Indri-like

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Indri-like
Indri (Indri indri)

Indri ( Indri indri )

Systematics
Superordinate : Euarchontoglires
without rank: Euarchonta
Order : Primates (Primates)
Subordination : Wet-nose primates (Strepsirrhini)
Partial order : Lemurs (Lemuriformes)
Family : Indri-like
Scientific name
Indriidae
Burnett , 1828
The silk sifaka , a representative of the sifakas

The Indriiformes (Indriidae) are a primate family from the group of lemurs . They include three living species - woolly , Sifakas and Indri , which are summarized as Indriinae, as well as the extinct groups of Palaeopropithecinae and Archaeolemurinae .

features

In terms of height, the members of this family differ considerably. The woolly lemur reaches a head body length of 25 to 30 centimeters and a weight of 0.6 to 1.6 kilograms, while the Indri is the largest living lemur with a head body length of up to 90 centimeters and a weight of up to 10 kilograms. Some of the extinct representatives were, however, considerably larger, with Archaeoindris reaching a weight of up to 200 kilograms. The common feature of the Indri-like is the loss of one incisor per half of the jaw in the lower jaw, so that the tooth comb found in almost all lemurs is only made up of four and not six teeth. The tooth formula is: I 2 / 1- C 1 / 1- P 2 / 2- M 3/3, so a total of 30 teeth. The upper incisors are enlarged, the upper canines elongated and sharp. The fur is long and often soft, the color ranges from whitish to gray-brown to black, and some species are patterned. In their physique, the groups have adapted to different ways of life: the Indriinae have greatly elongated hind legs and are therefore specialized for jumping locomotion. The first toe is enlarged, the other four toes are connected by a fold of skin and thus form a unit that can be placed opposite the first toe and enables a firm grip on the branch. Your hands are long and thin, and the thumb cannot be properly opposed to the other fingers. The tail of the woolly lemurs and sifakas is the same length or longer than the body, while the Indri is the only tailless lemur. The Palaeopropithecinae had very elongated arms and are sometimes compared to sloths in their physique . The Archaeolemuridae were partially adapted to a soil-dwelling way of life and showed similarities with the baboons .

distribution

Like all lemurs, indri species only live on the island of Madagascar . They inhabit both the dry forests of the west coast and the rainforests of the east coast, but they are absent in the central, unforested highlands.

Way of life

All species of the Indriinae are tree dwellers, which occasionally also come to the ground. They move in the branches by climbing and jumping vertically, on the ground they hop with their hind legs and hold their arms up high. In contrast to most lemurs, the Indri-like are diurnal, only the woolly lemurs have adapted - probably secondarily - to a nocturnal way of life. All species do not build nests, but sleep on forked branches. They live in groups of two to 15 animals, these are either family groups with an adult pair (in the case of the woolly lemurs) or groups of several males and females as well as the common young animals. They are territorial animals, the territories are marked with glandular secretions and sometimes with sounds.

Indriiformes are herbivores, with leaves often making up the main part of their diet. They also eat fruits, buds, flowers and other parts of plants to varying degrees. The composition of the food can also vary greatly depending on the habitat and season. Occasionally they eat soil on the ground, this can serve to supply them with trace elements or to neutralize the toxins contained in the leaves. Like many other leaf-eating mammals, they compensate for the low nutritional value of their food with long breaks.

Females and males usually live in long-term monogamous relationships. Usually at the end of the dry season, after a gestation period of four to five months, a single young is usually born. In contrast to many other lemurs, this does not grow up in a nest, but is carried by the mother first on the stomach and later on her back. It is weaned after a few months, but remains in its birth group for some time.

Danger

Many species are threatened in their population. The reasons for this lie on the one hand in the destruction of their habitat through slash and burn , deforestation , charcoal production or mining , and on the other hand in hunting. Some species such as the Indri were protected from hunting for taboo reasons , but this protection is increasingly being lost due to resettlement and the loss of traditions.

The extinction of the Palaeopropithecinae and Archaeolemurinae is probably related to the human settlement in Madagascar, although climatic reasons could also have been involved. The island was only settled by humans around 1500 years ago, and numerous large animals have subsequently disappeared.

Systematics

The Indri-like are classified in the sub-order of the lemurs (Lemuriformes), their sister group are probably the common Makis .

They are divided into three subfamilies, two of which are extinct.

Within the Indriinae, the woolly lemurs form the sister group of a common taxon from Sifakas and Indri, the ancestry relationships within the extinct representatives are not known.

literature

  • Nick Garbutt: Mammals of Madagascar. A Complete Guide . Yale University Press, New Haven & London 2007, ISBN 978-0-300-12550-4 .
  • Thomas Geissmann: Comparative Primatology . Springer, Berlin 2003, ISBN 3-540-43645-6 .
  • Russell A. Mittermeier , Jörg U. Ganzhorn, William R. Konstant, Kenneth Glander, Ian Tattersall , Colin P. Groves , Anthony B. Rylands, Andreas Hapke, Jonah Ratsimbazafy, Mireya I. Mayor, Edward Louis jr, Yves Rumpler, Christoph Schwitzer, Rodin Rasoloarison: Lemur Diversity in Madagascar. In: International Journal of Primatology. 29, 2008, ISSN  0164-0291 , pp. 1607-1656.
  • Ronald M. Nowak: Walker's Mammals of the World . 6th edition. Johns Hopkins University Press, Baltimore 1999, ISBN 0-8018-5789-9 (English).