Molassitherium
| Molassitherium | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Lower to Upper Oligocene ( Rupelian to Chattian ) | ||||||||||||
| 30 to 23.9 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Molassitherium | ||||||||||||
| Becker & Antoine , 2013 | ||||||||||||
Molassitherium is an extinct genus of rhinos thatlivedin what is now western and central Europe in the Oligocene , around 30 to 24 million years ago. She was a small representative of this odd ungulate group , which had no horn formations. It is mainly known from two well-preserved skull finds along with some teeth. Dating back to the Oligocene, Molassitherium is one of the earliest rhino records in Europe.
features
Molassitherium was a small representative of the rhinos , which is known from some skulls and tooth fragments. The skull was about 45 cm long and had a wide shape with up to 24 cm apart zygomatic arches . The occiput was clearly drawn out and at an acute angle; when viewed from above, it had a clear wedge-like incision and was only 9 cm wide. The pair of nasal bones was short and straight, and both bones were clearly separated from each other by a median groove. There was no roughening or other evidence of the presence of one or more horns on the surface. The forehead line between the nose and occiput was clearly straight, the frontal bone itself was extremely wide. Again, there was no sign of a horn. Due to the wide skull, the inside of the nose between the nasal bone and the upper jaw was also very wide, also U-shaped and it reached to the end of the third premolar . The median jawbone protruded far forward and clearly protruded beyond the end of the nasal bone.
The lower jaw has so far only been passed on in fragments and is only known for the rear areas, so that its anterior dentition is not documented. In the upper dentition, however, there was one incisor per jaw half, the canine was missing. There was a diastema to the posterior teeth measuring at least 4 cm. The rear dentition consisted of four premolars and three molars . These were generally low-crowned ( brachyodont ) and simply built, the enamel had no additional angles on the chewing surface. The anterior premolar in particular was very small, while the others were much larger and partially molarized. The entire row of teeth reached about 18 cm in length.
Fossil finds
Finds are mainly known from Western and Central Europe . One of the most important comes from the French department of Vaucluse with a skull fragment with a complete back row of teeth . A complete skull, in turn, was discovered near Moissac in southwestern France. There are also several skull and jaw finds from Alharting west of Linz in Austria . All finds are from the Oligocene and are between 30 and 24 million years old.
Systematics
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Internal systematics of Eurasian Aceratheriini according to Tissier et al. 2020
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Molassitherium is an extinct genus of the rhinoceros family . It represents one of the earliest, still hornless representatives of the rhinos in Europe and can be classified at the base of their phylogenetic development. In terms of tooth structure, it has similarities with Epiaceratherium , but is possibly more closely related to some North American rhino forms such as Diceratherium and Subhyracodon . As a result, Molassitherium most likely still belongs to the "parent group" of rhinos.
The genus Molassitherium was first scientifically described in 2013 by Damien Becker and Pierre-Olivier Antoine . The name refers on the one hand to molasses , a special form of sedimentary rocks , on the other hand θήριον ( thêrion ) is derived from the Greek language and means "animal". The authors determined M. albigense as the type species , which MF Roman had already established in 1911 as Acerotherium albigense on the basis of a fragment of a skull with a complete row of teeth from the Vaucluse department. The holotype was thought to be lost for a long time, but was rediscovered in the Museum of Toulouse in 2005 . In the M. albigense , Becker and Antoine also included Aceratherium kuntneri , created by Franz Spillmann in 1969 on the basis of finds from the area around Linz , as a synonym . In the period that followed, further finds of this type were made, in part, to Epiaceratherium or Protaceratherium .
Originally, Becker and Antoine also established the species M. delemontense together with the genus Molassitherium in 2013 , based among other things on an almost complete skull of an adult and a fragmented lower jaw of a non-adult animal from Poillat on the right bank of the Birs in the canton of Jura . They added further isolated teeth from Kleinblauen, also in northwestern Switzerland, as well as from Habach in Bavaria and Offenheim in Rhineland-Palatinate as well as from Monclar-de-Quercy in southern France to the species. This form was classified as somewhat older than M. albigense . New examinations of finds from early rhinos from Western and Central Europe, including associated phylogenetic analyzes, led to the fact that M. delemontense was separated from Molassitherium and incorporated into Epiaceratherium in 2020 . Thus only M. albigense remains as the only recognized species within the genus Molassitherium .
Individual evidence
- ↑ a b c d Damien Becker, Pierre-Olivier Antoine, Olivier Maridet: A new genus of Rhinocerotidae (Mammalia, Perissodactyla) from the Oligocene of Europe. Journal of Systematic Palaeontology, 2013, doi : 10.1080 / 14772019.2012.699007 .
- ↑ a b c d e Fabrice Lihoreau, Stéphane Ducrocq, Pierre-Olivier Antoine, Monique Vianey-Liaud, Sébastien Rafay, Geraldine Garcia, Xavier Valentin: First complete skulls of Elomeryx crispus (Gervais, 1849) and of Protaceratherium albigense (Roman, 1912 ) from a new oligocene locality near Moissac (SW France). Journal of Vertebrate Paleontology 29, 2009, pp. 242-253.
- ↑ a b Frédéric Roman: Sur un Acerotherium des collections de l'Universite de Grenoble et sur les mammiferes du Stampien des environs de L'Isle-sur-Sorgues (Vaucluse). Annales de l'Universite de Grenoble 24 (2), 1912, pp. 359-370 ( PDF ).
- ^ A b Franz Spillmann: New rhinocerotids from the Oligocene sands of the Linz basin. Yearbook of the Upper Austrian Museum Association 114, 1969, pp. 201–254 ( PDF ).
- ↑ a b c Jérémy Tissier, Pierre-Olivier Antoine, Damien Becker: New material of Epiaceratherium and a new species of Mesaceratherium clear up the phylogeny of early Rhinocerotidae (Perissodactyla). Royal Society Open Science 7, 2020, p. 200633, doi: 10.1098 / rsos.200633 .
- ↑ Kurt Heissig: The American genus Penetrigonias Tanner & Martin, 1976 (Mammalia: Rhinocerotidae) as a stem group elasmothere and ancestor of Menoceras Troxell, 1921. Zitteliana A 52, 2012, pp. 79-95.
- ^ Frédéric Roman: Les Rhinocérotidés de l'Oligocène d'Europe. Archives Muséum d'Histoire Naturelle de Lyon 11, 1911, pp. 1–92 ( PDF ).
- ↑ a b Damien Becker: Earliest record of rhinocerotoids (Mammalia: Perissodactyla) from Switzerland: systematics and biostratigraphy. Swiss Journal of Geosciences 102, 2009, pp. 489-504.