Masillabune
| Masillabune | ||||||||||||
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Skeleton from Masillabune , Geiseltal |
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| Temporal occurrence | ||||||||||||
| Middle Eocene | ||||||||||||
| 47.4 to 43.4 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Masillabune | ||||||||||||
| Tobien , 1980 | ||||||||||||
Masillabune is a small, now extinct, ungulates from the Choeroptamidae family, which lived in Europe in the Middle Eocene around 47 to 43 million years ago. It is known through two relatively complete skeletal finds from the Messel pit and the Geiseltal . It had a primeval physique with an upturned back, short front and longer hind legs and a long tail. Presumably Masillabune livedhidden in the forest and ate a vegetable diet.
features
Masillabune was a small representative of the artifacts , which with a head-trunk length of 43 cm did not quite reach the size of today's stag piglets . In addition there was a tail 18 cm long, which reached about 55% of the body length (33 cm without head). Such a long tail is typical of very primitive cloven-hoofed ungulates and is not found in those living today. Is known Masillabune mainly two skeletons, but the preservation of these fossils can only limited statements. The skull was about 10 cm long and had a more robust construction than is the case with the closely related Amphirhagatherium . The rostrum was short in shape. The occiput was also short and slightly indented when viewed from the side. The orbit was above the second molar .
The lower jaw was built rather gracefully and was up to 8 cm long. He had a lower jaw body that barely varied in height over the entire course and had straight lower edges. The set of teeth was similar to that of the other very early cloven-hoofed ungulates, but had some special features. It is not known whether the genus possessed the complete dentition of the higher mammals , since only a part of the incisors has survived in both the upper and lower dentition . The canine tooth attached to the button-shaped incisors, which resembled the incisors in the lower jaw but was clearly conical and pointed in the upper jaw . The posterior teeth, which each half of the jaw consisted of four premolars and three molars, had a short, only 3 mm long diastema . The anterior premolar in the lower jaw was also conically shaped ( canin- shaped ) and up to 7 mm long, all others had a slightly molarized, square and largely monobloced structure. The molars, on the other hand, were bunoselenodont, which means that the crescent-shaped enamel cusp structure typical of ruminants slowly began to develop on the chewing surface. Characteristically, five cusps were formed on the maxillary molars, while the typical four on the mandibular molars. All rear teeth showed only low crowns ( brachyodont ). The entire back row of teeth was up to 4.2 cm long, with the size of the teeth increasing towards the back. The first premolar was only 5 mm long, while the last molar was 9 mm. In contrast to the closely related Amphirhagatherium , the entire posterior row of teeth was almost closed.
The body skeleton has been passed down almost completely, but the individual bones are in part heavily fragmented. The spine comprised 7 cervical, 13 or 14 thoracic, 6 or 7 lumbar, 4 to 5 sacrum and at least 16 tail vertebrae. The course of the dorsal vertebrae showed the upward curvature typical of early cloven-hoofed animals. What is striking here is the significant increase in length of the first three caudal vertebrae, which then lose length again. The limbs were relatively slim and short. The front legs, which are shorter than the hind legs, are characteristic, which is also a typical feature of early cloven-hoofed animals. The humerus reached about 6.8 cm in length, the spoke 6 cm. In contrast, the femur was 9.2 cm and the shin 7.9 cm long. The limbs were significantly shorter than the Messelobunodon from the Messel Pit , which was the same old but more primitive and had a roughly comparable body length (32 cm compared to 33 cm in the Masillabune ). In the known finds, both the fore and the hind legs each end in four rays (II to V), although it is unclear whether a rudimentary fifth ray (I) was not formed on the forefeet, which is generally very primitive in cloven-hoofed animals . As with today's representatives, the middle rays (III and IV) were most strongly developed. The middle metatarsal bones of the hind feet reached 9 mm more in length than those on the sides.
Fossil record
Masillabune is only known about a few finds and is a comparatively rare element of fauna that lived in today's Europe in the Middle Eocene around 47 to 43 million years ago. An almost complete but poorly preserved find comes from the Messel mine near Darmstadt in Hesse and was discovered in 1974. The find is heavily crushed and affected by overburdening sediments. Another fairly complete skeleton was known from the Geiseltal near Halle in Saxony-Anhalt. This is also clearly damaged, especially in the skull area. In addition, there are individual teeth from the same location.
Paleobiology
The shape of the molars with their bunoselenodont design suggests that Masillabune is a specialized herbivore. According to analyzes, the remains of the stomach contents occurring during the Messel discovery revealed mainly remains of laurel plants . Since there are no additional grains of sand in the stomach, it is likely that the cloven-footed genus did not look for food in the ground, but rather ate in a higher plant storey, which is also indicated by the rather short snout.
The reconstruction of the body skeleton shows some changes compared to the earliest pair of ungulates, such as Diacodexis or Messelobunodon . Generally, at Masillabune the front legs shorter than the hind legs, the later representatives as the other early Paarhufern Masillabune seem to have this difference but already somewhat offset. However, the legs of Masillabune are generally shorter than those of Messelobunodon , despite their comparable body sizes. It can be assumed that Masillabune did not have the pronounced jump ability of early cloven-hoofed animals and may not be acted as a fast flight animal, after which the complete separation of the tibia and fibula points. As a result, the animals probably lived more hidden. Together with its more adapted diet, Masillabune appears to be significantly more specialized than its ancestral predecessors.
Systematics
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Internal systematics of the fossil family Choeropotamidae according to Hooker et al. 2001
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Masillabune is a genus of the now extinct family of the Choeropotamidae within the order of the artifacts . The Choeropotamidae were endemic to Europe in the Eocene and belong to the superfamily of the Hippopotamoidea (originally also Anthracotherioidea), so they are more closely related to today's hippos . Closer relatives of Masillabune are Choeropotamus but also Amphirhagatherium and Hallebune . General characteristics of the Choeropotamidae are the bunoselenodont molars and a short diastema between the first two premolars. Originally Masillabune was described as a member of the Haplobunodontidae, which typically have five cusps on the upper jaw molars, but recent analyzes combine these with the Choeropotamidae, although this is not general is recognized.
Two types are recognized today:
It is M. franzeni against M. martini slightly younger and more modern design.
The genus Masillabune was first described in 1980 by Heinz Tobien using the skeleton from the Messel pit . The holotype was discovered by Thomas Martin in 1974 and is in his private possession, but casts are available at the Institute for Geosciences at Johannes Gutenberg University Mainz and at the Hessian State Museum in Darmstadt. The name Masillabune goes back to Masilla, the original name used for Messel in the Lorsch Codex around 800 AD, and the Greek word βουνόν ( bounon ) means something like "hill" and refers to the design of the chewing surface of the molars .
literature
- Thomas Lehmann and Irina Ruf: The appearance of the artifacts. In: Stephan FK Schaal, Krister T. Smith and Jörg Habersetzer (eds.): Messel - a fossil tropical ecosystem. Senckenberg-Buch 79, Stuttgart, 2018, pp. 285–291
- Heinz Tobien: An anthracotherioid even-toed ungulate (Artiodactyla, Mammalia) from the Eocene from Messel near Darmstadt (Hesse). Geological Yearbook Hessen 108, 1980, pp. 11-22
Individual evidence
- ↑ a b c d e f g h i Heinz Tobien: An anthracotherioider even-toed ungulate (Artiodactyla, Mammalia) from the Eocene from Messel near Darmstadt (Hesse). Geological Yearbook Hessen 108, 1980, pp. 11-22
- ↑ a b c d e f g h Heinz Tobien: On the osteology of Masillabune (Mammalia, Artiodactyla, Haplobunodontidae) from the Middle Eocene of the Messel fossil site near Darmstadt (S-Hessen, Federal Republic of Germany). Geological Yearbook Hessen 113, 1985, pp. 5-58
- ↑ a b c d e f Jörg Erfurt and Hartmut Haubold: Artiodactyla from the Eocene brown coal of the Geiseltal near Halle (GDR). Palaeovertebrata 19 (1), 1989, pp. 131-160
- ↑ a b c Thomas Lehmann and Irina Ruf: The emergence of the artifacts. In: Stephan FK Schaal, Krister T. Smith and Jörg Habersetzer (eds.): Messel - a fossil tropical ecosystem. Senckenberg-Buch 79, Stuttgart, 2018, pp. 285–291
- ↑ Jörg Erfurt: Taxonomy of the Eocene Artiodactyla (Mammalia) of the Geiseltal with special consideration of the genus Rhagatherium. Hallesches Jahrbuch für Geoswissenschaften B 17, 1995, pp. 47–58
- ↑ a b Jerry J. Hooker and Katherine M. Thomas: New species of Amphirhagatherium (Choeropotamidae, Artiodactyla, Mammalia) from the late Eocene Headon Hill Formation of Southern England and phylogeny of endemic European Anthracotheroids. Palaeontology 44, (5), 2001, pp. 827-853
- ^ Jean Renaud Boisserie: Family Hippopotamidae. In: Donald R. Prothero and Scott E. Foss (Eds.): The Evolution of Artiodactyls. Johns Hopkins University, Baltimore, 2007, pp. 106-119
- ↑ Jessica M. Theodor, Jörg Erfurt and Grégoire Métais: The earliest Artiodactyls. In: Donald R. Prothero and Scott E. Foss (Eds.): The Evolution of Artiodactyls. Johns Hopkins University, Baltimore, 2007, pp. 32-58