Indriidae

Taxobox
name = IndridaeMSW3 Groves|pages=119-121|id=12100075]
fossil_range = Pleistocene to Recent

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image_width = 250px
image_caption = Indri ("Indri indri")
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Primates
subordo = Strepsirrhini
infraordo = Lemuriformes
superfamilia = Lemuroidea
familia = Indriidae
familia_authority = Burnett, 1828
subdivision_ranks = Genera
subdivision = "Indri"
"Avahi"
"Propithecus"

The Indridae (also spelled Indriidae) are a family of strepsirrhine primates. They are medium to large sized lemurs with only four teeth in the toothcomb instead of the usual six. Indriids, like all lemurs, live exclusively on the island of Madagascar.

The group was once much larger, and, in addition to the thirteen species living today, also contains eleven extinct species in six genera. Most if not all were larger animals, called 'Sloth Lemurs'. These included the chimpanzee-sized "Palaeopropithecus" and the gorilla-sized "Archaeoindris". Most went extinct within the last 1500 to 2000 years, after humans started inhabiting Madagascar.

Characteristics

The ten extant indrid species vary considerably in size. Not counting the length of their tails, the avahis are only 30cm in length, while the Indri is the largest extant strepsirrhine. The tail of the Indri is only a stub, while avahi and the sifaka tails are as long as their bodies. Their fur is long and mostly from whitish over reddish up to grey. Their black faces, however, are always bald. The hind legs are longer than their fore limbs, their hands are long and thin, and their thumb cannot be opposed to the other fingers correctly.

All species are arboreal, though they do come to the ground occasionally. When on the ground, they stand upright and move with short hops forward, with their arms held high. In the trees, though, they can make extraordinary leaps and are extremely agile, able to change direction from tree to tree. Like most leaf eaters they adjust for the low nutrient content of their food by long rests. Often it can be seen lying stretched on trees sunning themselves. Indrids live together in family federations from two to 15 animals, communicating with roars and also with facial expressions.

Indrids are strict vegetarians, eating mostly leaves, fruits and flowers. Like some other herbivores, they have a large cecum, containing bacteria that ferment cellulose, allowing for more efficient digestion of plant matter.cite book |editor=Macdonald, D.|author= Pollock, J.I.|year=1984 |title= The Encyclopedia of Mammals|publisher= Facts on File|location=New York|pages= 327-329|isbn= 0-87196-871-1] They have less premolar teeth than other lemurs, with the dental formula of:dentition2|2.1.2.3|2.1.2.3

Females and males usually mate monogamously for many years. Mostly at the end of the dry season, their four to five-month gestation ends with the birth of a single offspring, which lives in the family for a while after its weaning (at the age of five to six months).

Classification

There are 18 living species in the family, divided into 3 genera.

* ORDER PRIMATES
** Suborder Strepsirrhini: non-tarsier prosimians
*** Family Cheirogaleidae: dwarf and mouse lemurs
*** Family Lemuridae: lemurs
*** Family Lepilemuridae: sportive lemurs
*** Family Indriidae: woolly lemurs and allies
**** Subfamily †Archaeolemurinae
***** Genus †"Hydropithecus"
***** Genus †"Archaeolemur"
**** Subfamily †Palaeopropithecinae
***** Genus †"Archaeoindris"
***** Genus †"Babakotia"
***** Genus †"Palaeopropithecus"
**** Subfamily Indriinae
***** Genus "Indri"
***** Genus "Avahi"
***** Genus †"Mesopropithecus"
***** Genus "Propithecus"
*** Family Daubentoniidae: Aye-aye
*** Family Lorisidae: lorises, pottos and allies
*** Family Galagidae: galagos
** Suborder Haplorrhini: tarsiers, monkeys and apes

ee also

* Holocene extinction event

References