Canis arnensis

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Canis arnensis
Temporal range: Early Pleistocene 1.9-1.6 Ma
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Canis arnensis reconstruction from fossilized bone fragments
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Artist's rendition
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Canis
Species:
C. arnensis
Binomial name
Canis arnensis
Del Campana, 1913 [1]
Synonyms [2]
  • C. senezensisMartin, 1973 [3]
  • C. accitanusGarrido and Arribas, 2008 [4]

Canis arnensis, is an extinct species of canine that was endemic to Mediterranean Europe during the Early Pleistocene. Canis arnensis has been described as a small jackal-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.

Contents

Taxonomy

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. Some observations are debated by researchers who do not always agree and hypotheses that are supported by some authors are challenged by others. [5] Several species of Caninae from the Pleistocene of Europe have been described. Most of their systematic and phylogenetic relationships have not been resolved because of their similar morphology. [6]

Upper Valdarno is the name given to that part of the Arno Valley situated in the provinces of Florence and Arezzo, 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). [7] Forsyth Major did not publish a complete description of the Etruscan wolf, [6] and later Domenico Del Campana worked on expanding Forsyth Major's descriptions when he recognized among the specimens a smaller, jackal-sized species. [6] This he named Canis arnensis Del Campana 1913 in honour of the nearby Arno River. [6] [7] [8]

Canis senezensis

C. senezensis (Martin 1973) [3] is represented by two maxillary 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 Early Pleistocene 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. [2]

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. [7] Its taxonomic status remains disputed.

Lineage

Canis arnensis has been described as a small jackal-like canid [1] [9] because of the relative length of its upper molars M1 and M2. [9] The Finnish paleontologist Björn Kurtén described it as coyote-like [10] and not similar to the gray wolf (C. lupus) but similar to the early coyote-like C. priscolatrans . Kurten was uncertain if C. priscolatrans derived from C. lepophagus through C. arnensis, [11] 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 population of coyotes. [12]

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. [4]

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) [7] [13] 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. [7] It is probably the ancestor of modern jackals. [14]

Description

Canis arnensis.JPG
Canis arnensis skull at the Museum of Paleontology in Florence, Italy
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Canis arnensis skull (profile view) at the Museum of Paleontology in Florence, Italy

C. arnensis was a medium-sized canid, with a close affinity to modern canids. [7] 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, 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". [7] 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. [6]

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. [15]

Range

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Distribution of C. arnensis fossils ("advanced form" fossils in dark red). [16]

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. [7] The species was endemic to Mediterranean Europe and lived during the Early Pleistocene era. [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. The species arrived in Italy around 1.9 Ma [7] and was homogenized across southern Europe during the late Villafranchian. [17]

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. [7]

See also

Related Research Articles

<span class="mw-page-title-main">Canidae</span> Family of mammals

Canidae is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid. The family includes three subfamilies: the Caninae, the extinct Borophaginae and Hesperocyoninae. The Caninae are known as canines, and include domestic dogs, wolves, coyotes, foxes, jackals and other species.

<span class="mw-page-title-main">Dhole</span> Species of mammal

The dhole is a canid native to Central, South, East and Southeast Asia. It is genetically close to species within the genus Canis, but distinct in several anatomical aspects: its skull is convex rather than concave in profile, it lacks a third lower molar and the upper molars possess only a single cusp as opposed to between two and four. During the Pleistocene, the dhole ranged throughout Asia, with its range also extending into Europe but became restricted to its historical range 12,000–18,000 years ago.

<span class="mw-page-title-main">Jackal</span> Several species of canines

Jackals are canids native to Africa and Eurasia. While the word "jackal" has historically been used for many canines of the subtribe canina, in modern use it most commonly refers to three species: the closely related black-backed jackal and side-striped jackal of sub-Saharan Africa, and the golden jackal of south-central Europe and Asia. The African golden wolf was also formerly considered a jackal.

<span class="mw-page-title-main">Dire wolf</span> Extinct species of canine mammal

The dire wolf is an extinct canine. The dire wolf lived in the Americas during the Late Pleistocene and Early Holocene epochs. The species was named in 1858, four years after the first specimen had been found. Two subspecies are recognized: Aenocyon dirus guildayi and Aenocyon dirus dirus. The largest collection of its fossils has been obtained from the Rancho La Brea Tar Pits in Los Angeles.

<i>Canis</i> Genus of carnivores

Canis is a genus of the Caninae which includes multiple extant species, such as wolves, dogs, coyotes, and golden jackals. Species of this genus are distinguished by their moderate to large size, their massive, well-developed skulls and dentition, long legs, and comparatively short ears and tails.

<span class="mw-page-title-main">Golden jackal</span> Species of mammal

The golden jackal, also called common jackal, is a wolf-like canid that is native to Eurasia. The golden jackal's coat varies in color from a pale creamy yellow in summer to a dark tawny beige in winter. It is smaller and has shorter legs, a shorter tail, a more elongated torso, a less-prominent forehead, and a narrower and more pointed muzzle than the Arabian wolf. It is listed as Least Concern on the IUCN Red List due to its widespread distribution and high density in areas with plenty of available food and optimum shelter.

Canid hybrids are the result of interbreeding between the species of the subfamily Caninae.

<span class="mw-page-title-main">Armbruster's wolf</span> Extinct species of carnivore

Armbruster's wolf is an extinct species that was endemic to North America and lived during the Irvingtonian stage of the Pleistocene epoch, spanning from 1.9 Mya—250,000 years BP. It is notable because it is proposed as the ancestor of one of the most famous prehistoric carnivores in North America, the dire wolf, which replaced it.

<i>Xenocyon</i> Extinct subgenus of carnivores

Xenocyon is an extinct group of canids, either considered a distinct genus or a subgenus of Canis. The group includes Canis (Xenocyon) africanus, Canis (Xenocyon) antonii and Canis (Xenocyon) falconeri that gave rise to Canis (Xenocyon) lycanoides. The hypercarnivorous Xenocyon is thought to be closely related and possibly ancestral to modern dhole and the African wild dog, as well as the insular Sardinian dhole.

<i>Canis edwardii</i> Extinct species of canid

Canis edwardii, also known as Edward's wolf, is an extinct species of wolf in the genus Canis which was endemic to North America three million years ago from the Late Blancan stage of the Pliocene epoch and was extinct by the end of the Irvingtonian stage of the Pleistocene epoch.

Canis ferox is a species of canid which was endemic to North America and lived during the Late Miocene and Early Pliocene. Existing nearly 6 million years ago, this animal is thought to be an ancestor of the modern day coyote.

<i>Canis lepophagus</i> Extinct species of carnivore

Canis lepophagus is an extinct species of canid which was endemic to much of North America during the Early Pliocene. It is notable because its lineage is proposed to have led to both wolves and coyotes.

<i>Eucyon</i> Extinct genus of carnivores

Eucyon is an extinct genus of medium omnivorous coyote-like canid that first appeared in the Western United States during the late Middle Miocene 10 million years ago. It was the size of a jackal and weighed around 15kg. Its species E. zhoui was one of a number of North American mammals which invaded East Asia around 5–6 million years ago, followed by the genus going extinct 3 million years ago. This genus is proposed to have given rise to genus Canis 6 million years ago.

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<i>Lycaon</i> (genus) Genus of carnivores

Lycaon is a genus of canid which includes the African wild dog and the extinct species Lycaon sekowei and Lycaon magnus.

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<span class="mw-page-title-main">African wolf</span> Species of canine native to Africa

The African wolf is a canine native to North Africa, West Africa, the Sahel, northern East Africa, and the Horn of Africa. It is listed as least concern on the IUCN Red List. In the Middle Atlas in Morocco, it was sighted in elevations as high as 1,800 m (5,900 ft). It is primarily a predator of invertebrates and mammals as large as gazelle fawns, though larger animals are sometimes taken. Its diet also includes animal carcasses, human refuse, and fruit. They are monogamous and territorial; offspring remain with the parents to assist in raising their parents' younger pups.

<span class="mw-page-title-main">Evolution of the wolf</span>

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<i>Canis etruscus</i> Extinct species of carnivore

Canis etruscus, the Etruscan wolf, is an extinct species of canine that was endemic to Mediterranean Europe during the Early Pleistocene. The Etruscan wolf is described as a small wolf-like dog. It is widely agreed to be the ancestor of Canis mosbachensis, and thus ultimately the modern grey wolf.

<i>Canis mosbachensis</i> Extinct species of carnivore

Canis mosbachensis is an extinct wolf that once inhabited Europe 600,000—420,000 years ago. The Mosbach wolf was a short-legged carcass feeder adapted for scavenging megafauna on the mammoth steppe. Canis mosbachensis is widely considered to be the ancestor of the living grey wolf with some considering it as a subspecies of the wolf as Canis lupus mosbachensis.

References

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