Pantolestes

Taxonomy

Class: Mammalia

Order: Pantolesta

Family: Pantolestidae (includes Pentacodontidae, Paroxyclaenidae, and Ptolemaiidae) (Rose 2006)

Genus: Pantolestes

Species: Pantolestes longicaudus, P. intermedius,P. natans, P. elegans, P. phocipes

When and where Pantolestes lived: The five known species of Pantolestes are known from the Bridgerian and Uintan Biochronological Zones, early Eocene, 52 mya, in western North America. The Order first appeared in the early Paleocene of western North America, and disappeared in the Oligocene, some 35 mya, leaving no descendants. Pantolestids are found in Europe, Asia and Africa (Rose 2006)

General Description

General Description:   Pantolestes, according to the few skeletons known, had a robust body with a well-developed tail which possibly indicates semiaquatic habits (Matthew 1909), particularly in Pantolestes from the middle Eocene of Wyoming.  This conclusion was based on the humerus, which resembles that of otters in being short, robust, and slightly S-shaped in lateral profile.  The broad tail, proximally, and the strong hind limbs would be used for propulsion when swimming.  Some pantolestans appear to have been terrestrial, with digging ability, others almost certainly arboreal.   Pantolestes exhibited large canines, a wide snout, and a broad, well-developed occipital region where the neck muscles attach to the head(Rose 2006).  It was likely omnivorous in food habits based on its general dentition.

Habitat:   Pantolestes lived in subtropical forests of broad-leaved, evergreen and deciduous trees, which existed across North America to 60 degrees N, in a time of global warming (Stucky 1992).  Perhaps the gradual climatic cooling of habitat into the Oligocene, particularly the streams on which he may have depended, is a cause for his extinction.  By the late Eocene, data suggest that habitats became more open (/Stucky, 1992).  Pantolesta were never abundant or very diverse, but they include some of the most successful semiaquatic mammals of the early Tertiary.  There are no living pantolestids.

Dentition:    Pantolestes exhibits fairly low-crowned molars with rounded cusps; uppers with a narrow stylar shelf and a wide posterolingual cingulum; lowers have low trigonids and broad, basined talonids, thus emphasizing crushing, grinding and an adaptation to a hard diet (Rose 2006).   The pantolestan dental formula is generally 3.1.4.3/3.1.4.3, as in many primitive eutherians (Rose 2006).  Its molar teeth are basically low crowned and have a primitive mammalian morphology.

Bibliography:

Matthew, W.D. 1909 The Carnivora and Insectivora of the Bridger Basin, middle Eocene. Memoirs of the AMNH ;

Rose, Kenneth D., The Johns Hopkins University Press, 2006, Baltimore

Stucky, Richard K., Mammalian Faunas in North America of Bridgerian to Early Arikareean “Ages” (Eocene and Oligocene),: D. R. Prothero and W. A. Berggren, 1992,
 

 Authored by Jean Widman

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