Difference between revisions of "Amphisbaenia" - New World Encyclopedia
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| − | {{Approved}}{{Images OK}}{{Submitted}}{{ | + | {{Copyedited}}{{Approved}}{{Images OK}}{{Submitted}}{{Paid}} |
{{Taxobox begin | color = pink | name = Amphisbaenia}} | {{Taxobox begin | color = pink | name = Amphisbaenia}} | ||
{{Taxobox image | image = [[Image:Amphisbaenia_1.JPG]] | caption = }} | {{Taxobox image | image = [[Image:Amphisbaenia_1.JPG]] | caption = }} | ||
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{{Taxobox end placement}} | {{Taxobox end placement}} | ||
{{Taxobox section subdivision | color = pink | plural_taxon = Families}} | {{Taxobox section subdivision | color = pink | plural_taxon = Families}} | ||
| − | Amphisbaenidae (worm lizards)<br> | + | Amphisbaenidae (worm lizards)<br/> |
| − | Trogonophidae (short-head worm lizards)<br> | + | Trogonophidae (short-head worm lizards)<br/> |
Bipedidae (two-legged worm lizards) | Bipedidae (two-legged worm lizards) | ||
{{Taxobox end}} | {{Taxobox end}} | ||
| − | '''Amphisbaenia''' is a subgroup (suborder or infraorder) of the [[reptile]] order Squamata composed of peculiar, usually small and legless | + | '''Amphisbaenia''' is a subgroup (suborder or infraorder) of the [[reptile]] order Squamata composed of peculiar, usually small and legless [[animal]]s, known as ''worm lizards''. |
| − | Extant (living) reptiles (Class Reptilia) are generally placed into four orders: Testudines (turtles), Rhynchocephalia (tuatara), Crocodilia (crocodilians) and Squamata (lizards, snakes, and worm lizards). | + | Extant (living) reptiles (Class Reptilia) are generally placed into four orders: [[Testudines]] (turtles), [[Rhynchocephalia]] (tuatara), [[Crocodilia]] (crocodilians) and [[Squamata]] (lizards, snakes, and worm lizards). Thus, worm lizards are distantly related to [[lizard]]s and [[snake]]s, in spite of their resemblance to worms (due to their pink color and scales arranged in rings). |
Although reptiles are tetrapods, meaning they are "four-legged" [[vertebrate]]s, and worm lizards are usually legless, they are still considered tetrapods because it is assumed that they [[evolution|evolved]] from forms that did have appendages. The extraordinary diversity of nature complicates classification based on anatomical features; in general, [[taxonomy]] seeks for relationships based on common lineage. | Although reptiles are tetrapods, meaning they are "four-legged" [[vertebrate]]s, and worm lizards are usually legless, they are still considered tetrapods because it is assumed that they [[evolution|evolved]] from forms that did have appendages. The extraordinary diversity of nature complicates classification based on anatomical features; in general, [[taxonomy]] seeks for relationships based on common lineage. | ||
| − | Worm lizards are very poorly known, due to their burrowing lifestyle and general rarity. | + | Worm lizards are very poorly known, due to their burrowing lifestyle and general rarity. Only two [[species]] are known to exist in the [[United States]], with most worm lizards being in [[Africa]] and [[South America]]. |
==Characteristics== | ==Characteristics== | ||
| − | Little is known of worm lizards outside of their [[anatomy]], and even that is difficult to study due to the mechanics of dissecting something so small (most species are less than | + | Little is known of worm lizards outside of their [[anatomy]], and even that is difficult to study due to the mechanics of dissecting something so small (most species are less than six inches long). |
| − | The head is stout, not set off from the neck, and either rounded, sloped, or sloped with a ridge down the middle. | + | The head is stout, not set off from the neck, and either rounded, sloped, or sloped with a ridge down the middle. Most of the skull is solid bone, and they have a distinctive single median tooth in the upper jaw. They have no outer ears, and the eyes are deeply recessed and covered with skin and scales. The body is elongated, and the tail truncates in a manner that vaguely resembles the head. Their name is derived from Amphisbaena, a mythical serpent with a head at each end. |
| − | The [[skin]] of amphisbaenians is only loosely attached to the body, and they move using an accordion-like motion, in which the skin moves and the body seemingly just drags along behind it. | + | The [[skin]] of amphisbaenians is only loosely attached to the body, and they move using an accordion-like motion, in which the skin moves and the body seemingly just drags along behind it. Uniquely, they are also able to perform this motion in reverse, just as effectively. |
==Classification== | ==Classification== | ||
| Line 42: | Line 42: | ||
* Benton, M. J. 2004. ''Vertebrate Paleontology'', 3rd ed. Blackwell Science. | * Benton, M. J. 2004. ''Vertebrate Paleontology'', 3rd ed. Blackwell Science. | ||
* Uetz, P. 2005. The EMBL Reptile Database. http://www.embl-heidelberg.de/~uetz/db-info/SpeciesStat.html | * Uetz, P. 2005. The EMBL Reptile Database. http://www.embl-heidelberg.de/~uetz/db-info/SpeciesStat.html | ||
| − | * Wu, X. | + | * Wu, X.C., D.B. Brinkman, A.P. Russell, Z.M. Dong, P.J. Currie, L.H. Hou, and G.H. Cui. 1993. ldest known amphisbaenian from the Upper Cretaceous of Chinese Inner Mongolia. ''Nature'' 366: 57-59. |
{{credit|55251600}} | {{credit|55251600}} | ||
| − | |||
[[Category:Life sciences]] | [[Category:Life sciences]] | ||
| + | [[Category:Animals]] | ||
| + | [[Category:Reptiles]] | ||
Latest revision as of 17:35, 3 April 2008
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Amphisbaenidae (worm lizards) |
Amphisbaenia is a subgroup (suborder or infraorder) of the reptile order Squamata composed of peculiar, usually small and legless animals, known as worm lizards.
Extant (living) reptiles (Class Reptilia) are generally placed into four orders: Testudines (turtles), Rhynchocephalia (tuatara), Crocodilia (crocodilians) and Squamata (lizards, snakes, and worm lizards). Thus, worm lizards are distantly related to lizards and snakes, in spite of their resemblance to worms (due to their pink color and scales arranged in rings).
Although reptiles are tetrapods, meaning they are "four-legged" vertebrates, and worm lizards are usually legless, they are still considered tetrapods because it is assumed that they evolved from forms that did have appendages. The extraordinary diversity of nature complicates classification based on anatomical features; in general, taxonomy seeks for relationships based on common lineage.
Worm lizards are very poorly known, due to their burrowing lifestyle and general rarity. Only two species are known to exist in the United States, with most worm lizards being in Africa and South America.
Characteristics
Little is known of worm lizards outside of their anatomy, and even that is difficult to study due to the mechanics of dissecting something so small (most species are less than six inches long).
The head is stout, not set off from the neck, and either rounded, sloped, or sloped with a ridge down the middle. Most of the skull is solid bone, and they have a distinctive single median tooth in the upper jaw. They have no outer ears, and the eyes are deeply recessed and covered with skin and scales. The body is elongated, and the tail truncates in a manner that vaguely resembles the head. Their name is derived from Amphisbaena, a mythical serpent with a head at each end.
The skin of amphisbaenians is only loosely attached to the body, and they move using an accordion-like motion, in which the skin moves and the body seemingly just drags along behind it. Uniquely, they are also able to perform this motion in reverse, just as effectively.
Classification
Benton (2000) considers Amphisbaenia to be an infraorder within the Squamata Order, while considering the lizards (Lacertilia or Sauria) and snakes (Serpentes or Ophidia) to be orders. Uetz (2005) considers Amphisbaenia to be an suborder as with the lizards and snakes. (See reptile classification.)
Worm lizards are normally classified into three families:
- Family Amphisbaenidae (Worm Lizards)
- Family Trogonophidae (Shorthead Worm Lizards)
- Family Bipedidae (Two-legged Worm Lizards)
ReferencesISBN links support NWE through referral fees
- Benton, M. J. 2004. Vertebrate Paleontology, 3rd ed. Blackwell Science.
- Uetz, P. 2005. The EMBL Reptile Database. http://www.embl-heidelberg.de/~uetz/db-info/SpeciesStat.html
- Wu, X.C., D.B. Brinkman, A.P. Russell, Z.M. Dong, P.J. Currie, L.H. Hou, and G.H. Cui. 1993. ldest known amphisbaenian from the Upper Cretaceous of Chinese Inner Mongolia. Nature 366: 57-59.
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