Big Tenrek ( Tenrec Ecaudatus )
- Tenrecs ( Tenrecidae )
- Golden moles ( Chrysochloridae )
The Tenrekartigen ( Afrosoricida ) are a recently due determined by molecular genetic investigations order of mammals ( Mammalia). Summarize the tenrecs ( Tenrecidae ) and the golden moles ( Chrysochloridae ), two living in Africa and Madagascar families with a total of about 45 species. Morphologically share the Tenrekartigen with the insectivores " in the narrow sense " ( scientifically Eulipotyphla ), the taxon from hedgehogs, shrews, moles and other so much in common that they, until recently, a common order, insectivores " in the broad sense " ( scientifically Lipotyphla ) were asked. The molecular genetic findings, however, indicate that Tenrekartige and insectivores are not related, but have merely developed convergent.
- 3.1 General
- 3.2 Dining
- 3.3 Reproduction
- 4.1 Outer systematics
- 4.2 Internal systematics
- 4.3 phylogeny
- 4.4 Research and systematic history
Body and limbs
The Tenrekartigen have occupied different ecological niches and are therefore a diverse group. The golden moles are - similar to moles - adapted to a subterranean lifestyle grave; within the tenrecs are found next to wasserbewohnenden species (such as the otter -like otter shrews ) and shrew-like agents ( the Reistenreks ) and hedgehog -like animals ( the Igeltenreks ). The head fuselage lengths vary between 4 and 40 centimeters (which in some species can still get an equally long tail) and weight between 5 grams and 2.4 kilograms.
The limbs are relatively short. The front feet of the golden moles are transformed into highly specialized grave tools, in particular, the claw of the third finger is extended. The limbs of the tenrecs are unspecialized and each terminating in five toes. Both groups are tibia and fibula often fused at the bottom.
Head and teeth
The head is conical or elongated, pointed snout. As with many subterranean mammals lacking in a gold Mullen ear, whereas that of the Tenrek are relatively large. The eyes are small in tenrecs, covered in gold Mullen with fur and function.
The teeth are well characterized as those of the insectivores by sharp cusps and sharp melting strips. The dental formula is I 2-3/2-3 C 1/ 1 P 3/3 M 2-3/2-3, so overall they have 32 to 40 teeth.
Also in the internal anatomy have Tenrekartige very similar to insectivores. The digestive tract is built simply, the appendix is absent in both groups and the intestine is short and tubular. A special feature of Tenrekartigen is that the genitourinary system as in the Ursäugern in a single outlet opening, the cloaca, ends. A similar arrangement is also found in some shrews and is therefore not a morphological criterion. In the males of most species of Tenrekartigen ( an exception are the otter shrews ) are the testes in the abdominal cavity. This distinguishes them from the insectivores, but is possibly a primordial feature represents the mammalian females have, as in the insectivores a bicornuate uterus (uterus bicornis).
Distribution and habitat
Tenrekartige exclusively occur in sub-Saharan Africa and Madagascar. The tenrecs have located their distribution area in Madagascar, only the otter shrews on the mainland. The golden moles inhabit mainly the southern part of the continent, three species live in the central Africa, Madagascar they are missing.
Tenrekartige inhabit a range of habitats and are found both in dry desert regions as well as in grasslands and forests. Some Tenreks lead an aquatic life and are therefore to be found along rivers and other water bodies.
Way of life
Depending on body type and lifestyle Tenrekartige lead different lifestyles. The golden moles spend most of their lives in underground, self-dug Building. Also among the Tenreks there are some grave species, though not to the same extent. However, the majority of Tenreks lives on the ground, a few types keep in foraging mostly in the water. Most Tenrekartigen serve self-dug burrows for shelter. Most Tenrekartigen live solitary and avoid outside the mating season, the contact with other dogs.
A special feature of Tenrekartigen is that their body temperature is more flexible than that of most other mammals and can be adapted to the part of the environment. Many species fall into a torpor (rigid state), either daily or cool outside temperature and low food supply.
The food of Tenrekartigen consists of insects and other invertebrates such as earthworms, aquatic species take crustaceans to him. To varying degrees, small vertebrates, carrion, and plant material to supplement the diet.
Little is known about reproduction, but it is variable depending on the type. The litter sizes vary between one and 31 at Great Tenrek, the highest value of all mammals. Newborns are in the mother's protected building - brought to the world - which is usually solely responsible for rearing their young. They are at first helpless, but grow quickly.
Based on molecular genetic studies, the Tenrekartigen an externally heterogeneous group of mammals, which has its origin on the African continent are attributed to the Afrotheria. The relationships to other groups of mammals are not yet known. Perhaps the elephant shrews are the sister group of the Tenrekartigen, together with the aardvark could these groups form the taxon Afroinsectiphilia.
The Tenrekartige are divided into two families, tenrecs ( Tenrecidae ) and golden moles ( Chrysochloridae ) divided. The golden moles are based on a different construction of the ear in two subfamilies Chrysochlorinae Amblysominae and divided. The Tenreks can be divided into four morphologically well-defined subfamilies: the otter shrews ( Potamogalinae ), the Erdtenreks ( Geogalinae ), the Reistenreks ( Oryzorictinae ) and the Igeltenreks ( Tenrecinae ). (For details, see Nomenclature of golden moles and systematics of tenrecs. ) The monophyly of both families was confirmed by molecular genetic studies, which has previously sometimes refuted expressed suspicions that otter shrews could be the sister group of all other Tenrekartigen or Igeltenreks are closer to the gold Mullen as with the other Tenreks related.
The stratigraphic range of the Tenrekartigen is very poor and is also hampered by the fact that, as mentioned above, morphological differences among the insectivores are hardly detectable. The oldest fossils of both the tenrecs and golden moles of the date from the Miocene of Africa and are already very close to the recent species. The group is undoubtedly ancient origin: using the molecular clock has been calculated that the split into the two present-day groups at the latest in early Paleocene must be done.
Controversial is the position of Widanelfarasia whose fossil was found from the late Eocene of Egypt and may represent the earliest known representatives of Tenrekartigen.
Research and systematic history
Since the establishment of the order of insectivores ( Insectivora ) by Thomas Edward Bowdich in 1821, the affiliation of the tenrecs and golden moles was largely beyond doubt. This order had a checkered taxonomic history, and were spun off as some taxa, such as giant glider, tree shrews and elephant shrews later, the relationship was due to the morphological similarities to the 1990s, as backed up. However, the inner logic of those insectivores in the broad sense has always been controversial. Thus, the tenrecs for example, were often regarded as close relatives of the Solenodon, and the golden moles were, among others, as closely related to the moles or as a basal group that faced all other insectivores.
With the advent of molecular genetic research in zoological systematics, this view has changed. Mark Springer et al. established in 1997 for the first time the golden moles outside the insectivores and arranged them in a clade of African mammals, Afrotheria, a. The following year saw Michael Stanhope et al., That the tenrecs belong to this group and, with the gold Mullen a common taxon. They also coined the scientific name Afrosoricida. Other scientists prefer for this group the names Tenrecomorpha or Tenrecoidea that ( were that is used to refer to other groups ) older, but taxonomically " biased " are. Numerous studies have demonstrated the following molecular paraphyly of insectivores in the broader sense ( Lipotyphla ) confirmed, so that today about the division into two groups, the Tenrekartigen ( Afrosoricida ) and insectivores ( Eulipotyphla ) there is widespread consensus.