EXACT AND NATURAL SCIENCES

Ferrucyon avius: the new genus of canidae described by CONICET researchers

The find refutes a 30-year-old paleontological theory and contributes to reconstruct the evolution of mammals in America.


Ferrucyon avius. Illustration: Facundo López Fraga

A recent study published in the Journal of Vertebrate Paleontology, CONICET researchers Damián Ruiz Ramoni and Francisco Prevosti together with scientists from Mexico and Italy, proposed a new genus of canidae. The find solves a 30-year-old mystery in the evolutionary history of southern canidae. It was based on the reinterpretation of a fossil of a species of fox found in the seventies in Baja California, Mexico. 

About 3 million years ago, the emergence of the Isthmus of Panama  -a natural bridge in Central America- enabled the exchange of fauna between two continental masses that were separated until that moment. In this event, known as “The great American biotic interchange” , ancestors of several of the continent’s mammals entered, including canids. Millions of years later, a group of paleontologists discovered in Baja California the fossil of a canid from the early Pliocene, between 4.9 and 4.3 million years ago, which they interpreted as a relative of the group that reached South America. 

“In 1980, the Mexican researchers analyzed the fossil. According to the morphology of its bones, the scientists believed it was an ancient relative of the crab fox, Cerdocyon thous,” so they called it Cerdocyon avius”, explains Ruiz Ramoni, CONICET postdoctoral fellow at the ‘Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR, La Rioja – SEGEMAR – CONICET- UNLAR – UNCA).’ And adds: “Over the years, some researchers considered this species as the link that connected the Americas in the evolution of these mammals.” 

In 2010, Francisco Prevosti, CONICET principal researcher at the Museo de Ciencias Antropológicas y Naturales (Secretaria de Ciencia y Tecnología- Universidad Nacional de La Rioja), had questioned the taxonomic assignment of the fossil found in Mexico. In his PhD thesis, he observed a relationship between Cerdocyon avius and the gray fox, Urocyon cinereoargenteus, a fox that belongs to a natural group not related to the South American canids. This  deepened the mystery about the true relationship of the Baja California fox with the origin of the South American group. 

In order to reconstruct the history of this fossil, the researchers, the researchers made a detailed phylogenetic analysis and managed to obtain a complete description of the skeleton for the first time. So they concluded that “the key to understanding this fossil was in the jaw and teeth,” Ruiz Ramoni explains. The presence of extra cusps on the molars and a more graceful shape on the jaw indicated that this animal was neither related to the Cerdocyon thous nor to any canid of the South American lineage. It was not the missing link,” says the scientist. 

 

The Ferrucyon avius

Due to the morphological differences with the phylogenetic tree of South American canids, the researchers had to describe a new biological entity. The fossil was renamed Ferrucyon avius, in homage to Ismael Ferrusquia Villafranca, who participated in the original research on this specimen and made important contributions in the field of fossil mammals of the Mexican territory. “Ferrucyon avius is a new member of foxes from North America and old world,”Ruiz Ramoni affirms. “We confirmed that so far there is no evidence supporting that the genera of South American foxes have originated in North America, states Prevosti and adds “these carnivores found empty ecological niches in South America and managed to occupy them, diversify and generate many species and various genera. 

 

By Yasmín Noel Daus