Proboscidea

Asian Elephant

• Africa, Asia, Europe, North and South America

The order of Proboscidea ( Proboscidea ) was named after the most prominent feature, the trunk (Latin proboscis ), named. Your only still living representatives are the elephants.

• 4.1 Evolutionary Trends
• 4.2 Getting Radiation
• 4.3 Second Radiation
• 4.4 Third Radiation

Features

Generally

The Russell animals differ not only by the distinctive snout, but also by their body type and their characteristic dentition ( tusks or large molars ) from all other land mammals. Particularly striking is the trunk formation, which was initially scarce. Later the trunk, which is in present-day animals from up to 150,000 longitudinal, circular or oblique muscle fibers of a variety of different muscles developed to a sensitive prehensile organ, which on higher trees also enabled the achievement of the leaves as the tearing of tufts of grass in the steppes.

Skull and Skeleton

Particular skeletal anatomical features are the columnar limbs perpendicular under the body, wherein the upper and lower parts of the limbs at an angle of 180 °. This distinguishes the trunk of animals a number of other mammals, which legs are arranged at a slight angle. The clear vertical position, which may have been already fully formed in the Eocene, thereby supporting the enormous weight gain of the early members of this order. Furthermore, the long bones have no marrow cavity, but the room is filled with cancellous bone, which the legs are a greater strength. The blood formation takes place in the interstices. Another special feature on the feet have proboscids a sixth " toe " of each attaches behind the thumb or the big toe and is made of cartilage material that is partially ossified. It serves to support the other toes in the stabilization of high body weight. He is detectable even at the Deinotherien and goes so back to the early Miocene. The development of this anatomical peculiarity is due to the enormous increase in body size proboscids together in that time, which is connected with the purely terrestrial departure from the more amphibious lifestyle of the early Probodscidea representatives towards a.

Another special feature on the very large head of mammoths, whose skull roof is made of air-filled cavities. This honeycomb -shaped cavities separated by a thin bone plate, not only reduce the weight of the entire skull, but at the same time enabled an enormous increase in volume of the skull surface. This volume increase was necessary in order to ensure on the one hand, the powerful neck muscles to hold the head, including the evolutionary growing tusks, on the other hand also to the strong jaw muscles for the massive lower jaw to serve as a starting surface. The development of such air-filled skull began phylogenetically very early in the trunk animals and, in some representatives already in the Oligocene, possibly also detected already in the late Eocene.

Teeth

The original permanent tusker teeth still had complete dentition of the relatively ancient tertiary mammals with three incisors, one canine, four premolars and three molars each pine bough. In the course of phylogenetic evolution, the number of teeth continuously reduced to today's elephants, which have only one incisor in the upper jaw ( tusk ) and three molars each arch, but which is only one molar in the maxilla and the mandible in each half of the jaw available. These are badly worn during chewing of plant food, but can be pushed in today's elephants five times, and so six generations. These six generations include three Milchprämolaren (these will be addressed by some experts due to the strong similarity to the molars as a primary molars, but are from an ontogenetic perspective premolars ) and three Dauermolaren. The gear change takes place horizontally by a new tooth pushes out only from the rear when the front is largely chewed. This horizontal tooth change, significantly different from the vertical of most other mammals, due to the shortening of the jaw in the tusker evolution, so that not all the teeth found at the same place. Occurred for the first time this feature is in the middle Oligocene. The tusks of the upper jaw drop at the young elephant out after the first year, but will be replaced by ever-increasing.

For the systematic classification of the Proboscidea, the structure of the molars is mainly used. The occlusal surface of molars is very varied and adapted to the way of life of the animals. You may nodular structures ( bunodont ) such as in some very early proboscidean, or be made up of individual cross bars ( lophodont to zygodont ), which partially form by different degrees of wear harder and softer Make a roof-like structure as in the Stegodonten or lamellar shaped be like the mammoths and the modern elephant.

Tusks

The most striking skeletal element are the tusks, the straight, twisted, bent up or down, shovel-shaped, the upper or lower jaw or both springing, far apart or close together standing, and in a variety of lengths ( up to 4 m) and thicknesses were available. The tusks are a formation of the incisors, the still quite small and largely perpendicular to the jaws were initially, and later in connection with the general reduction in the number of teeth in the dentition of the mammoths but reached an oversized growth. Here now but the first incisor (I1 ) of the mandibular identified the tusks of the upper jaw of the second incisors emerged (I2 ) of the respective mandibular discussed during the origin of the lower jaw tusks among experts long. Today only the elephants live with their two tusks in the upper jaw.

Ecology

The adjustments to the shock and especially the molars allowed the proboscidean cataloging various plant sources, of the marsh plants that served the early Moeritherium as food, over leaves and branches that were torn down with the trunks, or bark, which, as in the Deinotherien could be peeled off with tusks, up to the grasses of savannas and steppes, which include the mammoths preferred and must be intensively chewed.

A shaggy coat protected some northern species of mastodons and mammoths rights against the cold of the Ice Age. The two huge curved tusks of mammoths seem to have done well as a snow plow in search of food beneath the snow valuable services. Dwarf defects in Stegodonten and elephants (see: dwarf elephant ) allowed for long periods survival on smaller islands in the Mediterranean region and in Indonesia.

In addition, Russell animals also have an influence on their immediate habitat. By debarking trees, feeding on leaves, snapping of twigs and branches, tearing out of bushes and small trees, or the columns of larger, they cooperate with other Megaherbivoren very involved in the landscape. This is true not only for today's elephants in the savannah grasslands of eastern and southern Africa, but also safe for the mammoths of the mammoth steppe. In this case, this is obviously a behavior that occurred very early in the tusker pedigree and dates back to the early Miocene or even Oligocene, as eg with the Deinotherien occurred the first major trunk animals with huge tusks, close their traditional signs of wear and damage to such behaviors leave.

Dissemination

The mammoths originated undoubtedly in Africa. This occurred at a time when the continent was not connected via land bridges with other parts of the world. Such land bridges emerged only in the lower Miocene more than 20 million years ago, when the northerly Tethys Ocean closed and so was a connection to today's Eurasia. Among the first emigrants were the rights mastodons and gomphotheres who entered Eurasian soil for the first time. Some representatives, such as Zygolophodon or Gomphotherium, reached over northern Asia even the North American continent and formed independent lines of development. The first emigrants followed the Deinotherien, but they spread not as far as the mastodons and gomphotheres, but remained limited to Eurasia. The first emigration wave was carried out in front of around 20 to 22 million years ago. The occurrence of mammoths outside Africa is referred to as proboscidean date event, this was originally viewed as a singular event was according to recent research from at least six individual phases. In the course of the formation of the Isthmus of Panama and the emergence of a closed American landmass in the Pliocene 3 million years ago it came to the Great American faunal, where ultimately some representatives of gomphotheres and South America populated.

The Proboscidea thus populated much of the Old and New World, only the Australian continent and most distant from the mainland islands, such as Madagascar and New Guinea, they never reached. This included their habitat both tropical arctic habitats, where they opened up but mostly lowlands, some species such as Cuvieronius also mountainous highlands. Until the late Pleistocene, were distributed with four families across America, Eurasia and Africa. Today they are found only in Africa and South Asia in the form of elephants.

Phylogeny

Evolutionary Trends

Mammoths are a relatively old order of mammals, first representative came to Paleocene more than 60 million years ago on. Here, the phylogenetic development are roughly divided into three stages, each associated with a diversification into numerous genera and species as well as adaptation to different ecological niches ( adaptive radiation ). General trends in the evolution of mammoths are a striking increase in size - the oldest forms were less than a meter tall, while later forms reached up to more than 4 meters shoulder height -, enlargement of the skull, especially of the cranial vault as a starting point for a powerful neck and masticatory muscles, coupled with the shortening of the jaw area, shortening of the neck region, the formation of a proboscis, hypertrophy of the respective second and first incisors with formation of large tusks as well as the tendency to form large molars and the simultaneous loss of the anterior premolars and largely also of the anterior dentition as well as the change of tooth replacement from the typical mammalian vertical towards the horizontal change. It is further significant that earlier proboscids rather leaf -eaters (browser ) were, during the later forms were more specialized in grass diet ( grazer ).

Getting Radiation

The first radiation occurred before 61 to about 24 million years ago. The representatives of this most primitive mammoths still had significantly bunodont constructed teeth with a maximum of four transverse ridges on the third molars, each having a high tooth enamel cusps at the ends. Some forms also still had a canine depending pine bough. Characteristic is the still occurring vertical gear change so that all the teeth were in use simultaneously.

As the oldest Rüsseltier currently applies Eritherium, which was first described in 2009. It was only a 3 to 8 -kg animal with three bars on the last molar and lived in northern Africa. Phosphatherium, which was excavated in 1996 in Morocco, lived about 55 million years ago and was hardly larger than a fox. It was purely externally little in common with later proboscidean be Zahnbau who owned the Eritherium of similar but more trained strips between the cusps and so has a tendency to Lophodontie, however, reveals the close relationship. An even stronger tendency to these tooth forms show, among other things Numidotherium and Daouitherium, which are about the same age. Moeritherium from the Eocene of North Africa was another early member of the mammoths. It was about the size of a tapir ( about 110 cm) and had a pig -like head with an extended nose and upper lip and slightly elongated incisors in the upper and lower jaw. In addition to elephants characteristics of the skull was also common features with the manatees. Furthermore, the genus was characterized by a very long body. With Barytherium the first enormous body size increase took place within the animal with a trunk line. The animals reached a shoulder height of 2.5 to 3 feet and had a total of eight tusks, two for each pine bough.

Also in the first phase include Radiation Deinotherien ( Deinotheriidae ), which first appeared in the mid- Oligocene and represent an early elimination. Characteristic of this Rüssseltiergruppe the tusks, which were only in the lower jaw and were bent downward. They were used as tools for scraping bark. The early forms, such Chilgatherium and Prodeinotherium were still relatively small, while in the Pliocene and Pleistocene Deinotherium partially reached up to 4 meters shoulder height. They represented one of the first successful animal with a trunk group and died in Europe from the Middle Pliocene ( Piacenzium ) in Africa in the Lower Pleistocene, about one million years ago. Some authors belonging to the Deinotherien the proboscis animals due to the teeth and dentition morphology in question and would like to make more in the near relationship to the manatees, this view is shared but only a little.

Palaeomastodon and Phiomia were other very early Proboscidea genera from the Eocene and Oligocene of North Africa. You also still belong to the representatives of the first radiation, but are with the later trunk species used already much closer than previous. It is currently still poses problems to connect the early forms of these two genera, since obviously still missing intermediate links. Probably Phiomia includes the sister line to the later gomphotheres ( Gomphotheriidae ), while Palaeomastodon representing those of the Real mastodons ( Mammutidae ).

The Real mastodons ( Mammutidae ) represent the last group within the first radiation out its line of development began, according to molecular genetic studies prior to at least 26 million years. The molars are zygodont with a maximum of four enamel ridges on the last tooth. The special structure of the molars identifying them as broad leaf eaters. Furthermore, these mammoths were characterized by two tusks in the upper jaw, while older forms also had two smaller tusks in the lower jaw, which went only reduced in the course of further evolution and later lost. The oldest genus represents Eozygodon, whereas the best-known genus Mammut, to including the American Mastodon (Mammut americanum ) was one who lived at the same time the representatives of the genus Mammuthus and later became extinct towards the end of the last ice age in the upper Pleistocene. The genus name Mammut often leads to confusion, as his representative, whose generic name Mammuthus is with the actual mammoths, are not closely related.

Second Radiation

The second phase took place in the Miocene Radiation. The representatives of this group for the first time, the horizontal change of teeth can be detected, which was created by the shortening of the jaw bone. It is noteworthy that the rights mastodons, although among the first radiation phase, the later representatives such as mammoth, the feature of horizontal dentition but also possessed. Other features in this phase are the Radiation significantly hochkronigeren molars and the development of bunodonten about lophodonte to zygodonten molars with a partly clear roof-like structure of the individual racks, with the number of these strips of the rearmost molar increased to six. Maybe at the base of the second radiation was Eritreum from the late Oligocene of Northeast Africa, which is still mediated in its tooth morphology between Phiomia or Palaeomastodon and the later proboscidean, but already had the horizontal tooth replacement. The most important groups in the second phase, the Radiation gomphotheres ( Gomphotheriidae ) and the Stegodonten ( Stegodontidae ), two tusker families that were originally grouped together with the genuine mastodons to the superfamily of mastodons ( Mastodontoidea ). The term Mastodon but is now used only for the rights mastodons.

The most important animal with a trunk line provided the gomphotheres ( Gomphotheriidae ) dar. These were a very successful group of mammoths as they segregating due to the strong expansion of open landscapes in the Miocene and the conversion to grass food in numerous groups. They now make up almost half of all known taxa, which are divided into several subfamilies. In general, it was at the gomphotheres to Russell animals with four tusks, two each in the upper and in the lower jaw. Another feature is a bunodonter to lophodonter Zahnbau of the molars, the deciduous teeth and the first two Dauermolaren three enamel strips had - which is why they were originally referred to as trilophodonte gomphotheres - while the last molar tooth four, five or more ribs had. To divide the gomphotheres also the tusks are used partially. So reported the Gomphotheriinae with Gomphotherium in the upper jaw two distinctly downward tusks, while those of the lower jaw were elongated and flattened. The Choerolophodontinae, however, had had short, significantly reduced mandibular tusks during the Rhynchotheriinae the first group were similar, but laterally flattened mandibular tusks. These were in the later stages, as Stegomastodon and Cuvieronius show additionally significantly reduced. Noteworthy are the Amebelodontinae as Platybelodon from Asia and Amebelodon from North America, which were equipped with highly elongated and widened, like a shovel reshaped lower jaw tusks, while the upper jaw tusks had only a small size. Some of the counted among the gomphotheres species survived until the late Pleistocene.

Significantly more advanced than gomphotheres were Tetralophodon and Anancus that occurred for the first time in the middle or in the late Miocene. Originally they were called tetralophodonte gomphotheres because their milk teeth and the front Dauermolaren four enamel strips possessed. At present, however, they are due more modern skull features in the near relationship to the Stegodonten ( Stegodontidae ) and elephants ( Elephantidae ) found and assigned to the superfamily Elephantoidea. Both classes showed much reduced mandibular tusks, some of which were pronounced only in the primary dentition.

The second major group within the second phase included the Radiation Stegodonten that developed in the mid- Miocene epoch, about 15 million years ago in North Asia from gomphotheres with bunodonten molars. The oldest form is Stegolophodon. From this then the later genres, such Stegodon who had typical ribbed and often very hochkronige molars emerged. In general, the Stegodonten had only upper tusks were lower during the largely reduced in the shortened mandibles or not trained. This tusker group was spread over much of Eurasia, in the late Miocene and early Pliocene, they also came in Africa while but did not reach America.

Third Radiation

The third phase began in the late Miocene Radiation 7 million years ago and included the group of elephants ( Elephantidae ), the only tusker family that has survived until today. In this phase, the skull was further reduced, and increases the end. The molars have been further extended and were now established clearly lamellar, wherein the number of the blades from eight to 30 varied. The lamellae were clearly flat and not as prominently increased as in the previous tusker groups. In addition, there was a decrease in enamel thickness per plate. All these features show that these mammoths were very well adapted to grass food.

The oldest form was Primelephas, which became little more than 7 million years ago in Africa Stegodon. From him the present genera Loxodonta and Elephas emerged. The separation of the two groups took place very early in the development of Primelephas and should be completed by genetic testing before 7.6 million years. A little later, before 6.7 million years, Elephas and Mammuthus seceded. While Loxodonta remained largely confined to the African continent, Elephas and Mammuthus reached around 3 million years ago and Eurasia, while some representatives of Mammuthus the only elephant in front of nearly 2 million years ago the first time America entered. Due to the proliferation and adaptation to the cooler to cold climate of northern Eurasia during the Pleistocene both species were characterized by a rather high radiation with numerous types. While all the elephants had a very large body size, with the Steppe mammoth Mammuthus brought (Mammuthus trogontherii ) produced probably the largest known proboscis species whose shoulder height was partially over 4.5 meters.

In the Neogene, especially in the Pleistocene, found a worldwide distribution of mammoths on all continents except Australia and Antarctica, with numerous types instead. This distribution may have occurred only through the adoption of extended hikes over land bridges that have formed before about 20 million years ago between Africa and Eurasia. At the end of the Pleistocene, ie until about 12,000 years ago were still alive 7 genera of proboscidean: Stegodon, Stegomastodon (including Haplomastodon ) Cuvieronius, mammoth, Mammuthus, Elephas and Loxodonta. Only the last two survived to this day. This was accompanied by the extinction of most trunk animal species, but also other large mammals until the beginning of the Holocene, possibly the spread of modern humans (Homo sapiens). However, the strong climatic fluctuations of the hot and cold periods can be regarded as the cause in addition to the people. The reasons for the so-called Quaternary extinctions is discussed intensively.

Today there are only three species of elephant animals belonging to two genera. This includes the African elephant Loxodonta (Loxodonta africana) and the forest elephant (Loxodonta cyclotis ), while including the Asian elephant Elephas (Elephas maximus).

External system

The closest living relatives of mammoths are the manatees. This, together with the extinct Desmostylia and Embrithopoda the taxon Tethytheria. Also related are relatively close to the hyrax, which form the outer group of Tethytheria and together form the taxon Paenungulata with them.

It summarizes these animals today with some other orders of mammals which are also of African origin are the superiority of the Afrotheria together. These include, besides the above -mentioned following surviving orders:

• Röhrenzähner ( Tubulidentata )
• Elephant shrews ( Macroscelidea )
• Tenrekartige ( Afrosoricida )

Internal system

Eritherium †

Numidotherium †

Barytherium †

Deinotheriinae †

Phiomia †

Mammut americanum †

Gomphoterium †

Eleven

Today, there are about 160 species of mammoths known, including more than 130 from Africa, Asia and Europe, spread over approximately 40 genera and more than 10 families. However, today all are extinct except for the elephants. Some species were discovered in the period after 2000, mainly representatives of the most ancient mammoths, like the Eritherium or Daouitherium. In general, two great form groups ( suborders ) are different: Plesielephantiformes and Elephantiformes that are differentiated on the basis of tooth morphology. Plesielephantiformes so have only two strips ( bilophodont ) on the first two Dauermolaren while Elephantiformes three, four (tri- and tetralophodont ) or more have. The position of the Deinotherien is within the Plesielephantiformes problematic as his second molar is biliphodont though, but maybe this is not an original but a derived character. Within the Elephantiformes there is the partial order Elephantimorpha, whose main feature is the horizontal change of teeth. Especially evolutionarily older genera are partially insecure in their position, as well as some more advanced as Eritreum, which is probably at the transition to the Elephantimorpha. But even in phylogenetically younger forms, especially the Gomphotherioidea there is taxonomic confusion. So originally Anancus and Tetralophodon the gomphotheres were assigned, in recent times we revised this assignment again and put both to the more modern Elephantoidea. The classification is based on the working of Shoshani and Pascal Tassy Jehezekel 2005 taking into account new results. In a study from the year 2012 there was a further revision of the gomphotheres, especially of the South American representatives, which eliminated some ambiguity from previous edits.

• Order: Proboscidea Illiger, 1811 Incertae sedis family: Eritherium Gheerbrant, 2009
• Incertae sedis family: Daouitherium Gheerbrant, Sudre, Cappetta, Iarochène, Amaghzaz & Bouya, 2002
• Family: Moeritheriidae Andrews, 1906 Moeritherium Andrews, 1906

• Phosphatherium Gheerbrant, Sudre & Cappetta, 1996

• Incertae sedis family: Arcanotherium Delmer, 2009

• Barytherium Andrews, 1901
• Omanitherium Seiffert, Nasir Al- Harthy, Groenke, Kraatz, Stevens & Al- Savigh, 2012

• Subfamily: Chilgatheriinae Sanders. Kappel man & Rasmussen, 2004 Chilgatherium Sanders, Kappelman & Rasmussen, 2004

• Deinotherium ( Prodeinoterium ) Kaup, 1829

• Incertae sedis family: Hemimastodon Pilgrim, 1912
• Incertae sedis family: Eritreum Shoshani, Walter, Abraha, Berhe, Tassy, Sanders, Marchant, Libsekal, Ghirmai & Zinner, 2006
• Family: Palaeomastodontidae Andrews, 1906 Palaeomastodon Andrews, 1901

• Phiomia Andrews & Beadnell, 1902

• About family: Mammutoidea Hay, 1922 Family: Mammutidae Hay, 1922 Mammut Blumenbach, 1799
• Eozygodon Tassy & Pickford, 1983
• Zygolophodon Vacek, 1877

• Family: Gomphotheriidae Hay, 1922 Subfamily: Choerolophodontinae Gaziry, 1976 Choerolophodon Schlesinger, 1917
• Afrochoerodon Pickford, 2001

• Archaeobelodon Tassy, 1984
• Protanancus Arambourg, 1945
• Serbelodon Frick, 1933
• Amebelodon Barbour, 1927
• Platybelodon Borissiak, 1928

• Gomphotherium Burmeister, 1837
• Serridentinus Osborn, 1923

• Eubelodon Barbour, 1912
• Rhynchotherium Falconer, 1868
• Stegomastodon ( Amahuacatherium ) Pohlig, 1912
• Cuvieronius Osborn, 1923
• Haplomastodon Hoffstetter, 1950
• Notiomastodon Cabrera, 1929
• Gnathabelodon Barbour & Sternberg, 1935
• Sinomastodon Tobien, Chen & Li, 1986

• Incertae sedis family: Tetralophodon ( Morrillia ) Falconer; 1857
• Incertae sedis family: Anancus Aymard, 1855
• Incertae sedis family: Paratetralophodon Tassy, 1983
• Family: Stegodontidae Osborn, 1918 Stegolophodon Pohlig, 1888
• Stegodon Falconer, 1847
• Selenotherium Mackaye, Brunet & Tassy, 2005

• Subfamily Stegotetrabelodontinae Aguirre, 1969 Stegotetrabelodon Petrocchi, 1941
• Stegodibelodon Coppens, 1972

• Primelephas Maglio, 1970
• Loxodonta Anonymous, 1827
• Elephas ( Palaeoloxodon ) Linnaeus, 1758
• Mammuthus Brookes, 1828