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Pliohyrax graecus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Hyracoidea
Family:	†Pliohyracidae
Subfamily:	†Pliohyracinae
Genus:	†Pliohyrax Osborn, 1899
Type species
Pliohyrax kruppi Osborn, 1899
Species
P. graecus (Gaudry, 1862) P. kruppi (Osborn, 1899) P. orientalis? (Tong & Huang, 1952) P. rossignoli (Viret, 1947) P. soricus (Dubrovo, 1978)
Synonyms
Genus synonymy Neoschizotherium Viret, 1947 Sogdohyrax Dubrovo, 1978 Species synonymy Pliohyrax occidentalis (Viret & Thenius, 1952)

Pliohyrax, is a genus of hyracoids (the cavy-like group of animals most closely related to elephants and manatees). It grew to sizes greatly exceeding those of any living hyrax, though it was by no means the largest member of this family.

Life restoration

Fossils of this Miocene-Pliocene, scansorial herbivore have been found in Afghanistan, France, and Turkey. In Spain, Pliohyrax graecus is among the large mammals species found in the Almenara site, deposited during the Messinian salinity crisis, together with Macaca sp., Bovidae indet., cf. Nyctereutes sp., and Felidae indet.

History

Holotype mandible of Pliohyrax graecus

In 1853, following a field trip in Cyprus, French palaeontologist and geologist Albert Gaudry stopped in Greece on his way back to France, and, on the invitation of the ambassador of France to Greece Alexandre de Forth-Rouen, visited a local fossil site at Pikermi, in the Attica peninsula, near Athens, first visited by German scientists. Gaudry immediatly recognized the importance of the deposits and led, in 1855 and in 1860, two excavation campaigns in Attica under the commission of the French Academy of Science. In Pikermi, Gaudry excavated the fossils of a diverse fauna whose preservation was almost unprecedented in the Neogene of Europe. Among those discoveries figured two large but isolated mandibles belonging to the same adult individual of a yet unknown large species of mammal. In a seminal book published in 1862, Gaudry described these incomplete remains under the name Leptodon graecus, after the slender shape of its molars. At the time of Gaudry, Hyracoids, Proboscideans, Perissodactyls and Artiodactyls were classified together within the order Pachydermata. Gaudry speculated that Leptodon was an extinct member of a clade including the modern rhinoceros and hyraxes. In 1886, Max Schlosser proposed that Leptodon was more closely related to the brontotheres.

The relationship between the Pikermi fossils and modern rhinoceros were however eventually contested, as more fossil localities were explored in Greece, particularly in the island of Samos in the Aegean Sea, and more material whose traits ressembled those of Leptodon were unearthed by German-led expeditions. In 1899, Schlosser and Karl von Zittel, from Munich, noted that a specimen found in Samos and storaged in the Stuttgart Natural History Cabinet, temporarily named "Hyrax kruppii" in honour of Friedrich Krupp, who had donated the specimen, to be described in the near future as a new genus of giant hyrax, shared several similarities with Leptodon graecus and with an undescribed specimen from Samos possessed by the Munich Palaeontological Museum. Schlosser and Von Zittel found that those remains, probably too similar to each other to belong to different species, belonged to a yet-unknown fossil group of large hyracoids, more closely related to modern hyraxes than to anything else. The same year, Henry Fairfield Osborn described formally the Stuttgart specimen, a very large fragmentary skull reaching twice the size of that of the largest modern hyrax, as Pliohyrax kruppii, a new type of hyracoid warranting the creation of the eponymous family Pliohyracidae, and the first fossil hyracoid known to science.

Finally, in the United Kingdom, Charles Forsyth Major published two papers regarding the genus ; the first, published in November, synonymyzed Leptodon graecus with Pliohyrax kruppi. Leptodon being already in use for a genus of kite, Pliohyrax was to be kept as the genus name, while at the species level the name graecus, given first, had priority over kruppi. The second article covered the anatomy of a new specimen from Samos, acquired in 1894 by the British Museum, firstly attributed by Johann Andreas Wagner to a newly described species of rhinoceros, Rhinoceros pachygnathus, being reassigned as belonging to Leptodon, now Pliohyrax. The specimen had been artificially altered to make it look more complete, but was nonetheless still complete enough to warrant a complete description, definitely prouving that the four then known specimens belonged to the same genus and possibly the same species, owing their differences to individual rather than interspecific variations.

The early 20th century

During the two first decades of the 20th century, the genus was recovered as part of a Saghatheriidae family that included most extinct genera of hyraxes by Charles William Andrews in 1906 and Schlosser in 1911. Subsequent digs at Pikermi yielded another fragmentary Pliohyrax mandible. In 1926, Matsumoto Hikoshichirō proposed the new monotypic family Pliohyracidae, in which he included Pliohyrax, Saghatherium and Pachyhyrax. The inclusion of the latter genus was only tentative, due to its fragmentary nature.

In 1916, Greek paleontologist Theodoros Skoupos led an expedition to Halmyropotamos, near Zarakes, in the Greek island of Euboea, to explore Miocene-aged fossiliferous outcrops. The abundant fossil remains found there, less complete than those of Pikermi and rarely found associated, were then storaged in the cellars of the Athens University Museum. In 1933, Camille Arambourg described formally a new species of Pliohyrax, as P. championi, that he had collected the year prior at Mount Losodok near Turkana Lake in Kenya. While seemingly more closely related to P. graecus from Pikermi, the new species had distinctly more primitive trait, more reminding of Saghatherium.

The 1940s and 1950s

In the aftermath of the Second World War, high demands in coal to reconstruct France led to the reopening of lignite exploitation near Saint-Martin-du-Mont, Ain, in the Soblay locality. There, paleontologists and biologists monitoring the exploitation collected several isolated dental remains, a molar and three premolars, of a new type of animal. In 1947, Jean Viret described several teeth collected by Robert Barone in the locality. Viret constated that the specimens shared several similarities with Postschizotherium, from the Pleistocene of Nihewan, in China, that was, at the time, thought to be a chalicothere. Hence, Viret described the remains as Neoschizotherium, without providing a species name, and thinking that it represented an ancestral form of Postschizotherium. The following year, 1948, Viret and Georges Mazenot properly described the remains from Soblay as Neoschizotherium rossignoli. A year later, in 1949, Viret described a second molar discovered among the last fossils extracted in Soblay, superficially ressembling that of Palaeotherium. Viret noted that the teeth anatomy of Postschizotherium and Neoschizotherium went against the evolutionary trends of the chalicotheres and more closely ressembled that of hyracoids. Therefore, he stated that Neoschizotherium was sufficiently similar in shape to Pliohyrax to be synonymized with the older genus, as the distinct species P. rossignoli. During a visit at the University of Lyon, Austrian paleontologist Erich Thenius noticed among indeterminate fossils found in the Pliocene-aged Sables de Montpellier near the eponymous city a single upper molar, that had been tentatively labelled as belonging to Palaeotherium by Maurice Gennevaux, and identified it as belonging to a fossil hyracoïd. In 1952, Thenius and Viret formally described this molar as the holotype specimen of the new species Pliohyrax occidentalis, noting that its shape was intermediate between the molars of the Miocene species of Pliohyrax and those of its Late Pliocene-Early Pleistocene relative Postschizotherium.

The assignation of P. championi to Pliohyrax was challenged in 1954 by Thomas Whitworth, who referred the species to Megalohyrax, as M. championi, due to an abundance of new and better preserved fossil remains belonging to the species being discovered in Rusinga Island and adjacent localities. Whitworth additionaly speculated that the apparition of Pliohyrax in the Hipparion fauna of Europe was only the result of a single island hoping colonisation event and that Eurasian hyraxes were limited to Greece, without taking into account however neither P. rossignoli nor Postschizotherium. He noted the great resemblance of Pliohyrax with the modern genus Procavia, that he attributed to the remoteness of the genus relatively to the .

The 1960s and 1970s

In 1966, Johann K. Melentis, formally describing the fossil remains uncovered by Skoupos in Halmyropotamos, assigned a second skull and two mandibles to P. graecus, and gave a more thorough analysis to the holotype skull from Pikermi. In 1970, Melentis described further remains of vertebrates discovered in the first expedition to Halmyropotamos, including the fragmentary and heavily worn frontal part of a mandible.

Between 1965 and 1969, lignite prospection in Anatolia directed by the BGR led to the discovery of an abundant Neogene fauna spanning from the Late Miocene to the Pleistocene, including pliohyracid remains. In 1972, during a scientific expedition in Shanxi, two hyracoid teeth presumably coming from the Baode locality were bought from a particular in Linfen. These two teeths were attributed to the genus Pliohyrax in 1974 by Tong Yongsheng and Huang Wanbo, as the new species P. orientalis. Tong and Huang additionally proposed that the French species P. rossignoli and P. occidentalis were distinct from Pliohyrax, and reerected the genus Neoschizotherium created by Viret for the species, as N. orientalis and N. rossignoli.

In 1974, Miquel Crusafont i Pairó and Juana Maria Golpe-Posse mentioned in passing the presence of Pliohyrax in Miocene deposits of the Can Llobateres locality, near Sabadell, in Spanish Catalonia. In 1975, Otto Sickenberg formally described vertebrate remains discovered between 1965 and 1969 in lignite-bearing Neogene strata in Anatolia. Among these remains he reported the presence of P. graecus in the Miocene-aged Eşme-Akçaköy, Garkın, Balçıklı Dere and Kayadibi, Konya localities, in the interior parts of the Aegean Region of Turkey. The next year, 1976, Siegfried E. Kuss described new remains of Pliohyrax, a fragmentary mandible and an associated calcaneus, discovered in 1973 in the Miocene-aged Pandánassa Formation, near Melabes in central Crete. He identified the specimen as a new species, distinguished by its smaller size and the presence of a diastema between the incisors. He speculated that the specimen represented a direct ancestral stage to P. graecus from Pikermi and Halmyropotamos, and that Pliohyrax might have colonized Continental Greece from Africa through a narrow land bridge across the Mediterranean.

In 1973, an expedition of the Paleontological Institute to Tajikistan led to the discovery, in Pliocene-aged deposits near Sor, Panjakent, of a single, isolated but relatively complete maxilla belonging novel type of hyracoid. Irina Dubrovo formally described these remains in 1978, as the new genus and species Sogdohyrax soricus. Comparing giant hyraxes and amynodont rhinoceroses, she noted the great similarities between both groups, which she speculated were the consequences of similar ecologies. Dubrovo adittionally dismissed claims of synonymity between Pliohyrax and Postschizotherium, but conceded that the chinese P. orientalis likely belonged to the latter genus.

The 1980s and 1990s

In 1981, Crusafont i Pairó and Golpe-Posse formally described the remains from Can Llobateres, a lower incisor and an astragallus, as ?Pliohyrax sp., although the lack of better material prevented a more stable assignation. Between 1982 and 1984, Michel Brunet, Emile Heintz and Bernard Battail noted in passing in a serie of papers the presence of a new species of Pliohyrax in Miocene deposits near Molayan, Afghanistan, discovered during a geologic survey in 1976-1978.

In 1985, Karl Alban Hünermann formally described some of the remains of Pliohyrax from turkish lignite deposits reported a decade before., and refered formally the hyracoid material from Garkın, Kayadibi and Paşalar to P. graecus, with reservations. In 1986, Luis Alcalá, Carmen Sesé and Jorge Morales described, among fossils coming from the Late Miocene La Cantera locality, remains of Pliohyrax collected in 1963 by José Orrios and that had been instrumental in the identification of the site as a fossiliferous locality. The remains, a fragmentary jaw, were tentatively described as P. cf. graecus.

In 1987, while describing the new species Parapliohyrax ngororaensis, Martin Pickford and Martin S. Fischer criticized the recovery of P. occidentalis as a distinct taxon, and synonymized it with P. graecus. He, however, had little access to the Asian material, and still recovered P. orientalis as part of the genus, and Sogdohyrax as the earliest diverging member of the pliohyracid lineage. In 1990, Mikael Fortelius proposed that the material assigned to P. graecus from Paşalar had been transported there from another locality, and that the species was not present here, despite the presence of hyracoid remains. While redescribing P. kruppi, confirming that the holotype had not be destroyed during the Second World War, and reestablishing it formally both as a distinct taxon and as the type species of Pliohyrax in 1992, Fischer and Elmar Heizmann synonymized P. occidentalis with P. graecus and did not recovered P. orientalis as part of the genus. They also reffered the specimens from Garkın, and tentatively referred the specimens from Kayadibi and Esme-Akçaköy, to P. kruppi. In 1994, within an edited volume directed by Sevket Sen, Mylène Baudry reported the collection of several fragments of the mandible, the maxilla and the humerus attributed to P. graecus in the KTA and KTB levels of the Kemiklitepe locality near Uşak, in western Turkey. In 1995, a study by Gary T. Schwartz, David Tab Rasmussen and Richard J. Smith estimated the size of extinct hyracoids based on the of their dentition and proposed that P. soricus weighed between 319 and 1331 kg. In 1996, Jan van der Made assigned the Melambes specimen to cf. Prohyrax hendeyi. In 1997, Pickford, Salvador Moyà-Solà and Pierre Mein described additional remains attributed to Pliohyrax from western Europe, referring isolated teeth and fragmentary limb bones collected by Moyà-Solà in 1988 in the fissure fillings of the Casablanca locality, Castellón, Spain, to P. graecus, and several isolated teeth from the Lo Fournas locality, Pyrénées-Orientales, France, to a juvenile P. rossignoli.

The 2000s

In 2002, Qiu Zhanxiang, Wei Qi, Pei Shuwen and Chen Zheying reexamined the heavily worn holotype remains of Sogdohyrax and determined that it represented a juvenile form of a larger species of Pliohyrax, that they renamed P. soricus.

Citations

• Stromer, E. (1926). "Reste Land- und Süsswasser-Bewohnender irbeltiere aus den Diamantenfeldern Deutsch-Südwestafrikas". Die Diamantenwüste Südwestafrikas. 2: 107–153.
• von Koenigswald, G.H.R. (1932). "Metaschizotherium fraasi n.g.n.s.p., ein neuer Chalicotheriide aus dem Obermiocän von Steinheim". Palaeontographica. 8 (8): 21.
• von Koenigswald, G.H.R. (1966). "Fossil Hyracoidea from China". Kon. Ned. Akad. Wetenschappen. 69 (3).
• Melentis, J.K. (1966). "Studien uber fossile Vertebraten Griechenlands. 12. Neue Schadel-und Unterkieferfunde von Pliohyrax graecus aus dem Pont von Pikermi (Attika) und Halmyropotamos (Euboea)". Annales Geologiques des Pays Helleniques. 17: 182–209.
• Meyer, G.E. (1978). "Hyracoidea". In Maglio, V.J.; Cooke, H.B.S. (eds.). Evolution of African Mammals. Harvard University Press. pp. 284–314.
• Becker Platen, J.D.; Sickenberg, O.; Tobien, H. (1975). "Die Gliederung der känozoischen Sedimente der Türkei nach Vertebraten. Faunengruppen". Geologisches Jahrbuch. 15: 47–100.
• Becker Platen, J.D.; Sickenberg, O.; Tobien, H. (1975). "Vertebraten. Lokalfaunen der Türkei und ihre Altersstellung". Geologisches Jahrbuch. 15: 47–100.
• Kuss, S.E. (1976). "Ein erster Fund von Pliohyrax aus dem Vallesian von Kreta/Griechenland". Neues Jahrbuch für Geologie und Paläontologie. ?: 157–162.
• Brunet, M.; Heintz, E.; Battail, B. (1984). "Molayan (Afghanistan) and the Khaur Siwaliks of Pakistan: an example of biogeographic isolation of Late Miocene mammalian faunas". Geologie en Mijnbouw: 31–38.
• Dubrovo, I.A. (1978). "New data on fossil Hyracoidea". Paleontologicheskii Zhurnal. (3): 97–106.
• Heintz, E.; Brunet, M. (1982). "Stand der Kenntnisse über die fossilen Wirbeltierfaunen von Afghanistan". Wissenschaftliche Zeitschrift der Humboldt-Universität zu Berlin / Mathematisch-naturwissenschaftliche Reihe. 31(3): 135–141.
• Gabunia, L.K.; Vekua, A.K. (1966). "Peculiar representative of Hyrax in the Upper Pliocene in Eastern Georgia". Soobscenija Akademii Nauk Gruzinskoj SSR. 42: 643–647.
• Gabunia, L.K.; Vekua, A.K. (1977). "On the mode of life and the status of the Giant Hyrax from Kvabebi". Soobscenija Akademii Nauk Gruzinskoj SSR. 73: 489–492.

• Fischer, M.S.; Heizmann, E.P.J. (1992). "Über neogene Hyracoiden (Mammalia) Die Gattung Pliohyrax". Neues Jahrbuch für Geologie und Paläontologie. 186(3): 321–344.
• Zong, G.F. (1996). "Hyracoidea Huxley". In Zong, G.F.; Chen, W.Y.; Huang, X.S. (eds.). Cenozoic Mammals and Environment of Hengduan Mountains Region. pp. 61–80.

Megalohyrax

In 1932, during an expedition in East Africa, French paleontologist Camille Arambourg had the opportunity to explore fossil bearing deposits in Mount Losodok, near Lake Turkana, in Kenya. The fossils discovered were shipped to the National Museum of Natural History in Paris, in which they were studied under the supervision of Marcellin Boule. In 1933, Arambourg, back from Africa, published the description of the fauna uncovered. Among the remains was a single fragmentary left mandible bearing two molars, presenting important similarities with several fossil hyraxes, and seemingly more closely related to the Pliohyrax graecus from Pikermi. The first remains of Pliohyrax discovered in Africa, it was still substantially different from the European species, seemingly retaining primitive traits more typical of Oligocene hyraxes such as Saghatherium. Arambourg named the new species P. championi, to honour the colonial Provincial Commissionner of Turkana County, M. Champion.

Hengduanshanhyrax

Larrayal/sandbox Temporal range:
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Hyracoidea
Family:	†Pliohyracidae
Subfamily:	†Pliohyracinae
Genus:	†Hengduanshanhyrax Chen, 2003
Type species
Postchizotherium tibetensis Zong, 1996

History of research

Between 1982 and 1983, during an expedition to the Hengduan Mountain, on the eastern slopes of Tibetan Plateau, the Chinese paleontologist Zong Guanfu collected abundant remains of mammals in the Pliocene-aged locality 82003 belonging to the Wangbunding Formation, in Dege County, western Sichuan, China. While describing the remains collected in the early 1980s, Zong Guanfu described in 1996 a new species of the giant hyracoid Postschizotherium, P. tibetensis, based on a fragmentary skull, HV 7788.1, as holotype. He also referred to the new species two mandibles found in the same locality, and estimated the age of the locality as being Early Pleistocene in age. In 2002, Qiu, Wei Qi, Pei Shuwen and Chen Zheying reviewed the material assigned to the species and determined that the two referred mandibles belonged to schizotheres, although the type maxilla was genuine. In 2003, Chen Guanfang determined that the differences between the holotype mandible of P. tibetensis and the other species of Postschizotherium were ample enough to warrant its erection as a distinct genus, that he named Hengduanshanhyrax, and corrected the age of the deposits to the Late Pliocene.

Kvabebihyrax

Larrayal/sandbox Temporal range:
Skull of a young individual
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Hyracoidea
Family:	†Pliohyracidae
Subfamily:	†Pliohyracinae
Genus:	†Kvabebihyrax Gabunia & Vekua, 1966
Type species
Kvabebihyrax kachethicus Gabunia & Vekua, 1966

History of research

Life restoration

During the 1965 spring expedition of the Institute of Paleobiology of the Georgian SSR Academy of Sciences in Kakheti, Georgia were excavated in the Kvabebi locality of the Aghchagil Formation a diverse fauna of Late Pliocene age. Among the vast collection of bovines and other mammals, Georgian paleontologists Leonide Gabunia and Abesalom Vekua took a special interest to the peculiar remains of a large animal seemingly closely related to the modern hyraxes. In 1966, they formally described the first remains, a single, isolated but mostly complete mandible, as a new genus and species, Kvabebihyrax kachethicus, closely related to the Eurasian genus Pliohyrax within the family Pliohyracidae. They speculated that these giant hyraxes had specialized for feeding by digging roots and hard buds in densely forested environments. Subsequent expeditions in the locality led to the discovery of numerous additional material, including the complete crania of an adult and two immature individuals, three isolated mandibles of various qualities of preservation, skull fragments and isolated teeths. These new remains were formally assigned to the genus in 1972 by Vekua, in a monograph on the Kvabebi fossil fauna, alongside a redescription of the genus to include autapomorphies of the newly known cranial material. In a following reassessment of the material in 1977, Gabunia and Vekua additionaly speculated that it may have had semi-aquatic dispositions, and may have sported a small tapir-like proboscis. In 1995, a study by Gary T. Schwartz, David Tab Rasmussen and Richard J. Smith estimated the size of extinct hyracoids based on the of their dentition and proposed that Kvabebihyrax weighed between 289 and 423 kg.

Meroehyrax

Larrayal/sandbox Temporal range:
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Hyracoidea
Family:	†Pliohyracidae
Subfamily:	†Pliohyracinae
Genus:	†Meroehyrax Whitworth, 1954
Type species
Meroehyrax batae Whitworth, 1954

History of research

In 1954, Thomas Whitworth described several new genera and species of hyracoids found in Early Miocene deposits in Rusinga Island and adjacent localities, in Kenya. Among these taxa, Whitworth described a new type of Sagatheriinae, Meroehyrax batae (then orthographied Meroëhyrax), based on a single, holotype fragmentary right mandible bearing molars and premolar, mostly distinguished from the genus Saghatherium by the presence of a distinct fossa on the mandible, resembling that of Geniohyus. Two additional cheek teeth from Rusinga, and another from an unknown Kenyan locality, were also proposed to belong to the genus. In 1978, Grant E. Meyer recovered the genus as the basalmost member of the subfamily Pliohyracinae, proposed it was synonymous with Prohyrax due to the lack of overlapping material, and tentatively attributed to the later genus a specimen collected by Bryan Patterson in 1964 in Early Miocene deposits of the Turkana Grits near Loperot.

In 1997, Pickford, Salvador Moyà-Solà and Pierre Mein tentatively proposed that Meroehyrax was closer to the Saghatheriidae and resolved its affinities with Prohyrax. In 2004, Pickford confirmed that Meroehyrax was not closely related to Prohyrax and was indeed a saghatheriid. He also referred to the type species the remains from Loperot previously attributed to Pliohyrax, as well as fragments of a mandible and isolated teeth collected in the late 1990s in Early Miocene deposits of the Moroto II locality in north-east Uganda. In 2005, Meroehyrax was recovered by Pickford as the sister taxa of all modern hyracoid genera.

The species name, bateae, honours Welsh palaeontologist Dorothea Bate.

Postschizotherium

Larrayal/sandbox Temporal range:
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Hyracoidea
Family:	†Pliohyracidae
Subfamily:	†Pliohyracinae
Genus:	†Postschizotherium Von Koenigswald, 1932
Type species
Postchizotherium chardini Von Koenigswald, 1932
Species
P. chardini (Von Koenigswald, 1932) P. intermedium (Von Koenigswald, 1966) P. orientalis? (Tong & Huang, 1952)
Synonyms
Postschizotherium licenti (Von Koenigswald, 1966)

History of research

Between 1924 and 1926, Emile Licent, founder and director of the Musée Hoangho Paiho of Tianjin, and his fellow Jesuit Pierre Teilhard de Chardin led extensive field work in the Nihewan Basin, collecting a vast diversity of fossils belonging to a then unknown Pleistocene fauna. Those fossils were then formally described by Teilhard de Chardin and Jean Piveteau in 1930, forming the basis of what is today known as the Nihewan Fauna. Among the remains found by Licent in Nihewan figured a first upper left molar and an associated third premolar. Teilhard de Chardin and Piveteau noted that, by their general shape, those teeth shared considerable similarities with those of the chalicotheres, a group of large, clawed perissodactyls also present in Nihewan. However, the differences with known chalicotheres being substantial, Teilhard de Chardin and Piveteau concluded that those remains represented a new genus of chalicothere.

In 1932, following this identification, Gustav von Koenigswald, considering that the gap between the Nihewan fossils and its nearest relatives within the chalicotheres was too important for the former to belong to a pre-existing genus, redescribed those remains as the new genus and species Postschizotherium chardini, honouring in the species name Teilhard de Chardin. He speculated that the animal was the most recent and derived representative of an hypsodont line of chalicotheres, related to Metaschizotherium. In 1933, Teilhard de Chardin and Pei Wenzhong tentatively refered a lower molar discovered in the Locality 12 of Zhoukoudian, near Beijing, to the genus. In 1936, Teilhard de Chardin and Licent described additional material referable to Postschizotherium sp., the anterior parts of a mandible and a maxilla belonging to the same individual, discovered in the Yushe Basin in Shanxi ; they noted that Postschizotherium represented an abherrant type of chalicothere. In 1939, Teilhard de Chardin described two additional anterior parts of the mandible discovered by Licent and Trassaert in the same Pliocene-aged deposits in Shanxi that had yielded the first mandible. He considered that all three specimens represented different species, firstly differentiated by their size, one much larger, the other much smaller than the jaw described in 1936, and tentatively restricted P. chardini to the largest specimen. The exact zoological affinities still puzzled Teilhard de Chardin ; the discovery of postcranial chalicothere material in Nihewan seemed to support his previous assumption, while George Gaylord Simpson noted that the teeth shared similarities with those of hyracoids, and Edwin H. Colbert proposed an affinity with the palaeotheres, based on the shape of the molars. Between 1937 and 1939, an additional tooth of enigmatic affinities was uncovered in the Middle Pliocene Cap Travertin in Zhoukoudian by Pei Wenzhong, which tentatively attributed it to Postschizotherium.

During the late 1940s, teeth remains discovered in the Soblay lignites in southern France were identified as belonging to a close relative of Postschizotherium, that Jean Viret named Neoschizotherium rossignoli. In 1949, with the discovery of additional material from the same locality, Viret constated that the Soblay specimens likely belonged to the widespread hyracoid genus Pliohyrax, as P. rossignoli. Therefore, on the basis of the ressemblance with the dentition of Pliohyrax, and as Gaylord Simpson had predicted, Viret repositionned Postschizotherium as an hyracoid closely related to Pliohyrax. He inferred that, originating in Africa, the hyracoid lineage had expanded northward, briefly entering Europe up to the Atlantic, and surviving up to the Quaternary in East Asia.

In 1966, Von Koenigswald distinguished three distinct species of Postschizotherium in China, representing three different stages, P. chardini being the younger, dating from the Early Pleistocene. He therefore established two new species : the Early Pliocene P. licenti, based on a single tooth he bought in a drugstore in Hong Kong, of unknown provenance, and to which he referred an additional fragmentary mandible from the Yushe Basin examined by Teilhard de Chardin in 1939 ; and the Middle Pliocene P. intermedium, based on the third mandible from Yushe and the tentatively assigned fossilized teeth from Zhoukoudian discovered by Pei in 1939. He formally refered the genus as belonging to Pliohyracinae, and speculated that the adaptations towards hypsodonty were typical of an environmental shift towards drier, savannah-like

In a 1974 article which reestablished Neoschizotherium for the two French species of Pliohyrax, Tong Yongsheng and Huang Wanbo criticized this split as premature due to a lack of overlapping material and difficulties to ensure precise datations. They also signaled the discovery of additional remains tentatively assigned to the genus in Zhoukoudian, and removed the mandible fragment from P. licenti, as the absence of overlapping material limited its exact identification.

In 1978, Emile Heintz, Léonard Ginsburg and Jean-Louis Hartenberger described formally remains collected in the 1970s in Afghanistan. Among the remains figured an hyracoid radius of large size, found in Pliocene-aged deposits near Jalalabad, in the east of the country. Similar in size to the two smaller species of Postschizotherium, P. intermedium and P. licenti, it was tentatively referred to the genus, although the absence of overlapping material hindered additional identification. The subsequent discovery of Pliohyrax in Miocene layers of the same country led to further discussions regarding the assignation of the remains.

In 1981, Qiu Zhangxiang referred to the genus an additional mandible found in the collection of the Tianjin Natural History Museum, of unknown provenance, to the genus, as Postschizotherium cf. chardini. Qiu speculated that, due to anatomical similarities, the genus was closely related to Parapliohyrax. In 1995, a study by Gary T. Schwartz, David Tab Rasmussen and Richard J. Smith estimated the size of extinct hyracoids based on the of their dentition and proposed that P. chardini weighed between 900 and 1432 kg. In 1996, Zong Guanfu described a new species of Postschizotherium, P. tibetensis, from the Hengduan Mountains of Sichuan, China, based on a maxilla and two mandibles, and referred to the genus an additional maxilla from the same site. In 2002, Qiu, Wei Qi, Pei Shuwen and Chen Zheying redescribed P. intermedium on the basis of two new crania associated with their mandibles collected by Wei and Chen between 1981 and 1983 in the locality 81018, in Tianzhen County, Shanxi. Additionaly, they considered that the holotype of P. licenti had been misidentified and that it was therefore a junior synonym of P. chardini, and that most of the material referred to Postschizotherium by Zong in 1996 belonged in reality to schizotheres, although the maxilla designated as type for P. tibetensis was genuine. In 2003, Chen Guanfang erected P. tibetensis as its own genus, Hengduanshanhyrax.

Prohyrax

Larrayal/sandbox Temporal range:
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Hyracoidea
Family:	†Pliohyracidae
Subfamily:	†Pliohyracinae
Genus:	†Prohyrax Stromer, 1926
Type species
Prohyrax tertiarius Stromer, 1926
Species
P. hendeyi (Pickford, 1994) P. tertiarius (Stromer, 1926)

During the First World War, German geologist Erich Kaiser led the first paleontological expedition into the Cenozoic diamond-bearing beds of German South West Africa, in modern day Namibia. Subsequent researches on the area were led by Werner Beetz under Kaiser's directions. Remains coming from three distinct localities were uncovered during these expeditions and were assembled in three collections, to which Ernst Stromer, well-versed in African palaeontology and geology, was given access for further studies. In 1926, Stromer published the result of these studies. Among the heavily worn fossil remains collected by Beetz in the Langental locality, in the heart of the Sperrgebiet, between the Bogenfels and Pomona mining settlements, still in activity at the time, were a left maxilla and a single fragmentary tooth tip probably belonging to the same individual. Stromer determined that it belonged to an immature individual belonging to a new genus, short-snouted and substantially larger than any modern hyraxes, that he named Prohyrax tertiarius. These remains were destroyed, like many others, during the widespread destructions of the Second World War ; however, casts survived. In 1954, Thomas Whitworth tentatively assigned the genus as an early-diverging member of the subfamily Saghatheriinae, along with Saghatherium and Meroehyrax.

In 1972, Cary T. Madden reported the presence of remains tentatively assigned to P. tertiarius among Late Miocene-aged fossils collected in 1948 at Muruarot Hill, near Lake Turkana, in Kenya during a field expedition from the University of California led by H. Basil S. Cooke. In 1978, Grant E. Meyer recovered it as belonging to the family Procaviidae, being potentially closely related with extant hyraxes. He referred to the genus a specimen collected by Bryan Patterson in 1964 in Early Miocene deposits of the Turkana Grits near Loperot, and noted that William Roger Hamilton reported the presence of the genus in Gebel Zelten, in Cyrenaica. While Meyer believed that those specimens and that reported in 1972 by Madden in Muruarot likely represented at least a new species, the lack of overlapping material and the fragmentary nature of the type species limiting further speculation.

Around 1976, numerous hyracoid remains were collected in the Miocene-aged Arrisdrift locality, near Oranjemund, in the ǁKaras Region of Namibia. These specimens, including a relatively complete skull, numerous fragmentary maxilla, mandibles, isolated teeth, limb bones, belonging to all sexes and ages, were described in 1994 by Martin Pickford and assigned to a new species of Prohyrax, P. hendeyi. He also refered a fragmentary maxilla from Langental to P. tertiarius. In 1995, Pickford et al. reported the presence of Prohyrax sp. in the early Miocene AM 02 quarry of the Auchas locality, in southern Namibia. The following year, Pickford described teeth from the Middle Miocene Berg Aukas locality in northern Namibia that he tentatively referred to Prohyrax or Parapliohyrax.< In 1996, Jan van der Made assigned a mandible of large hyracoid, collected in the Miocene Melambes locality of the Pandánassa Formation in Crete, and initially considered in 1973 by Siegfried E. Kuss as a new species belonging to the genus Pliohyrax, to cf. P. hendeyi.

In 1997, Pickford, Salvador Moyà-Solà and Pierre Mein described additional remains attributed to P. tertiarius, including several maxilla, mandibles and isolated teeth from Langental and Elizabethfeld. The authors noticed the great similarities with those of P. hendeyi, the only difference being the size. This additional material was instrumental to resolve its affinities with Meroehyrax and with modern Procaviidae. In 2003, Pickford mentionned in passing that the specimen from Berg Aukas tentatively assigned to the genus belonged to its larger relative Parapliohyrax ngororaensis, and estimated the size and weight of P. hendeyi.

Thyrohyrax

Larrayal/sandbox Temporal range:
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Hyracoidea
Family:	†Pliohyracidae
Genus:	†Thyrohyrax Meyer, 1973
Type species
Thyrohyrax domorictus Meyer, 1973

From 1961 to 1967, expeditions organized by Yale University to the Fayoum uncovered a rich diversity of fossil taxa from the Jebel Qatrani Formation. Among the remains were a vast array of fragmentary dentaries and associated postcranial remains belonging to a new type of hyracoid, collected between 1962 and 1967 in the quarries G, M and I. In 1973, Grant E. Meyer, who had participated in the expeditions, described formally the remains as the new genus and species that he named Thyrohyrax domorictus, based on the only fragmentary right mandible collected in Quarry M during the last year of the expeditions by Meyer himself. Meyer noted the great resemblance between Thyrohyrax and Meroehyrax, then placed among the Pliohyracinae, and proposed that T. domorictus, while a Sagatheriinae, was closely related to the last common ancestor of the more derived pliohyracins. In 1978, in an overview of the fossil African hyraxes, Meyer still excluded Thyrohyrax from Pliohyracinae, but speculated that it was at least closely related in its dental anatomy to the earliest stage of a lineage leading directly to Pliohyrax through Meroehyrax.

The genus name, Thyrohyrax, is formed from the Greek prefix "thyra-", meaning "window", and the suffix "-hyrax", referring to the internal fenestra in the mandible of the presumed females. The type species name is formed from the Greek "domos-", meaning "house" and the Latin -ramus, meaning "jaws", referring to the chambered jaws of the type species.

References

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Most important fossiliferous localities

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Most important fossiliferous localities

N. khun

Larrayal/sandbox Temporal range:
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Anseriformes
Genus:	†Naranbulagornis Zelenkov, 2018
Type species
Naranbulagornis khun Zelenkov, 2018

Naranbulagornis is an extinct monotypic genus of basal waterfowl. Its type and only known species, N. khun, is known from two Late Paleocene localities in Southern Mongolia.

History and Etymology

The holotype and paratype remains of Naranbulagornis were collected between 1970 and 1971 during the Joint Russian-Mongolian Paleontological Expedition in the Naran-Bulag and Tsagaan-Khushuu localities, both representing the Late Paleocene Naran Member of the Naran-Bulak Formation. The known material was described as the new genus and species Naranbulagornis khun in 2018 by Nikita Zelenkov. The genus name is formed from the prefix "Naranbulag", designing the name of the type locality, meaning "sunshine spring" in Mongolian, and the suffix "-ornis", meaning "bird". The species name, "khun", means "swan" in Mongolian.

Description

Naranbulagornis was a quite large waterfowl, a fourth larger than the contemporary Anatalavis ; it was presumably the largest anseriform of its time, reaching the size of the modern coscoroba swan. The holotype, the proximal end of a right carpometacarpus, reached 58 mm in length ; most notably, and contrarily to all other anseriforms, its pisiform process was positioned at the level of the proximal margin of the extensor process.

Paleontology

Invertebrates

Genus	Species	Order	Family	Notes	Images
Aspidoceras	A. cf. catalaunicum	Aspidoceratidae	Ammonitida
Oppeliidae indet.		Oppeliidae	Ammonitida
Perisphinctidae indet.		Perisphinctidae	Ammonitida
Hibolites		Belemnopseidae	Belemnitidae	Very small members of the genus.
Terebratulida indet.			Terebratulida
Rhynchonellida indet.			Rhynchonellida
Solanocrinites	S. thiollieri		Comalutida
Pentasteria	P. (Archastropecten) lithographica	Astropectinidae	Paxillosida
Comptoniaster	C. chantrei	Goniasteridae	Asteroidea