Eurohippus

Eurohippus parvulus parvulus, live reconstruction at the Natural History Museum Berlin

• France
• Germany ( Messel, Geisel, Grube Prinz von Hessen, Fuerstenau )

Eurohippus is an extinct genus of Perissodactyla and an early relative of today's horse, who lived in the Middle and Upper Eocene in the central and western Europe. Significant and extensive findings are from the Messel Pit, where numerous, partly complete skeletons have been preserved. The animals lived in the tropical rain forest and subsisted mainly leaf eating. We distinguish between the subspecies Eurohippus parvulus parvulus parvulus and Eurohippus messelensis.

Features

In Build Eurohippus resembled the other known genera of Hyracotheriinae and had a slender physique with significantly curved back on. It was smaller and slimmer than Propalaeotherium but larger than Lophiotherium. The limbs ended as with all early Eocene horse relatives in four toes on the front and three toes on the hind foot. The skull was from 13.4 to 16.4 cm long and was clearly wedge-shaped than Propalaeotherium. The dentition of the teeth had the full unreduced number of teeth and tooth pointed by the following formula:. The molars were characterized by significantly lower crowns ( brachyodont ), the premolars were different from the molars, not or only slightly molarisiert. However, the molars had already asked two transverse enamel ridges ( bilophodont ) on the chewing surfaces and were not as bumpy ( bunodont ) designed as even older genera, such as Hyracotherium.

Fossil finds

Finds of Eurohippus have been found in Central and Western Europe, dating to the Middle to Upper Eocene. The earliest fossils were discovered in the early 19th century in Argenton -sur -Creuse in France. Most important reference but is the Messel Pit near Darmstadt, which is assigned to the Geiseltalium and where are alone at least 43, passed down through the storage in oil shale nearly complete skeletons. This Eurohippus is there, the most common representatives of the equine. Further findings with teeth and upper jaw fragments originate from the pit Prince of Hesse, also from near Darmstadt. One of the latest and northernmost Europe finds include those of Fuerstenau in Lower Saxony and Ghent in Belgium, but which also include only isolated teeth.

Paleobiology

Eurohippus lived in the tropical forests, mainly the finds from the Messel Pit show where on the basis of flora excellently preserved the habitat of the species can be reconstructed. Here lived the animals as bush panties as her body shape would suggest. They subsisted mainly on soft plant foods ( browsing ), as evidenced by the niederkronigen molars with their partly nodular surface structure. Studies of the also excellent traditional stomach content from Messel revealed leaf debris of at least twelve different types of laurel family, beyond which five other plant families, as hickory, figs, myrtles and Hundsgiftgewächse be determined. Further investigation revealed countless seeds of vines plants. This shows that even fruit still had a considerable share in the food spectrum. The ingested food may have been digested as in today's horses in the rectum, with the participation of numerous microorganisms. Then can the findings of an animal from the Messel pit close, while the closely related genus of Hallensia belongs, which suggests a large cecum but by Bakteriennachzeichnung of the internal organs ( Bakteriographie ).

Furthermore, it was demonstrated that Eurohippus like horses today, only one foal brought to the world, which is typical for a narrow social organization during the breeding period and as a k- strategy is referred to in the reproduction. A total of eight complete skeletons from the Messel pit remains were found one each singular fetus. A similar finding was found in an animal of the genus Propalaeotherium in Eckfelder Maar, so this can be regarded as typical of the earliest horses. It is also known by the bacterial tracing of the former soft tissues that Eurohippus had a tassel -shaped Schwanzbehaarung and the ears were rather short as the wild horse and not as long and cone- shaped as in today's donkeys and zebras.

System

The genus was described in 2006 by Eurohippus Jens Lorenz Franzen for the first time, the name derives from the continent of Europe and the Latin name hippus for " horse " come from. It is monotypic with the only kind Eurohippus parvulus, but two subspecies are assigned to the:

• E. p. parvulus Laurillard, 1849
• E. p. messelensis Main, 1925

The first in Les Prunes in Argenton -sur -Creuse ( France) found fossils have been described parvulum 1849 by Charles Léopold Laurillard as Lophiodon, but she continued in 1891 with Ludwig Rutimeyer Propalaeotherium equal and described it as P. parvulum. However, the holotype represents only a single first upper molar dar. In 1925, led the way Oskar main Lophiotherium a fair lense, which was renamed in 1965 messe lense Propalaeotherium and 1981 synonymized with P. parvulum. As lectotype applies a mostly headless skeleton ( copy number HLMD -Me 58, originally 4358 ) from the Messel pit, which was determined in 2006 by Franzen, is shown in Haupt's first publication, though; this skeleton are also attached to some upper and lower jaw fragments. The cleavage of the genus Eurohippus of Propalaeotherium was due to different anatomical features, but it also the family relationships were re-evaluated. So Eurohippus is phylogenetically possibly back on Pachynolophus from the European Eocene and not as Propalaeotherium on Propachynolophus.

In his first description Franzen Eurohippus refers to the family of Equidae, within that it belongs to the subfamily Hyracotheriinae with close relationship to Hyracotherium, Propalaeotherium and Lophiotherium. However, in the research is a position of this subfamily within the Equidae controversial and is mainly favored by central European researchers who view this as a base group in the development of the horse. Anglo American researchers prefer a position of Hyracotheriinae within the largely known only from Eurasia family of Palaeotheriidae, the sister group of the Equidae, however, occurred more recently also votes for an assignment to the horses. The difference between the Palaeotheriidae to the early representatives of the horses is in some higher tooth crowns on the molars, a larger nose interior, longer vertebral bodies and over the longer metatarsals metacarpals. Furthermore, they are stratigraphically younger than the earliest horses. Both families together form the superfamily of Equoidea and the subordination Hippomorpha.