| Prodeinotherium | |
|---|---|
 | |
| Prodeinotherium bavaricum | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Proboscidea |
| Family: | †Deinotheriidae |
| Subfamily: | †Deinotheriinae |
| Genus: | †Prodeinotherium Ehik, 1930 |
| Species[2] | |
| Synonyms[2][3] | |
ProdinotheriumEhik, 1930 P. bavaricum P. pentapotamiae
P. hobleyi
| |
Prodeinotherium is anextinct representative of the familyDeinotheriidae that lived in Africa, Europe, and Asia in the early and middleMiocene.Prodeinotherium, meaning "before terrible beast", was first named in 1930, but soon after, the only species in it,P. hungaricum, was reassigned toDeinotherium. During the 1970s, however, the two genera were once again separated, withProdeinotherium diagnosed to includeDeinotherium bavaricum (=P. hungaricum),Deinotherium hobleyi, andDeinotherium pentapotamiae, which were separated based on geographic location. The three species are from Europe, Africa, and Asia, respectively. However, because of usage of few characters to separate them, only one species,P. bavaricum, or many more species, includingP. cuvieri,P. orlovii, andP. sinense may be possible.
Prodeinotherium is one of three genera of theDeinotheriidae, the others beingChilgatherium from Africa, andDeinotherium from Europe, Africa, and Asia.Chilgatherium precededProdeinotherium, whileDeinotherium succeeded it.P. hobleyi was the first species ofProdeinotherium, and it migrated into Asia and Europe before evolving intoP. pentapotamiae and thenP. bavaricum.Prodeinotherium lived for theEarly Miocene andMiddle Miocene before being replaced byDeinotherium. The deinotheriids are an early branch ofproboscideans, although more derived thanBarytherium andMoeritherium.
All deinotheres were large animals that evolved to be even larger, and many features are shared throughout the group.Prodeinotherium andDeinotherium both had large, downcurved tusks on the lower jaw, but none on the upper jaw. This could have been used to grasp food while the tusks moved branches out of the way.Prodeinotherium was slightly smaller thanDeinotherium, yet much larger than more primitive proboscideans. AllProdeinotherium species were similar in size, ranging from 2.5 to 2.8 m (8.2 to 9.2 ft) tall and weighing about 3.1 to 4.3 t (490 to 680 st).
Prodeinotherium was the size of the presentAsian elephant, about 3–4 m (9.8–13.1 ft) at the shoulders, but differing from elephants by lacking upper tusks and instead possessing downward-facing lower tusks.[4][5] In appearance and many characters, it was likeDeinotherium, but differed in being of smaller size, having shorter fore limbs, and also in various details in the shape and form of the teeth.[1] A potentially adult female specimen ofP. bavaricum is estimated to be 2.47 m (8.1 ft) tall and weigh 3.1 t (3.1 long tons; 3.4 short tons), while an adult male measured 2.78 m (9.1 ft) tall and was about 4.3 t (4.2 long tons; 4.7 short tons). The earliest speciesP. hobleyi was estimated at similar 2.7 m (8.9 ft) tall and 4.0 t (3.9 long tons; 4.4 short tons).[4]Prodeinotherium hobleyi was larger and more specialised than itsOligocene predecessorChilgatherium. It flourished for several millions of years, before being replaced in the middle Miocene by the much largerDeinotherium.[1]
_Prodeinotherium_bavaricum_(von_Meyer%2c_1831)_skull%2c_and_palate.jpg)
_Prodeinotherium_bavaricum_(von_Meyer%2c_1831)_tusk.jpg)
Prodeinotherium is distinguished fromDeinotherium from multiple features, including possessing a different dental formula of 003/103 and 0023/1023; M2-3 with an ornamentation; therostrum turns down parallel to themandibular symphysis; the rostrum and external nares narrow; the swelling of thepreorbital is close to theorbit; the roof of the skull is longer and wider than inDeinotherium; the articulation between the neck vertebrae and skull is more upturned; the skeleton isgraviportally adapted; thescapula has a prominent spine and a stoutacromion andmetacromion; and thecarpal bones andtarsal bones are narrow, but notdolichopodous.[2]
Deinotheres such asProdeinotherium have a muscle attachment for a trunk-like structure. However, instead of an elephant-like trunk, the appendage was more muscular and similar to atapirs snout. Within the evolution of Deinotheriidae, the paired "tongs" arrangement consisting of upper and lower incisors possessed by earlier Proboscideans was lost.[5]
P. bavaricum, fossils of which come from theUpper Freshwater Molasse, is the most well-studied species ofProdeinotherium, with multiple features shared among all specimens, not necessarily to the exclusion of other species. Some of these features include "small size, generally simple dental structure, less enamel plication and crenulation, ... thus the valleys of the premolars are well separated, slender teeth, bicuspid mesial lophid in P3 (the cuspids are distinct but more compressed against each other than in P. hobleyi), and clear mesial projection (“preprotolophide”) in P3; sometimes is bicuspid." Other features noted earlier in 1957 include "the mesial lophid of P3 is well separated into two cuspids, the mesial projection of P3 is well developed and often bicuspid, and the base of the protoconid in P3 is longer than that of the metaconid."P. hobleyi differs in morphology fromP. bavaricum mostly in these P3 characteristics.[6]
All deinothere mandibles have the same basic anatomy, with a downturnedsymphysis, and lowerincisors. Most differences of deinothere genera are in the P3 tooth morphology and dimensions of the mandible and teeth. Measurements of the mandible have shown that the curve of the jaw is relative to the length of the jaw; a longer jaw means a stronger curve. A distinguishing feature ofProdeinotherium is that the area at the base of the curve in the jaw is flat, while a depression is seen in all specimens ofDeinotherium.[7]
Prodeinotherium lived during theEarly Miocene andMiddle Miocene, about 19.0 to 18.0 million years ago (Mya).[6]Prodeinotherium likely evolved fromChilgatherium, or the common ancestor of the two genera.[1] The earliest remains ofProdeinotherium come fromKenya, where two deposits preserving the genus date to 22.5 and 19.5 Mya according to one 1978 study. The same study found that fossils fromUganda date to 20.0 Mya. However, more recent studies (from 1988, 1991, and 2002) find that the deposits date to >17.9, 19.5, and 17.0 Mya, respectively. After evolving in Africa,Prodeinotherium spp. likely migrated into Asia and then Europe with the formation of the "Gomphotherium land bridge".Prodeinotherium may have gone extinct around 15.5 Mya, based on the last known fossils from the Arabian Peninsula.[6]P. hobleyi was the first species to evolve, followed soon afterP. pentapotamiae and thenP. bavaricum around the same time. These species are from Africa, Europe, and South Asia, respectively.[1]Prodeinotherium was replaced in Asia byDeinotherium indicum, in Europe byD. giganteum, and in Africa byD. bozasi.[2][8]
Deinotheres are quite controversial with regards to the systematics. Many species have been named, yet major studies by Harris and Huttunen find that only three species in each genus are valid, based on distribution and smaller details. WithinProdeinotherium, the species found valid by these authors includeP. bavaricum,P. pentapotamiae, andP. hobleyi. Many descriptions of new species of deinotheres are based upon limited material compared to only a small number of the species. Thus, many species of deinotheres are no longer valid.[2] In addition to invalid species,Prodeinotherium has on occasion been synonymized withDeinotherium. Species ofProdeinotherium found to be valid by multiple studies includeP. cuvieri,[9]P. sinense,[10] andP. orlovii.[8] In a study 2011 analyzed the mandibles of multiple genera in a phylogenetic analysis. Their results are shown below:[11]
Deinotherium bavaricum was originally mentioned in a paper byChristian Erich Hermann von Meyer in 1831. However, his first description of the material came in 1833, in which he also created the new speciesDinotherium bavaricum, the accidental change in genus spelling making it alapsus calami. The material known is thelectotype P3, in theBayerische Staatssammlung für Paläontologie und historische Geologie, selected from a group of specimens (asyntype) fromBavaria. Meyer compared the tooth to the material ofDeinotherium gigantium, and found enough features to distinguish it as a separate species. Most deinotheres were lumped intoDeinotherium until the studies of Harris, who concluded that morphology separated them into two genera,Prodeinotherium andDeinotherium. As the earliest description of a small deinothere in Europe,P. bavaricum became thetype species ofProdeinotherium.[2]Prodeinotherium was named in 1830 by Ehik, and its name is derived frompro – "before"Deinotherium – "terrible beast".[8]
Another early description ofProdeinotherium is that of Kaup (1832). He described teeth previously assigned toTapir gigantesque, finding them to be a new deinothere. Kaup assigned these toDinotherium cuvieri, using size to distinguish it fromD. giganteum. However, the size, morphology, and distribution match that ofP. bavaricum, thus the latter became the senior synonym. Later in 1836, Lartet described yet another deinothere that eventually becameP. bavaricum. This new species was namedDeinotherium secondarium, for teeth from France. Lartet published no description, and did not mention this species in later works. Huttunen showed that the distribution ofD. secondarium was within that ofP. bavaricum, thus considered the two species likely synonymous. Later, Ehik (1930) described the genus and the new speciesProdinotherium hungaricum, misspelling the genus name. The species was known from a jaw with teeth and some post cranial elements. This material was fromKiráld, and was destroyed, but casts of it remain in theHungarian Natural History Museum. Diagnosed by dental features, and post cranial morphology, the specimen was later found similar to specimens from elsewhere in Europe, which were assigned toP. bavaricum. Harris foundP. hungaricum to be a synonym ofP. bavaricum, a conclusion followed by Huttunen.P. petenyii was described in 1989 by Vörös, who found it to differ from all otherProdeinotherium species. FromHungary, the material includes a jaw with teeth. The tooth morphology is very similar to that ofP. bavaricum, and although the species has the unique feature of tusks that do not curve down and instead project forwards, Huttunen considered it a synonym ofP. bavaricum.[2]
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In 1868,Hugh Falconer's notes from before his death were published, including the description of material that he labelledDinotherium pentapotamiae. This was from the Sewalik of India, he noted that the teeth were possibly the same asD. indium, but were within the range of a midsized individual. This presumption asD. indium was based on the possibility thatD. giganteum was the only species ofDeinotherium in Europe, and the variation of individuals ofMastodon longirostris within a population.[12] This species was later reassigned toProdeinotherium, distinct fromD. indicum.[2]
The African species,P. hobleyi, was first described in 1911 byCharles William Andrews. The species was from East Africa, and was namedDinotherium hobleyi. Andrews described these remains, which included a mandible with teeth, acalcaneum, apatella, and other indeterminable fragments, shipped to him byC.W. Hobley. It was compared toDinotherium cuvieri, and although they were similar, the minor differences and geographical separation were enough for Andrews to create a new species.[13] This species was later reassigned toProdeinotherium, as the only species from Africa.[2]
P. sinense was described in 2007 as a late species ofProdeinotherium; it was described by Quiet al., and is known from dental material and jaw. It was first found in 2005, inGansu, China. It is of aLate Miocene age, thus is younger than otherProdeinotherium species. That study also found that the material ofP. hungaricum is distinct fromP. bavaricum.[14] A study in 2010 by Vergiev & Markow noted that the teeth are quite similar to those ofDeinotherium, and based on these features and age the species was thought to either be a species in betweenProdeinotherium andDeinotherium, or belonging to the latter genus.[10]
Early depictions of deinotheres such asProdeinotherium were scientifically incorrect. Before postcranial material was known, the genera were considered to berhinos, giant tapirs,sirenians,whales, andmarsupials. However, with postcranial material came the proposal of an elephantine relation. However, early depictions of deinotheres were too elephantine, practically only with the addition of lower tusks. These restorations were inaccurate, because they showed the lower lip directly beneath the trunk, with the tusks projecting from the "chin". According to a 2001 study, the tusks more likely projected above the lip, which followed the curvature of the jaw down. Another inaccuracy is likely the length of the trunks. Having a long, elephantine trunk was thought of as unlikely by multiple authors, including Harris and the 2001 study. Besides the large opening often associated with a trunk, the general skull structure makes it unlikely for the trunk to be elongated. The upper tusks, retained in all more derived proboscideans, were likely lost so that the upper lip could directly manipulate the food ofProdeinotherium.[5]
Deinotheres were browsers, meaning they ate plants above ground level. Deinotheres possibly ate specificdicots. These could be found in closed woodland forests.[15][16] The way they chewed their food was probably similar to that of modern tapirs, with the front teeth being used to crush the food, while the second and third molars have a strong vertical shearing action, with little lateral movement. This chewing action differs from both that ofgomphotheres (lateral grinding) andelephants (horizontal shearing). Deinothere molars show little wear, indicating a diet of soft, nongritty,forest vegetation, with the down-turned lower tusks being used for strippingbark or other vegetation.[16] The supports for the tusks used in feeding is also based on the fact that juveniles have a different tusk morphology, which is consistent on them likely possessing a slightly different diet or feeding strategy. The trunks of deinotheres were likely similar to a tapirs, which could have been used for grasping plant matter and moving it to where the tongue could manipulate it.[5]
Prodeinotherium was a herbivorous organism. Based on the known distribution of fossils,Prodeinotherium could only survive along the coast in closed forests. Rodents and fish may have lived in the same environment or region asProdeinotherium.[8] In Europe, fossils ofGomphotherium have been found alongside those ofProdeinotherium, showing that the genera likely ate different plants.[3] Dental wear analysis ofP. bavaricum andG. angustidens from theMiddle Miocene site of Gračanica inBosnia and Herzegovina confirms that while both taxa were strict browsers, the latter's diet consisted of more abrasive plants.[17]
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