Nothrotheriidae

Nothrotheriidae Temporal range: 11.6–0.011 Ma PreЄ Є O S D C P T J K Pg N Late Miocene to Late Pleistocene
Shasta ground sloth (Nothrotheriops shastense), Peabody Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Class:	Mammalia
Order:	Pilosa
Suborder:	Folivora
Family:	†Nothrotheriidae (Ameghino, 1920) C. Muizon et al., 2004
Genera
see text

Nothrotheriidae is a family of extinct ground sloths that lived from approximately 11.6 mya—11,000 years ago, existing for approximately 11.49 million years.^[1] The nothrotheres have recently been moved from the tribe Nothrotheriini or subfamily Nothrotheriinae within Megatheriidae to their own family, Nothrotheriidae.^[2] Nothrotheriids appeared in the Tortonian, some 11.6 million years ago, in South America. The group includes the comparatively slightly built Nothrotheriops, which reached a length of about 2.75 meters. While nothrotheriids were small compared to some of their megatheriid relatives, their claws provided an effective defense against predators, like those of larger anteaters today.

During the late Miocene and Pliocene, the nothrotheriid Thalassocnus of the west coast of South America became adapted to a shallow-water marine lifestyle.^[2][3][4]

The earliest nothrotheriid in North America was Nothrotheriops, which appeared at the beginning of the Pleistocene, about 2.6 Ma ago.^[5] Nothrotherium reached Mexico (Nuevo Leon) by the late Pleistocene.^[6]

Mounted skeleton of Pronothrotherium typicum in the Field Museum of Natural History, Chicago

The last ground sloths in North America belonging to Nothrotheriops died so recently that their dried subfossil dung has remained undisturbed in some caves, as if it were just recently deposited. One of the skeletons, found in a lava tube (cave) at Aden Crater, adjacent to Kilbourne Hole, New Mexico, still had skin and hair preserved, and is now at the Yale Peabody Museum. The American Museum of Natural History in New York City has a sample of dung with a note attached to it that reads "deposited by Theodore Roosevelt". The largest samples of Nothrotheriops dung can be found in the collections of the Smithsonian Museum.

Classification

FAMILY †Nothrotheriidae (Ameghino, 1920) C. Muizon et al., 2004

• Subfamily Thalassocninae C. Muizon et al., 2004
  • Genus Thalassocnus
• Subfamily Nothrotheriinae (Ameghino, 1920) C. Muizon et al., 2004
  • Genus Amphibradys
  • Genus Chasicobradys
  • Genus Huilabradys
  • Genus Mionothropus
  • Genus Nothropus
  • Genus Nothrotheriops
  • Genus Nothrotherium
  • Genus Pronothrotherium
  • Genus Xyophorus

References

1. PaleoBiology Database: Nothrotheriidae, basic info
2. Muizon, C. de; McDonald, H. G.; Salas, R.; Urbina, M. (June 2004). "The Youngest Species of the Aquatic Sloth Thalassocnus and a Reassessment of the Relationships of the Nothrothere Sloths (Mammalia: Xenarthra)". Journal of Vertebrate Paleontology (Society of Vertebrate Paleontology) 24 (2): 387–397. doi:10.1671/2429a. Retrieved 2009-01-29.
3. Muizon, C. de; McDonald, H. G.; Salas, R.; Urbina, M. (June 2004). "The evolution of feeding adaptations of the aquatic sloth Thalassocnus". Journal of Vertebrate Paleontology (Society of Vertebrate Paleontology) 24 (2): 398–410. doi:10.1671/2429b. JSTOR 4524727.
4. Amson, E.; Muizon, C. de; Laurin, M.; Argot, C.; Buffrénil, V. de (2014). "Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru". Proceedings of the Royal Society B: Biological Sciences (Royal Society of London) 281 (1782): 1–6. doi:10.1098/rspb.2014.0192.
5. PaleoBiology Database: Nothrotheriops, basic info
6. PaleoBiology Database: Nothrotherium, basic info

External links