Its anatomy and morphology relate it more to the modern golden jackal (Canis aureus) than to the larger Etruscan wolf of that time.

The fossil record for ancient vertebrates is composed of rarely occurring fragments from which it is often impossible to obtain genetic material.

Researchers are limited to morphologic analysis, but it is difficult to estimate the intraspecies and interspecies variations and relationships that existed between specimens across time and place.

[6] Upper Valdarno is the name given to that part of the Arno Valley situated in the provinces of Florence and Arezzo, Italy.

The Upper Valdarno Basin has provided the remains of three fossil canid species dated to the Late Villafranchian era of Europe 1.9-1.8 million years ago that arrived with a faunal turnover around that time.

He noted that C. arnensis of Europe showed striking similarities to C. priscolatrans, and they could represent what once was a Holarctic population of coyotes.

[3] In 2016, a study looked at previously undescribed specimens of C. arnensis from the Poggio Rosso site located in the northeastern Upper Valdarno and dated 1.9-1.8 million years ago.

Its anatomy and morphology relate it more to the modern golden jackal (C. aureus)[7][13] than to the ancient Etruscan wolf (C. etruscus).

C. arnensis featured a lower and more pronounced forehead, with less-developed sagittal and nuchal crests and a bulkier braincase than C. etruscus; in addition, the nasal bones were found to be shorter, stopping short of the maxillofrontal suture.

[6] C. arnensis and C. etruscus have been compared, as they are morphologically similar and are believed to have spread to Western Europe together during the so-called "Canis Event".

[8] It is believed that C. arnensis spread across Europe as the result of a dispersal event which populated the continent with the first modern canids.