Xenorhinotherium

Xenorhinotherium Temporal range: Late Pleistocene-Early Holocene (Ensenadan-Lujanian) ~0.126–0.0035 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Mounted skeleton of X. bahiense
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Litopterna
Family:	†Macraucheniidae
Subfamily:	†Macraucheniinae
Genus:	†Xenorhinotherium Cartelle & Lessa, 1988
Species:	†X. bahiense
Binomial name
†Xenorhinotherium bahiense Cartelle & Lessa, 1988
Map showing the distribution of Macrauchenia in red, and Xenorhinotherium in yellow, inferred from fossil finds

Xenorhinotherium is an extinct genus of macraucheniine macraucheniids, native to northern South America during the Pleistocene epoch, closely related to Macrauchenia of Patagonia. The type species is X. bahiense.^[1]

Some authors have proposed that the genus Xenorhinotherium a synonym of Macrauchenia, though this has not been widely accepted.^[2] The name Xenorhinotherium means "Strange-Nosed Beast" and bahiense refers to the Brazilian state of Bahia, where the first fossils were found.^[3]

Xenorhinotherium was a rather derived representative of the Macraucheniidae, a group of litopterns with camel-like appearances. Probably derived from lower Miocene forms such as Cramauchenia and Theosodon, this animal probably closely related to the large macraucheniids of the Pliocene and Pleistocene, such as Macrauchenia and Windhausenia.^[4][5]

Below is a phylogenetic tree of the Macraucheniidae, based on the work of McGrath et al. 2018, showing the position of Xenorhinotherium.^[4]

X. bahiense was a megafaunal herbivore that probably looked very much like Macrauchenia, weighing about 940 kg (2,070 lb).^[6] In life, X. bahiense would have vaguely resembled a tall, humpless camel with three toes on each foot and either a saiga-like proboscis^[7] or a moose-like nose.^[8] Pictographs from the Serranía de La Lindosa rock formation of Guaviare, Colombia, show what might possibly be Xenorhinotherium with three toes and a trunk, though the claims are highly controversial, and it is uncertain whether they even date to the last Ice Age.^[9][10]

Paired δ¹³C and δ¹⁸O measurements from fossils in the Brazilian Intertropical Region indicate that X. bahiense was primarily a browser.^[11] These findings are supported by its hypsodonty index.^[12]

Fossils of Xenorhinotherium, dating from the Late Pleistocene to the Early Holocene, have been found in the states of Bahia, the Jandaíra Formation of Rio Grande do Norte,^[1] and Minas Gerais in modern Brazil,^[13] and also in Venezuela, in the localities of Muaco, Taima-Taima and Cuenca del Lago.^[14][15]

Though not known from other countries, computer modelling suggests that the habitat in the western Andean slopes of Colombia, Ecuador, and Peru would have been suitable for this animal, particularly in areas that have not been extensively excavated yet.^[2]

In 2025, a study found evidence of Xenorhinotherium surviving until about 3,500 years ago.^[16]

• Morón, Camilo (January 2015). "Panorama geológico, paleontológico, arqueológico, histórico y mitológico del estado Falcón" [Geological panorama, paleontology, archeology, history and mythology in the State of Falcon, Venezuela]. Boletín Antropológico (in Spanish). 89 (1).
• Socorro, Orangel Antonio Aguilera (2006). Tesoros paleontológicos de Venezuela: el cuaternario del Estado Falcón [Paleontological treasures of Venezuela: the quaternary of the Falcón State] (in Spanish). Ministerio de la Cultura. ISBN 978-980-12-1379-6.

• Nascimento, Karoliny de Oliveira (27 February 2019). Paleoecologia alimentar de macrauchenia patachonica e xenorhinotherium bahiense (macraucheniidae: litopterna: mammalia) e o reconhecimento de seus nichos ecológicos [Food paleoecology of macrauchenia patachonica and xenorhinotherium bahiense (macraucheniidae: litopterna: mammalia) and the recognition of their ecological niches] (Thesis) (in Portuguese).
• McGrath, Andrew J.; Anaya, Federico; Croft, Darin A. (4 May 2018). "Two new macraucheniids (Mammalia: Litopterna) from the late middle Miocene (Laventan South American Land Mammal Age) of Quebrada Honda, Bolivia". Journal of Vertebrate Paleontology. 38 (3): e1461632. Bibcode:2018JVPal..38E1632M. doi:10.1080/02724634.2018.1461632. S2CID 89881990.
• de Oliveira, Karoliny; Araújo, Thaísa; Rotti, Alline; Mothé, Dimila; Rivals, Florent; Avilla, Leonardo S. (March 2020). "Fantastic beasts and what they ate: Revealing feeding habits and ecological niche of late Quaternary Macraucheniidae from South America". Quaternary Science Reviews. 231: 106178. Bibcode:2020QSRv..23106178D. doi:10.1016/j.quascirev.2020.106178. S2CID 213795563.