Lophiodon
| Lophiodon | ||||||||||||
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Skeleton of Lophiodon from the Geiseltal |
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| Temporal occurrence | ||||||||||||
| Lower to Upper Eocene | ||||||||||||
| 51 to 42 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Lophiodon | ||||||||||||
| Cuvier , 1822 | ||||||||||||
Lophiodon is an extinct genus of mammals , the representatives of which lived in the Eocene and have been found predominantly in present-day Europe , where they were very common at that time. The genus is known for numerous skeletal finds, some of which are complete, mainly from the Geiseltal , but also from the Messel pit and large areas of western and southern Europe . Theanimals belongingto Lophiodon were outwardly similar to today's tapirs and belong to their wider circle of relatives, but are possibly more closely related to the also extinct Chalicotherien . The animals lived on rivers in tropical rainforests andlivedmainly on leaves. The genus was first described in 1822. In the course of research history, numerous species belonging to this genus have been described.
features
The representatives of Lophiodon were medium-sized to large early unpaired ungulates and, in the largest specimens, with a head-trunk length of around 250 cm and a shoulder height of 100 cm, almost reached the dimensions of today's tapirs , which they also resembled externally. The genus is known for numerous, well-preserved skeleton finds. Depending on the species, the skull was between 18 and 36 cm long and had an arched forehead line, which is rather unusual for odd-toed ungulates and arose from a rather large brain chamber. The zygomatic arches formed a clearly cantilevered arch and thus stood distinctly apart. In contrast, the entire rostrum had a very narrow shape. Also unusual was the very long and narrow nasal bone , which still had a connection with the intermaxillary bone roughly in the middle , which represents a very original condition among the early odd-toed ungulates. As a result, the intermaxillary bone formed the entire rear part of the interior of the nose (in later unpaired hoofed animals this is done through the upper jaw ), making it extremely short. This special design of the intermaxillary bone also resulted in a greater thickness than its length. The occiput was shaped rather overhanging backwards and clearly curved inwards when viewed from the side.
The lower jaw had a massive shape and reached a length of up to 36 cm, with the body of the lower jaw sometimes over 5 cm high. Above all, the symphysis was robustly designed and extended to the second premolar . In the teeth structure representatives pointed to the genus lophiodon few differences to today's tapirs and possessed with the exception of the missing first premolars an unreduced teeth so that the teeth formula as follows was: . The incisors were small in size and pointed in shape. The canine , on the other hand, was particularly large and clearly conical with a length of up to 2.8 cm . Behind this there was a very extensive diastema to the rear dentition. In this case, the tooth size increased from front to back, but the penultimate molar was sometimes larger than the last, which was up to 4 cm long. The premolars were only partially molarized, so they only resembled the molars to a limited extent. These in turn had a typical bilophodontic structure with two raised and transversely positioned tooth enamel ridges and were low-crowned ( brachyodont ). The entire back row of teeth was up to 14 cm long.
The skeleton of the body has been partially passed down through several skeletal finds and tends to show deviations from today's tapirs and other unpaired ungulates, which are mainly reflected in the musculoskeletal system. So the proportions of the limbs are different. While numerous Eocene odd-toed ungulates had parts of the upper and lower hind legs of about the same length, which suggests that they originated from rather fast-moving ancestors, the shin of Lophiodon species was around 19 cm long, significantly shorter than the femur , which was around 31 cm long , and thus already indicates an adjustment to a more cumbersome gait. In addition, due to its flattened shaft and the elevated position of the head, the femur had similarities to that of the Chalicotheria , 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 untypical for odd ungulates. Both the forearm and the upper arm had lengths of up to 29 cm and thus had about the same dimensions. The forelimbs ended in four rays, an archaic feature of the odd ungulate, which today is only handed down to the tapirs. The outermost toes (ray V) were reduced in length, but had two toe joints and thus show that they were in use during his lifetime. Like all odd ungulates, the hind feet each had three rays.
Fossil finds
Fossils of the genus Lophiodon are very numerous in Europe and date from the end of the Lower Eocene to the beginning of the Upper Eocene 51 to 42 million years ago, some of the finds have the character of guide fossils . The remains from the Geiseltal in Saxony-Anhalt , which date to the Middle Eocene, are of great importance . More than 180 individual individuals have been discovered here. These include not only numerous skulls, but also well-preserved postcranial skeletal material. A highlight is a find area with 110 animals on an area of 130 m², which were found together with remains of crocodiles and turtles . This find possibly represents a feeding place for the large armored lizards. Also outstanding are the finds from the Messel Pit in Hesse , which is roughly the same age , where, among other things, an almost complete skeleton of a young animal has been preserved, while from the equally important Eckfelder Maar in Rhineland-Palatinate so far only individual jaw fragments and tooth remnants were known. Individual tooth finds have also been discovered from the phosphorite bank near Dalum near Fürstenau in Lower Saxony . These also date to the Middle Eocene and are among the northernmost mammal fossils from this geological epoch in Central Europe.
Outside of Central Europe, numerous finds from France have been reported. Particularly noteworthy are the finds from Issel in the Aude department in southern France , which include several skulls. The remains from Bouxwiller in Alsace , which come from marly freshwater limestone, are also of great importance . Both sites are roughly comparable in time with those of the Geiseltal. The findings of Eygalayes in the Drôme department in south-east France date from the end of the Lower Eocene and therefore somewhat older . These include cranial and mandibular fragments as well as parts of the musculoskeletal system. Other remains come from Spain , Italy and Switzerland .
Paleobiology
Above all, the fossil-rich sites of the Geiseltal , but also the other fossil sites with Lophiodon remains enable the reconstruction of a species-rich tropical rainforest that existed in Europe in the Middle Eocene and where the animals lived mainly in river valleys and swamps. Lophiodon representatives shared this biotope with crocodiles , pond turtles and giant snakes , but also with demi-monkeys and cloven-hoofed animals . The typical structure of the chewing surface of the molars with the two transverse enamel ridges ( bilophodont ) and the low tooth crowns ( brachyodont ) indicate that Lophiodon species mainly consumed soft leaf food, thereby occupying a similar ecological niche as today's tapirs . The high enamel ridges ( Lophen ) only allow vertical chewing movements, so that the food was first cut on the transverse ridges and then crushed in the grooves between these ridges when the teeth are tight . There were hardly any horizontal chewing movements. With a higher degree of chewing of the bars, they lost their cutting function and only had a squeezing or grinding effect. In contrast to the tapirs, however, the short inner space of the nose indicates that Lophiodon representatives did not have a proboscis that could be used for foraging and ingesting food. The typical diet of soft plant-based food ( browsing ) suggests an elongated, pointed upper lip, similar to what is the case with numerous herbivores today with such food specialization.
The body weight of Lophiodon varied between 68 and 307 kg, which was determined by the size of the lower first molar. Above all, the numerous finds from the Geisel valley, which were deposited over a period of around 3 million years, showed a considerable increase in body size from an initially average of 124 to later 223 kg. This may be associated with a stronger niche use, as the wooded landscapes were also used by other mammals with a similar preference for leafy food, such as the early equine Propalaeotherium .
Systematics
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Position of the genus Lophiodon within the Tapiromorpha according to Holbrook and Lapergola 2011
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Lophiodon is a genus from the family of the Lophiodontidae , now extinct representatives of the order of the odd ungulate . Originally, the Lophiodontidae were placed close to the tapirs due to their clearly bilophodontic posterior dentition and assigned to the higher-ranking group of the Tapiroidea . The Tapiroidea form together with the Rhinocerotoidea , the further relationship of the rhinos , the subordination of the Ceratomorpha , which traditionally oppose the Hippomorpha with the horses within the odd- toed systematics . In the mid-1980s, however, analyzes revealed a closer relationship between the Lophiodontidae and the Chalicotheriidae , also extinct odd-toed ungulates, which at that time played a mediating role between the two major subordinates and therefore had their own subordination, the Ancylopoda . Due to their general similarity to the tapirs, these were again classified together with the Ceratomorpha in the newly formed intermediate order Tapiromorpha in the same study . A possible ancestor of the Lophiodontidae was most likely Homogalax from the group of Isectolophidae , which are the sister taxons of the Ancylopoda-Ceratomorpha group.
Atalonodon and Lophiaspis are still closely related to Lophiodon , but only very little is known about them. Studies on phylogeny revealed that lophiodon possibly from Eolophiodon developed out which was introduced in 2015 on a nearly complete skull from La Borie in southern France. This comes from the Lower Eocene and shows an intermediate size between Lophiodon and Lophiaspis and, compared to the former, a simpler tooth design, especially with regard to the premolars. Accordingly, could lophiodon over Eolophiodon from Lophiaspis have emerged.
Numerous types of Lophiodon have been described in the course of research history, the following are valid today:
- L. baroensis Checa , 1997
- L. buchsowillanum Desmarest , 1822
- L. cuvieri Watelet , 1864
- L. eygalayense Laberrère & Montenat , 2011
- L. filholi Fischer , 1964
- L. isselense Filhol , 1888
- L. lautricense Noulet , 1851
- L. leptorhynchum Filhol , 1888
- L. parisiense Gervais , 1848-1852
- L. remense Lemoine , 1878
- L. rhinocerodes Rütimeyer , 1862
- L. sardus Bosco , 1902
- L. tapiroides ( Cuvier , 1812)
- L. tapirotherium Desmarest , 1822
- L. thomasi Depéret , 1906
In the 19th century in particular, American palaeontologists established numerous species in North America , which today are mostly associated with Heptpdon or Helaletes , which are somewhat more modern in their tribal history . It is unclear whether all of the species listed above have an independent character, as there has not yet been a major revision of Lophiodon or Lophiodontidae.
The genus Lophiodon was first scientifically described in 1822 by Georges Cuvier using finds from Issel , Bouxwiller , Montpellier and other French sites . Before that, however, he had already put some fossils of this genus on the tapirs ( Le petit tapir ) in 1804 , and a year later he referred further finds to the palaeotheria , extinct relatives of horses, and the rhinos. Henri Marie Ducrotay de Blainville provisionally placed all these fossil remains from Tapirotherium in 1817 , which prompted Cuvier to introduce the new genus Lophiodon in 1822 . A lower jaw from Issel, which had already been depicted by Cuvier and is now kept in the Muséum national d'histoire naturelle in Paris , is considered a lectotype . Since the majority of the finds at that time consisted of individual teeth, Lophiodon was initially still considered to be related to pigs . This only changed with the description of several skull finds at the end of the 19th century, which also came from Issel. Above all, however, the finds from the Geiseltal, which were mainly discovered in the first half of the 20th century, expanded our knowledge of the genus considerably. Sometimes in the course of the 20th century, some species were of lophiodon spun off into other genres, so in 1977 L. buchsowillanum in Rhinocerolophiodon or L. isselense the same period in Paralophiodon . Some researchers also see Paralophiodon and Rhinocerolophiodon as congeneric , whereby the species are then listed accordingly and plus L. leptorhynchum under Paralophiodon . Due to the fact that the characteristics are too few, the separation of the two genera of Lophiodon is not generally recognized. The name Lophiodon comes from ancient Greek and means λόφος ( lophos "hill", "comb") and ὀδούς ( odoús "tooth"), which refers to the characteristic shape of the chewing surface of the molars.
Individual evidence
- ↑ Walter Steiner: Europe in the primeval times. The geological development of our continent from prehistoric times to today. Munich, 1993, pp. 1–192 (p. 161)
- ↑ a b c d e f g h i Karl-Heinz-Fischer: The tapiroid perissodactyls from the Eocene brown coal of the Geiseltal. Geologie 45, 1964, pp. 1-101
- ↑ a b c d e f g Luke T. Holbrook: Osteology of Lophiodon (Mammalia, Perissodactyla) and its Phylogenetic Implications. Journal of Vertebrate Paleontology 29 (1), 2009, pp. 212-230
- ^ A b Luke T. Holbrook: Comparative osteology of early Tertiary tapiromorphs (Mammalia, Perissodactyla). Zoological Journal of the Linnean Society 132, 2001, pp. 1-54
- ^ Robert M. Schoch: A review of the Tapiroids. In: Donald R. Prothero and Robert M. Schoch (Eds.): The evolution of Perissodactyls. New York and Oxford, 1989, pp. 298-320
- ↑ Günter Krumbiegel, Ludwig Rüffle and Hartmut Haubold: The Eocene Geiseltal: a Central European brown coal deposit and its flora and fauna. Wittenberg, Ziemsen, 1983
- ↑ Karl-Heinz-Fischer: New finds of Rhinocerolophiodon (n. Gen.), Lophiodon, and Hyrachyus (Ceratomorpha, Perissodactyla, Mammalia) from the Eocene of the Geiseltal near Halle (GDR). Part 2. Lophiodon. Journal of Geological Science 5, 1977, pp. 1129-1152
- ↑ a b c Jens Lorenz Franzen: The primeval horses of the dawn. Munich, 2007, pp. 147–149
- ↑ State Collection for Natural History Rhineland-Palatinate / Natural History Museum Mainz: The Eckfelder Maar , homepage
- ↑ Jens Lorenz Franzen and Thomas Mörs: The northernmost occurrence of palaeogenic mammals in Europe. Paläontologische Zeitschrift 81 (4), 2007, pp. 447–456
- ^ A b c Henri-Pierre Labarrère and Christian Montenat: Le Lophiodon (Mammifère périssodactyle) du Lutétien d'Eygalayes (Drôme, France). Annales de Paléontologie 97, 2011, pp. 139–156
- ^ Wighart von Koenigswald, Ulrike Anders, Sandra Engels, Julia A. Schultz and Ottmar Kullmer: Jaw movement in fossil mammals: analysis, description and visualization. Paläontologische Zeitschrift 87, 2013, pp. 141–159
- ^ Wighart von Koenigswald: Mastication and wear in Lophiodon (Perissodactyla, Mammalia) compared with lophodont dentitions in some other mammals. Annales Zoologici Fennici 51, 2014, pp. 162-176
- ↑ Simon J. Ring, Hervé Bocherens, Oliver Wings and Márton Rab: Divergent mammalian body size in a stable Eocene greenhouse climate. Scientific Reports 10, 2020, p. 3987, doi: 10.1038 / s41598-020-60379-7
- ^ Luke T. Holbrook and Joshua Lapergola: A new genus of Perissodactyl (Mammalia) from the Bridgerian of Wyoming, with comments on basal Perissodactyl phylogeny. Journal of Vertebrate Paleontology 31 (4), 2011, pp. 895-901
- ^ A b Leonard B. Radinsky: Origin and Early Evolution of North American Tapiroidea. Peabody Museum of Natural History, Yale University, Bulletin 17, 1963, pp. 1-106
- ↑ JJ Hooker: A primitive ceratomorph (Perissodactyla, Mammalia) from the early Tertiary of Europe. Zoological Journal of the Linnean Society of London 82, 1984, pp. 229-244
- ↑ a b c Céline Robinet, Jean Albert Remy, Yves Laurent, Laure Danilo and Fabrice Lihoreau: A new genus of Lophiodontidae (Perissodactyla, Mammalia) from the early Eocene of La Borie (Southern France) and the origin of the genus Lophiodon Cuvier, 1822. Geobios 48, 2015, pp. 25-38
- ↑ Georges Cuvier: Recherches sur les Ossemens Fossiles (Nouvelle Edition), Tome second, 1re partie. Paris, 1822, pp. 176–222 ( [1] )
- ↑ Karl-Heinz-Fischer: New finds of Rhinocerolophiodon (n. Gen.), Lophiodon, and Hyrachyus (Ceratomorpha, Perissodactyla, Mammalia) from the Eocene of the Geiseltal near Halle (GDR). 1st chapter. Rhinocerolophiodon. Journal of Geological Science 5, 1977, pp. 909-919
