Fossil find introduces a new ancestor to the jackal family tree

By Alberto Valenciano Vaquero, Jorge Morales Romero, and Romala Govender for The Conversation
The family Canidae is an instantly recognisable group of carnivores that includes dogs, wolves, jackals and foxes. It originated more than 35 million years ago in North America and migrated to the rest of the planet only about 7.5 million years ago.

Jackals are among the most remarkable and sneaky canids. They sit somewhere between the red fox and the Australian dingo in terms of shape and size – for instance, the average side-striped jackal of both sexes weighs 7-12kg and stands 40cm tall.

They’re generally known for their scavenging activities in open savanna and grassland ecosystems. Jackals are omnivorous (eating both meat and plants); they scavenge and actively hunt and are considered nocturnal, most active in the early evening and at dawn. Their prey includes small vertebrates like rabbits, and they also eat birds, eggs, fruit and seeds and have been known to go through people’s trash.

Today there are five jackal species worldwide – four of them in Africa. These African species are the side-striped jackal, the black-backed jackal, the African golden wolf and the Ethiopian wolf.

They were all classified within the genus Canis (which also includes wolves and domestic dogs), but recent DNA analyses have re-classified them into different genera.

In other words, they are close relatives: they have the same evolutive relationship as, for example, the one between lions and cougars. Scientists know very little about their evolutionary origin. Until now, it was thought that Eucyon davisi, a North American canid that lived between 10 million and 5 million years ago, was the common ancestor of all wolves, jackals, and coyotes.

Our research, conducted at a rich fossil site about 120km outside Cape Town in South Africa, changes that: we now know there’s another ancestor in the mix. We’ve described a new species of canid, named Eucyon khoikhoi, based on fossils found at the Langebaanweg site, which dates back to about 5.2 million years ago.

This provides novel and vital information about the origin of jackals, showing that jackals appeared and established themselves in Africa in at least the last 5 million years. These animals have evolved and adapted to the changing environment, allowing them to survive.

The name of the new species honours the heritage of the Khoikhoi (KhoeKhoen) people, an indigenous people who were among the first to live in South Africa. The name allows us to recognise the importance of the Khoikhoi’s culture and heritage.

The site

Langebaanweg lies 120km north of Cape Town, on South Africa’s west coast. It is the site of one of the world’s richest and most diverse terrestrial and aquatic fossil vertebrate ecosystems from the late Miocene (about 6 million years ago) and early Pliocene (5.2 million years ago) epochs.

The site is home to fossil remains of more than 250 distinct species including otters, sabretooth felids, bears, hyaenids, giraffes, elephants, rhinos, wild pigs, and a wide variety of birds, including parrots, ostriches, and penguins, as well as fishes, sharks, rays, skates, seals, and cetaceans. Langebaanweg continues to shed light on the evolution of several mammal groups in Africa and improves our knowledge of them as they spread and diversified through the continent.

Eucyon khoikhoi fossils were unearthed at the site by palaeontologist Brett Q. Hendey and his team in the 1970s, though they weren’t identified as a new species until now. We studied both these fossils, which are part of the Iziko Museum of South Africa’s collection, and some that we newly unearthed at the Langebaanweg site.

Iziko’s sample comprises more than 50 fossils. These include a very well-preserved, nearly complete skull, several jaws, deciduous (milk) teeth, parts of the neck, forelegs and hind legs.

By studying the proportions of the mandibles and long bones of these fossils from the site we estimated that Eucyon khoikhoi weighed 9kg on average and that it was an omnivorous scavenger, similar to the living side-striped jackal.

Another novelty of the research is that it represents the first evolutive analysis of medium-size canids from the Late Miocene and Pliocene together with a wide sample of living jackals and wolves, with a special emphasis within the African fossils. Essentially, it’s the first time that the genus Eucyon is linked with both an African species, the side-striped jackal, and North American and European species through the black-backed jackal and wolves.

This is a particularly important result of our research: the morphological (physical) traits of E. khoikhoi indicate a direct relationship with the side-striped jackal and confirms the presence of this group in Africa more than 5 million years ago.

So, how does this new species fit in with other canids and their paths around the world?

Three events

Medium-sized canids have an intricate evolutive history. Three main migration events have occurred since canids first left North America about 7.5 million years ago.

The oldest canid outside North America is Canis cipio from the Spanish localities of Concud and Los Mansuetos, about 7.5 million years ago. That’s the first event.

Then came the second event, between 6.2 million and 5.5 million years ago, when three new canid species appeared simultaneously in different parts of the globe: Eucyon debonisi in western Spain, Eucyon monticinensis in Italy, and Eucyon intrepidus, in Kenya and Ethiopia.

These first fossil species outside North America are rare and not well known; their evolutive relationship with extinct and extant relatives is unknown.

The third event starts with the new species Eucyon khoikhoi. This marks a critical moment in the evolution of medium-size jackal-like canids 5 million years ago, when they began to diversify outside North America. Later, they become more diverse and common in Eurasia and Africa, until they culminated in the four living species of jackals in Africa.

This is an exciting find that adds to our understanding of jackals’ ancient origins and how they developed. Future research will help us learn more about these extinct carnivores from South Africa’s west coast – and, hopefully, shed even more light on the ancestors of today’s jackals.

(The authors work at Universidad de Zaragoza; Museo Nacional de Ciencias Naturales (MNCN-CSIC), and University of Cape Town respectively)