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| Rhizosmilodon | |
|---|---|
 | |
| Fossil specimens | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Suborder: | Feliformia |
| Family: | Felidae |
| Subfamily: | †Machairodontinae |
| Tribe: | †Smilodontini |
| Genus: | †Rhizosmilodon Wallace & Hulbert, 2013 |
| Type species | |
| Rhizosmilodon fiteae Wallace & Hulbert, 2013 | |
Rhizosmilodon is anextinctgenus of saber-tooth cat of thesubfamilyMachairodontinae that lived during theEarly Pliocene and was discovered in theU.S. state ofFlorida.[1]
The first fossils ofRhizosmilodon were discovered in fossil beds of central Florida by Steven C. Wallace and Richard C. Hulbert Jr and described in 2013. The holotype specimen,UF 124634, consists of a single right mandible. Many bones ofRhizosmilodon have been discovered including; Teeth; mandibles; foot bones; leg bones; and a single skull. All specimens ofRhizosmilodon have only been found in Florida.[2][3]
The locality ofRhizosmilodon suggests a North American origin of the Dirk-Toothed cats.
Specimens ofRhizosmilodon were originally referred underMegantereon hesperus. The Etymology of the genus name was given by Wallace & Hubert to mean "root of Smilodon", with "rhizo" meaning "root" because of the apparent ancestral relation toSmilodon. The species name "fiteae" was named in honor of Barbara Fite, who donated the paratype specimen,UF 135626, to the Florida Museum of Natural History.[1]
Comparable in size to a medium-sized modernjaguar at about 165 lb,[4] some estimates ranging between 55.7 to 58.3 kg (122.9 to 128.5 lbs) and 76.6 to 85.0 kg (168.9 to 187.4 lbs).[1]
Fossils ofRhizosmilodon are known only from Florida. The best specimens for this species are its lower jaw, a single skull, and teeth, which carry intermediate characteristics between advanced forms such asSmilodon and primitive forms such asParamachairodus. Based on the mandible alone,Rhizosmilodon has the primitive traits traits: a large lower canine and a small but evident jaw flange. The derived traits include various measurements of the incisors, p3, p4, and m1 teeth, with the lower canine being laterally compressed.[1]
Serrations only on the canine teeth support the placement ofRhizosmilodon within the tribeSmilodontini rather than the scimitar-toothedHomotherini. The severity of the serrations placeRhizosmilodon as a more ancestral genus thanMegantereon andSmilodon.[1]
It was likely an ambush predator, preying on animals such as deer, tapirs and horses.[5] Its size and robustness would have allowed it to climb into trees.
Phylogenetic relationships ofRhizosmilodon with other Machairodonts based on analysis of 37 cranio-mandibular characters.[1]
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| Homotherini |  | |
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| Metailurini | ||
| Smilodontini | ||
| Incertae sedis: | ||