristatum Wortman 1896]
* Type species of generic name indicated
[edit] References
Campbell, N. A. 1996. Biology (4th ed.) The Benjamin/Cummings Publishing Company, Inc.: Menlo Park (California).
Cope, E. D. 1876. Report upon the extinct Vertebrata obtained in New Mexico by parties of the expedition of 1874. Geographical Surveys West of the One Hundredth Meridian 4(2): i-iv, 1-370.
Froehlich, D. J. 2002. Quo vadis eohippus? The systematics and taxonomy of the early Eocene equids (Perissodactyla). Zoological Journal of the Linnean Society 134: 141-256.
Janis, C., & P. J. Jarman. 1984. The hoofed mammals. In All the World’s Animals: Hoofed Mammals (D. Macdonald, ed.) pp. 28-39. Torstar Books: New York.
Meng, J., Y. Hu & C. Li. 2003. The osteology of Rhombomylus (Mammalia, Glires): Implications for phylogeny and evolution of Glires. Bulletin of the American Museum of Natural History 275: 1-247.
Wang Y. & Wang J. 1997. A new brontothere from late Middle Eocene of Qufu, Shandong. Vertebrata PalAsiatica 35 (1): 68-77.
[edit] External links
Introduction to the Perissodactyla
Fossil Horses in Cyberspace
The Tapir Gallery - Welcome
Perissodactyla
Order PERISSODACTYLA
Order Perissodactyla: Rhinoceroses, Horses
ISIS - taxon perissodactyla
Journal of Molecular Evolution 50: 11-21 (2000)
Order Perissodactyla
Rhinoceros Skulls and Rhino Horns from Skulls Unlimited
Perissodactyla (Hoofed (Odd-toed))
Bibliography of Ungulates: Perissodactyla and Artiodactyla, etc.
Breeds of the World
Vertebrates : Mammals : Perissodactyla
World's oldest horse runs free in Mongolia
[edit] Credits
Phylogeny: Christopher 01:15, 17 June 2008 (PDT) Characters and Links: ATW020617
Editing: MAK061122
