Lophiodon
Skeleton of Lophiodon
Lophiodon is an extinct genus of mammals, whose representatives lived in the Eocene and were predominantly detected in the present-day Europe, where they were abundant at that time. Well known is the genus numerous, sometimes complete skeletal remains, which mainly come from the Geiseltal, but also from the Messel pit and a wide range of Western and Southern Europe. Belonging to Lophiodon animals resembled modern tapirs externally and include in their other relatives circle, but are possibly more closely related to the equally extinct Chalicotherien. The animals lived along rivers in tropical rain forests and fed mainly on leaves. The genus was first described already 1822. Throughout the history of research numerous belonging to this genus species have been described.
Features
The representatives of Lophiodon were medium to large early Perissodactyla and reached for the largest specimens with a head -body length of 250 cm and a shoulder height of 100 cm, almost the size of today's tapir, which they also resemble externally. Well known is the genus by numerous, well-preserved skeletal remains. The skull was long depending on the type 18-36 cm and had a vaulted forehead line, which is rather unusual for Perissodactyla and was created by a fairly large brain chamber. The zygomatic arches formed a clearly projecting bow and were thus significantly apart. In contrast, the entire rostrum had a very narrow shape. Also unusual was the very long and narrow nose, which still exhibited approximately in the middle connects to the premaxillary bone, which is a very primitive state among the early odd-toed ungulates. Thus, the Zwischenkieferbein formed the complete back of the nose interior (for later perissodactyls this is done by the upper jaw ), so that this was extremely short pronounced. This particular design of the intermaxillary bone also resulted in a greater thickness than length for this. The occiput was integrally molded rather backward and bent in the side view clearly inside.
The lower jaw had a massive figure and reaches up to 36 cm length, the mandible body part was about 5 cm high. Especially the symphysis was designed as a robust and extended to the second premolar. In the teeth structure representative of the genus Lophiodon showed few differences to today's tapirs and possessed with the exception of the missing first premolar an unreduced dentition, so that the dentition formula was as follows: . The incisors had only a small size and had a pointed shape. The canine was against it is extremely large and distinctly conical with up to 2.8 cm in length. Behind this came a very extensive diastema on the posterior teeth. In this, the tooth size from the front to the back increased, but the penultimate molar was sometimes greater than the last, which was up to 4 cm long. The premolars were only partly molarisiert, that resembled the molars is limited. This in turn had a typical bilophodonten structure with two transversely positioned higher and enamel strips and were niederkronig ( brachyodont ). The entire back row of teeth was long up to 14 cm.
The body skeleton is fully narrated by several skeletal remains part and tends to exhibit deviations to today's tapirs and other odd-toed ungulates, which are reflected mainly in the musculoskeletal system. Thus, the proportions of the limbs are different. While numerous Eocene Perissodactyla approximately equally long parts of the upper and lower hind legs possessed, suggesting an origin of more schnellläufigen ancestors in Lophiodon types of the tibia with approximately 19 cm in length was significantly shorter than the femur, which reached about 31 cm in length, and thus refers already to adapt to a more cumbersome gear. In addition, had the femur by its flattened stem and the elevated position of the head of similarities to that of the Chalicotherien, also extinct odd-toed ungulates. In contrast, the humerus showed some morphological similarities to the rhinos. Also noteworthy is the very short upper joint of the ulna ( olecranon ), which is rather unusual for odd-toed ungulates. Both the lower arm and the upper arm had lengths of up to 29 cm and thus had approximately the same dimensions. The front limbs ended in four beams, an archaic feature of the Perissodactyla, which today survives only in the tapirs. The respective outermost toes ( V -ray ) were thereby reduced in length, but had two phalanges, thus showing that they were in his lifetime in use. The hind feet were like all the odd-toed ungulates of three rays.
Fossil finds
Fossils of the genus Lophiodon are very numerous in Europe, dating from the late Lower until the beginning of Upper Eocene, 51-42 million years ago, in part, the findings have the character of index fossils. Of great importance are the remains of the Geisel valley in Saxony -Anhalt, which date from the Middle Eocene. Here more than 180 single individuals were discovered. These include not only numerous but also well-preserved skull postcraniales skeletal material. These is a fund range with 110 animals in an area of 130 m², which were found together with the remains of crocodiles and turtles. Possibly, this finding one feeding place of the large crocodilians dar. also are outstanding, the findings from the about the same old Messel Pit in Hesse, where among other things apart from some isolated teeth an almost complete skeleton of a young animal has survived, while in from the also significant Eckfelder Maar Rhineland- Palatinate been single jaw fragments and teeth remains were only known. Likewise, individual tooth finds have been further discovered from the Phosphoritbank at Dalum near Fuerstenau in Lower Saxony. These date as well into the Middle Eocene and among the most northerly mammal fossils from this geological period in Central Europe.
Outside Central Europe numerous finds from France were reported. Of particular note are the findings of the Aude department in southern France Issel that span multiple skull finds. A high significance of the remains of Bouxwiller in Alsace, which come from a marly Süßwasserkalk. Both sites are temporally comparable to those of the Geisel. From the late Eocene, slightly older, the findings of the department of la Drôme Eygalayes dating in southeastern France. These include skull and lower jaw fragments and parts of the musculoskeletal system. Other groups are derived from Spain, Italy and Switzerland.
Paleobiology
Above all, the fossil-rich sites of Geiseltal, but also the other fossil sites with Lophiodon residues allow the reconstruction of a species-rich tropical rain forest, which consisted in the Middle Eocene in Europe and in which the animals lived mainly in river valleys and swamps. This biotope shared Lophiodon representatives, among others, crocodiles, terrapins and giant snakes, but also with prosimians and artiodactyls. The typical structure of Kauoberfläche the back teeth with the two transversely positioned enamel strips ( bilophodont ) and low tooth crowns ( brachyodont ) indicate that Lophiodon species mostly took soft leaf food, while thus a similar ecological niche as today's tapirs occupied. The high enamel strips ( Lophen ) allow only vertical jaw movements, so that the food remains are crushed only in the grooves between the bars, horizontal jaw movements are hardly available. However, in contrast to the tapirs, the only short nose interior out that at Lophiodon representatives no trunk was formed, which could be used in search of food and consumption. However, the typical diet of soft vegetable diet ( browsing ) can take an extended, pointed upper lip, similar is the case with many modern herbivores with such dietary specialization.
System
Outgroup
Isectolphidae
Helaletidae
Tapiridae
Rhinocerotidae
Chalicotheriidae
Lophiodon
Lophiaspis
Lophiodon is a genus of the family of Lophiodontidae, now extinct representatives of the order Perissodactyla. In the immediate relationship to Lophiodon also includes Atalonodon and Lophiaspis that are known but only very little archaeological material. Originally Lophiodontidae were asked due to the significantly bilophodonten posterior dentition near the tapirs and assigned to the parent group of Tapiroidea. The Tapiroidea form together with the Rhinocerotoidea, the extended family of rhinos, the subordination of Ceratomorpha which face the Hippomorpha with the horses within the Unpaarhufersystematik traditional. But later analysis revealed a closer relationship of Lophiodontidae to Chalicotheriidae, also extinct odd-toed ungulates, which occupy about a mediating role between the two major sub- systems and therefore their own subordination, who so Ancylopoda. These in turn are classified because of their general similarity to the tapirs together with the Ceratomorpha in the newly formed interim order Tapiromorpha. A possible ancestor of Lophiodontidae was most likely Homogalax from the group of Isectolophidae which represent the sister taxon of Ancylopoda - Ceratomorpha group.
Numerous types of Lophiodon have been described over the history of research, valid today, including the following:
- L. buxovillanum Desmarest, 1822
- L. cuvieri Watelet, 1864
- L. eygalayense Laberrère & Montenat, 2011
- Filholi L. Fischer, 1964
- L. isselanum Filhol, 1888
- L. lautricense Noulet, 1851
- L. leptorhynchum Filhol, 1888
- L. parisiense Gervais, 1848-1852
- Remensis L. Lemoine, 1878
- L. rhinocerodes Rutimeyer, 1862
- Sardus L. Bosco, 1902
- L. tapiroides Desmarest, 1822
- L. tapirotherium Desmarest, 1822
- L. thomasi Depéret, 1906
Especially in the 19th century established American paleontologists numerous species in North America, which are nowadays mostly Heptpdon or Helaletes which are designed phylogenetically something more modern. Whether all species listed above have an independent character, is unclear, as it has so far not led to major revision of Lophiodon or the Lophiodontidae.
The genus Lophiodon was first described by Georges Cuvier in 1822 on the basis of findings from scientific Issel. But before that he had already in 1804 made some fossils of this genus to the tapirs (Le petit tapir ), a year later, he referred to the other finds Palaeotherien, extinct horses relatives, as well as the rhinos. Provisionally placed Henri Marie de Blainville in 1817 Ducrotay all these fossil remains to Tapirotherium what Cuvier led, in 1822 to establish the new genus Lophiodon. As lectotype applies a lower jaw from Issel, who had already been imaged by Cuvier and is now preserved in the Muséum national d' histoire naturelle in Paris. Initially Lophiodon was still regarded as related with the pigs, this changed with the description of several skull finds the end of the 19th century, who also came from Issel. Above all, the findings from the Geiseltal, which were mainly discovered in the first half of the 20th century, the knowledge of the genus expanded considerably. In some cases some types of Lophiodon were spun off into other genres such as Rhinocerolophiodon or Paralophiodon during the 20th century, but this is not generally accepted due to less specific traits. The name Lophiodon derived from Ancient Greek and means λόφος ( Lophos "hill", "comb" ) and ὀδούς ( Odous "tooth" ), which also refers to the characteristic features of Kauoberfläche the molars.