''Canis arnensis'', is an extinct species of canine that was endemic to Mediterranean Europe during the

Early Pleistocene The Early Pleistocene is an unofficial epoch (geology), sub-epoch in the international geologic timescale in chronostratigraphy, representing the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently esti ...

. ''Canis arnensis'' has been described as a small

jackal Jackals are Canidae, canids native to Africa and Eurasia. While the word has historically been used for many canines of the subtribe Canina (subtribe), canina, in modern use it most commonly refers to three species: the closely related black-b ...

-like canid. Its anatomy and morphology relate it more to the modern golden jackal (''Canis aureus'') than to the larger Etruscan wolf of that time. It is probably the ancestor of modern jackals.

Taxonomy

The

fossil record A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

for ancient

vertebrates Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

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. Some observations are debated by researchers who do not always agree and hypotheses that are supported by some authors are challenged by others. Several species of

Caninae Caninae (whose members are known as canines () is the only living subfamily within Canidae, alongside the extinct Borophaginae and Hesperocyoninae. They first appeared in North America, during the Oligocene around 35 million years ago, subsequent ...

from the Pleistocene of Europe have been described. Most of their systematic and

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

relationships have not been resolved because of their similar morphology. Upper Valdarno is the name given to that part of the Arno Valley situated in the provinces of

Florence Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025. Florence ...

and

Arezzo Arezzo ( , ; ) is a city and ''comune'' in Italy and the capital of the Province of Arezzo, province of the same name located in Tuscany. Arezzo is about southeast of Florence at an elevation of Above mean sea level, above sea level. As of 2 ...

, Italy. The region is bounded by the Pratomagno mountain range to the north and east and by the Chianti Mountains to the south and west. 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. The Swiss paleontologist Charles Immanuel Forsyth Major discovered two species in this region, these being the Falconer's wolf ('' Canis falconeri'' Forsyth Major 1877) that was later reclassified as ''Lycaon falconeri'', and the smaller Etruscan wolf (''C. etruscus'' Forsyth Major 1877). Forsyth Major did not publish a complete description of the Etruscan wolf, and later Domenico Del Campana worked on expanding Forsyth Major's descriptions when he recognized among the specimens a smaller,

-sized species. This he named ''Canis arnensis'' Del Campana 1913 in honour of the nearby Arno River.

''Canis senezensis''

''C. senezensis'' (Martin 1973) is represented by two

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

ry bone fragments. This medium-sized canid was discovered in Senez, France and dated 2.1-2.0 million years ago. In 2011, a study compared all of the 55

wolf-like specimens found across Europe and found that their morphometric variation was no different than that of modern wolf populations, with their difference in size representing male and female specimens. However, the study proposed two lineages. One lineage is ''C. arnensis'' which includes ''C. accitanus'' and ''C. senezensis'', and the other lineage being '' C. etruscus'' that includes ''C. appoloniensis''.

''Canis accitanus''

A later study based on better-quality specimens of ''C. arnensis'' found the proportions and dental morphology of ''C. senezensis'' to be close and supported ''C. senezensis'' to be an early form of ''C. arnensis'', however it disputed that ''C. accitanus'' was close to ''C. arnensis''. Its taxonomic status remains disputed.

Lineage

''Canis arnensis'' has been described as a small jackal-like canid because of the relative length of its upper molars M1 and M2. The Finnish paleontologist Björn Kurtén described it as coyote-like and not similar to the

gray wolf The wolf (''Canis lupus''; : wolves), also known as the grey wolf or gray wolf, is a canine native to Eurasia and North America. More than thirty subspecies of ''Canis lupus'' have been recognized, including the dog and dingo, though gr ...

(''C. lupus'') but similar to the early coyote-like '' C. priscolatrans''. Kurten was uncertain if ''C. priscolatrans'' derived from '' C. lepophagus'' through ''C. arnensis'', but believed that ''C. priscolatrans'' was a population of large coyotes that were ancestral to Rancholabrean and recent ''C. latrans''. He noted that ''C. arnensis'' of Europe showed striking similarities to ''C. priscolatrans'', and they could represent what once was a

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical reg ...

population of coyotes. In 1993, the Italian paleontologist Lorenzo Rook identified a new taxon dating from the end of the Villafranchian. It was found at the Mediterranean sites of Venta Micena, Pirro Nord, Le Vallonet, Cueva Victoria, Huescar-1, Colle Curti, Cúllar de Baza-1, L’Escale, Petralona, and the Israeli site of Oubeidiyah. The taxon was named ''Canis aff. arnensis'' as it was assessed as an advanced form of ''C. arnensis''. In 1996, Rook and the Italian paleontologist Danilo Torre propose that during the Lower Pleistocene to Mid Pleistocene transition, Europe was home to two different lineages. In the Mediterranean areas existed the lineage of ''C. arnensis'' (primitive form) that gave rise to ''C. aff. arnensis'' (advanced form). In Central and northern Europe existed the lineage of ''C. etruscus'' that gave rise to ''C. mosbachensis''. 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. There was little deformation in these fossils which allowed a more defined assessment of the morphology of the species. The study found that the phylogenetic position of ''Canis arnensis'' is not resolved. Its anatomy and morphology relate it more to the modern golden jackal (''C. aureus'') than to the ancient Etruscan wolf (''C. etruscus''). Although the Etruscan wolf was the first of the genus ''Canis'' to reach Europe around 2.2 million years ago, ''Canis arnensis'' was the first of the more modern canids to arrive in Europe around 1.9 million years ago. It is probably the ancestor of modern jackals.

Description

''C. arnensis'' was a medium-sized canid, with a close affinity to modern canids. It had a slightly smaller cranial length than both ''C. etruscus'' and the extant ''C. lupus''. ''C. arnensis'' featured a lower and more pronounced

forehead In human anatomy, the forehead is an area of the head bounded by three features, two of the skull and one of the scalp. The top of the forehead is marked by the hairline, the edge of the area where hair on the scalp grows. The bottom of the fo ...

, 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. ''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". Morphometric analysis of the cranium and upper teeth show that both ''C. arnensis'' and ''C. etruscus'' showed characteristics of an intermediate between extant wolves and jackals, with ''C. arnensis'' being slightly more jackal-like and ''C. etruscus'' slightly more wolf-like; however, in some cranial characteristics, ''C. arnensis'' is more wolf-like.

Paleoecology

The dispersal of carnivoran species occurred approximately 1.8 million years ago and this coincided with a decrease in precipitation and an increase of annual seasonality which followed the 41,000 year amplitude shift of Milankovitch cycles. First to arrive was ''C. etruscus'', which was immediately followed by ''C. arnensis'' and ''Lycaon falconeri'' and then by the giant hyena ('' Pachycrocuta brevirostris''). These were all better adapted to open, dry landscapes than the two more primitive canini '' Eucyon'' and '' Nyctereutes'' that they replaced in Europe.

Range

The first identification of ''C. arnensis'' followed the discovery of a fossil in the Upper Valdarno. Fossils of the species have only been found in the period of time known as the Tasso Faunal Unit of Italy. The species was endemic to Mediterranean

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and lived during the

era. 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. The species arrived in Italy around 1.9 Ma and was homogenized across southern Europe during the late Villafranchian.

Extinction

''Canis arnensis'' and the Etruscan wolf both disappeared from the fossil record in Italy after the end of the Tasso Faunal Unit and were replaced by the mid-Pleistocene era Mosbach wolf (''C. mosbachensis'' Soergel, 1925) by 1.5 million years ago.

References

{{Taxonbar, from=Q30682080 Extinct wolves Pleistocene carnivorans Prehistoric mammals of Europe Prehistoric canines Fossil taxa described in 1913