Podocnemididae
Encyclopedia
Podocnemididae is a family
of turtle
s native to Madagascar
and northern South America
. They are side-necked turtles (Pleurodira), which means they do not retract their heads backwards, but hide it sideways.
These turtles are all aquatic, inhabiting streams, and other flowing water. Their shells are streamlined to aid in swimming.
, under the latter name, with both groups being treated as subfamilies. Under that scheme, the present group is named Podocnemidinae. Some authors still maintain this classification, but here it is preferred to keep them distinct families in the superfamily
Pelomedusoidea instead.
The family Podocnemididae contains only three living genera
, two of them monotypic
:
The prehistoric genus Stupendemys
also belongs to this family. Living around 5.5 million years ago in northern South America, these were the largest freshwater turtles and the largest pleurodires known to date.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s native to Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
and northern 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...
. They are side-necked turtles (Pleurodira), which means they do not retract their heads backwards, but hide it sideways.
These turtles are all aquatic, inhabiting streams, and other flowing water. Their shells are streamlined to aid in swimming.
Taxonomy and systematics
The Podocnemididae have been united with their closest living relatives, the PelomedusidaePelomedusidae
Pelomedusidae is a family of freshwater turtles, native to eastern and southern Africa. They range in size from to in shell length, and are generally roundish in shape...
, under the latter name, with both groups being treated as subfamilies. Under that scheme, the present group is named Podocnemidinae. Some authors still maintain this classification, but here it is preferred to keep them distinct families in the superfamily
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
Pelomedusoidea instead.
The family Podocnemididae contains only three living genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
, two of them monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
:
- Erymnochelys – Madagascar Big-headed Turtle
- Peltocephalus – Big-headed Amazon River Turtle
- PodocnemisPodocnemisPodocnemis is a genus of aquatic turtles commonly known as South American River Turtles. The genus consists of six species occurring throughout South America.-Species:* Podocnemis erythrocephala - Red-headed Amazon River turtle...
– South American side-necked river turtles
The prehistoric genus Stupendemys
Stupendemys
Stupendemys is a prehistoric genus of freshwater turtle. Its fossils have been found in northern South America, in rocks dating from the late Miocene to the very start of the Pliocene, about 6 to 5 million years ago....
also belongs to this family. Living around 5.5 million years ago in northern South America, these were the largest freshwater turtles and the largest pleurodires known to date.