Osbornodon is an extinct genus of bone-crushing canid (canidae

Canidae

Canidae is the biological family of carnivorous and omnivorous mammals that includes wolves, foxes, jackals, coyotes, and domestic dogs. A member of this family is called a canid . The Canidae family is divided into two tribes: Canini and Vulpini...

) that were endemic to North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and which lived from the Orellan

Orellan

The Orellan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 33,900,000 to 33,300,000 years BP, a period of . It is usually considered to fall within the Early Oligocene...

 age of the Early Oligocene to Early Miocene

Early Miocene

The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....

 epoch 33.9—15.97 Ma (AEO

Appearance Event Ordination

Appearance Event Ordination or AEO is a scientific method for biochronology through the ordering of the appearance of fossil mammal genera by multivariate analysis, using conjunctional and disconjunctional range distributions in large sets of data.-Process:AEO is based on faunal overlap and...

) and existed for approximately .

Taxonomy

Osbornodon was named by Wang (1994). Its type is Osbornodon fricki. It was assigned to Canidae by Wang (1994) and Munthe (1998).

Morphology

Two fossil specimens were examined by Legendre and Roth for body mass. The first specimen was estimated to have weighed 22.2 kg (48.9 lb). The second specimen was estimated to have weighed 20.2 kg (44.5 lb).

Genus

Seven known species of the genus Osbornodon existed:

• Osbornodon fricki (18 Ma)
• Osbornodon iamonensis (synonyms: Cynodesmus nobilis, Paradaphoenus tropicalis) (21 Ma), Osbornodon renjiei (33 Ma), and Osbornodon sesnoni (32 Ma).

Species

Osbornodon scitulus appears to be a transitional species that partially fills a large morphological and stratigraphical gap within the Osbornodon genus. Compared to Osbornodon renjiei and Osbornodon sesnoni, Osbornodon scitulus possesses derived characters such as large frontal sinus

Frontal sinus

Sinuses are mucosa-lined airspaces within the bones of the face and skull. The frontal sinuses, situated behind the superciliary arches, are absent at birth, but are generally fairly well developed between the seventh and eighth years, only reaching their full size after puberty...

, high sagittal crest

Sagittal crest

A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull of many mammalian and reptilian skulls, among others....

, narrow infraorbital canal, short bulla

Bulla

-People:* Anton Bulla, a Slovak footballer and coach* Clyde Robert Bulla , an American author of books for children* Johnny Bulla, an American golfer* Karl Bulla, a Russian photographer* Max Bulla, an Australian bicycle racer...

, and broad premolars. O. scitulus differs from Osbornodon wangi in larger size and relatively wider P3 and shorter P4. O. scitulus is distinguishable from Osbornodon iamonensis

Osbornodon iamonensis

Osbornodon iamonensis is an extinct species of bone-crushing Hesperocyoninae, a predecessor of modern dogs that were endemic to North America and which lived from the Orellan age of the Early Oligocene to Early Miocene epoch 23.6—16.3 Ma and existed for approximately .O. iamonensis was named by E. H...

and later species in its primitive characters such as a non-elongated rostrum

Rostrum (anatomy)

The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....

, paroccipital process that is not expanded posteriorly, mastoid process not reduced, and p4 not differentially enlarged relative to p3 (Wang, 2003).