PARACERATHERIIDAE OSBORN, 1923

Bai, Bin, Wang, Yuan-Qing, Li, Qian, Wang, Hai-Bing, Mao, Fang-Yuan, Gong, Yan-Xin & Meng, Jin, 2018, Biostratigraphy and Diversity of Paleogene Perissodactyls from the Erlian Basin of Inner Mongolia, China, American Museum Novitates 2018 (3914), pp. 1-60 : 10-12

PARACERATHERIIDAE OSBORN, 1923

Pappaceras Wood, 1963

Three species of Pappaceras , P. confluens , P. minuta , and P. meiomenus , have been reported from the Erlian Basin ( Wood, 1963; Lucas et al., 1981; Wang et al., 2016). Although Radinsky (1967) considered Pappaceras a junior synonym of Forstercooperia , the validity of Pappaceras has been supported by other authors ( Qiu and Wang, 2007; Wang et al., 2016). The type of P. confluens (AMNH FM 26660) was recovered from the “Upper Gray clays” of the Arshanto Formation at Chaganboerhe. A referred mandible of P. confluens (AMNH FM 26666) was found in the Arshanto Formation at Huheboerhe. A left P2 of P. confluens (AMNH FM 26667) presumably derives from the Arshanto Formation in the Camp Margetts area.

The type of P. minuta (AMNH FM 26672) was found in the “Upper Gray clays” of the Arshanto Formation at Chaganboerhe (Lucas et al., 1981). The species also is known from the Arshanto Formation at Huheboerhe and Daoteyin Obo (Lucas et al., 1981; Wang et al., 2018). A nearly complete mandible of P. minuta (AMNH FM 26056) also was reported from the Shara Murun Formation (?), 6 mi east of Spring Camp at East Mesa.

The type of P. meiomenus is known from a nearly complete skull (IVPP V 20254 ), which was found in the upper part of the Arshanto Formation at Huheboerhe ( fig. 2C ) ( Wang et al., 2016). Wang et al. (2018) further separated the original specimens of F. minuta into different groups (i.e., P. minuta , P. meiomenus , and P. sp.) mainly based on the presence or absence of p1.

Forstercooperia Wood, 1938

Two species of Forstercooperia , F. totadentata and F. ulanshirehensis , have been reported from the Erlian Basin ( Wood, 1938; Wang et al., 2018). Forstercooperia totadentata (AMNH FM 20116) was discovered in the Irdin Manha Formation at Irdin Manha. Recently, Wang et al. (2018) reported a new species F. ulanshirehensis from the Ulan Shireh Formation at Wulanhuxiu and Wulantaolegai, as well as from the Irdin Manha Formation at Irdin Manha. Forstercooperia ulanshirehensis is known from a nearly complete skull, mandibles, and some fragmentary maxillae. Wang et al. (2018) further considered “ Forstercooperia ” huhebulakensis, erected by Qi (1987), to be a junior synonym of Pappaceras confluens .

Juxia Chow and Chiu, 1964

Two species of Juxia , J. sharamurenensis and J. shoui , have been reported from the Erlian Basin ( Chow and Chiu, 1964; Qi and Zhou, 1989; Qiu and Wang, 2007). Juxia sharamurenensis , known from a nearly complete skeleton (IVPP V 2891), was discovered in the Shara Murun Formation at Ula Usu ( fig. 2D ). Additional specimens housed at the American Museum of Natural History were referred to J. sharamurenensis ( Radinsky, 1967) , but they have not been studied in detail. Those specimens include: skeletal material (AMNH FM 20286–20288) from the Shara Murun Formation at Ula Usu, a mandible (AMNH FM 26753) from the base of “Lower Gray” at Erden Obo, and a mandible (AMNH FM 26750) from the “Shara Murun Formation” at Twin Obos.

Juxia shoui , known from a fragmentary skull with C–M2 (IVPP V 8757) and a lunar (IVPP V 3268), was recorded from the “Ulan Gochu Formation” at Erden Obo ( Qi and Zhou, 1989). The lunar was discovered in the “Lower White” where the skull (V 8757) presumably was also found.

Urtinotherium Chow and Qiu, 1963

Two species of Urtinotherium , U. intermedium and U. parvum , have been reported from the Erlian Basin ( Chow and Qiu, 1963; Qiu and Wang, 2007). The type of U. intermedium (IVPP V 2769) was recovered from the “Middle Gray” at Erden Obo. Qiu and Wang (2007) referred a radius (AMNH FM 26062) to U. intermedium from the same horizon and locality. Qiu and Wang (2007) also referred a mandible (AMNH FM 26032) from the “Ulan Gochu Formation” at Jhama Obo to the species, and the specimen was initially assigned to “ Indricotherium ” parvum by Radinsky (1967). Urtinotherium intermedium is also known from an atlas (AMNH FM 26390) and a right Mc III (AMNH FM 26389) from the “Houldjin Formation” at Huheboerhe and Camp Margetts, respectively. Qiu and Wang (2007) further considered “ Dzungariotherium erdenensis ” (IVPP V 8803) from the “Ulan Gochu Formation” at Erden Obo (Qi, 1989) to be a synonym of U. intermedium . However, its specific horizon remains unclear.

Urtinotherium parvum is known from a maxilla with P1–M3 (EMM 0146) from the “Lower White” at Erden Obo, and a few postcranial specimens (AMNH FM 26190) from the “Baron Sog beds” at Jhama Obo.

Paraceratherium Forster-Cooper, 1911

Only one species of Paraceratherium , P. grangeri , has been reported from the Erlian Basin ( Qiu and Wang, 2007). The following specimens were assigned to the species: AMNH FM 26166 and 26179 from the “Baluchitheres bed” (= “Upper White”) at Erden Obo and AMNH FM 26387 from the “Houdljin gravels” at Daoteyin Obo ( Qiu and Wang, 2007).

Aralotherium Borissiak, 1939

Qiu and Wang (2007) assigned some dental and postcranial material (e.g., EMM 0016 ) to Aralotherium sp. from the type Houdljin Formation near Erlian Hot .

Figures

FIG. 2. Cranial and mandibular reconstructions of typical Eocene perissodactyls from the Erlian Basin of Inner Mongolia, China. tapiroid A, Lophialetes expeditus; B, Paracolodon fissus; paraceratheriid C, Pappaceras meiomenus; D, Juxia sharamurenensis; amynodontid E, Rostriamynodon grangeri; F, Sharamynodon mongoliensis; brontotheriid G, Protitan grangeri; H, Embolotherium andrewsi. Scale bar equals 10 cm.