Hispanotherium
| Hispanotherium | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Middle Miocene to Upper Miocene (Upper Burdigalium to Upper Serravallian ) | ||||||||||||
| 18 to 11.2 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Hispanotherium | ||||||||||||
| Crusafont & Villalta , 1947 | ||||||||||||
Hispanotherium is an extinct genus of rhinos and lived in the Middle and Upper Miocene around 18 to 11 million years ago. It is closely related to the Elasmotherium , but due to its age and features it is a rather original representative of this rhinoceros line.
features
Hispanotherium was a relatively early representative of the Elasmotherium and was characterized by a smaller and generally slimmer body. The skull reached a length of 53 to 57 cm and was elongated and flat. The occiput was drawn out long and at an acute angle, resulting in a low head position. The occipital bulge as the attachment point for the neck muscles showed a clear constriction when viewed from above. Furthermore, the nasal bone had a narrow shape without lateral extensions. In the side view, it showed a distinctly convex curve, so that the front part was clearly directed forward and also formed rather flat. This is also where the horn comes in, which is indicated by the pearl-like roughened structures on the bone surface. The nasal septum showed no ossification, as is typical for some later representatives of Elasmotheria. The forehead line between the nasal and occiput was slightly saddled.
The lower jaw was up to 43 cm long and built relatively strong. The symphysis was less strong and narrow and ended behind the second premolar . The four premolars and three molars of the upper dentition are known. The lower jaw, which has been handed down several times, each has three incisors , three premolars and also three molars; a canine was not formed. The significantly larger number of teeth compared to later Elasmotherium shows the basal position of Hispanotherium . The incisors were shaped like a dagger, the second being larger and up to 3 cm long, so that it resembled small tusks. However, the generally small size shows that they were already in the reduction process overall. The molars were relatively high crowned (hypsodont) , but not as extreme as later Elasmotheria. The proportion of dental cement reached high values and there were clearly curved enamel folds on the chewing surfaces. The anterior premolar was rather small, the size of the following ones increased backwards, the largest tooth in the dentition was the second molar.
Skeletal elements of the rest of the body ( postcranium ) are passed down quite often and include the limbs with the long bones as well as the hand and foot bones, but also remnants of the spine and shoulder blades . The long bones were relatively delicate, the matching size of the humerus and radius is striking , both were up to 30 cm long. The femur and the tibia , on the other hand, had lengths of sometimes over 40 cm. The hind limbs ended in three toes, with the central ray ( metatarsus III) being the strongest with a length of 15 cm. As is typical for Elasmotheria, however, the front legs had four toes. Here, too, the central ray ( metacarpus III), 17 cm long, was the most massive toe. The additional fourth ray (metacarpus V) was significantly reduced with a length of 3 cm.
Fossil finds
Significant sites come from Spain , where they occur, among other things, in the catchment area of the Tagus . In addition to skull and dentition remains, extensive remains of the post-ocean skeletal parts were found in Torrijos ( Toledo province ), which mainly include the bones of the musculoskeletal system . The same range of finds shows remains from La Retama ( province of Cuenca ), where around 40 bones were found that belong to three individuals, two of them fully grown and one juvenile . The finds from Córcoles ( Province of Guadalajara ), which also include finds from the spine, are very extensive . The first known complete skull from Spain comes from near Madrid, but it is badly bruised. Another complete skull comes from Lengshuigou near Lintong in the Chinese province of Shaanxi , while there are numerous isolated teeth from Laogou in the district of Hezheng (province of Gansu) . At least two individuals are from the Tunggur formation of Inner Mongolia, each with a skull, mandibular remains and postcranial skeletal elements Traditionally, a third individual is indicated by another juvenile lower jaw.
Paleobiology
The partly well-preserved fossil material from Hispanotherium allows conclusions to be drawn about the way of life of the rhinoceros genus. The low-hanging skull and the relatively hochkronigen teeth with its large proportion of dental cement suggest that it is mainly grass eating malnourished (grazing) and was a resident of open landscapes. This is also indicated by the generally slim limbs. In addition, the front legs show only a few differences in the length of the humerus and radius, which suggests that the Hispanotherium was quite fast moving, but the metadodies are too short for a persistent runner . In the form of the second incisors in each case, two size groups can be distinguished in the fossil material. This is interpreted by some paleontologists as an indication of a sexual dimorphism between the sexes.
Tribal history
Hispanotherium probably developed on the Iberian Peninsula in Western Europe, where it is found in Portugal and Spain, but also in France . One possible initial form was the genus Caementodon . The oldest finds of the rhino species come from the Middle Miocene and are around 18 million years old. Around 15 million years ago, towards the end of the Middle Miocene, it was first found in Asia. Finds are from Turkey and China. At that point in time it is no longer detectable in Europe, probably due to the changing climate from warm and dry to cooler and more humid conditions. The most recent finds so far come from Inner Mongolia and are around 11 to 12 million years old.
Systematics
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Internal systematics of the Elasmotheriini according to Sanisidro et al. 2012 and Deng 2008
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Hispanotherium belongs to the Elasmotheriini, who have a generally large physique and molars with high crowns. Due to its older age, its smaller size and more extensive dentition with less highly developed tooth crowns, it represents an earlier representative. Within the Elasmotheriini, the rhinoceros belongs to the sub- tribus Iranotheriina, which are characterized by a nasal horn, and is thus more closely related to Iranotherium and Ningxiatherium than with the actual Elasmotherium . The Elasmotheriini themselves form the sister taxon to the Rhinocerotini, which contain the rhinos living today.
Overall, different types of Hispanotherium have been described in the course of research history , of which only five are generally recognized today:
- H. beonense ( Antoine , 1997)
- H. corcolense Antoine, Alférez & Iñigo , 2002
- H. matritense ( Prado , 1864)
- H. tungurense Cerdeño , 1996
- H. wushanense Sun , Wang , Ji , Pang , Shi , Hou , Sun & Wang , 2017
The other species described, H. grimmi , H. alpani and H. lintungensis are now considered synonymous with H. matritense . But there are other types of synonym that were originally assigned to other genera such as Caementodon , Bergertherium or Chilotherium .
The type species is H. matritense . This was first described in 1864 by the Spanish geologist Casiano de Prado as Rhinoceros matritensis . The holotype includes individual teeth found in Madrid . The now correct generic name Hispanotherium , however, was introduced by the Spanish geologists Miguel Crusafont and Josep Fernández de Villalta in 1947. In 1996 Esperanza Cerdeño described the species H. tungurense on the basis of finds from Tunggur (Inner Mongolia, China), which were found in 1928 and are kept in the local museum. Pierre-Olivier Antoine wrote the description of the species Aegyrcitherium beonensis in 1997 , which was based on more than 200 finds of skull remains and postcranial skeletal material from Montréal-du-Gers ( Département Gers , France), which can be assigned to at least twelve individuals. Kurt Heissig saw this species as the predecessor of the genus Hispanotherium in 1999 . Today it forms the basic form of Hispanotherium as H. beonense .
Individual evidence
- ↑ a b c d e f g Esperanza Cerdeño: Rhinocerotidae from the Middle Miocene of the Tung-gur Formation, Inner Mongolia (China). American Museum Novitates 3184, 1996, pp. 1-43
- ↑ a b c d Carlos Iñigo, Esperanza Cerdeño: The Hispanotherium matritense (Rhinocerotidae) from Cercoles (Guadalajara): its contribution to the systematics of the Miocene Iranotheriina. Geobios 30 (2): 243-266
- ↑ a b c Esperanza Cerdeño: New remains of the rhinocerotid Hispanotherium matritense at La Retama site: Tagus basin, Cuenca, Spain. Geobios 25 (5), 1992, pp. 671-679
- ↑ Esperanza Cerdeño, MT Alberdi: Estudio descriptivo de esqueleto postcraneal de Hispanotherium matritense de yacimento mioceno de Torrijos (Toledo). Estudios geologicos 39, 1983, pp. 225-235
- ↑ a b c Oscar Sanisidro, María Teresa Alberdi, Jorge Morales: The First Complete Skull of hispanotherium matritense (Prado, 1864) (Perissodactyla Rhinocerotidae) from the Middle Miocene of the Iberian Peninsula. Journal of Vertebrate Paleontology, 32 (2), 2012, pp. 446-455
- ↑ a b c d e Deng Tao: New material of Hispanotherium matritense (Rhinocerotidae, erissodactyla) from Laogou of Hezheng County (Gansu, China), with special reference to the Chinese Middle Miocene elasmotheres. Geobios 36, 2003, pp. 141-150
- ^ E. Aguirre, MT Alberdi, E. Jimenez, C. Martin Escorza, J. Morales, C. Sese, D. Soria: Torrijos: nueva fauna con Hispanotherium de la cuenca media del Tajo. Acta Geologica Hispanica 17, 1983, pp. 39-61
- ↑ a b Deng Tao: A new elasmothere (Perissodactyla, Rhinocerotidae) from the late Miocene of the Linxia Basin in Gansu, China. Geobios 41, 2008, pp. 719-728
- ↑ Pierre-Olivier Antoine, Francisco Alférez, Carlos Iñigo: A new elasmotheriine (Mammalia, Rhinocerotidae) from the early miocene of Spain. Comptes Rendus Palevol 1, 2002, pp. 19-26
- ↑ Bo-Yang Sun, Xiu-Xi Wang, Min-Xiao Ji, Li-Bo Pang, Qin-Qin Shi, Su-Kuan Hou, Dan-Hui Sun and Shi-Qi Wang: Miocene mammalian faunas from Wushan, China and their evolutionary, biochronological, and biogeographic significances. Palaeoworld 2017 doi: 10.1016 / j.palwor.2017.08.001
- ↑ C. de Prado: Descripción física y geológica de la provincia de Madrid. Junta General de Estadistica, Madrid, 1864, pp. 1–219 (p. 152) ( [1] )
- ↑ M. Crusafont Pairo and JF de Villalta Comella: (.. Hispanotherium nov gen) Sobre un interesante Rinoceronte del valle del Manzanares MIOCENO del. Las Ciencias 12 (4), 1947, pp. 869-883
- ↑ Pierre-Olivier Antoine: Aegyrcitherium beonensis ngnsp., Nouvel élasmothère (Mammalia, Rhinocerotidae) du gisement miocene (MN 4b) de Montreal-de-Gers (Gers, France): position phylogenetique au sein des Elasmotheriini. New Yearbook for Geology and Paleontology 204 (3), 1997, pp. 399-414