aardvark

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aardvark
Aardvark (Orycteropus afer) (specimen in the Natural History Museum Berlin)

Aardvark ( Orycteropus afer )
(specimen in the Natural History Museum Berlin )

Systematics
Superordinate : Afrotheria
without rank: Afroinsectiphilia
Order : Tubulidentata
Family : Orycteropodidae
Genre : Orycteropus
Type : aardvark
Scientific name of the  order
Tubulidentata
Huxley , 1872
Scientific name of the  family
Orycteropodidae
JE Gray , 1821
Scientific name of the  genus
Orycteropus
É. Geoffroy Saint-Hilaire , 1796
Scientific name of the  species
Orycteropus afer
( Pallas , 1766)

The aardvark ( Orycteropus afer ) is a species of mammal and is the only recent representative of the genus Orycteropus in the family of Orycteropodidae and the order of the Tubulidentata (tubular tooth). Within the systematics of today's higher mammals , tubular teeth are the only order that only includes some kind.

Outwardly striking are the strong body of the aardvark with arched back and muscular legs as well as the tubular elongated snout and the fleshy tail. The range of the species covers the entire sub-Saharan Africa . The animals inhabit open and closed landscapes. They live solitary, are nocturnal and dig in the ground, which makes observation more difficult. The way of life of the aardvark has therefore only been insufficiently investigated. Its diet consists of state-building insects, which is a highly specialized adaptation. The distinctive behavior means that loose soils and a sufficient number of ants and termites are basic requirements for the presence of the aardvark in a certain region.

The relationship of the aardvark to other groups of higher mammals was not clear for a long time. Initially, due to its specialized diet, the species was placed in a common taxon called Edentata together with the similarly living pangolins , the anteaters and the armadillos . However, the similarities of the individual representatives are largely based on convergent evolution , not on relationship. Many researchers later favored a closer relationship with ungulates . Only molecular genetic studies at the end of the 20th century showed that the aardvark actually forms a family group with originally African animals. The results of the studies suggest a phylogenetically early elimination of the aardvark from the other lines of this lineage accept. Fossil finds are generally rare and currently only reflect the last 20 million years of evolution. Within these, however, relatives of the aardvark also reached today's Europe and Asia, where they are now extinct again. The only recent representative is considered safe in its existence.

features

Habitus

aardvark

The aardvark is a medium-sized to large representative of the mammals . It generally reaches a head-torso length of 94 to 142 cm and a shoulder height of 60 to 65 cm, the tail measures 44 to 63 cm. The weight is 40 to 65 kg, but since the onset of sexual maturity is unknown in animals in the wild, the variations are difficult to determine. A conspicuous sexual dimorphism is not developed. In 31 examined animals from Zimbabwe a total length of 149 to 175 cm and a tail length of 44.3 to 63.0 cm could be determined. The corresponding dimensions in 10 animals from the Democratic Republic of the Congo were 161 to 185 cm and 58 to 72 cm, respectively. Overall, the aardvark is a compact animal that has a strong body with a prominent arched back, a relatively small head and a long, fleshy tail. The fur on the back is relatively short, around 1.8 cm long, the covering is sparse and partly interspersed with bare spots. It shows a gray-brown basic color, but this can be overprinted by the locally prevailing soil conditions. On the sides of the body and the legs, the body hair becomes thicker and longer, the hair here reaches around 4 cm in length. The neck of the aardvark is short and wide. The head is characterized by an elongated shape, the most striking feature of which is the tubular, elongated snout. This ends in a soft, flexible nose and a small mouth opening. There are bristle-like hairs on the nostrils, which usually appear slit-shaped but can be opened wide and closed completely. The ears have an elongated shape reminiscent of rabbits and are between 15.8 and 21.0 cm long. They are also extremely agile. The eyes are on the sides of the head, are relatively small and have a brownish iris . Both above and below the eyes and beyond on the chin there are numerous bristly vibrissae . The legs are short and extremely strong. The front feet have four, the rear feet five rays, each ending in massive claws, the front being larger than the rear. The individual toes are connected by small membranes that are useful for digging. The length of the rear foot is 22.5 to 29.0 cm. Females have two pairs of teats located on the chest and abdomen. Both sexes have glands in the genital area.

Skull and dentition features

Skull of an aardvark
(Collection Museum Wiesbaden )

The aardvark's skull is between 24.0 and 25.5 cm long and 9.4 to 9.8 cm wide. Due to its rather elongated shape, it appears tubular. Similar to the other highly specialized insectivores such as anteaters and pangolins lacks distinctive bone surveys or -aufrauungen perhaps in the form of a crown comb as muscle attachment points. In contrast to the other two representatives, the aardvark has a closed, albeit slender, zygomatic arch . The upper jaw, intermaxillary bones and the nasal bone are well developed and form an elongated rostrum . The nasal bone has a triangular shape with a forward pointing tip and a widening rear part, but the paired bone is never fused. The frontal bone shows a characteristic bulge that is created by the extraordinarily developed olfactory bulb , which means that the interior of the nose has a relatively large volume. The parietal bone is mostly completely fused; in the front area it is connected to the wing process of the sphenoid bone , so that the frontal bone and the temporal bone have no contact with one another. The palatine bone is long and narrow, the laterally ascending area forms part of the edge of the orbit . There are noticeable openings in the back of the palatine bone. The middle ear has a simple structure, there is no tympanic membrane .

The overall slender lower jaw widens in the area of ​​the molars. In today's aardvarks, the symphysis is rarely fused. At its rear end is the mental foramen . The ascending branch rises high, the crown process (processus coronoideus) is higher than the articular process (processus condylaris). The mandibular joint is flat or slightly dented. As a result, the joint pit on the temporal bone, where the lower jaw engages, also has a rather weakly developed or arched design. In adult animals, the dentition has a heterodontic and reduced structure consisting of premolars and molars with, however, the number of teeth that vary from person to person. The tooth formula is: The number of teeth thus varies between 20 and 28. Young animals, on the other hand, still have incisors and canines . The front molars are shaped like nails, the rear teeth show the shape of an 8 in cross-section and are extremely high crowned ( hypsodontic ) and rootless, and they lack hard enamel . The internal structure differs significantly from the typical teeth of higher mammals . They consist of columnar structures of four to seven, but often six-sided prisms made of dentin , which are embedded in a matrix of substance similar to tooth cement . Each of these pillars has its own, rounded pulp . The number of pillars varies from person to person and can range from several hundred to over 1500. In some cases, they are not fully developed, but can either divide or unite. Due to this structure, the teeth have no crowning whatsoever. In the deciduous dentition, each molar has only one pulp; the individual tubes only appear when the teeth change and grow.

Body skeleton

Skeleton of an aardvark (in the Brussels Natural History Museum )

The spine is made up of 7 cervical, 13 thoracic, 8 lumbar, 6 sacrum and 25 to 28 tail vertebrae. In non-adult animals and some extinct forms, only 5 sacral vertebrae occur. The musculoskeletal system shows clear adjustments to a digging way of life. So a collarbone is formed with a strong and strongly curved shape. On the long bones of the arms and legs, there are numerous raised ridges as muscle attachment points and also wide joints. The shafts of the long bones largely consist of the compacted trabeculae of the interior of the bone ( substantia spongiosa ), while the outer bone shell is largely resorbed. This particular bone structure, which differs from other large mammals, is explained by the strong adaptation to excavation activities in connection with sometimes extreme external environmental conditions and thus limited food supply. On the foreleg, the humerus is equipped with an extremely massive lower ( distal ) joint, the width of which is over 35% of the length of the total bone. There is also a strong bone ridge on the shaft, the deltopectoral ridge. A massive upper ( proximal ) articular process, the olecranon , is formed on the ulna , the radius shows significant shortenings and noticeable bony ridges on the shaft. The pelvis also has a massive structure and is also stretched towards the back and tail. The sacrum has no connection to the ischium , and the pubic symphysis is barely reduced in length compared to other burrowing mammals. The thigh bone is short and sturdy and has a strong third roll hill (trochanter tertius), which rises on the shaft above a prominent rib. On the lower leg are the tibia and fibula fused together in the region of the upper joint end, the shaft of the tibia is also bent. The carpal and tarsal bones are characterized by a serial ( taxeopode ) arrangement, which also prevails in the proboscis and snakes . On the hand the central bone is fused with the scaphoid bone , on the foot the talus is not connected to the cuboid bone .

Soft tissue anatomy

The aardvark's stomach corresponds to the simple blueprint of mammals and is about 15 cm long with a diameter of 7.3 cm. It consists of two uniform sacks that are separated by a constriction. As a special feature, however, the rear section in the area of ​​the pylorus has extremely strong, ring-like muscles around 2 cm thick. This takes over the chopping of the food, which is usually done through chewing. The appendix, which is unusually large for insectivores, is also striking . The extremely enlarged olfactory bulb on the brain is noticeable; it is one of the largest among the higher mammals and thus also indicates the dominance of the sense of smell . Outwardly, the forehead bulges more strongly due to the enlargement of the olfactory brain. The eyes represent adaptations to the darkness, cones are not formed so that color vision is not possible. The cornea has a keratin layer on the outside to protect it from insect bites . The strap-shaped tongue is long, warts and always moist and sticky due to profuse saliva. It can be stretched out 25 to 30 cm from the mouth and has a pointed end. The nose is made up of only two muscles. These are fleshy and do not form tendons . This means that the nose can only be moved to a limited extent.

distribution and habitat

Distribution area of ​​the aardvark

The aardvark is endemic to Africa and there spread over the entire continent south of the Sahara . It has not yet been found in Lesotho , but it is most likely also found there. It is sometimes assumed that the species does not occur in the Congo Basin , but numerous observations have been made from there, for example from the Ituri forest in the Democratic Republic of the Congo . The distribution in West Africa has been little studied. Due to the wide distribution area, the aardvark lives in very different habitats . It is found mainly from open landscapes such as savannahs , bush and grasslands up to the semi-desert Karoo , but also from transitional regions from open to closed landscapes and from dense forests. The animals avoid extremely dry deserts and swampy regions. In eastern Africa the species is also found in higher mountain areas, for example in the Udzungwa Mountains in Tanzania or in the Bale Mountains in Ethiopia , where it could be spotted at an altitude of up to 3200 m. The aardvark is bound to loose soils and prefers flat plains or easy slopes that allow earthworks to be created. It is therefore rarely found in stony or rocky terrain. In principle, the presence of ants and termites is a prerequisite for the presence of the aardvark, accessible water sources only play a subordinate role. The population density is rather low, in habitats that are beneficial for the animals it is around 10 individuals per 10 km².

Relatives of today's aardvark from the amphiorycteropus genus , including A. depereti and A. gaudryi , and also Eurasia, were settled in the geological past from the Middle Miocene onwards . Here they died out at the beginning of the Pliocene and long before the arrival of humans. Representations on vessels and in tombs suggest that the aardvark was found in predynastic and ancient Egypt in the middle and lower Nile valley .

Way of life

Territorial behavior

Aardvark during its natural activity time

Despite its widespread distribution, the aardvark's way of life must be viewed as little researched. The most detailed information has so far been obtained from studies on animals from the Tussen die Riviere Nature in the Karoo of southern Africa. The aardvark is nocturnal and solitary. The activity phase begins shortly after dusk at around 7:30 p.m. when the animals leave their den and continues uninterrupted until dawn around 5:30 a.m. They are seldom seen during the day, exceptions are the cold winter months in southern Africa, when temperatures drop below freezing point. Then they appear in the late afternoon hours around 6:00 p.m. and end their daily rhythm shortly after midnight around 1:30 a.m. The reasons for this shift in activity are the poor coat coverage and a lack of body fat, which means that body heat is only moderately stored. The aardvark spends most of the available daily budget looking for food, regardless of the prevailing local weather. It moves on the floor in the toe gait . Sometimes it can reach high speeds of up to 40 km / h. In addition, the aardvark can swim across rivers and other bodies of water.

Aardvark in the entrance of an earthworks
Entrance to the earthworks of an aardvark
The aardvark has large digging shovel-like front and rear feet

The individual animals use their own territory or action spaces . In the Karoo these are between 1.33 and 3.02 km² in size, their extension shows only a few variations in the course of the seasons. However, if there is less food available, they can definitely take up larger areas. Within the action areas there is a large number of earth structures that are used for the retreat, protection and rearing of the offspring. The aardvark lays its burrows with the help of its strong front legs, the earth pushes it away with its hind legs and sometimes with its tail, which whips over the ground. The construction of a new building takes only a little time, an animal can burrow in about 5 minutes. In many cases the aardvark limits itself to renovating abandoned burrows. The density of such shelters varies depending on the type of landscape. In the Karoo, 101 dwellings were counted on an area of ​​1.5  hectares or 58 dwellings on an area of ​​200 by 40 m. In the open woodlands in the valley of the Mngeni River in the South African province of KwaZulu-Natal , the density was up to 29 burrows per hectare, in the adjacent open grasslands it fell to around 4. In the Ruwenzori Mountains in Uganda, however, 15 burrows were found on one hectare. According to surveys in the Bui National Park in Ghana , up to 11 burrows are distributed over one hectare in the river bank areas, while the open savannas only contain an average of 2 burrows over a comparable area. The reasons for the different number of shelters in the various regions are probably the nature of the subsoil, with soft soil favoring a higher number of earthworks. The threat from predators and bushfires can also play a secondary role. The strength of the soil substrate also affects the size and depth of the shelter. The burrows have one or more entrances. In Uganda, 13 of the 18 buildings examined had one entrance, two each with two or three and one with five entrances. In seven buildings from the Congo Basin examined, two had one entrance, four had two and one had three entrances. These were each around 14 m apart. The more complex structures with several entrances consist of corridors up to 13 m long, while the unborked structures are usually between 2 and 3 m long. The entrance extends steeply into the ground at an angle of around 40 °, later the passage becomes flatter, its diameter varies between 28 and 45 cm depending on the size of the animal. It opens into an enlarged chamber that is between 70 and 100 cm wide and 74 to 80 cm high. It can be up to 3 m deep, its dimensions enable an animal to turn and leave the shelter head first. The great depth of the living chamber also helps to compensate for the sometimes sensitive temperature fluctuations on the earth's surface during the day. The temperatures inside the building only fluctuate by 5 to 10 ° C compared to the outside temperature. A single animal only uses a shelter for a few days in a row and then looks for a new one. In the Karoo, an average length of stay of 5 to 9 days in one and the same burrow was recorded with a maximum of 38 days in a row. To sleep in the living room, the aardvark rolls up so that the head is covered by the tail and the hind feet.

The social system has hardly been researched in detail. The territories partially overlap within and between the sexes. The degree of territoriality is unknown, however, encounters between two same-sex animals in the wild have so far been observed extremely rarely. With a larger population density, aardvark of both sexes can occur together. However, social interactions are limited to short meetings of a maximum of 10 minutes, after which the animals return to foraging. The interactions are accompanied by vocalizations and the sniffing of the genital area, sometimes the animals get up on their back legs. The poorly developed social behavior is presumably a result of the specific, highly specialized insectivorous way of life, as the search for food takes a lot of time and leaves little room for a distinctive social life. The intra-species communication takes place through hearing and the sense of smell , a special body language is not developed due to the restricted sense of sight . As a rule, individual animals only very rarely utter noises, and the well-known utterances include grunting and bleating. The deposition of scent marks from glands , which are located on both sides of the vulva in females and behind the foreskin in males, is important. These secrete a strong smelling, greenish-colored secretion reminiscent of musk , which is sprayed over freshly dug earth at feeding places and at the entrances of buildings. Burying the excrement , which is buried in pits around 10 cm deep and partly covered with secretions, is a special behavior . The markings are not only used for communication with conspecifics, but also for one's own orientation, as the poorly defined eyes combined with the low head position and the nocturnal activity allow the determination of landmarks to a rather limited extent.

nutrition

The aardvark feeds on insects, its main diet consists of ants and termites , a specialty known as myrmecophagy . Due to the extremely widespread distribution, the composition of the food can be very different locally. In the Karoo, ants represent the main basis and, among them, the representatives of the genus Anoplolepis , which make up an average of 68.4% of the amount eaten. Among the termites, members of the genus Trinervitermes are preferred prey; their share reaches an average of 15.3%. In addition, the ant genera Dorylus , Messor and Crematogaster were detected in examinations of dung heaps , as well as Hodotermes among the termites . Overall, the range of prey in the Karoo includes more than a dozen species. In relation to the total amount, the aardvark consumes more than four times as many ants as termites. In the valley of the Mngeni River in KwaZulu-Natal, observations show that ants of the genus Dorylus make up about 78.2% of the food consumed, with Odontotermes accounting for the largest share of 12.2% among the termites . In addition, the aardvark occasionally eats other insects, such as scarab beetles or grasshoppers , and under certain circumstances it also preyes on small vertebrates such as fat mice . The food composition can vary with the seasons. In the Karoo, the proportion of termites increases sharply in winter from May to August. At this time of year the termites are less active and gather in their nests, at Trinervitermes a state can contain up to 80,000 individuals, so that the aardvark has a larger amount of food available by breaking the burrows. In addition, the larvae grow during this time and thus form an energy-rich food base. In Uganda, on the other hand, according to observations, the proportion of termites is lower during the dry season than during the rainy season.

When searching for food, the aardvark moves slowly through the area, the average speed is around 0.2 to 0.9 km / h. It runs in a zigzag and searches for a strip about 30 m wide. The nose keeps the animal close to the ground and sniffs constantly. As soon as a nest has been found, the aardvark presses its nose to the ground to sniff out the exact location of the prey. It keeps its ears upright during all foraging for food , which is likely more likely to be used to track down predators than food resources. Feeding on an ant or termite nest usually only lasts a short time, between ten seconds and two minutes. As a result, the aardvark can visit around 25 different burrows in one hour or around 200 within one night; the amount of insects eaten is an estimated 50,000 individuals. It covers between 0.5 and 7.0 km in the Karoo, and observations from Uganda have shown that it can cover distances of up to 14 km on its nightly forays. The individual nests are dug up with the strong claws of the front feet, the digging depth varies from 5 to 30 cm. For the creation of deep holes in the ground of up to 2 m, which are necessary for example in the nests of Hodotermes , the aardvark's residence time increases to up to 30 minutes. In some of the regions studied, the aardvark opens its nests significantly more often on the southern and western sides. The animals may look for the warmest areas of the termite burrow, as their prey is concentrated here in the cooler parts of the day in the southern hemisphere and thus more food is available. The long tongue is used to pick up the prey; its worm-like shape is particularly well suited to licking ants and termites out of the narrow passages of the nest. On the other hand, free-roaming insects cannot be captured as effectively in open terrain. Bristle-like hairs in the nostrils prevent the simultaneous penetration of soil while eating. The aardvark is less susceptible to the chemical defense of ants and termites than other insectivores ; this also applies to the strong bites of Dorylus and Trinervitermes . The prey is usually swallowed whole by the aardvark.

In addition to animal nutrition, there is also evidence that aardvark eats vegetable products. The fruits and seeds of the cucumber plant Cucumis humifructus are known , which grow underground at a depth of up to 30 cm and therefore have to be dug up. These are found relatively often in the faeces of the aardvark, so that the species contributes to the spread of the seeds of the plant. It is partly assumed that the animals eat the plants because of the high water content. Since the aardvark largely covers its fluid requirements through the insects and the teeth are less suitable for breaking up the hard, water-repellent shell, there is also the possibility that the animals swallow the seeds and fruits as by-catch when the ants and termites eat. In addition, some fungi of fungus-growing termites have been found in the stomach contents, which are probably mainly consumed in the dry season.

Reproduction

Young aardvark

There are only a few reports on the reproduction of the aardvark from field observations; the majority of the information comes from animals in human care. Births in the wild were observed in Ethiopia between May and June, in Uganda in early November, in the Democratic Republic of the Congo in October and November, and in southern Africa from May to August. The mating season in the Karoo is recorded in October and November. During the sexual act , the male sits on the female, the sharp claws of the front feet often cause deep scratches on the back of the female. The act itself consists of several repetitions that last an average of only 15 seconds. The wearing time ranges from 210 to 266 days, which corresponds to an average of about 8 months (243 days) and is longer than the often assumed six to seven months. Usually one young is born per litter, rarely two young animals. The newborn is around 55 cm long and weighs between 1.4 and 1.95 kg. It has bare, flesh-colored skin, well-developed claws, and open eyes. It is active and alert from birth. The young spends the early days in a nest chamber in a cave, after around 2.5 weeks it leaves the burrow with its mother for the first time. The first tooth erupts after about 12 weeks and the youngster begins to eat solid food at 14 weeks. The young animal buries its own droppings for the first time at the age of six months , before observations indicate that it is eaten by the mother animal. The father animal does not participate in the rearing. The time of weaning is unknown, as is that of complete independence, zoo animals reach sexual maturity at around two years of age. Young animals grow relatively quickly in captivity and weigh around 10 kg after seven weeks and around 40 kg after seven months. In the wild, however, this process is likely to take place much more slowly. The life expectancy of wild animals is unknown; animals in human captivity can live up to 30 years.

Predators, commensals and others

The most important predators include lions , leopards , cheetahs , spotted hyenas and African wild dogs . Sometimes pythons prey on young animals in their hiding places . When predators are sighted, the aardvark usually flees into the nearest earthwork or burrows, sometimes knocking out its hind legs. Animals that are directly threatened often defend themselves standing on their hind legs with the tail or the sharp claws of the front feet or lying on their back with all fours.

Aardwolf

A special feature can be found in a certain commensalism with other animal species. The aardwolf , which also feeds on termites, should be emphasized . However, he does not have the physical prerequisites to break open the hard burrows of Trinervitermes , for example . In winter, when the termites retreat to their nests in southern Africa and the aardwolf's main food is dwindling, the aardvark often follows the aardvark and benefits from the previously opened termite burrows. Similar relationships also exist with some bird species, such as the termite gossip and the grass rattle lark .

Overall, interactions between the aardvark and other animal species are rather rare. However, its earthworks are of great importance, as they are reused by numerous other animals when abandoned. In southern Africa alone, more than two dozen species have been found that occupy the aardvark's shelter. These include 21 representatives of mammals, 2 of birds, 3 of reptiles and 1 of amphibians. The larger users include warthog , bucket dog , aardwolf and black-backed jackal . Small mammals such as the South African gerbil , the African welted grass mouse , the short-tailed hamster rat or the natal multi-teat mouse also use the hiding places particularly frequently . It is possible that the more balanced climate inside the burrows compared to the more extreme outside temperatures of dry, southern Africa is a reason for other animal species to visit the underground passages. Numerous animals have also been identified from other areas of Africa that benefit from the abandoned burrows, such as porcupines , pangolins and gorse cats or the black-footed cat . The burrows are used to raise the offspring or generally as a shelter.

Parasites

The most important external parasites include ticks from the genera Haemaphysalis and Rhiphicephalus . In addition, animal lice such as Haemotopinus and Hybophthirus or fleas such as Aucheromyia , Neocordylobia and Pachychoeromyia occur. Among the internal parasites, flagellates and amoebas , among others, could be found. The former include several types of Trypanosoma , the latter Entamoeba . There is a wide variety of worms, including scratch worms , roundworms and tongue worms . In the nematode alone, more than a dozen genera have been documented that parasitize the aardvark, including Angulocirrus , Gendrespirura and Filaria .

Systematics

External and internal systematics

Internal systematics of Afrotheria according to Kuntner et al. 2011
 Afrotheria  
  Paenungulata  

 Sirenia (manatees)


   

 Hyracoidea (hyrax)


   

 Proboscidea ( proboscidea )




  Afroinsectiphilia  

 Tubulidentata (aardvark)


   

 Macroscelidea (elephant)


  Afrosoricida  

 Chrysochloridae (golden mole)


   

 Potamogalidae (Otter shrews)


   

 Tenrecidae (Tenreks)







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The aardvark forms as a species under the scientific name Orycteropus afer the sole recent member of the genus Orycteropus , as well as the family of the Orycteropodidae and the order of the Tubulidentata. As an organizational group, the Tubulidentata are the only mammals that contain only one species. The Tubulidentata in turn belong to the parentage of the Afrotheria , which represents one of the four main lines of the higher mammals . The Afrotheria themselves are a group defined by molecular genetics , made up of animals predominantly native to Africa or native to Africa. Within the Afrotheria two larger kinship communities can be distinguished, the Paenungulata and the Afroinsectiphilia . The Paenungulata include today's elephants , hyrax and manatees , they have been known as a group for a long time due to their anatomical similarities. On the other hand, it was not until the end of the 20th century that Afroinsectiphilia could be recognized as belonging together. They enclose the elephant shrews , tenreks , otter shrews and golden mole , the last three named together form the order of the tenre-kitties (Afrosoricida). Usually the aardvark is also regarded as part of the Afroinsectiphilia. The exact relationships have not yet been fully clarified, as the current data support a sister-group relationship between the aardvark and the elephants as well as with all other Afroinsectiphilia (in this case the elephants and tenrekids are combined under the name Afroinsectivora) as well as with the paenungulata . Some researchers therefore advocate a position of the Tubulidentata as the third higher structural unit within the Afrotheria. Based on the results obtained by molecular genetics, the origin of the Afrotheria can be traced back to the Upper Cretaceous 90.4 to 80.9 million years ago. The split between the two main groups occurred about 15 million years later. Within the Afroinsectiphilia, the aardvark as an organizational group may represent a very early split.

Graphic representation of the aardvark from Brehms Tierleben (1927), there called Kapisches Erdferkel ( Orycteropus capensis )

A distinction is made between up to 18 subspecies, the differentiation of which is mostly based on a different body color, body size and a varying bulge of the frontal bone . In some cases, deviations in the structure of the ear region can be found. The validity of some subspecies is controversial and their number is sometimes viewed as too high, since, for example, it cannot be assumed that five subspecies alone occur in Tanzania. The exact distribution of the individual subspecies is also not known due to the limited availability of material. The following subspecies can be found in the scientific literature:

  • O.a. adametzi Grote , 1921; northwestern Cameroon
  • O.a. aethiopicus Sundevall , 1843; Sudan, Uganda
  • O.a. afer Pallas , 1766; South Africa (Western Cape Province , Cape of Good Hope)
  • O.a. albicaudus Rothschild , 1907; Angola, western Zambia, Namibia, Botswana
  • O.a. angolensis Zukowsky & Haltorth , 1957; western Angola
  • O.a. erikssoni Lönnberg , 1906; northern Democratic Republic of the Congo
  • O.a. faradjius Hatt , 1932; northeastern Democratic Republic of the Congo, northwestern Uganda
  • O.a. haussanus Matschie , 1900; Togo
  • O.a. kordofanicus Rothschild , 1927; central sudan
  • O.a. lademanni Grote , 1921; central Tanzania
  • O.a. leptodon Hirst , 1906; Cameroon
  • O.a. matschiei Grote , 1921; southeastern Tanzania
  • O.a. observandus Grote , 1921; southern Tanzania
  • O.a. ruvanensis Grote , 1921; Rwanda, northern Tanzania
  • O.a. senegalensis Lesson , 1840; Senegal
  • O.a. somalicus Lydekker , 1908; Somalia
  • O.a. wardi Lydekker , 1908; eastern Democratic Republic of the Congo, northeastern Zambia
  • O.a. Wertheri Matschie , 1898; northeastern Tanzania

A phenomenon that has not been investigated so far is the striking difference between forest dwellers and open land forms. According to this, aardvarks from dense forests have a larger build with longer tails, and they also have smaller ears, longer claws and shorter hair. These particularly large representatives include, for example, the subspecies O. a. erikssoni and O. a. leptodon , which have total lengths of up to 1.98 m, while open land forms such as O. a. faradjius can only reach a total length of up to 1.77 m.

Internal systematics of the Tubulidentata according to Lehmann 2009
 Orycteropodidae  
  Leptorycteropus  

 Leptorycteropus guilielmi 


   
  Myorycteropus  

 Myorycteropus africanus 


   
  Orycteropus  


 Orycteropus afer


   

 Orycteropus crassidens



   

 Orycteropus djourabensis



  Amphiorycteropus  


 Amphiorycteropus abundulafus


   

 Amphiorycteropus gaudryi


   

 Amphiorycteropus mauritanicus


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 Amphirycteropus depereti






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In the recent genus Orycteropus with its current representative Orycteropus afer , some extinct forms are known. There are also four other genera that no longer exist today. The oldest form in tribal history is Eteketoni from the Lower Miocene . It was scientifically introduced in 2019 by Martin Pickford . Special features can be found in the flat back skull and a body skeleton that was already similar to that of today's aardvark and also had four-pointed hands. The tubular teeth were also already formed. The musculoskeletal system speaks for a good grave, the long, slender snout, combined with their small size, made it possible for the animals to lick food out of narrow crevices and cavities. Myorycteropus is somewhat more recent , but due to the description by DG MacInnes in 1956, it again represents the representative first discovered in research history. Its musculoskeletal system differs from today's aardvark and is characterized by significantly larger hands and feet and a humerus, the extremely massive lower joint end of which was over 46% of the total length of the bone. In contrast, he had a slimmer thighbone with a joint head sitting on a prominent neck. The features suggest that Myorycteropus was a good digger , but probably used a slightly different excavation method. Further differences can be found in the structure of the lower jaw with its articular branches that rise less steeply. Due to the strong specialization, the genus is not the ancestral form of the Tubulidentata, but is to be understood as a side branch. In contrast, the late Miocene Leptorycteropus , the scientific description of which goes back to Bryan Patterson from 1975, had a generalized physique and thus no good burial properties. This can be seen from the missing deltopectoral bar on the humerus and the slimmer joint ends. In addition, the dentition of this extinct genus is more extensive and still shows a large canine tooth, which was probably still fully functional in connection with the strongly pulled back mandibular symphysis. The snout did not have the striking elongation of today's representatives, while the differently oriented pelvis suggests a less arched back. Overall, Leptorycteropus appears to have lived less insectivorous and probably did not dig any underground burrows. Despite the comparatively late appearance, Leptorycteropus is the most original generic representative of the tubule deeds to date. The third recognized genus is Amphiorycteropus . It was named by Thomas Lehmann in 2009 and includes largely the Eurasian and some older African forms of the Middle and Upper Miocene of the order. Differences to today's aardvark can be found, among other things, in the hand and foot skeleton, whereby in Amphiorycteropus the hand is significantly smaller than the foot and the central ray of the hand is thus shorter than that of the foot. In general, the limb bones are also relatively slim. There are also individual differences in the structure of the skull. Overall, the characteristics suggest that Amphiorycteropus does not belong in the direct ancestral line of today's aardvark.

The genus Plesiorycteropus was partially incorporated into the Tubulidentata. Their representatives lived in Madagascar until around 1000 years ago and are sometimes referred to as "Malagasy aardvarks". Investigations from 1994 showed that there is no closer relationship between Plesiorycteropus and the actual aardvark , so Plesiorycteropus was placed in its own order (Bibymalagasia). Genetic studies, on the other hand, suggest a close relationship with the Tenreks .

Overview of the fossil and recent representatives of the Tubulidentata

The order of the Tubulidentata today consists of five genera with more than a dozen species:

  • Order: Tubulidentata Huxley , 1872
  • Family: Orycteropodidae Gray , 1821
  • E. platycephalus Pickford , 2019; Uganda
  • M. africanus MacInnes , 1956; East Africa
  • M. minutus Pickford , 1975; East Africa
  • M. chemeldoi Pickford , 1975; East Africa
  • O. djourabensis Lehmann, Vignaud, Mackaye & Brunet , 2004; northern central and east Africa
  • O. crassidens MacInnes , 1956; Kenya
  • O. afer Pallas , 1766; the aardvark living today

Some forms such as A. seni and A. pottieri have so far only had an uncertain position within the genera due to their fragmented finds. The independence of the genus Amphiorycteropus is doubted by some researchers who consider it to be synonymous with Leptorycteropus .

Research history

Taxonomy and Etymology

Peter Simon Pallas
Étienne Geoffroy Saint-Hilaire

The aardvark was first scientifically described by Peter Simon Pallas (1741–1811) in 1766. He carried it out using a fetus that came from the Cape of Good Hope in southern Africa, which is now also regarded as a type region. Pallas gave the aardvark the scientific name Myrmecophaga afra and thus placed it close to the anteater . Later, in 1780, Pallas described another adult animal under the same name. Eight years later, Johann Friedrich Gmelin established the new species Myrmecophaga capensis in his revision of Linnaeus' Systema naturae . The specific epithet capensis has long been the valid name for the aardvark. It is not known whether Gmelin knew Pallas' writings or was influenced by other naturalists.

The generic name Orycteropus in use today goes back to Étienne Geoffroy Saint-Hilaire (1772-1844), who first used it in 1796 in his text Extrait d'un mémoire sur le Myrmecophaga capensis and chose it because of clear deviations from Myrmecophaga . The name is of Greek origin and is made up of the words όρύκτης ( oryctes " digger ") and πους ( pous , "foot"), thus referring to the burrowing way of life of the animals. The year of publication of the article is sometimes given as 1795, but this is due to confusion with regard to the revolutionary calendar of post-revolutionary France. The occasional mention of the author with “C. Geoffroy ”is to be seen in this context, since at that time the term Citoyen for“ citizen ”was common. On Orycteropus further based the family name Orycteropodidae. Officially, today John Edward Gray (1800-1875) is the first name, but in 1821 he chose the name Orycteropidae, which was only corrected in 1850 by Charles Lucien Jules Laurent Bonaparte . Bryan Patterson divided the family into two subfamilies in 1975, Orycteropodinae for the real aardvark and Plesiorycteropodinae for the genus Plesiorycteropus , the latter no longer forms part of the Tubulidentata.

The order Tubulidentata for the aardvark was created by Thomas Henry Huxley (1825–1895) in 1872. The name refers to the characteristic teeth and consists of the Latin words tubus for "tube" and dens for "tooth". However, the name did not establish itself until the 1920s with the extensive anatomical studies by Charles F. Sonntag.

The German trivial name is derived from Dutch or Afrikaans , in which the animals were called Aardvark ("Erdschwein" or "Erdferkel") (today's forms are "Aardvarken" in Dutch and "Erdvark" in Afrikaans). In the English- speaking world, the term Ant bear is sometimes used, which literally means "anteater".

From the toothless to the tubular teeth - to the systematic position

The systematic position of the aardvark was discussed controversially in the history of research and has not yet been fully clarified. The initial equation of the aardvark with the South American anteater was abolished in 1796 by Geoffroy Saint-Hilaire with the establishment of the genus Orycteropus . The year before, he and Georges Cuvier had already introduced the term edentata (toothless), under which both then united the anteaters, pangolins and armadillos and in the vicinity of which Geoffroy Saint-Hilaire also saw the aardvark. In 1798, Cuvier officially incorporated the aardvark into the Edentata in addition to the sloths . Characteristic features of the Edentaten were the extensive absence of teeth or the formation of a homodontic dentition with simultaneous loss of tooth enamel . With the exception of the sloths, they comprised specialized or generalized insectivores. The concept of a systematic group called Edentata persisted in part into the 20th century, even if its composition varied greatly over time. John Edward Gray, for example, led the aardvark in 1821 within the "Oligodontae" together with the Megatheriidae and the armadillos. He separated the group from the "Tardigradae" and the "Edentulae", in the former he placed today's sloths, in the latter the anteaters and pangolins. Four decades later, Gray incorporated all these forms with the exception of the sloths into the "Edentata Entomophaga", which in his opinion contained two divisions: on the one hand the pangolin and armadillos, on the other hand the anteater and the aardvark, in addition but also the platypus , which, however, does not count among the higher mammals. Thomas Henry Huxley took up this view and divided the Edentata into the groups of "Phytophaga" (leaf eater) and "Entomophaga" (insect eater). However, criticism of the Edentata concept arose as early as the end of the 19th century because it summarized animals that were not originally related to each other. This was carried out by William Henry Flower in 1882, when he referred to the old-world distribution of pangolins and the aardvark compared to the new-world distribution of armadillos, sloths and anteaters. In the years that followed, Charles F. Sonntag in particular was able to show through detailed anatomical studies in the 1920s that the connecting characteristics of the Edentata are rather original, whereas the numerous deviating characteristics of both the skeletal and soft tissue anatomy allow for an independent classification of pangolins, the aardvark and the siblings speak. Sunday's work also led to the Tubulidentata being recognized as an ordering group, proposed by Huxley in 1872.

In the period that followed, the Tubulidentata were mostly considered to be an independent group, whose relationship was poorly known. Sonntag favored an origin from the circle of the " condylarthra ", an extensive group of primitive ungulates, which, according to today's view, is not closed, whereby there were similarities mainly in the structure of the spine and the skeleton of the feet. He also recognized numerous similarities to the snakes and elephants . The joined Edwin H. Colbert 1941 fossil after examining the extensive skeletal material aardvark the Greek island of Samos in, even George Gaylord Simpson supported this view in 1945 in his general taxonomy of mammals and referred the Tubulidentata as fine group together with the "condylarths" and " South American ungulates " in the parentage of the Protungulata. The aardvark had a similar position with Malcolm C. McKenna , who included it in his classification of mammals in 1975 in the ungulata group, which he repeated again later. It was not until the end of the 20th century that molecular biological and biochemical analysis methods brought new perspectives into the relationships between the higher mammals. An initial study of structural proteins in the early 1980s placed the aardvark in the vicinity of hyrax, manatee and elephants. The results could be reproduced several times in the following years and included, among other things, the elephants in the closer relationship. These first investigations were then confirmed by genetic analysis methods in the transition from the 20th to the 21st century. They brought about a direct relationship between groups native to Africa or originally formed there, to which, in addition to those mentioned, the Tenreks and Goldmulle also belong. The resulting extremely diverse family group was then united under the name Afrotheria . This view is also supported by studies, according to which the aardvark carries specific retroposons , so-called Afro SINEs , in its genome , which it has in common with other representatives of Afrotheria.

Tribal history

The Tubulidentata most likely split off from the other lineages of Afrotheria very early on, but their fossil history is only documented for the last 20 million years. The earliest occurrence falls in the beginning of the Lower Miocene in East Africa, but radiation occurred in large parts of Africa, Europe and Asia. In addition to some not exactly traceable remains of the lower jaw from the Muhoroni agglomerate in western Kenya , which are dated around 23 million years ago, the Napak finds in Uganda are the earliest evidence. A partial skeleton was recovered, the basis for the genus introduced in 2019 Eteketoni made. The age is estimated at around 20 to 18.5 million years, the reconstructed animals weighed around 8.5 kg. The fossil remains of Songhor, such as the Muhoroni agglomerate, also located in western Kenya, are probably only a little younger. They belong to the genus Myorycteropus and more precisely to the species M. minutus . The material found here, on which the first description is based, consists mainly of the hand and foot skeleton together with individual teeth. Some remains of the lower jaw and parts of the musculoskeletal system also prove the species from Arrisdrift in southern Namibia , they indicate an animal that possibly weighed only 4 kg. M. africanus , which was originally described on the basis of a fragmented skull plus some elements of the skeleton of a not fully grown animal from the island of Rusinga in Lake Victoria , is similarly old . Further finds have come down to us from Mfwangano, which is geographically close to Rusinga in Kenya. It was also relatively small, but showed the strongest adaptations to digging activities, as can be deduced from the structure of the humerus . Thus, the representatives of the genus Myorycteropus are relatively small animals, which at maximum were only about half the size of today's aardvarks, but already followed a myrmecophage (specializing in ants and termites) diet and a fossorial (underground burrowing) way of life were able.

Only a few finds from Africa are known from the Middle Miocene (16.0 to 11.6 million years ago). M. chemeldoi is covered with individual remains of the lower jaw and parts of the hand from the Tugen Hills in Kenya. The molars, however, were remarkably narrow. At this time, for the first time, representatives of the tubules outside Africa have been identified. According to recent studies, they belong to the genus Amphiorycteropus . Most likely, after the closure of the Tethys and the creation of a land bridge to Eurasia , the early aardvarks emigrated along with many other African mammals, such as the proboscis . The oldest finds come with a few teeth and foot elements from Paşalar in western Anatolia . Other fossils were found in the important Çandir site in central Anatolia northwest of Ankara . They are assigned to the species A. seni , but since the material is only fragmentary, the closer relationships are unclear.

In the Upper Miocene from 11.6 to 5.3 million years ago the tubule dates reached their greatest diversity. In Eastern Europe and Western Asia A. pottieri replaced the previous form A. seni . It is known from a partially preserved skeleton from Pentalofos in Macedonia and a lower jaw from Sinap Tepe northwest of Ankara in Turkey and represented a medium-sized aardvark that, in contrast to today's representatives, still had long canine teeth. A. gaudryi , which was scientifically described in 1888 using a skull from the Greek island of Samos , was very widespread . The species is not only the first described, but also the best studied fossil representative of the aardvark. He was about three-quarters the size of today's aardvark, but was slimmer and shorter-snouted. Its distribution area ranged from southern Europe to central Asia. However, the species is a rather rare accompanying element of the late Miocene mammal fauna, significant finds come from the Greek island of Evia in the form of a remains of the lower jaw and elements of the foot skeleton from the Yatağan formation in southwestern Turkey. The species A. browni , which occurs at the same time, is less known and less studied , a small representative that has been documented as early as the end of the Middle Miocene through skull fragments from the Siwaliks of Pakistan . In the Upper Miocene it also occurred in southeastern Europe, where, among other things, a skull from the valley of the Goiter in Bulgaria came to light. In Africa there are no known finds of tubules from the beginning of the Upper Miocene up to 8 million years ago, which is probably due to the relatively small number of sites from this period. In the northern part of the continent the larger A. mauretanicus appeared, for example in Bou Hanifia in northwest Algeria . In northern Chad , several partial skeletons of another aardvark were discovered, which are referred to the species A. abundulafus and already dated in the transition to the Pliocene . Their relatives were rather poor graves and had very wide teeth, together with the stronger muscle attachment points of the chewing muscles, it can be concluded that insect food was stronger, such as scarab beetles . Leptorycteropus guilielmi is a medium-sized form with a shoulder height of 24 cm from the transition from the Upper Miocene to the Pliocene, a partial skeleton and individual additional bones were found in the Nawata Formation of Lothagam in the Turkana Basin in northwestern Kenya. Compared to Orycteropus, the aardvark representative had an atypically well-developed set of teeth, large canine teeth, a strong jaw and showed no adaptation to a digging way of life. Presumably it did not feed on state-building insects, but was rather omnivorous.

The Pliocene (5.3 to 2.6 million years ago) marked the disappearance of the aardvark from Eurasia. In the lower part of the phase, only A. depereti with a complete skull from Perpignan in France is found . In Africa, however, the rise of the modern aardvark is becoming apparent. The oldest representative of the genus Orycteropus is O. djourabensis , which was first found in northern Chad and whose description is based on a partially preserved skeleton. It was very similar to today's aardvarks, but had shorter limbs. However, other finds from East Africa are also known, such as two partial skeletons from the early human discovery site Koobi Fora in northwestern Kenya. The species O. crassidens is documented from the following Pleistocene (2.6 million to 10,000 years ago) . It has been proven through several skeletons from the island of Rusinga in Lake Victoria and reached the size of today's aardvark, but also had relatively larger teeth compared to it. In addition, numerous other fossil material from Africa has come down to us. Some skull remains and postcranial skeletal material from the Pliocene fossil deposit Langebaanweg in southwestern South Africa were interpreted as possibly the earliest evidence of today's aardvark O. afer , but recent studies have not been able to confirm this. Other important sites, such as Laetoli in Tanzania or Swartkrans in South Africa, also contained finds of aardvark that look very similar to the modern form, but they are often not meaningful enough to be able to assign them precisely to this or another species.

Aardvark and humans

Local art and culture

Occasionally local ethnic groups in southern Africa depicted the aardvark on rock drawings . Two representations can be found in Mashonaland in Zimbabwe . They were hidden in a cave: one representation shows a composition together with six people and a Cape buffalo , the second is isolated. Both drawings are reddish-brown and surrounded by strong dots. In South African belief, aardvarks are powerful but also mysterious nocturnal animals to which the Bantu assign magical powers. The dots may indicate the latter.

Threat and protection

Mother with cub in a zoo

The aardvark is hunted as a food resource in many regions of Africa; its meat is said to taste similar to pork . As a result, it often ends up in local markets that offer bushmeat . Traditionally there are several methods of capturing an aardvark, for example by crawling into an occupied building, by fumigating or flooding the tunnels. However, the aardvark is considered to be difficult to capture, as a harassed animal can cause severe injuries with the claws of its front feet. In addition to food production, parts of the animals are also used in local traditional medicine or serve as lucky charms, such as claws, teeth or bristle-like hair. Conflicts with people mainly arise in areas used for agriculture and grazing, where, for example, livestock can be injured or machines can be damaged if the ceilings of underground structures collapse. However, the aardvark locally influences and controls the populations of termites and ants. In the past, local extermination of the animals resulted in an explosive increase in the number of insects that formed the colonies, which in some cases caused up to 60% annual crop losses. On the other hand, the destruction of the local termite and ant colonies also leads to the disappearance of the aardvark population. In some cases, the species also benefits from the development of some regions through agriculture and grazing, as the landscape is opened up and the soils are loosened as a result.

Because of its widespread distribution in sub- Saharan Africa, the IUCN classifies the aardvark as "not at risk" ( least concern ). The populations in southern Africa are considered stable, in western and central Africa there may have been a sharp decline as a result of the expansion of human living and economic areas. The species is represented in numerous protected areas, but difficult to observe due to its nocturnal and partly underground way of life, which also influences scientific monitoring programs.

An aardvark was first shown at London Zoo in 1869. The keeping of the species can be divided into three temporal phases, whereby during the first in the 19th century mostly wild catches dominated, which only survived for a short time in human care. In the second phase, which began in the mid-1950s, a young animal was successfully born in the Frankfurt zoo for the first time in 1962, but the newborn only survived a few days. The increase in knowledge from zoo keeping led to further births in the following decades, but difficulties in reproducing in human captivity ultimately resulted in inbreeding. The third phase started in 2008 with the crossing of unrelated animals from African stocks. There are currently three attitudes in Germany (Berlin, Frankfurt am Main and Saarbrücken) and more than twenty throughout Europe with a total of over 50 individuals (as of the end of 2012). In numerous institutions, aardvarks are kept in special nocturnal animal houses , in which the lighting conditions are switched in the reverse day-night rhythm.

literature

  • Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (Eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 288-295
  • Ronald M. Nowak: Walker's Mammals of the World. Johns Hopkins University Press, 1999, ISBN 0-8018-5789-9
  • Jeheskel Shoshani, Corey A. Golden and JGM Thewissen: Orycteropus afer. Mammalian Species 300, 1988, pp. 1-8
  • W. Andrew Taylor: Order Tubulidentata. In: John D. Skinner and Christian T. Chimimba (Eds.): The Mammals of the Southern African Subregion. Cambridge University Press, 2005, pp. 35-40
  • W. Andrew Taylor: Family Orycteropodidae (Aardvark). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 18-27

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p Jeheskel Shoshani, Corey A. Golden and JGM Thewissen: Orycteropus afer. Mammalian Species 300, 1988, pp. 1-8
  2. ↑ a b c d e f g h i j k l m n o p W. Andrew Taylor: Family Orycteropodidae (Aardvark). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 18-27
  3. ↑ a b c d e f g h i j k l m n o p q r Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 288-295
  4. ↑ a b c d e f g h i j W. Andrew Taylor: Order Tubulidentata. In: John D. Skinner and Christian T. Chimimba (Eds.): The Mammals of the Southern African Subregion. Cambridge University Press, 2005, pp. 35-40
  5. ↑ a b c d e W. E. Le Gros Clark and Charles F. Sonntag: A Monograph of Orycteropus afer. III. The skull. The skeleton of the trunk and limbs. Proceedings of the Zoological Society of London 96 (2), 1926, pp. 445-485
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  21. ↑ Gwenola Graff: Le représentations prédynastiques d'oryctéropes. In Jean-Claude Goyon and Christine Cardin (eds.): Proceedings of the ninth International Congress of Egyptologists, Grenoble, 6-12 September 2004. Paris 2007, pp. 829-835
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  37. ↑ a b c Michael Buckley: A Molecular Phylogeny of Plesiorycteropus Reassigns the Extinct Mammalian Order 'Bibymalagasia'. PlosOne 8 (3), 2013, p. E59614, doi: 10.1371 / journal.pone.0059614
  38. ↑ a b c d e Martin Pickford: Orycteropodidae (Tubulidentata, Mammalia) from the Early Miocene of Napak, Uganda. Munich Geoscientific Treatises Series A: Geology and Paläontologie 47, 2019, pp. 1–101
  39. ↑ a b c d e f Thomas Lehmann: Amended taxonomy of the order Tubulidentata (Mammalia, Eutheria). Annals of the Transvaal Museum 44, 2007, pp. 179-196
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