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. 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, 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.
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. ==Description==