Impalas

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Impalas
Male black heel antelope (Aepyceros melampus)

Male black heel antelope ( Aepyceros melampus )

Systematics
Subordination : Ruminants (ruminantia)
without rank: Forehead weapon bearer (Pecora)
Family : Horned Bearers (Bovidae)
Subfamily : Antilopinae
Tribe : Aepycerotini
Genre : Impalas
Scientific name of the  tribe
Aepycerotini
JE Gray , 1872
Scientific name of the  genus
Aepyceros
Sundevall , 1847

The impalas ( Aepyceros ) are a genus of African antelopes , which at the same time form the monotypical tribe of the Aepycerotini. The genus includes two species: the black heel antelope and the black-nosed impala . These occur in eastern and southern Africa , where they inhabit open landscapes interspersed with bush and trees. Outwardly, the impalas resemble medium-sized antelopes. Characteristic are their slim build with a straight back line and long legs as well as the elongated head. The black mark on the heel can be highlighted as the most striking feature. Horns are only developed in male individuals. The animals live in small herds consisting of mother and young animals. The males form bachelor groups, dominant individuals show territorial behavior during the reproductive phase. The main diet consists of hard grasses and soft plant components with seasonal variations. As a rule, a female gives birth to a young at a time, which is initially hidden away from the herd. Originally, the impalas were considered more closely related to the gazelles or the hartebeest , but genetic studies have shown a closer bond with the goats . The genus was established in 1847 in order to separate the then known black heel antelope from other gazelles and antelopes. From a phylogenetic point of view, the Impalas first appeared in the Upper Miocene around 6 million years ago. The entire population is now classified as not endangered, but regionally the individual species are subject to certain threats.

features

Habitus

Male black-nosed impala ( Aepyceros petersi )

Impalas reach a head-torso length of 120 to 150 cm, a shoulder height of 80 to 90 cm and a weight of 23 to 64 kg. Due to the clearly pronounced sexual dimorphism , females are noticeably smaller than males. In addition, the black-nosed impala ( Aepyceros petersi ) is on average slightly larger than the black- heeled antelope ( Aepyceros melampus ). The animals are colored fawn-brown at the top, the flanks are a little lighter in color. The lower abdomen, the chest, the throat, the chin and the inside of the legs stand out whitish. The rump is decorated with a vertical black stripe on both sides. A dark tuft of hair also appears on the heels , covering a gland , the metatarsal gland . This gland is a unique formation among the hornbeams . The head is elongated in the facial area, the eyes are large and the ears narrow and pointed. The black-nosed impala has an eponymous dark stripe on the forehead that runs from the nose to between the eyes. This appears much more diffuse in the black heel antelope. The males have lyre-like horns that can be up to 90 cm long and swing backwards, sideways and upwards. They are circular in cross-section with circumferences of 12.6 to 15 cm at the base and 9.8 to 12.3 cm in the second third. In addition, the skin on the neck of males is thickened.

Skeletal features

Skeleton of an impala

The skull is between 25.5 and 28.6 cm long and on the zygomatic arch between 9.2 and 11.2 cm wide. A distinctive feature is the appearance of a gap between the middle jawbone and the upper jaw , a feature that the impalas share with the goats ( Nesotragus ). The gap was probably caused by the stretching of the skull. Furthermore, the pre-eye pit (Fossa praeorbitalis) is missing . Large hollow chambers are formed on the frontal bone . The cavernous spaces extend to the base of the horns. The dentition includes 32 teeth with the following dental formula : . The two outer lower incisors and the canine tooth each have a needle-like or pin-like shape and form a tooth comb . The molars are characterized by their generally high-crowned ( hypsodontic ) structure.

The limbs are long and slender, especially the metapodia are elongated. The distal fingers and toes, on the other hand, are narrow and short. The hind limbs exceed the fore limbs in all dimensions. As is usual with the cloven-hoofed animals , the forefoot and rear foot are composed of two rays each (ray III and IV), but the laterally adjacent rays (II and V) are rudimentary on the underside. The two rays each have three toe links and three sesame bones , the last toe is characteristically triangular in shape and carries the hoof . The metapodia are extremely long compared to the other leg elements. The metacarpal bone takes up 33.4 % , the metatarsal bone 29.4% of the respective leg length. Especially for the hind legs, this is significantly longer than that of the reedbuck ( Redunca ) or the waterbuck ( Kobus ), but about shorter than that of the springbok ( Antidorcas ). As a result, the overall structure of the foot can be assessed as an adaptation to the rapid movement in the open landscape, which is sometimes associated with powerful jumps.

distribution

Distribution area of ​​the impalas:
  • Black heel antelope ( A. melampus )
  • Black-nosed Impala ( A. petersi )

    • The range of the Impalas includes the eastern, southeastern and southwestern Africa . The black heel antelope occurs from Kenya and Uganda via Tanzania , Zambia , Mozambique and Zimbabwe to Botswana and northeastern South Africa . The black-nosed impala lives isolated from this area in the border area of Angola and Namibia . This species is particularly common in the southern and eastern part of the Etosha National Park in Namibia, where it was settled in five selected locations in the 1960s and 1970s and has now spread to a good two dozen waterholes. The animals mainly use open savannah areas interspersed with bushes and trees. Often they find themselves in landscapes with acacia - Mopane - and Tamboti inventories directly. Since impalas are dependent on drinking water, they often stay in close proximity to bodies of water.

    Way of life

    Territorial behavior

    Female black-nosed impala at a waterhole in Etosha National Park

    Impalas are both diurnal and nocturnal. They form a complex social structure. Female impalas live with their young in herds of ten to sometimes over a hundred animals. As a rule, however, the groups usually only comprise around a dozen individuals. The herds roam action areas , which can be of different sizes depending on the inhabited region. In the case of the black heel antelope they reach an area of ​​0.8 to 3 km² in eastern and south-eastern Africa, and data of up to 33 km² are available for the black-nosed impala in the drier south-western Africa. Separated from these, young and old males form in bachelor associations, and sometimes individual individuals also stay in the herds. Dominant males show territorial behavior in the reproductive phase and then establish territories that are within the herds' action areas. Here they claim every female who wanders through their territory for themselves. The territories are often located in areas with high quality food sources, while the tail areas of the bachelor groups occupy less abundant feeding grounds. The territories are marked by scent marks through glands on the forehead, which is rubbed into the vegetation. There is hardly any identification with urine and feces , but the animals defecate in extensive latrines, which may also be used by other species. Another territorial sign is a loud roar that can be heard over great distances in the open landscapes.

    Bounce of the black-nosed impala

    Impalas spend most of their active time eating, which takes up about a third. Other activities consist of walking, ruminating, and resting. For the latter, the herds often seek out open grass areas. A specialty is mutual grooming ( allo-grooming ), which takes place with alternating bites and serves to remove external parasites such as ticks or lice . Both male and female individuals are involved in grooming. It is noteworthy that this also takes place among unrelated males, which rarely occurs in antelopes. Overall, however, males deal with it less intensively than females, which leads to a higher parasite load. The lower tooth comb is used to nibble out the parasites .

    Especially on the run from predators , Impalas can reach high speeds and jump up to 12 m. Their defense strategy against predators also includes so-called bounce jumps , in which the animals jump stiff-legged into the air. In contrast to other antelopes with similar behavior as springboks , Impalas kick their hind legs in the air so that within one jump the front legs touch the ground several times before the rear legs follow. The most important hunters of the impala are leopards , cheetahs , African wild dogs and hyenas .

    nutrition

    Impalas feed on hard plant foods such as grasses as well as on soft ones such as leaves , twigs or flowers . The respective composition varies over the year. Grasses are eaten fresh, especially in the rainy season. In the dry season, the proportion of soft vegetative food increases. In addition to the seasonal differences in food consumption, there are also differences between the sexes, as male animals predominantly eat more grass than females. The animals are dependent on water and therefore usually stay near bodies of water.

    Reproduction

    Mother and young of the black heel antelope in the Serengeti

    In eastern Africa, which is more characterized by a tropical climate , the impala can reproduce almost all year round. In contrast, it is limited in southern Africa with the stronger seasonal influences that occur there. It then takes place largely in the dry season. Dominance fights take place among the male animals of equal rank. They show a ritualized sequence beginning with a parade in which the horns and the thickened neck are presented. Often the head is turned away and the tongue pops out. A high head position challenges the rival, a low one demonstrates submissive behavior. The climax is a sliding competition, in which the horns wedge together. This takes place until a rival surrenders. Injuries are rare because the thickened neck protects the animals.

    The gestation period lasts between 27 and 28 weeks. During this time, the fetus develops from around 1.5 cm in length in the 4th week to almost 50 cm in length in the 28th week. The weight increases from 0.4 g to over 5 kg. The mother withdraws from the herd for the birth of the offspring. The newborn initially spends the nights hidden in the tall grass or bushes, and during the day it returns to the herd with the mother. Only after a week does it remain completely with the herd. Through this behavior, the impalas mediate between antelopes, which completely hide their offspring, and those who integrate them directly into the herd. Within the herd, the bond with the mother gradually decreases and the boys form “kindergarten groups”. Weaning takes place after 17 to 25 weeks. Female young animals usually remain in the herd, males are driven away by the dominant older males.

    Systematics

    Position of the impalas within the hornbeam according to Zurano et al. 2019
     Bovidae  

     Bovinae


      Antilopinae  

      Aepycerotini  

     Aepyceros (Impalas)


       

     Nesotragus (goat)



       


     Reduncini (water buck and reed buck)


       

     Antilopini (gazelle-like)



       



     Neotragini (small lobes )


       

     Oreotragini (Klipspringer)



       

     Cephalophini (duiker)



       


     Alcelaphini (hartebeest)


       

     Hippotragini (horse rams)



       

     Caprini (goat-like)







    Template: Klade / Maintenance / Style

    The impalas are a genus of the horned bearer family (Bovidae). Within the horn-bearers they belong to the subfamily of the Antilopinae and to their own tribe of the Aepycerotini . Their closest relatives are the goats ( Nesotragus ). The lyre-like, strongly ribbed horns, which are only developed in male individuals, as well as the lack of scent glands in the face, feet and in the groin area can be emphasized as special characteristics. Otherwise the animals largely resemble the other antelopes. Together with the genus Nesotragus , the Aepycerotini represent a relatively old group of Antilopinae. According to molecular genetic data, they separated from the other Antilopinae as early as the Middle Miocene , around 16 to 17 million years ago. The splitting of this common line into the goats and impalas took place in the transition to the Upper Miocene about 9 million years ago.

    The range of the Impalas is in eastern and southern Africa. Especially in the course of the 20th century, the animals were considered to belong to only one species , which was led under the scientific name Aepyceros melampus and which in turn was divided into several subspecies. The populations of eastern, southeastern and southern Africa formed a larger unit. They were commonly equated with the black heel antelope ( A. m. Melampus ), which in turn sometimes contained individual subpopulations ( A. m. Melampus from the southern, A. m. Johnstoni and A. m. Katangae from the southeast, and A. m . suara and A. m. rendilis from eastern Africa). Separated from this, the black-nosed impala ( A. m. Petersi ), which occurs endemically in the southwestern part of the continent, represented a separate taxonomic unit. This was sometimes viewed as a separate species by individual authors in the course of the first and second third of the 20th century.

    Several molecular genetic studies from the beginning of the 2000s then showed that the two main populations of Impalas could be clearly separated from each other. The impalas of eastern and southern Africa form a closer family group (black heel antelope), which differ from the animals of south-western Africa (black-nosed impala). In addition, in the Etosha National Park in Namibia , where the black-nosed impala occurs naturally, but the black-heeled antelope had been introduced by humans, no hybridization between the two forms was found. The genetic separation of the two groups was also confirmed by morphological analyzes. Based on these findings, Colin P. Groves and Peter Grubb then split the impalas into two species in their revision of the ungulate systematics from 2011. In further investigations, a certain genetic distance within the East and South African black heel antelopes could be shown.

    Internal systematics of the Impalas according to Lorenzen et al. 2006
     Aepyceros  

     Aepyceros petersi


      Aepyceros melampus  

     A. melampus (Eastern Africa)


       

     A. melampus (southern Africa)




    Template: Klade / Maintenance / Style

    According to today's view, the tribe and the genus are structured as follows:

    • Tribe Aepycerotini Gray , 1872
    • Genus Aepyceros Sundevall , 1847

    In addition to the two recent species, some fossils are also known:

    To some extent, with Aepyceros helmoedi distinction still a form that was based on Pleistocene finds from South Africa described the 1,932th A still unnamed species with extremely high-crowned teeth is from the Lake Victoria region.

    Tribal history

    The origin of the impalas is still unclear. They first appeared in fossil form in the transition from the Upper Miocene to the Lower Pliocene around 5 to 6 million years ago. The oldest evidence includes skull finds from Lothagam in western Kenya , which belong to the species Aepyceros premelampus . It differs from today's Impalas in that it has more simply structured horns, which probably lacked clear ribbing. Individual finds from the Hadar formation in the Afar region in Ethiopia date back to the Upper Pliocene . Among them are over 30 horn fragments of a large shape with almost the dimensions of today's black heel antelope. The finds were referred to Aepyceros afarensis . In the same region, stratigraphically but slightly higher, was found Aepyceros datoadeni , a small form of which one of the best preserved skulls of an extinct impala is present. From the Upper Pliocene site of Kanapoi in Kenya, horn fragments and remains of teeth have been described in a form that may correspond to Aepyceros afarensis . Laetoli in northern Tanzania, on the other hand, produced a rich collection of Impala remains consisting of horn remains, jaw fragments and isolated teeth. They represent a medium-sized form that was named Aepyceros dietrichi . Aepyceros shungurae was also a smaller representative and is passed down from Kobi Fora in northwestern Kenya , among others . The site belongs to the uppermost Pliocene. It is possible that the first evidence of black heel antelope came from here. However, since the found material is quite intermediate, this cannot yet be clearly confirmed. Further fossil remains of early representatives of today's species are from the Olduvai Gorge and Peninj in northern Tanzania and from Makapansgat in South Africa. They can all be assigned to the Lower Pleistocene . In the Upper Pleistocene , an impala appeared in the region around Lake Victoria , which had significantly higher-crowned teeth and a more massive lower jaw and was probably more adapted to grass forage.

    Research history

    Carl Jakob Sundevall

    Impalas were first mentioned scientifically in 1812 when Martin Hinrich Lichtenstein introduced the black heel antelope . He had observed the animals during his travels through southern Africa from 1803 to 1806 in what is now the South African province of North Cape . In its first description , Lichtenstein used the scientific name Antilope melampus . As a "black-footed antelope", Johann Christian von Schreber made the species known to a wider audience in the fifth part of his work The mammals in pictures from nature with descriptions from 1836. Carl Jacob Sundevall introduced the generic name Aepyceros , which is valid today, in 1845. Sundevall set the black heel antelope from other forms listed under the genus antelope . The name is of Greek origin and is made up of the words αἰπύς ( aipus ) for "high" or "steep" and κέρας ( kéras ) for "horn". The second species recognized today, the black-nosed impala , goes back to José Vicente Barbosa du Bocage . He defined it in 1879 based on two individuals from southwestern Angola.

    The exact systematic position of the impalas within the horn-bearers has long been under discussion. The Aepycerotini as a higher taxonomic unit of the Impala go back to John Edward Gray from 1872. Gray used the name Aepycerotidae, with which he distinguished the impalas from other horned bearers at the family level. Together with a dozen other families, he placed them in the superordinate group of Cavicornia ("hollow horns", an old term for those who bear horns, which is no longer valid today). Other researchers partially adopted and varied the classification scheme. Most of the hornbearers were downgraded to family status and the following taxonomic groups, including Gray's Aepycerotidae, were listed at the subfamily or tribe level. The type and number of subgroups incorporated within the hornbeams were very different. Philip Lutley Sclater and Oldfield Thomas defined seven subfamilies in their Book of Antelopes at the end of the 19th century and classified the impalas in the group of Antilopinae, which mainly included the gazelles. The impalas held a similar position in George Gaylord Simpson's taxonomic overview from 1945. He divided the hornbeams into five subfamilies with 13 branches. Simpson referred the Impalas to the subfamily of the Antilopinae and within this to the Antilopini. As a result, some of the leading zoologists of the time saw the impalas as being generally related to other gazelles and antelopes. Alan W. Gentry undertook a further attempt to classify the hornbeams based on skeletal anatomical characteristics in 1992. He came to a similar conclusion as Simpson, but differently assigned the impalas to the hartebeest . The view was later shared by other researchers. Only molecular genetic research methods revealed in the transition from the 20th to the 21st century that the horn-bearers are divided into two main lines, which are a bovine group on the one hand (cattle, buffalo and forest buck and their closer relatives) and on the other hand a non-bovine group (gazelles, Duiker, sheep and goats, reed and waterbuck, klipspringer, cow and roan antelopes as well as their close relatives). Both lines represent subfamilies (Bovinae and Antilopinae). According to genetic studies, the impalas belong to the Antilopinae and have a relatively basal position within them. The previously assumed closer relationship with the gazelles or hartebeest could not be confirmed.

    In the course of the history of research, other forms of impala have been described. Oldfield Thomas named Aepyceros melampus johnstoni in 1892 . The subspecies was based on two skulls from Zomba in Malawi . Thomas differed in shape from the black heel antelope due to its lighter construction with relatively shorter horns, the rings of which were also not as prominent. An impala form from the Zambezi region, named by Ludwig von Lorenz-Liburnau in 1894 as Aepyceros melampus holubi , is synonymous with A. m. johnstoni . The same year as Thomas had Matschie Strepsiceros suara defines an antelope representatives, he near the Großkudus saw and was distinguished by its finely designed horns. Matschie specified the Ugalla River in Tanzania as the distribution area. Only three years later, Matschie referred the species to the genus Aepyceros and recognized the greatest similarities to Thomas' A. m. johnstoni . By Einar Lönnberg again the name comes Aepyceros melampus rendilis which he coined in 1912 and their copies he himself had collected in East Africa. Compared to Matschies A. suara , Lönnberg emphasized its shape as being significantly darker and larger. With Aepyceros melampus katangae , Lönnberg introduced another form two years later from the Katanga region in the southeast of what is now the Democratic Republic of the Congo . He described this as even smaller than Thomas' Southeast African subspecies A. m. johnstoni . The validity of the individual subspecies varied over time. Also in 1914 Richard Lydekker put out two groups of shapes, in which he grouped the representatives with conspicuous facial stripes on the one hand and those without such a mark on the other. Only the black-nosed impala belongs to the former, to the latter all forms around the black heel antelope (according to Lydekker A. m. Melampus , A. m. Johnstoni , A. m. Rendilis , A. m. Suara and A. m. Katangae ).

    etymology

    The name "Impala" comes from the Zulu language , the emphasis is on the a in the middle (Imp a la). In his first description of the black heel antelope, Lichtenstein gave P'halla as the local name of the Batswana for the animals. Other common names derived from it that were used in the past are “Pala” or “Palla (h)”.

    Danger

    The greatest threats to the impala population are illegal hunting and the expansion of agricultural land. The animals are mainly used as a food resource and for trophy hunting. Due to its wide distribution, the IUCN classifies the total population as “not at risk” ( least concern ). In detail, the nature conservation organization sees the black heel antelope as not endangered, but the black-nosed impala as endangered. Both species are found in nature reserves.

    literature

    • Hervé Fritz and Mathieu Bourgarel: Aepyceros melampus Impala. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume VI. Pigs, Hippopotamuses, Chevrotain, Giraffes, Deer and Bovids. Bloomsbury, London 2013, pp. 480-487
    • Colin P. Groves and David M. Leslie Jr .: Family Bovidae (Hollow-horned Ruminants). In: Don E. Wilson and Russell A. Mittermeier (Eds.): Handbook of the Mammals of World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 444-779 (pp. 623-625)
    • JT du Toit: Ruminantia. In: JD Skinner and Christian T. Chimimba (Eds.): The Mammals of the Southern African Sub-region. Cambridge University Press, 2005, pp. 616-714 (pp. 702-707)

    Individual evidence

    1. ↑ a b c d e f g h i J. T. du Toit: Ruminantia. In: JD Skinner and Christian T. Chimimba (Eds.): The Mammals of the Southern African Sub-region. Cambridge University Press, 2005, pp. 616-714 (pp. 702-707)
    2. ↑ a b c d e f g h i j k l Colin P. Groves and David M. Leslie Jr .: Family Bovidae (Hollow-horned Ruminants). In: Don E. Wilson and Russell A. Mittermeier (Eds.): Handbook of the Mammals of World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 444-779 (pp. 623-625)
    3. ↑ a b c d e f g h i Hervé Fritz and Mathieu Bourgarel: Aepyceros melampus Impala. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume VI. Pigs, Hippopotamuses, Chevrotain, Giraffes, Deer and Bovids. Bloomsbury, London 2013, pp. 480-487
    4. ↑ a b c Henriette Oboussier: To the knowledge of the black heel antelope (Impala) Aepyceros melampus with special consideration of the cerebral furrow pattern and the pituitary gland. Results of the research trips to South Angola and East Africa. Journal for Morphology and Ecology of Animals 54, 1965, pp. 531-550
    5. ↑ a b c Alan William Gentry: Bovidae. In: Lars Werdelin and William Joseph Sanders (eds.): Cenozoic Mammals of Africa. University of California Press, Berkeley, Los Angeles, London 2010, pp. 741–796 (pp. 765–766)
    6. ↑ Mohamed Mostafa, Lee Martin Koma and Osman Ssengoba: Radiographic visualization of the metacarpus and phalanges in the impala (Aepyceros melampus). Veterinarski Arhiv 76 (1), 2006, pp. 75-83
    7. ↑ Wendy CH Green and Aron Rothstein: Translocation, Hybridization, and the Endangered Black ‐ Faced Impala. Conservation Biology 12 (2), 1998, pp. 475-480, doi: 10.1111 / j.1523-1739.1998.96424.x
    8. ↑ a b Eline D. Lorenzen and Hans R. Siegismund: No suggestion of hybridization between the vulnerable black ‐ faced impala (Aepyceros melampus petersi) and the common impala (A. m. Melampus) in Etosha National Park, Namibia. Molecular Evolution 13 (10), 2004, pp. 3007-3019
    9. ↑ Tammie K. Matson, Anne W. Goldizen, Peter J. Jarman and Anthony R. Pople: Dispersal and seasonal distribution of black-faced impala in the Etosha National Park, Namibia. African Journal of Ecology 44, 2006, pp. 247-255
    10. ↑ Torsten Wronsky: Feeding ecology and foraging behavior of impala Aepyceros melampus in Lake Mburo National Park, Uganda. African Journal of Ecology 40, 2002, pp. 205-211
    11. ↑ M. Sponheimer, CC Grant, DJ de Rutter, JA Lee-Thorp, DM Codron and J. Codron: Diets of Impala from Kruger National Park: evidence from stable carbon isotopes. Koedoe 46 (1), 2003, pp. 101-106
    12. ^ N. Fairall: Prenatal development in of the Impala Aepyceros melampus. Light. Koedoe 12, 1969, pp. 97-103
    13. ↑ a b c Juan P. Zurano, Felipe M. Magalhães, Ana E. Asato, Gabriel Silva, Claudio J. Bidau, Daniel O. Mesquita and Gabriel C. Costa: Cetartiodactyla: Updating a time-calibrated molecular phylogeny. Molecular Phylogenetics and Evolution 133, 2019, pp. 256-262
    14. ↑ a b c Alexandre Hassanin and Emmanuel JP Douzery: The Tribal Radiation of the Family Bovidae (Artiodactyla) and the Evolution of the Mitochondrial Cytochrome b Gene. Molecular Phylogenetics and Evolution 13 (2), 1999, pp. 227-243
    15. ↑ a b M. V. Kuznetsova and MV Kholodova: Revision of Phylogenetic Relationships in the Antilopinae Subfamily on the Basis of the Mitochondrial rRNA and β-Spectrin Nuclear Gene Sequences. Doklady Biological Sciences 391 (1-6), 2003, pp. 333-336
    16. ^ Eva V. Bärmann and Tim Schikora: The polyphyly of Neotragus - Results from genetic and morphometric analyzes. Mammalian Biology 79, 2014, pp. 283-286
    17. ↑ Jonathan Kingdon: Tribe Aepycerotini Impala. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume VI. Pigs, Hippopotamuses, Chevrotain, Giraffes, Deer and Bovids. Bloomsbury, London 2013, pp. 477-479
    18. ↑ Alexandre Hassanin, Frédéric Delsuc, Anne Ropiquet, Catrin Hammer, Bettine Jansen van Vuuren, Conrad Matthee, Manuel Ruiz-Garcia, François Catzeflis, Veronika Areskoug, Trung Thanh Nguyen and Arnaud Couloux: Pattern and timing of diversification of Cetartiodactalia, Lauriala (Mammia ), as revealed by a comprehensive analysis of mitochondrial genomes. Comptes Rendus Palevol 335, 2012, pp. 32-50
    19. ↑ Fayasal Bibi: A multi-calibrated mitochondrial phylogeny of extant Bovidae (Artiodactyla, Ruminantia) and the importance of the fossil record to systematics. BMC Evolutionary Biology 13, 2013, p. 166
    20. ↑ Don E. Wilson and DeeAnn M. Reeder: Mammal Species of the World . Johns Hopkins University Press, Baltimore, 2005 ISBN 0-8018-8221-4 ( [1] )
    21. ↑ a b C. Bastos-Silveira and AM Lister: A morphometric assessment of geographical variation and subspecies in impala. Journal of Zoology 271 (3), 2007, pp. 288-301
    22. ^ Eugene Jaubert: Observations on the habitat preferences and population dynamics of the Black-faced impala Aepyceros petersi Bocage, 1875 in South West Africa. Madoqua Ser. 1 3, 1971, pp. 55-65
    23. ↑ Louise Gray Listeners Ting and Peter Arctander: Phylogeography and conservation of impala and kudu greater. Molecular Ecology 10 (3), 2001, pp. 711-719, doi: 10.1046 / j.1365-294x.2001.01205.x
    24. ^ A b Colin Groves and Peter Grubb: Ungulate Taxonomy. Johns Hopkins University Press, 2011, ISBN 978-1-4214-0093-8 , pp. 1-317 (pp. 108-280)
    25. ↑ a b Eline D. Lorenzen, Peter Arctander and Hans R. Siegismund: Regional Genetic Structuring and Evolutionary History of the Impala Aepyceros melampus. Journal of Heredity 97 (2), 2006, pp. 119-132, doi: doi: 10.1093 / jhered / esj012
    26. ↑ Patrick Schwab, Paul V. Debes, Thorsten Witt, Günther B. Hartl, San San Hmwe, Frank E. Zachos and J. Paul Grobler: Genetic structure of the common impala (Aepyceros melampus melampus) in South Africa: phylogeography and implications for conservation. Journal of Zoological Systematics and Evolutionary Research 50 (1), 2012, pp. 76-84, doi: 10.1111 / j.1439-0469.2011.00638.x
    27. ↑ a b Denis Geraads, Stephanie Melillo and Yohannes Haile-Selassie: Middle Pliocene Bovidae from Hominid-bearing sites in the Woranso-Mille area, Afar region, Ethiopia. Palaeontologia Africana 44, 2009, pp. 59-70
    28. ^ A b Alan William Gentry: Bovidae. In: T. Harrison (Ed.): Paleontology and Geology of Laetoli: Human Evolution in Context. Volume 2: Fossil Hominins and the Associated Fauna. Springer Science + Business Media, 2011, pp. 363–465 (pp. 375–379)
    29. ↑ a b Denis Geraads, René Bobe and Kaye Reed: Pliocene Bovidae (Mammalia) from the Hadar formation of Hadar and Ledi-Geraru, Lower Awash, Ethiopia. Journal of Vertebrate Paleontology 32 (1), 2012, pp. 180-197
    30. ↑ a b J. Tyler Faith, Christian A. Tryon, Daniel J. Peppe, Emily J. Beverly and Nick Blegen: Biogeographic and Evolutionary Implications of an Extinct Late Pleistocene Impala from the Lake Victoria Basin, Kenya. Journal of Mammalian Evolution 21 (2), 2013, pp. 213-222
    31. ↑ Fayasal Bibi, Maia Bukhsianidze, Alan W. Gentry, Denis Geraads, Dimitri S. Kostopoulos and Elisabeth S. Vrba: The Fossil Record and Evolution of Bovidae: State of the Field. Palaeontologia Electronica 12 (3), 2009, p. 10A ( PDF )
    32. ↑ Denis Geraads, René Bobe and Fredrick Kyalo Manthi: New ruminants (Mammalia) from the Pliocene of Kanapoi, Kenya, and a revision of previous collections, with a note on the Suidae. Journal of African Earth Sciences 85, 2013, pp. 53-61
    33. ↑ Alan William Gentry and Anthea Gentry: Fossil Bovidae (Mammalia) of Olduvai Gorge, Tanzania, Part 1. Bulletin of the British Museum (Natural History) 29, 1977–1978, pp. 289–446 (p. 416) ( [2 ] )
    34. ^ LH Wells and BS Cooke: Fossil Bovidae from the Limeworks quarry, Makapansgat, Potgietersus. Palaeontologia Africana 4, 1957, pp. 1-55 (pp. 36-37)
    35. ↑ J. Tyler Faith: Late Pleistocene and Holocene mammal extinctions on continental Africa. Earth-Science Reviews 128, 2014, pp. 105-121
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    38. ^ Carl Jakob Sundevall: Methodisk öfversigt af Idislande djuren, Linnés Pecora. Kongl. Svenska vetenskapsakademiens handlingar series 3, 32–33, 1844–1845, pp. 267–330 (p. 271) ( [6] )
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    46. ↑ Malcolm C. McKenna and Susan K. Bell: Classification of mammals above the species level. Columbia University Press, New York 1997, pp. 1-631 (p. 450)
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