Nanotitanops is an extinct genus of Brontotheriidae from the middle Eocene of China.
Description
This genus is currently known only from dental evidence. Described specimens do not exceed 13.55 millimeters in length and 12 millimeters in width. While it retains some basal traits, the teeth possess features which point toward it being relatively derived. It differs from basal designs in having relatively longer and narrower molars with stronger development of buccal shearing crests and only a vestigial paraconule on the upper molars.
The dental morphology is most similar to the much larger genera
Epimanteoceras and
Rhinotitan.
[Li, S. (2018). A new species of Brontotheriidae from the Middle Eocene of Junggar Basin, Xinjiang, China. Vertebrata PalAsiatica, 56(1), 25-44.]
Relationships
The exact placement of
Nanotitanops within Brontotheridae is uncertain. There are other small brontotheres from the Eocene of Asia such as
Microtitan,
Pygmaetitan, and
Protitan though morphological evidence does not support a monophyletic relationship between them. Morphological analysis tends to put
Nanotitanops in a polytomy near the node of the subfamily Brontotheriinae.
[Mihlbachler, M. C. (2007). Eubrontotherium clarnoensis, a new genus and species of brontothere (Brontotheriidae, Perissodactyla) from the Hancock Quarry, Clarno Formation, Wheeler County, Oregon. PaleoBios, 27(1), 19-39.][Mihlbachler, M. C., & Samuels, J. X. (2016). A small-bodied species of Brontotheriidae from the middle Eocene Nut Beds of the Clarno Formation, John Day Basin, Oregon. Journal of Paleontology, 90(6), 1233-1244.] It has been proposed as a possible sister taxon to
Epimanteoceras formosa. was originally named
Nanotitan, but this genus name was preoccupied by an
orthopteroid insects from the
Triassic of
Kyrgyzstan.
The genus name is derived from the Greek
nanos, meaning dwarf,
titan, referring to the
Titans of Greek mythology, and the Greek suffix -
ops, meaning face. The specific epithet of the only species refers to the village in which the first and only specimens have been found.
Paleobiology
This genus is only described from the astoundingly rich middle Eocene fissure-filling near the village of Shanghuang in southern
Jiangsu, China. The fissures also held another small brontothere,
Microtitan, a species known from the Irdin Manha Formation of the Nei Mongol Autonomous Region of China. They are both known only from a site dubbed Fissure D. This fissure contained various other mammalian fauna including the primitive
Cricetidae rodent
Pappocricetodon and the
Omomyidae or omomyid-like primate
Macrotarsius. The nearby fissures have included a large diversity of
.
[Beard, K. C., Qi, T., Dawson, M. R., Wang, B., & Li, C. (1994). A diverse new primate fauna from middle Eocene fissure-fillings in southeastern China. Nature, 368(6472), 604-609.] There is also a
Dichobunidae known from the area, called
Elaschitotherium[GRÉGOIRE, M., GUO, J., & BEARD, K. C. (2004). A new small dichobunid artiodactyl from Shanghuang (middle Eocene, eastern China): implications for the early evolution of proto-selenodonts in Asia. Bulletin of Carnegie Museum of Natural History, 2004(36), 177-197.]
