Pappaceras

Pappaceras; Temporal range: Early Eocene, 50–48 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Illustration of the skull and life restoration of P. minuta
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Perissodactyla
Superfamily:	Rhinocerotoidea
Family:	† Paraceratheriidae
Genus:	† Pappaceras ; Wood, 1963
Type species
	†Pappaceras confluens; Wood, 1963
Other species
	†P. minuta(Lucas et al., 1981); †P. meiomenusWang et al., 2016 ;
Synonyms
	Species synonymy P. minuta:; Forstercooperia minuta Lucas et al., 1981; ?"Forstercooperia crudus" Gabunia, 1977 (nomen nudum);

Last updated December 31, 2023

Pappaceras is an extinct genus of rhinocerotoids from the Early Eocene of Asia belonging to Paraceratheriidae.

Taxonomy

In 1963, material including a partial skull containing cheek teeth was unearthed in Late Eocene deposits of Mongolia. These remains were identified as from a true rhinoceros by Wood, who found them an important discovery with the scant amount of previous cranial material of early rhinocerotids available. On July 25, the same year, a paper was published by Wood concerning the taxonomy and osteology of these remains, in which he named them a new genus and species (or binomial) as well as re-ranking a previously named family as a subfamily containing the new taxon. The binomial created was Pappaceras confluens, classified as a close relative of Forstercooperia within Forstercooperiinae (before Forstercooperiidae, named in 1940 by Kretzoi). Wood noted that the generic name is derived from the Latin word πaππos, "grandfather", and the Greek words alpha, "without", and keras, "horn", translating as "Grandfather without horn". The species name is based on the confluent morphology of the teeth. The catalogue number for the skull is AMNH 26660, and it specifically preserved a "front half of the skull and a complete lower jaw, with most of the teeth and remaining alveoli, totaling a full placental series". Other remains included a portion of the mandible and a premolar. All of these specimens were from the lame locality, the Upper Gray Clays, of the Irdin Manha Formation in Inner Mongolia.^[1] In the revision by Radnisky, it was found that this species was assignable to Forstercooperia, and the new combination F. confluens was erected.^[2] This species is well known, although in the 1981 review of Forstercooperia, it was synonymized with F. grandis.

In the 1960s, newly uncovered material from the Arshanto Formation was identified as belonging to a new species of rhinocerotoid. Originally, they were found to be from F. confluens, as they were in the same location as that species holotype. They were later assigned to Forstercooperia sp., with no new name being given. The material included an almost complete skull, an almost complete lower jaw, an anterior portion of the skull, and an astragalus. These bones were first assigned a new species by Lucas et al., Forstercooperia minuta. They were found to be a unique species based on their size and the anatomy of their teeth. The species has been retained in the species complex of Forstercooperia throughout major revisions, by Lucas et al. in 1981,^[3] Lucas and Sobus in 1989,^[4] and Holbrook and Lucas in 1997.

In 1977, some the first description of a dentary from Kazakhstan's Sargamys Formation was published. Authored by Gabunia, the paper figured the dentary, as well as some other material. In the images caption, the dentary was assigned to as Forstercooperia sp. although the text used a different name. In the text, the dentary and its teeth were assigned to Forstercooperia crudus, although no size was mentioned. As the text did not have a description in it of F. crudus, the name is now considered a nomen nudum . Its material is possibly assignable to F. minuta, however.^[3] In 1997, other material from Kazakhstan, specifically the Kolpak Formation, was assigned to F. minuta, meaning that it certainly lived in Kazakhstan at the same time as F. crudus.^[5]

In a 1981 paper focusing purely on the genus Forstercooperia, it was found that there was very little diversity in the species found valid by Radinsky. This paper, authored by Spencer G. Lucas and Robert Schoch and Earl Manning and published in 1981 reviewed all currently-named species of Forstercooperia, and named the new species F. minuta. F. crudus, named in 1977 by Gabunia, was found to be a nomen nudum, and Pappaceras synonymized with Forsterocooperia.^[3] However, recent study has found Pappaceras to be generically distinct.^[6]

Evolution

The superfamily Rhinocerotoidea can be traced back to the early Eocene—about 50 million years ago—with early precursors such as Hyrachyus. Rhinocerotoidea contains three families; the Amynodontidae, the Rhinocerotidae ("true rhinoceroses"), and the Hyracodontidae. The diversity within the rhinoceros group was much larger in prehistoric times; sizes ranged from dog-sized to the size of Paraceratherium. There were long-legged, cursorial forms and squat, semi aquatic forms. Most species did not have horns. Rhinoceros fossils are identified as such mainly by characteristics of their teeth, which is the part of the animals most likely to be preserved. The upper molars of most rhinoceroses have a pi (π) shaped pattern on the crown, and each lower molar has paired L-shapes. Various skull features are also used for identification of fossil rhinoceroses.^[7]

Description

Pappaceras is known from a vast amount of cranial material, although only some scant postcranial remains. The largest species is P. confluens, followed P. minuta.^[3] The average size of all species, is about equal with a large dog, even though later genera like Juxia reached the size of a modern horse and Paraceratherium exceeded the size of the largest African elephant.^[7] Each species is distinguished by cheek tooth morphology, with the remaining skull quite similar.^[3] Like primitive rhinocerotoids, Pappaceras possesses blunt ends on the tips of its nasals, above the nasal incision. Unlike all modern rhinoceroses, the nasals of Pappaceras, as well as many related genera, lack rugosities, which suggests that they lacked any form of horn. The nasal incision extends fairly far into the upper jaw, ending just posterior to the canine. Pappaceras possesses a small post-incisor diastema, not as large as its descendants, and similar in size to that of Hyracodon.^[8]

Distribution and habitat

Remains of Pappaceras have been found all across Asia. Most important remains are from the Early Eocene Arshanto Formation of Inner Mongolia (China).^[3] In 1963, the species Pappaceras confluens was described from the same region, probably within the same formation.^[1]Pappaceras minuta, is based on a maxilla from the Irdin Manha Formation as well.^[3]P. confluens is known from Shara Murun Formation, Ulan Shireh Formation and Houldjin Formation, as well as the Arshanto Formation. P. minuta is known from specimens only from the Arshanto Formation, as is P. meiomenus, and possibly the Shara Murun Formation of China,^[3] and the Kolpak Formation of Kazakhstan,^[5]

Related Research Articles

Perissodactyla is an order of ungulates. The order includes about 17 living species divided into three families: Equidae, Rhinocerotidae (rhinoceroses), and Tapiridae (tapirs). They typically have reduced the weight-bearing toes to three or one of the five original toes, though tapirs retain four toes on their front feet. The nonweight-bearing toes are either present, absent, vestigial, or positioned posteriorly. By contrast, artiodactyls bear most of their weight equally on four or two of the five toes: their third and fourth toes. Another difference between the two is that odd-toed ungulates digest plant cellulose in their intestines, rather than in one or more stomach chambers as even-toed ungulates, with the exception of Suina, do.

Paraceratherium is an extinct genus of hornless rhinocerotoids belonging to the family Paraceratheriidae. It is one of the largest terrestrial mammals that has ever existed and lived from the early to late Oligocene epoch. The first fossils were discovered in what is now Pakistan, and remains have been found across Eurasia between China and the Balkans. Paraceratherium means "near the hornless beast", in reference to Aceratherium, the genus in which the type species P. bugtiense was originally placed.

Paraceratheriidae is an extinct family of long-limbed, hornless rhinocerotoids native to Asia and Eastern Europe that originated in the Eocene epoch and lived until the end of the Oligocene.

Sinotherium is an extinct genus of single-horned elasmotheriine rhinocerotids that lived from the late Miocene to Early Pliocene. It was ancestral to Elasmotherium, demonstrating a very important evolutionary transition from nasal-horned elasmotheriines to frontal-horned elasmotheriines. Its fossils have been found in the Karabulak Formation of Kazakhstan, lower jaw and teeth have been found in Mongolia, and a partial skull is known from the upper part of the Liushu Formation of western China. Sinotherium diverged from the ancestral genus, Iranotherium, first found in Iran, during the early Pliocene. Some experts prefer to lump Sinotherium, and Iranotherium into Elasmotherium.

<span class="mw-page-title-main">Amynodontidae</span> Extinct family of mammals

Amynodontidae is a family of extinct perissodactyls related to true rhinoceroses. They are commonly portrayed as semiaquatic hippo-like rhinos but this description only fits members of the Metamynodontini; other groups of amynodonts like the cadurcodontines had more typical ungulate proportions and convergently evolved a tapir-like proboscis.

Iranotherium is an extinct genus of large elasmotheriine rhinocerotids, comparable in size to a modern white rhino. It is known from the Late Miocene (Tortonian) of Maragha, Iran and the middle part of the Liushu formation of northwestern China. It was a precursor to the related Sinotherium and may have been ultimately outcompeted by its descendant. This species is most well known for showing unique sexual dimorphism among rhinos.

Juxia, ‘joo-she-a’, is an extinct genus of paraceratheriid, a group of herbivorous mammals that are related to the modern rhinoceros. The type species is Juxia sharamurenensis, named by Zhou Mingzhen and Qiu Zhanxiang in 1964. Juxia was around the size of a horse. It lived in Asia during the upper Eocene.

Tillodontia is an extinct suborder of eutherian mammals known from the Early Paleocene to Late Eocene of China, the Late Paleocene to Middle Eocene of North America where they display their maximum species diversity, the Middle Eocene of Pakistan, and the Early Eocene of Europe. Leaving no descendants, they are most closely related to the pantodonts, another extinct group. The tillodonts were medium- to large-sized animals that probably feed on roots and tubers in temperate to subtropical habitats.

Brachyhyops is an extinct genus of entelodont artiodactyl mammal that lived during the Eocene Epoch of western North America and southeastern Asia. The first fossil remains of Brachyhyops are recorded from the late Eocene deposits of Beaver Divide in central Wyoming and discovered by paleontology crews from the Carnegie Museum of Natural History during the early 20th century. The type species, Brachyhyops wyomingensis, is based on a single skull and was named by E.H. Colbert in 1937, but was not officially described until 1938. During the latter half of the 20th century, additional specimens from North America have been recorded from Saskatchewan and as far south as Texas, indicating that Brachyhyops had a broad distribution and was well-dispersed throughout western North America.

The Irdin Manha Formation is a geological formation from the Eocene located in Inner Mongolia, China, a few kilometres south of the Mongolian border.

Brontotheriidae is a family of extinct mammals belonging to the order Perissodactyla, the order that includes horses, rhinoceroses, and tapirs. Superficially, they looked rather like rhinos with some developing bony nose horns, and were some of the earliest mammals to have evolved large body sizes. They lived around 56–34 million years ago, until the very close of the Eocene.

Homogalax is an extinct genus of tapir-like odd-toed ungulate. It was described on the basis of several fossil finds from the northwest of the United States, whereby the majority of the remains come from the state of Wyoming. The finds date to the Lower Eocene between 56 and 48 million years ago. In general, Homogalax was very small, only reaching the weight of today's peccaries, with a maximum of 15 kg. Phylogenetic analysis suggests the genus to be a basal member of the clade that includes today's rhinoceros and tapirs. In contrast to these, Homogalax was adapted to fast locomotion.

Eggysodontidae is a family of perissodactyls closely related to rhinoceroses. Fossils have been found in Oligocene deposits in Europe, the Caucasus, Central Asia, China, and Mongolia.

Urtinotherium is an extinct genus of paracerathere mammals. It was a large animal that was closely related to Paraceratherium, and found in rocks dating from the Late Eocene to Early Oligocene period. The remains were first discovered in the Urtyn Obo region in Inner Mongolia, which the name Urtinotherium is based upon. Other referred specimens are from northern China.

The San Jose Formation is an Early Eocene geologic formation in the San Juan Basin of New Mexico and Colorado.

Forstercooperia is an extinct genus of forstercooperiine paraceratheriid rhinocerotoids from the Middle Eocene of Asia.

Astorgosuchus is an extinct monospecific genus of crocodilian, closely related to true crocodiles, that lived in Pakistan during the late Oligocene period. This crocodile may have reached lengths of up to 8 m (26 ft) and is known to have preyed on many of the large mammals found in its environment. Bite marks of a large crocodile have been found on the bones of juvenile Paraceratherium, however if these were left by Astorgosuchus cannot be said with certainty. The genus contains a single species, Astorgosuchus bugtiensis, which was originally named as a species of Crocodylus in 1908 and was moved to its own genus in 2019.

Ronzotherium is an extinct genus of perissodactyl mammal from the family Rhinocerotidae. The name derives from the hill of 'Ronzon', the French locality near Le Puy-en-Velay at which it was first discovered, and the Greek suffix 'therium' meaning 'beast'. At present 5 species have been identified from several localities in Europe and Asia, spanning the Late Eocene to Upper Oligocene.

Allacerops is an extinct genus of odd-toed ungulate belong to the rhinoceros-like family Eggysodontidae. It was a small, ground-dwelling browser, and fossils have been found in Oligocene deposits throughout Central and East Asia.

Uintaceras is an extinct genus of medium-sized early rhinocerotoids that lived in North America during the Middle Eocene, with only the type species U. radinskyi, named in 1997, currently contained within the genus. Traditionally considered the oldest and most primitive species of the Rhinocerotidae, it may instead have been a close relative of the Asian Paraceratheriidae. The dubious species Forstercooperia (Hyrachyus) grandis is also possibly the same animal as Uintaceras, although the Asian material of F. grandis was assignable to Forstercooperia confluens.

References

1 2 Wood, H.E. (1963). "A Primitive Rhinoceros from the Late Eocene of Mongolia". American Museum Novitates (2146): 1–12.
↑ Radinsky, L.B. (1967). "A Review of the Rhinocerotoid Family Hyracodontidae (Perissodactyla)". Bulletin of the American Museum of Natural History. 136 (1): 1–46. hdl:2246/1987.
1 2 3 4 5 6 7 8 Lucas, S.G.; Schoch, R.M.; Manning, E. (1981). "The Systematics of Forstercooperia, a Middle to Late Eocene Hyracodontid (Perissodactyla: Rhinocerotoidea) from Asia and Western North America". Journal of Paleontology. 55 (4): 826–841. JSTOR 1304430.
↑ Lucas, S.G.; Sobus, J.C. (1989). "The Systematics of Indricotheres". In Prothero, D. R.; Schoch, R. M. (eds.). The Evolution of Perissodactyls. New York, New York & Oxford, England: Oxford University Press. pp. 358–378. ISBN 978-0-19-506039-3. OCLC 19268080.
1 2 Lucas, S.G.; Emry, R.J.; Bayshashanov, B.U. (1997). "Eocene Perissodactyla from the Shinzhaly River, Eastern Kazakhstan". Journal of Vertebrate Paleontology. 17 (1): 235–246. Bibcode:1997JVPal..17..235L. doi:10.1080/02724634.1997.10010967. JSTOR 4523800.
↑ Haibing Wang; Bin Bai; Jin Meng; Yuanqing Wang (2016). "Earliest known unequivocal rhinocerotoid sheds new light on the origin of Giant Rhinos and phylogeny of early rhinocerotoids". Scientific Reports. 6: Article number 39607. doi:10.1038/srep39607.
1 2 Prothero, D.R. (2013). Rhinoceros Giants: The Palaeobiology of Indricotheres. Indiana University Press. pp. 1–160. ISBN 978-0-253-00819-0.
↑ Wood, H.E. (1938). "Cooperia totadentata, a remarkable rhinoceros from the Eocene of Mongolia" (PDF). American Museum Novitates (1012): 1–20.

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[wood1963-1] 1 2 Wood, H.E. (1963). "A Primitive Rhinoceros from the Late Eocene of Mongolia". American Museum Novitates (2146): 1–12.

[radinsky1967-2] Radinsky, L.B. (1967). "A Review of the Rhinocerotoid Family Hyracodontidae (Perissodactyla)". Bulletin of the American Museum of Natural History. 136 (1): 1–46. hdl:2246/1987.

[lucasetal1981-3] 1 2 3 4 5 6 7 8 Lucas, S.G.; Schoch, R.M.; Manning, E. (1981). "The Systematics of Forstercooperia, a Middle to Late Eocene Hyracodontid (Perissodactyla: Rhinocerotoidea) from Asia and Western North America". Journal of Paleontology. 55 (4): 826–841. JSTOR 1304430.

[lucas&sobus1989-4] Lucas, S.G.; Sobus, J.C. (1989). "The Systematics of Indricotheres". In Prothero, D. R.; Schoch, R. M. (eds.). The Evolution of Perissodactyls. New York, New York & Oxford, England: Oxford University Press. pp. 358–378. ISBN 978-0-19-506039-3. OCLC 19268080.

[lucasetal1997-5] 1 2 Lucas, S.G.; Emry, R.J.; Bayshashanov, B.U. (1997). "Eocene Perissodactyla from the Shinzhaly River, Eastern Kazakhstan". Journal of Vertebrate Paleontology. 17 (1): 235–246. Bibcode:1997JVPal..17..235L. doi:10.1080/02724634.1997.10010967. JSTOR 4523800.

[6] Haibing Wang; Bin Bai; Jin Meng; Yuanqing Wang (2016). "Earliest known unequivocal rhinocerotoid sheds new light on the origin of Giant Rhinos and phylogeny of early rhinocerotoids". Scientific Reports. 6: Article number 39607. doi:10.1038/srep39607.

[prothero2013-7] 1 2 Prothero, D.R. (2013). Rhinoceros Giants: The Palaeobiology of Indricotheres. Indiana University Press. pp. 1–160. ISBN 978-0-253-00819-0.

[wood1938-8] Wood, H.E. (1938). "Cooperia totadentata, a remarkable rhinoceros from the Eocene of Mongolia" (PDF). American Museum Novitates (1012): 1–20.

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