Cynotherium

C. sardous. Credit: Mariomassone on the Wikimedia Commons.

*Cynotherium*, also known as Sardinian dhole or Sardinian fox, is an extinct genus of canid that lived in Sardinia and Corsica from the Middle Pleistocene to the Early Holocene.

## History

Many morphological traits of this genus are anomalous. Originally, it was thought to be related to the racoon dog based on cranial traits in 1990. However, these were later revealed to be superficial, lacking several key traits that would otherwise suggest affinities. Additionally, it was more hypercarnivorous, unlike the latter. It was also thought to be connected to *Eucyon* based on proportions, which was also denied in favour of the hypothesis that it is an island dwarf. It is closer related to lupine canids based on dentition and external brain anatomy. It began to go extinct upon modern human incursion.

## Description

With a skull similar to a jackal, teeth similar to *Cuon*, it is most similar to *Xenocyon*. The jugal dentition has an enlarged cutting edge and a reduced crushing edge (like hypercarnivores). The skull has a low sagittal crest, weak zygomatic arches and a slender mandible, suggesting chewing muscles that could not create force to dispatch large prey. This indicates a diet of small animals such as birds or the pica. The setting of the enamel prisms on the premolars and molars reinforces the hypercarnivory theory, further showing the occasional bone material in its diet. This may be plesiomorphic, suggesting that the maximum-sized prey it could take were *Megaloceros*. The cervicals show wide and deep muscle anchors that correlate with superior neck flexibility and rotation, extension and flexion of the atlanto-occipital joint and the raising/lowering of the head. The forelimbs have well-developed muscle anchors on the triceps and shoulder, humerus and ulna, suggesting that the triceps were more developed. The elbow had greater flexion than *Canis*, *Cuon* and *Vulpes*. These suggest hunting by ambush with the body kept low while stalking, with sturdy shoulder flexors allowing for great sprinting capability and the cervical muscles suggesting quick movements necessary to catch fast prey with zig-zagging movements. The circumference of the femoral midshaft suggests that it was of medium size (10 kilograms in weight and ~44 centimeters in height (the latter as proposed by some)).

## Classification

Because the islands of Sardinia and Corsica were joined in the Pleistocene, and only separated later, the species was native to the one, and after two islands. *Cynotherium* was thought to be related to the dhole, but after further reevaluation, it was closer related to the subgenus of *Canis*, *Xenocyon* and *Lycaon*. Adaptations of this canine like the long legs and short neck support a stalking/pouncing lifestyle. *Xenocyon* was determined an ancestor of *Cynotherium* or to *Canis arnensis*/*Canis mosbachensis*. A hypercarnivorous dentition with the non-robust skull is paradoxical, since they seem to be contemporary features. Instead, it is inferred that the dentition is ancestral and the gracility is derived. The lower third molar is present. In 2015, the species *C. malatestai* was named from the lower Middle Pleistocene of Grotta dei Fiori, Carbonia. It is transitional of *Xenocyon* and *C. sardous*, being larger with a heavier jaw.

## References

* https://en.wikipedia.org/wiki/Sardinian\_dhole
* https://it.wikipedia.org/wiki/Cynotherium\_sardous