Merck's Rhinoceros

''Stephanorhinus kirchbergensis'', also known as Merck's rhinoceros or the forest rhinoceros, is an extinct species of rhino known from the Middle to Late Pleistocene of Eurasia. One of the last members of the genus ''Stephanorhinus'', it is considered to be a typical component of the interglacial ''Palaeoloxodon'' large faunal assemblage in Europe. Among extant species of rhinoceroses it is most closely related to the Sumatran rhinoceros, while the well known woolly rhinoceros was another close relative. In the western part of its range, it was sympatric with ''Stephanorhinus hemitoechus''.

Etymology and taxonomy

The first part of the genus name is derived from that of King Stephen I of Hungary, and the second part from 'rhinos' (ρινος, meaning "nose"), as with ''Dicerorhinus.'' The species name was given by Georg Friedrich von Jäger in 1839 for Kirchberg an der Jagst in Baden-Württemberg, Germany where the type specimens had been found. It is often known in English (and equivalents in other languages) as Merck's rhinoceros after Carl Heinrich Merck, who gave the initial name to the species in 1784 as ''Rhinoceros incisivus'', that is now considered a ''nomen oblitum'', and who after a widely used junior synonym of the species, ''Rhinoceros/Dicerorhinus mercki'' (historically several alternate spellings) was named by Johann Jakob Kaup in 1841.

Description

Merck's rhinoceros is considered to be large for a rhinoceros, with a particularly large specimen from Poland reaching an estimated height at the withers of 182 centimetres. The bones of the skeleton are robust and massive. The skull of Merck's rhinoceros is elongated, with the septum nasalis ossified only towards its anterior (front) end. The mandibular symphysis is relatively long and the mandible has a horizontal high, thick branch.Selected records of Stephanorhinus kirchbergensis (Jäger, 1839 (Mammalia, Rhinocerotidae) in Italy
Emmanuel M.E. BILLIA & Carmelo PETRONIO Bollettino della Società Paleontologica Italiana, 48 (1), 2009, xx-xx. Modena

Dental anatomy

The enamel of the teeth is very thick, and often bright coloured and smooth, with very thin or absent coronal cement. The buccal (cheek-facing) sides of the teeth often have sub-vertical bluish lines. Tooth dimensions are highly variable in comparison to other ''Stephanorhinus'' species. The upper teeth, especially the molars, are much higher towards the buccal side than to the lingual (towards the tongue) side. The ectolophs of the first and second upper molars have shallower folds, especially the fold between the paracone and mesostyle, than those of '' S. hemitoechus,'' resulting in a less pronounced undulation. In comparison to other species of ''Stephanorhinus,'' the premolars of ''S. kirchbergensis'' are mesially (towards the front of the tooth) broad and relatively lingually short. The upper premolar ectoloph folds are shallow, and have narrow anterior valleys. The ectoloph curves strongly mesially and often distally (towards the hind portion of the tooth) towards the inside of the tooth. In both upper molars and premolars, the metalophs and the protolophs are distinctly bulbous. The lower premolars and molars are similar and hard to distinguish.

Origin

The origin of the species is obscure, with various authors suggesting either a European or Asian origin. The earliest definitive records are from Choukoutien Locality 13, in Fangshan District near Beijing at around the Early-Middle Pleistocene transition, though the older records of ''Stephanorhinus lantianensis'' and ''Stephanorhinus yunchuchenensis'' have been suggested to be synonyms of ''S. kirchbergensis'' by some sources. It appears in Europe during the early Middle Pleistocene between 0.7 and 0.6 million years ago, existing alongside the already present ''S. hundsheimensis''. Mitochondrial and nuclear genomes obtained from a permafrost specimen and a dental proteome suggest that it is more closely related to the woolly rhinoceros than the Sumatran rhinoceros, but its relationship to other ''Stephanorhinus'' species remains unclear.

Range

Its range spans from Europe to East Asia, but appears to be absent from the Iberian Peninsula.Billa, E.M.E. 2011a. Occurrences of Stephanorhinus kirchbergensis (Jäger, 1839) (Mammalia, Rhinocerotidae) in Eurasia - An account. Acta Palaeontologica Romaniae 7: 17-40 It is presumed to have had a preference for closed forest and woodland habitats, as opposed the to open grassland habitats favoured by ''S. hemitoechus''. Its range extended into the Arctic Circle, with a 70–48 thousand-year-old skull known from arctic Yakutia in the Chondon River valley and a late Middle Pleistocene aged lower jaw from the Yana River valley. Teeth are known from caves in Primorsky Krai , suggested to date between 50,000 and 25,000 years ago based on dates of other bones found in the deposit, which are the easternmost known records. A tooth of ''S.'' cf''. kirchbergensis'' of an unknown age is known from the Lut Desert in eastern Iran. It is fairly common throughout the Pleistocene in North China, but is a rarer component of South Chinese assemblages, being known from around 30 localities in the region. Antoine (2012) states that ''D.'' ''choukoutienensis'', ''D. lantianensis'', and ''D. yunchuchenensis'' are local names for the taxon, without elaboration. Its range was strongly controlled by glacial cycles, with the species experiencing repeated cycles of expansion and contraction as the ice sheets advanced, this accounts for the relative rarity of its remains in comparison to the woolly rhinoceros. The species' range underwent significant reduction during the Last Glacial Period, with the youngest records from Italy being in Marine isotope stage (MIS) 4 and 3. Radiocarbon dated remains from the Altai date to around 40,000 years ago. The youngest reliable records in China are from the Rhino Cave in Hubei, which is early Late Pleistocene in age. Though less definitive remains are known from near Harbin in Heilongjiang, which are thought to be 20 kya in age. Records from Migong Cave just south of the Yangtze River in the Three Gorges area are suggested to date to MIS 2 (29,000-14,000 years ago).

Diet

Merck's rhinoceros has been interpreted as a browser, feeding on the branches and leaves of trees and shrubs. It had a more specialised diet than ''S. hundsheimensis'' and was clearly distinct from the grazing diet hypothesised for ''S. hemitoechus''. Despite their morphological differences, dental wear analysis of several European ''S. kirchbergensis'' and ''S. hemitoechus'' populations were similar and indicative of mixed feeding, suggesting dietary convergence due to low habitat variability during the Pleistocene. Analysis of plant material embedded within teeth from the Neumark-Nord locality in Germany found remains of ''Populus'' (poplar or aspen) ''Quercus'' (oak), ''Crataegus'' (hawthorn), ''Pyracantha'', ''Urtica'' (nettles) and ''Nymphaea'' (water lilies) as well as indeterminate remains of Betulaceae, Rosaceae, and Poaceae (grass). Preserved plant remains found with the teeth on the arctic Chondon skull included twigs of ''Salix'' (willow), ''Betula'' (birch) and abundant ''Larix'' (larch) alongside fragments of Ericaceae (heather); sedges were notably absent. A specimen from Eemian aged deposits in Gorzów Wielkopolski in Poland had twigs of ''Corylus'' (hazel), ''Carpinus'' (hornbeam), and ''Viscum'' (mistletoe)'','' alongside fruit scales of birch, with hazel and birch dominating amongst the pollen. The pollen from a specimen found at Spinadesco in Italy was dominated (~50%) by trees, particularly ''Alnus'' (alder) and ''Fagus'' (beech), with ''Hippophae rhamnoides'' (sea buckthorn), dominating amongst the shrubs, with around 30% of the total contribution being from a variety of herbaceous plants.

Human exploitation

At the Taubach travertine site in Thuringia, Germany, which dates to the Eemian (approximately 130,000-115,000 years ago) remains of Merck's rhinoceros with cut marks are known. The vast majority of remains were of young subadults, alongside a much smaller number of adults. It has been suggested that the rhinoceroses were killed and butchered on site by Neanderthals.Bratlund, B. 1999
Taubach revisited
''Jahrbuch des Römisch-Germanischen Zentralmuseums Mainz'' 46: 61-174.

Gallery

File:Dicerorhinus kirchbergensis.JPG
File:Stephanorhinus kirckbergensis skull.jpg, Partial skull in Stuttgart
File:Stephanorhinus kirchbergensis.JPG, 300,000 year old dentary fragment from the United Kingdom in the NHM, London
File:Naturgeschichte Museum Schaffhausen Waldnashorn aus Flurlingen.jpg, Remains of Merck's rhinoceros from Germany
File:Stephanorhinus kirchbergensis skull with horn attachment positions.png, View of the top of the snout of a ''S. kirchbergensis'' skull, showing the rugose texture of the horn attachment area

References

{{Taxonbar, from=Q310972

Pleistocene rhinoceroses
Prehistoric mammals of Europe
Pleistocene mammals of Asia