Actiocyon
From Wikipedia, the free encyclopedia
| Actiocyon | |
|---|---|
 | |
| Part of the holotype (name-bearing specimen) of Actiocyon parverratis | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Ailuridae |
| Genus: | †Actiocyon Stock, 1947 |
| Type species | |
| Actiocyon leardi Stock, 1947 | |
| Other species | |
| |
Actiocyon is an extinct genus of ailurid mammal that lived in western North America during the Middle Miocene. It was named by Chester Stock in 1947 for the species Actiocyon leardi. A second species, Actiocyon parverratis, was described in 2016. A. leardi is only known from one specimen, while A. parverratis is known from three specimens.
Both species of Actiocyon were small carnivores, with A. leardi known to have lived in a coastal environment while A. parverratis lived in a high-altitude temperate forest. They differ from the closely-related European genus Alopecocyon in the characteristics of the teeth, and from Simocyon in their overall smaller size. A. leardi may have weighed about 7 kilograms (15 lb), while A. parverratis was somewhat smaller.
Classification
In 1938 Robert Leard collected mammalian fossils in Ventura County, California for the California Institute of Technology. Among them was a partial carnivoran skull which was identified as a new genus of canid. American paleontologist Chester Stock in 1947 described the new genus and species Actiocyon leardi based on the specimen. The fossil was found in rocks of the Caliente Formation. The genus name comes from the Greek aktlos, meaning 'pertaining to the coast', and κύων/kúon, meaning 'dog'. The specific name honored Leard for collecting the specimen.[1]
The second species Actiocyon parverratis was described by paleontologists Smith, Czaplewski, and Cifelli in 2016 based on fossils from the lowermost section of the Monarch Mill Formation in Middlegate Basin, Nevada. The specific name comes from the Latins words parvus 'small', and erratis 'wanderer', together meaning 'small wanderer'.[2]
When Stock described A. leardi in 1947, he considered it a close relative of Alopecocyon, at the time considered a canid, and called it an aberrant genus that had acquired procyonid traits.[1] Webb, in his 1969 work on Pliocene canids, considered Actiocyon a junior synonym of the Alopecocyon, though he noted that De Beaumont had suggested in 1964 that Alopecocyon was a musteloid descended from Broiliana and the lack of material made its position difficult to resolve.[3]
Jon Baskin, while writing a book chapter on Procyonidae in 1998, listed Actiocyon as closely related but distinct from Alopecocyon, and included both in the clade Simocyoninae, itself in the clade Baskin called "Ailuridae or Unnamed Group" that he stated was controversially placed in Procyonidae.[4]
In 2010, paleontologists Michael Morlo and Stéphane Peigné published a review of what they stated was the family Ailuridae, in which they included A. leardi as a species of Alopecocyon in the subfamily Simocyoninae.[5] The 2016 description of A. parverratis unambiguously considered Actiocyon a separate genus in the subfamily Simocyoninae in the family Ailuridae.[2]
A 2025 review of ailurid taxonomy included both A. leardi and A. parverratis as valid species, with the genus placed in the subfamily Simocyoninae, but noted the inclusion of A. parverratis in Actiocyon was tentative given the overall lack of fossils for both species.[6]
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