''Pseudhyrax'' is an extinct genus of archaeohyracid notoungulate. It lived from the Late

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

to the Early

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

, of what is now

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Description

This animal was approximately the size of a modern

raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the North American, northern or common raccoon (also spelled racoon) to distinguish it from Procyonina, other species of raccoon, is a mammal native to North America. It is the largest ...

, and its skull was approximately 13 centimeters long. The length of its body, excluding the tail, was approximately 65–75 centimeters, and it weighed around 7–9 kilograms. ''Pseudhyrax'' had a low and elongated skull, mainly characterized by its dentition. The

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

s and

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

of ''Pseudhyrax'' were particularly high-crowned (hypsodont).

Classification

The genus ''Pseudhyrax'' was first described in 1901 by

Florentino Ameghino Florentino Ameghino (born Giovanni Battista Fiorino Giuseppe Ameghino; September 19, 1853 – August 6, 1911) was an Argentine naturalist, paleontologist, anthropologist and zoologist, whose fossil discoveries on the Argentine Pampas, especial ...

, based on fossil remains found in

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

in terrains dated from the Late

. The type species is ''Pseudhyrax eutrachytheroides'', and the species ''P. strangulatus'' was also named by Ameghino. The name ''Pseudhyrax'' ("false

hyrax Hyraxes (), also called dassies, are small, stout, thickset, herbivorous mammals in the family Procaviidae within the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Modern hyraxes are typically between in length a ...

") reflects Ameghino's belief that this animal was related to hyraxes, due to the shape of its skull. The species name of the type species, ''eutrachytheroides'', means "similar to ''Eutrachytherus''", another genus of notoungulate currently considered as a synonym of '' Trachytherus''. ''Pseudhyrax'' is traditionally considered a member of

Archaeohyracidae Archaeohyracidae is an extinct family of Notoungulata, notoungulate mammals known from the Paleocene through the Oligocene of South America.McKenna, Malcolm C., and Bell, Susan K. 1997. ''Classification of Mammals Above the Species Level.'' Colum ...

, a clade of notoungulates sharing similarities with the modern

rock hyrax The rock hyrax (; ''Procavia capensis''), also called dassie, Cape hyrax, rock rabbit, and (from some interpretations of a word used in the King James Bible) coney, is a medium-sized terrestrial mammal native to Africa and the Middle East. Common ...

, but larger in size and with hypsodont teeth. The family Archaeohyracidae, however, may be paraphyletic, and some of its members may be basal to other groups of typotheres.

Paleoecology

''Pseudhyrax'' was a terrestrial animal, probably fast and agile, and perhaps social. It was

herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

and its high-crowned premolars and molars indicates that it was able to feed on hard and abrasive plants in open areas.

Bibliography

*F. Ameghino. 1901. Notices préliminaires sur des ongulés nouveaux des terrains crétacés de Patagonie reliminary notes on new ungulates from the Cretaceous terrains of Patagonia Boletin de la Academia Nacional de Ciencias de Córdoba 16:349-429 *G. G. Simpson. 1967. The beginning of the age of mammals in South America. Part II. Bulletin of the American Museum of Natural History 137:1-260 *M. A. Reguero and F. J. Prevosti. 2010. Rodent-like notoungulates (Typotheria) from Gran Barranca, Chubut Province, Argentina: phylogeny and systematics. In R. H. Madden, A. A. Carlini, M. G. Vucetich, R. F. Kay (eds.), The Paleontology of Gran Barranca: Evolution and Environmental Change through the Middle Cenozoic of Patagonia 148–165

References

Typotheres Eocene genus first appearances Oligocene extinctions Eocene mammals of South America Oligocene mammals of South America Paleogene Argentina Fossils of Argentina Paleogene Chile Fossils of Chile Fossil taxa described in 1901 Taxa named by Florentino Ameghino Prehistoric placental genera Golfo San Jorge Basin Sarmiento Formation {{notoungulate-stub