An extinct species of carnivorous mammal discovered

Amphibians are an extinct family of carnivorous terrestrial mammals. An analysis has revealed the existence of a hitherto unknown species of this family. The species has been given the name Ammitocyon kainos.

The discovery has been made in Spain by researchers from the Catalan Institute of Paleontology Miquel Crusafont (ICP), the National Museum of Natural Sciences (MNCN-CSIC), the University of Alcalá (UAH), the University of Zaragoza and the University Research Institute of Environmental Sciences of Aragon (IUCA). These specialists have described the new species from the craniodental remains of three specimens unearthed at the Batallones-3 site (Madrid).

The study is titled “Ammitocyon kainos gen. et sp. nov., a chimerical amphicyonid (Mammalia, Carnivora) from the Late Miocene carnivore traps of Cerro de los Batallones (Madrid, Spain) ”. And it has been published in the academic journal Journal of Systematic Palaeontology.

The fossils that have allowed the new species to be described were found between 2008 and 2011 and initially assigned to the genus Thaumastocyon, but subsequent and detailed analyzes of its dentition have revealed that they really belong to a species new to science, previously unknown.

Ammitocyon kainos is characterized by the length and robustness of its chin and muzzle, as well as the incisors and canines that contrast with the absence of the first premolars and last molars. In addition, it had highly developed carcasses, with large cutting surfaces, and relatively small chewing molars. Both characteristics are considered as adaptations to hypercarnivorism (a condition that occurs when more than 70% of an animal’s diet is based on meat), and they are not present in any current species of carnivore.

Recreation of the appearance that a typical adult individual of the amphithoid species Ammitocyon kainos must have had in life. (Image: Oscar Sanisidro / University of Alcalá)

Biomechanical studies performed on its bite show that different areas of the jaw served different functions. While the most anterior area served them to grab the prey and tear off large pieces of meat by making sudden lateral movements, the most posterior part was used almost like a guillotine, which would cut this meat into smaller pieces. “His mouth is like a Swiss army knife!” Jokes Juan Abella, ICP researcher and study co-author.

Also, the combination of the characteristics of the chewing apparatus with those of its skeleton has not been observed before and reveals unique ecological adaptations. Their front and hind legs were sturdy and strong, their hands and feet very short, and the research team estimates that Ammitocyon kainos weighed more than 230 kg.

“We are in front of a very specialized carnivore”, explains Abella. “Due to its anatomical characteristics, it could not be an active hunter or too agile, like the current canids or felids. It had to hunt by stalking or prey on prey hunted by other carnivores. Or both! ””, Says the paleontologist.

A. kainos lived about 9 million years ago and is the last member of the Thaumastocyoninae subfamily to be included within the amphithoid family, popularly known as ‘bear-dogs’, although they are not actually closely related to dogs. nor with bears. This family has no current representatives, but in the past they were one of the most numerous and diverse groups of carnivores in the terrestrial ecosystems of Europe and North America.

“In Battalions 3 it coexisted with other large predators weighing more than 150 kg such as the amphithoid Magericyon anceps, the saber-toothed tiger Machairodus aphanistus and the relative of the panda bear Indarctos arctoides, so the role in the ecosystem of each of them it should be quite defined, to be able to support these species in the same area ”, explains co-author Alberto Valenciano, paleontologist at the University of Zaragoza and IUCA.

The new species name Ammitocyon kainos means ‘Ammit’s dog’. Ammit was an Egyptian deity with the head of a crocodile and the legs of a lion and a hippopotamus, anatomical features that remotely recall the anatomy of this carnivore. The suffix ‘cyon’ means ‘dog’ in Greek while ‘kainos’ means ‘new’.

“After 30 years of excavations, the Cerro de los Batallones sites continue to give pleasant surprises,” highlights the MNCN researcher Jorge Morales and co-author of the study. The first deposit of Cerro de los Batallones was discovered in July 1991 due to the exploitation of the land to obtain sepiolite. In 2001 it was declared an Asset of Cultural Interest as a Paleontological Zone by the Community of Madrid, which has been financing the excavations of the sites to date. In total, 9 cavities with fossiliferous sedimentary fillings have been found.

Some of these cavities are characterized by the large number of carnivores that contrasts with the almost total absence of herbivores. In Battalions-3, the percentage of carnivores increases to 99%, when the usual in a site would be between 10-15%. The explanation for this phenomenon lies in its geological nature. They are natural cavities in which carnivores had to enter in search of prey or water and then they could not get out.

“But the interest of the Batallones deposits lies not only in the quality and quantity of the fossils found, but also in the verification of new models of continental paleontological deposits formation and in the enormous potential for carrying out paleobiological and geological studies of all type ”, summarizes Jorge Morales who has directed the paleontological excavations from 1991 to 2020. (Source: ICP)

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