Prong bracket

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Prong bracket
Male pronghorn (Antilocapra americana)

Male pronghorn ( Antilocapra americana )

Systematics
Order : Artiodactyla (Artiodactyla)
Subordination : Ruminants (ruminantia)
without rank: Forehead weapon bearer (Pecora)
Family : Fork horn carrier
Genre : Antilocapra
Type : Prong bracket
Scientific name of the  family
Antilocapridae
JE Gray , 1866
Scientific name of the  genus
Antilocapra
Ord , 1818
Scientific name of the  species
Antilocapra americana
( Ord , 1815)
Male pronghorn in Yellowstone National Park

The fork block ( Antilocapra americana ) also known as Gabelhorn antelope , antelope , Gabelhorn animal , Gabelhorn carrier or Pronghorn known, is a North American ruminants the prairie . Although his form to the antelopes reminiscent of Africa and Asia, he does not belong to the family of Bovidae . He forms the today monotypical family of the fork-horned bearers (Antilocapridae) as their only living representative today.

features

Habitus

The pronghorn is about the size of a fallow deer . It has a head body length of up to 150 centimeters (the tail is 8 to 15 cm long), a body height of 90 centimeters and a weight of 50 to 70 kilograms. The males are slightly larger than the females ( sexual dimorphism ). The fur is yellow to red-brown on the upper side and white to the flanks on the underside; white bands are also found on the front of the neck and around the mouth. The males also have black markings on their face and neck. A pronghorn can straighten its body hair. By putting up the white trunk hair, he gives a signal that is visible from afar, which is perceived as a warning in a herd.

The sexes can also be distinguished by the horns. In the male, they can be up to 25 cm long (usually they are twice as long as the ears) and fork into a short end pointing forward and a long end pointing upwards and slightly bent back - their German name is derived from this property . Females often have no horns at all; if so, then these are never longer than the ears.

Among the sensory organs of the pronghorn, the eye is of the greatest importance. Due to the position of the eyes on the sides of the head, a fork bracket has the possibility of observing a field of vision of almost 360 °. Hearing and smell are of slightly less importance, but both are nonetheless well developed. The ears can be set up and turned in different directions. The nose plays a role, above all, when recognizing territorial boundaries.

In contrast to other even-toed ungulates, the dewclaws are completely absent , so the limbs only carry the third and fourth toes.

Clevis trees are characterized by their extraordinary bounce. You can jump forward up to six meters with a single jump.

Skull and dentition features

Pronghorn head and horns

The prong bracket has a reduced set of teeth: in the lower jaw there are 3 incisors , 1 canine , 3 premolars and 3 molars per jaw half , while the incisors and canines are missing in the upper jaw. The tooth formula is thus , a total of 32 teeth are formed. The lower incisors have a spatula-like shape, similarly to the canine tooth ( incisiform ). The molars are generally high-crowned ( hypsodont ) and have a crescent-shaped ( selenodont ) enamel pattern on the chewing surfaces . Particularly noteworthy is the high crown, which in some cases exceeds that of the specialized grazers among cattle .

horns

The horns that start directly above the eye window are a specialty . Like those of the horns , they consist of a bony base (shaft) that is coated with keratin (horn sheath). The horn shaft does not fork itself in today's fork bracket, only the keratin coating forms the two horn tips. Every year the horn sheaths are changed after the rut from around October. Only the bone cones remain for life, while the horny sheath detaches and falls to the ground. At this point in time, new horn mass has already formed underneath, which is still covered with a furry coating. The annual growth of the keratin coating is completed after around ten months. In this respect the pronghorn resembles the deer , who change their antlers annually, but differs markedly from the horn-bearers, in which the horn sheath is not exchanged. Fossil representatives of the forked horns had partly very complex horns with several or multiple forked or twisted shafts. It is unclear here whether the horn sheath was also worn annually. Some experts see this as a special feature of the pronghorn living today. The earliest fork-horn carriers still had skin-covered horns, which was demonstrated by the presence of blood tubules on the horn shafts.

distribution

Distribution area of ​​the pronghorn
Two pronghorn females

The pronghorn developed in the grasslands of North America and was once widespread across the prairie and also in the deserts and semi-deserts of the southwestern United States and northwestern Mexico . He prefers regions with a wide field of vision and a mosaic-like vegetation of open steppe and herbaceous landscapes. Originally spread over large areas of the Great Plains up to the Saskatchewan River in the north, it has been pushed back into higher mountain regions of the western continental part since the colonization of North America by the Europeans. In the Rocky Mountains it occurs up to an altitude of 3350 m. In general, the pronghorn avoids more closed landscapes ( see also: threats and protection ).

Way of life

Pronghorns can be active at all times of the day and night, but are mostly active during twilight. Where the circumstances make it necessary, they conduct seasonal hikes, which can lead over distances of up to 260 kilometers. This is necessary, for example, in deserts to look for watercourses, or in rocky areas that do not have sufficient food supply in winter. The most extensively studied hikes lead from Grand Teton National Park over the Gros Ventre Range to the upper reaches of the Green River in Wyoming .

In summer older males become loners and try to fight for territory. In this they gather a harem around them. A territory can cover four square kilometers and is marked by urine and thus marked out. The male is now busy preventing other males from entering and females from leaving the territory. When two males meet, threatening gestures with loud screams and sham attacks are usually sufficient to decide between winners and losers. If a fight does occur, the sharp-edged horns can cause serious injury and even death.

In autumn and winter all the small associations with solitary males join together to form large herds, which in historical times could contain several tens of thousands of animals, but today consist of little more than 1000 animals at most.

Prong-jack herd

Younger males who cannot fight yet come together in small associations; old males who have become too weak to fight remain solitary and try to avoid the territories of their conspecifics. The females live in groups of around 20 animals. After a gestation period of eight and a half months, the female separates from the herd and gives birth to one or two, very rarely three, young with a birth weight of around three kilograms. These initially have a gray coat, which after three months takes on the typical colors of the old animals. They are kept in hiding for the first three days, and after about a week young pronghorns can run on their own. Although they start eating grass after three weeks, they will be suckled for another five to six months. The females reach sexual maturity at 15 to 16 months, the males at around 24 months.

Prong braces have a short life expectancy and rarely get older than ten years, even under favorable circumstances.

nutrition

The pronghorn is very picky about its food behavior. In general, it feeds on various plants, especially herbs, leaves, sprouts and grasses. Often an animal only spends a relatively short time, around half a minute, on a food resource. The pronghorn prefers grass, especially in spring and early summer, while it eats leaves on perennials in autumn and winter. Artemisia plants are particularly important here . In arid landscapes, cacti also form part of the nutritional basis.

speed

While running, fork jacks can reach speeds of 60 to 70 km / h; Based on measured stride lengths, a speed of 86.5 km / h was even assumed. Such high speeds can be maintained over a distance of up to five kilometers. They can cover a distance of 11 kilometers in 10 minutes at an average speed of 65 km / h. The animals are therefore more likely to be long-distance runners than sprinters. The physical adaptation to such speeds consists not only in the slim physique and strong legs, but also in an enlargement of the lungs and heart - the heart of a pronghorn is about twice as big as that of a domestic sheep . Other adjustments include, for example, an increased number of mitochondria per muscle volume. It is such reinforcements of general mammalian structures - and not the development of new structures - that enable the pronghorn to absorb and utilize a higher proportion of oxygen from the air it breathes than would be expected for a mammal of its size.

One often comes across the statement that pronghorns are the fastest mammals in the world after the cheetah . But here the question is whether the maximum or the average speed is meant. Some African-Asiatic antelopes, such as the stag goat antelope , can reach the same speed over very short distances . However, pronghorns are the fastest mammals on the American double continent and, measured over a distance of five kilometers, probably the fastest mammals at all.

Natural enemies

The wolf , coyote and puma are the main natural enemies of the pronghorn . Due to the speed of their prey, however, these usually only tear young, old or sick individuals. By means of targeted kicks with the rear hooves, fork jacks try to defend themselves against the attackers, which is often successful, especially with coyotes. The main weapon against predators , however, is their speed. In addition to these natural enemies, however, humans also pose a great threat to the pronghorn.

The original natural enemies included the cheetah Miracinonyx trumani , the lion Panthera atrox and possibly the short-faced bear . Since the maximum speed of 86 km / h is far higher than necessary to escape today's hunters, it was partly assumed that the fork bracket developed its good running properties due to adjustments by Miracinonyx . This presumed example of a coevolution in the predator-prey relationship (also known as the Red Queen hypothesis ) cannot be proven in the opinion of numerous scientists: While the earliest representatives of the fork-horned carriers from the early Miocene on about 20 million years ago for anatomical reasons as extremely fast runners are to be seen, the oldest record of the cat in North America comes from the end of the Pliocene .

Systematics and evolution

Taxonomy

Internal systematics of the recent cetartiodactyla according to Zurano et al. 2019
 Cetartiodactyla  
  Suina (pig-like)  

 Tayassuidae (umbilical pigs)


   

 Suidae (real pigs)



   

 Camelidae (camels)


   
 Cetancodonta  

 Hippopotamidae (hippos)


   

 Cetacea (whale)



 Ruminantia (ruminant)  

 Tragulidae (deer piglets)


  Pecora (forehead weapon bearer)  

 Antilocapridae


   

 Giraffidae (giraffes)


   

 Cervidae (deer)


   

 Moschidae (musk deer)


   

 Bovidae (hornbeam)










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The Gabelbock is as a separate type and monotypic genus Antilocapra the ruminants (Ruminantia) within the cloven- associated (Artiodactyla). There it also forms the family of the fork-horned species (Antilocapridae). For a long time, the closer relationship of the fork jack was completely unclear. Although it was placed in its own family at an early stage, some authors considered it to be part of the horned bearers (Bovidae) until the 1980s, where it was assigned to its own subfamily Antilocaprinae. On the basis of morphological data, the pronghorn was originally classified as a sister species of the deer (Cervidae), mainly due to the structure of the tear bone , which is similar in the two groups and differentiates them from all other cloven-hoofed animals. Genetic studies, on the other hand, suggested a sister group relationship between the musk deer (Moschidae) and the deer, while the pronghorn was no longer related to the deer. Karyological analyzes showed that the pronghorn with its genome consisting of 58 chromosomes represents a comparatively original state within the forehead weapon bearer (Pecora). Although the giraffes ( Giraffa ) with only 30 chromosomes have numerous mergers in the genome, a close relationship between these two taxa is assumed at the base of the Pecora. The structure of the X chromosome indicates that the pronghorn could be the sister species of the giraffes, alternatively they represent - as shown here in the cladogram - the sister species of all other Pecora. The shift of the Antilocapridae to the base of the forehead weapon bearers shows that the formation of the keratin- coated, bony horns is a real convergent and not just parallel development to the horns of the bovids. In addition, the Antilocapridae and thus also the pronghorn play a key role in understanding the development of the forehead weapons in ruminants.

Internal systematics of the Antilocapridae according to Semperbon et al. 2007 and Davis 2007 (not complete)
 Antilocapridae  

 Paracosoryx


   
 Ramocerotini  

 Meriamoceros


   

 Ramoceros



   

 Merycodus


   

 Cosoryx


  Antilocaprinae  


 Proantilocapra


   

 Osbornoceros



   
 Ilingocerotini  

 Plioceros


   

 Sphenophalos


   

 Ilingoceros




   
 Antilocaprini 

 Texoceros


   

 Antilocapra



  Stockocerotini  


 Hayoceros


   

 Stockoceros


   

 Hexameryx


   

 Hexobelomeryx





   

 Capromeryx


   

 Tetrameryx











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Today the fork horns represent a monotypical family with the pronghorn as the only member. Fossil, however, at least 20 genera with a total of around 60 species are known, all of which come from North America . The phylogenetic predecessor of the Antilocapridae is unknown, but is likely to be found in Asiatic cloven-hoofed animals of the Oligocene . The distinction between the individual members of the fork horns is mainly based on the differently designed horn shafts, less on the anatomical features of the skull and skeleton. Since the last revision of the family took place in 1937, a new one is called for, which should be carried out at the genus and species level and which should also include features of the skeleton and skull structure.

The family is divided into two main lines. On the one hand belong the smaller "Merycodontinae", which weighed only 7 to 10 kg, but possibly represent a paraphyletic subfamily. In addition to their generally smaller body size, they are characterized by narrower and round horn shafts with one or more bony ridges or rings at the base, by the presence of the upper canine teeth and by rudimentary, lateral toes on the front feet. They occurred mainly in the Lower Miocene to the beginning of the Upper Miocene, about 20.6 to 10.3 million years ago. The latest forms overlap somewhat with the Antilocaprinae , the phylogenetically younger group with averagely larger animals (30 to 80 kg) that first appeared in the Middle Miocene around 15 million years ago. Their special features include laterally flattened horn shafts without basal ridges, a keratin sheath around the horns, high-crowned teeth and missing side rays on the front feet. In addition, the metapodia are clearly elongated and are reminiscent of those of the deer . There are also some lines of development within the Antilocaprinae. For example, the put Ilingocerotini forms is with twisted horns removed to those of Kudus remember. The Stockocerotini in turn denote four to six bony horn shafts that grow above the orbit . The antilocaprini are represented by the pronghorn. Its closest related genus is Texoceros , which, in contrast to the pronghorn , has a forked bony horn shaft. Within the genus Antilocapra , Antilocapra pacifica is the sister species , which was described in 1991 on the basis of several horn shafts and skull fragments. These were found in Contra Costa County in the US state of California , but they can only be dated generally to the Pleistocene . The representatives of this species reached about the size of today's fork jack, but had more pronounced horns.

Depending on the doctrine, four to six subspecies of today's pronghorn can be distinguished, of which the status of the following four is undisputed:

The Antilocapra americana anteflexa and Antilocapra americana oregona, which are sometimes also listed as subspecies, are probably synonyms of the subspecies Antilocapra americana americana . The first description of the species was in 1815 by George Ord as Antilope americanus based on individuals from the plains and the highlands along the Missouri River in the United States. In 1818 Ord also established the genus Antilocapra and assigned this to Antilocapra americana as a type species.

Tribal history

Ramoceros skeleton

The fork-horned family, once rich in species, first appeared in the Lower Miocene around 20 million years ago in the grass and savannah landscapes of western North America. The animals were already relatively well developed; There is no evidence of phylogenetic predecessors. As graceful and relatively long-legged animals, they were adapted to the open landscapes from the start and represented fast-moving ( cursorial ) animals. First, the small "Merycodontinae" appeared, whose horns were still covered with skin. The earliest known representative was Paracosoryx with a very long, forked horns. Other early forms are represented by Meriamoceros , which had short horns formed into small shovels at the top. Ramoceros , which only disappeared 10 million years ago and had multi-forked horns similar to the antlers of the deer , was quite successful . This was partly asymmetrical, so that one side was longer than the other. The type form of the early Antilocapridae represented Merycodus , whose specialty is a forked horn shaft with two rungs of equal length. Since slightly more than half of the skulls found are hornless, scientists assume that female animals did not have horns. As one of the first representatives of the fork horn carriers, Merycodus is also proven in the northern part of today's Mexico . Despite their occurrence in open landscapes, the early fork-horn carriers largely fed on a mixed vegetable diet.

Live reconstruction of Osbornoceros

In the Middle Miocene, around 15 million years ago , the first representatives of the Antilocaprinae with keratin-coated horns, Plioceros , a short-necked animal with very broad and short horns, were found . Plioceros was still relatively small, but already had extremely high-crowned teeth. It is also one of the most widespread members of the fork-horned group and has been handed down from the west coast of the North American continent to Florida on the east coast. Another important find area is the Ash Hollow Formation in the Midwest. In the Upper Miocene and in the Pliocene the Antilocaprinae reached their greatest diversity, at that time they are known with 9 genera and 30 species. Osbornoceros from the Upper Miocene looked similar to today's pronghorn , but had rather twisted horns. He was still one of the first representatives to eat harder grass.

Skeletal reconstruction of Capromeryx

In the course of the Pliocene the decline of the forked horns slowly began. However, at that time, the Stockocerotini, a group of stocky animals that adapted to the Ice Age climate and represent a now-extinct sideline, appeared. The oldest representative, however, was Hexameryx , which was characterized by six widely diverging horn shafts, three on each side of the head, but is only known from the Upper Miocene of Florida. Capromeryx is also a form that is characterized by a marked reduction in body size. The two horn shafts on each side of the head were very close to one another and, according to studies, were probably surrounded by a layer of keratin. Here is one Capromeryx to the frequently discovered Gabelhorn carriers both in the United States today and in neighboring Mexico. In the same line of development, Hexobelomeryx and Hayoceros belong to the most highly adapted grass-eaters within the fork-horned species. The Stockoceros , which gave the group its name , had a total of four equally long horn shafts, which were worn by both sexes, and fewer hypsodontal molars; it remained largely with the mixed vegetable diet. In addition, Stockoceros is one of the latest representatives of the fossil fork-horn carriers and appeared around the same time as the first members of today's genus Antilocapra . 7 partial skeletons, 55 skulls and almost 800 other skeletal remains are known of this fossil genus from Papago Springs Cave near Sonoita in Arizona . While all these species became extinct at the end of the Last Ice Age, the pronghorn, which had already existed in the Pleistocene, was the only one to survive.

People and pronghorns

Significance of the pronghorn for the Indians

For the Indians of the prairie , fork jacks were valuable sources of meat. Since they were an extremely common game - in 1800 there were around 40 million individual animals on the prairie - they often played a major role in everyday Indian life. The Western Shoshone knew a ceremonial pronghorn hunt initiated by a shaman . Like bison hunting , pronghorn hunting had a religious dimension. One group of hunters drove the animals into the hands of a second group of hunters with the help of a fire, in the direction of a river or in a previously prepared corral, a catchment for wild animals. The Northern Shoshone, on the other hand, put on the skins of fork jacks and stalked as close as possible to a herd, camouflaged. Even after the horse was available, pronghorn hunting was a demanding challenge, as pronghorns can run faster than horses.

The Lakota coveted the pronghorn not only for their meat, but also for their skins, which they liked to use to make clothes. However, the Native Americans were unable to significantly affect the existence of the pronghorn with their hunting methods.

Modern developments, threats and protection

The pronghorn was unknown to the European colonists for a long time until the species was described by Lewis and Clark on their expedition (1804-1806). At that time the grasslands of the North American West were abundant with large game such as bison and pronghorn.

After the large-scale colonization of North America by white settlers, the fate of the fork jack was similar to that of the American bison . They were initially shot for their furs and flesh, later only for sport or pleasure. Travelers shot thousands of fork jacks from moving trains along the railway lines, the carcasses of which were decaying on both sides of the railway lines. By 1920 the number of animals had fallen to only 20,000 animals due to uncontrolled hunting. Only then were protective measures issued, which is why there are now a million pronghorns in the USA and Canada again , so that the species as a whole is not considered endangered.

In Mexico , on the other hand, the population has never been able to recover. Even today there are only a little more than 1000 animals there. Logically, the international organization for the coordination of nature conservation ( IUCN ) lists the two Mexican subspecies as threatened. These are the Sonoran pronghorn ( A. a. Sonoriensis ) and the Baja California pronghorn ( A. a. Peninsularis ). The latter is only native to the Baja California peninsula and is listed as critically endangered.

Pronghorns are susceptible to some major cloven-hoofed infectious diseases . In this way, they form a pathogen reservoir for malignant catarrhal fever , BVD / MD and Epizootic Hemorrhagic Disease (EHD). There is also a high sensitivity to anthrax , rabies and various parasitoses.

Pronghorns in the zoo

As a contribution to safeguarding the population, fork jacks are also kept as zoo animals . Their fearfulness and their tendency to panic when dealing with people represent a particular animal care problem. If the escape distance is not reached, the animals often react with an uncompromising attack, which can be dangerous due to the effectively used horns. Any use of restraint can lead to self-traumatization or stress myopathy . Physical examinations can therefore only be carried out under sedation or anesthesia . An effective anesthetic can only be achieved with highly potent anesthetics of the morphine type . Pronghorns are difficult to socialize with other ungulate species in the zoo, and even integrating hand-reared males can lead to conflicts due to their aggressiveness. The natural jumping and swimming ability of the fork jacks must also be taken into account when setting up the enclosure. Unlike in the wild, the life expectancy of animals in captivity is up to 17 years.

literature

  • Heinrich Weidinger: Pronghorn, the North American antelope . Weidinger, Fürth, 1995, ISBN 3-00-005546-0
  • John A. Byers: Built for Speed. A Year in the Life of Pronghorn . Harvard University Press, Cambridge Mass, 2003, ISBN 0-674-01142-2
  • Gary Turbak: Pronghorn. Portrait of the American Antelope . Northland Publishing, Flagstaff (Arizona), 1995, ISBN 0-87358-595-X
  • Valerius spirit ; Michael H. Francis (photographer): Antelope Country: Pronghorns - The Last Americans , Krause Publications 2001, ISBN 978-0-87349-279-9

Web links

Commons : Antilocapra americana  - album with pictures, videos and audio files

Individual evidence

  1. a b c d e Bart W. O'Gara: Antilocapra americana. Mammalian Species 90, 1978, pp. 1-7
  2. a b c J. A. Byers: Antilocapridae. 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. 780-787
  3. a b c d e f g h i Edward Byrd Davis: Family Antilocapridae. In: Donald R. Prothero and Scott E. Foss (Eds.): The Evolution of Artiodactyls. Johns Hopkins University, Baltimore, 2007, pp. 227-240
  4. Bart W. O'Gara and Gary Matson: Growth and Casting of Horns by Pronghorns and Exfoliation of Horns by Bovids. Journal of Mammalogy 56 (4), 1975, pp. 829-846
  5. Hall Sawyer, Fred Lindzey and Doug McWhirter: Mule Deer and Pronghorn migration in Western Wyoming. Wildlife Society Bulletin 33 (4), 2005, pp. 1266-1273 ISSN  0091-7648
  6. Joel Berger, Steven L. Cain, K im Murray Berger: Connecting the dots: an invariant migration corridor links the Holocene to the present . In: Biology Letters , 2006 2, pp. 528-531. doi: 10.1098 / rsbl.2006.0508
  7. ^ A b c d John Byers: American Pronghorn: Social Adaptations and the Ghosts of Predators Past. Chicago University Press, 1998, pp. 1–300 (pp. 10–14) ISBN 978-0226086996 ( [1] )
  8. a b Milton Hildebrand and George E. Goslow: Comparative and functional anatomy of the vertebrates . Springer-Verlag, Berlin Heidelberg 2004, p. 623.
  9. a b c James R. Heffelfinger, Bart W. O'Gara, Christine M. Janis and Randall Babb: A bestiary of ancestral Antilocaprids. Proceedings of the 20th Biennial Pronghorn Workshop 20, 2004, pp. 87-111
  10. 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
  11. a b c Don E. Wilson & DeeAnn M. Reeder (eds.): Antilocapra americana . in Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed).
  12. a b M. V. Kuznetsova, MV Kholodova, AA Danilkin: Molecular Phylogeny of Deer (Cervidae: Artiodactyla). Russian Journal of Genetics 41 (7), 2005; Pp. 742-749.
  13. Manuel Hernández Fernández and Elisabeth S. Vrba: A complete estimate of the phylogenetic relationships in Ruminantia: a dated species-level supertree of the extant ruminants. Biological Reviews 80, 2005, pp. 269-302
  14. Halina Cernohorska, Svatava Kubickova, Olga Kopecna, Anastasia I. Kulemzina, Polina L. Perelman, Frederick FB Elder, Terence J. Robinson, Alexander S. Graphodatsky, Jiri Rubes: Molecular cytogenetic insights to the phylogenetic affinities of the giraffe (Giraffa camelopardalis ) and pronghorn (Antilocapra americana). Chromosome Research 21, 2013; Pp. 447-460 doi : 10.1007 / s10577-013-9361-0
  15. a b c d e Gina M. Semperbon and Florent Rivals: Was grass more prevalent in the pronghorn past? An assessment of the dietary adaptations of Miocene to Recent Antilocapridae (Mammalia: Artiodactyla). Palaeogeography, Palaeoclimatology, Palaeoecology 253, 2007, pp. 332-347
  16. ^ Gary D. Richards and Monte L. McCrossin: A new species of Antilocapra from the Late Quaternary of California. Geobios 24 (5), 1991, pp. 623-635
  17. ^ E. Jiménez-Hidalgo, O. Carranza-Castañeda and M. Montellano-Ballesteros: A Pliocene record of Capromeryx (Mammalia: Antilocapridae) in México. Journal of Paleontology 78 (6), 2004, pp. 1179-1186
  18. ^ S. David Webb: Pliocene Pronghorns of Florida. Journal of Mammalogy 54 (1), 1973, pp. 203-221
  19. ^ Richard S. White Jr. and Gary S. Morgan: Rancholabrean Tramperos Creek Fauna, Union County, New Mexico, with a review of the occurence and paleobiology of Capromeryx in the Rancholabrean of New Mexico. New Mexico Museum of Natural History and Science, Bulletin 53, 2011, pp. 641-651
  20. Victor M. Bravo-Cuevas, Eduardo Jiménez-Hidalgo, Miguel A. Cabral-Perdomo and Jaime Priego-Vargas: Taxonomy and paleobiological notes of the late Pleistocene (Rancholabrean) antilocaprids (Mammalia, Artiodactyla, Antilocapridae) from the state of Hidalgo, central Mexico. Revista Mexicana de Ciencias Geológicas 30 (3), 2013, pp. 601-613
  21. Florent Rivals and Gina M. Semprebon: A comparison of the dietary habits of a large sample of the Pleistocene pronghorn Stockoceros onusrosagris from the Papago Springs Cave in Arizona to the modern Antilocapra americana. Journal of Vertebrate Paleontology 26 (2), 2006, pp. 495-500
  22. ^ Morris F. Skinner: The fauna of Papago Springs Cave, Arizona and a study of Stockoceros with three new antilocaprines from Nebraska and Arizona. Bulletin of the American Museum of Natural History 80, 1942, pp. 143-220
This version was added to the list of excellent articles on November 3rd, 2004 .