Cave Paintings Reveal Surprising Clues to Bovid Evolution

The cave paintings left by our ancestors can be very evocative.  The often elaborate and highly stylised frescoes represent life in the very distant past, a life so far removed from today.  However, the paintings, in most cases, a record of the animals that shared the environment with these hunter/gatherers, hide hidden clues regarding prehistoric animals that modern-day researchers are only just beginning to appreciate. Cave art has helped to confirm the exisitence of a newly described bison species, nicknamed the “Higgs Bison”.

Climate Change Affecting Large Animal Populations

A report published in the journal “Nature Communications” by scientists from the University of Adelaide, documents the study of DNA recovered from fossil bones in order to map how climate change affects large animals.  A surprise awaited the scientists, they have discovered a previously unknown species of bison, only to find out that this bovine was already recorded on the walls of caves across Europe, such as in the Niaux Cave (south-western France).  These cave paintings are dated to around 17,000 years ago (Late Upper Palaeolithic).

In 1999, the Australian-based research team commenced the study of DNA extracted from bison bones excavated from a number of sites located in the Northern Hemisphere, where the Steppe bison (Bison priscus) roamed.  The objective of the study was to assess the impact of changing global climate upon animal populations and in North America the fossil record for bison reflected the impact of a changing world.  Bison numbers crashed around the Last Glacial Maximum (between 18,000 and 21,000 years ago.)

Megafauna Extinction

Such data supports the idea that climate change played a significant role in the extinction of “megafauna”.

The scientists then expanded the boundaries of their research by examining data from South America, this also revealed that rapid warming events were a significant factor in large animal extinctions, often with species being further pushed towards extinction by the effect on animal populations by human hunters.

A Puzzle from Europe

When the focus of the research was directed at the fossil record and climate data from Europe, a rather puzzling picture emerged.  By studying mitochondrial DNA (which is inherited exclusively through the maternal line), recovered from fossilised remains, the team realised that the genetic signatures they were finding did not match those expected if the fossils had come from the Steppe bison (Bison priscus).  This was something of a puzzle as palaeontologists had thought that the Steppe bison was the only species to have been present in Europe before 10,000 years ago.

The European Bison (Bison bonasus)

The researchers realised that there were looking at the genes of something novel, an unknown species distantly related to modern cattle and to the exceptionally rare European bison (Bison bonasus), also called the Wisent.  The European bison is Europe’s largest, native, extant terrestrial mammal.  Once widespread, this bovine is now found in a few, remote and protected forests, particularly the Białowieża Forest between Belarus and Poland.

In a story, somewhat similar to the more famous Przewalski’s horse, the last wild Wisent was shot in 1927, but the species clung on thanks to a handful of animals kept in protected reserves.  Modern herds are descended from just a dozen individuals, including one bull from the Caucasus.

The European Bison Also Known as the Wisent (Bison bonasus)

The European bison.

Picture credit: Rafał Kowalczyk

To read about the conservation of Przewalski’s horse: Przewalski’s Horse – A Conservation Success Story.

For models and replicas of prehistoric animals including, whilst stocks last, Przewalski’s horse: Safari Ltd Prehistoric Animal Models and Figures.

The Elusive “Higgs Bison”

That famous Australian dry sense of humour came to the fore, when the DNA from the fossil bones proved to be neither Steppe bison or modern European bison, the team thought they had a new species but they could not be certain.  The elusive animal was nick-named “Higgs bison”, after all, the team had found evidence of something new, but they were not quite sure what this animal looked like, a parallel with physicists and their search for the Higgs boson particle.

In order to unravel this “Higgs bison” puzzle, the University of Adelaide research team set out to confirm their mitochondrial DNA results by obtaining nuclear DNA from the sixty-four European bison bones involved in the study.  Although, much harder to retrieve, nuclear DNA records all aspects of ancestry, not just the maternal line.  The small amount of nuclear DNA retrieved from the samples demonstrated that the “Higgs bison” was a hybrid, a cross between a female wild cow (extinct Aurochs) and a male Steppe bison.

The “Higgs Bison” and Hybridisation

The team dated this hybridisation event to more than 120,000 years ago.  This ancestry was the same for the Wisent and even though the mitochondrial DNA was different, a consequence of the recent near extinction event for the European bison, the “Higgs bison” was revealed as the ancestor of the Wisent.

Pressure on bovine populations as a result of rapid fluctuations in climate could have triggered the hybridisation process.

Male offspring of the Aurochs/Steppe bison cross were sterile, a common outcome for mammal hybrids.  As a result, several generations of females back-crossed with Steppe bison males (maybe even the same bull), resulting in a genetic ancestry of about 10 percent Aurochs and 90 percent Steppe bison.

Hybridisation Between Female Aurochs and Male Steppe Bison Leads to a New Species

Wisent evolution.

Picture credit: Nature Communications

Genetics and cave art reveal the assymmetric hybridisation between female Aurochs and male Steppe bison. Male hybrid offspring are sterile, and female offspring backbred with Steppe bison for several generations, possibly the same bull.

Looking for More Evidence – the North Sea and Cave Paintings

Having reached this conclusion, the Australian team then set about finding other sources of evidence to support the idea of a newly discovered species of prehistoric bison, resulting from the cross breeding between wild cattle and Bison priscus.  Two strands of supporting evidence were identified, both from surprising sources.

1. Scientists from Holland reported that amongst the many numerous Steppe bison and Aurochs bones dredged up by fisherman from the North Sea (for much of the Pleistocene Epoch sea levels were much lower and Scotland was joined to Denmark by a wide and extensive plain), bones of a less common, smaller bovine had been found.
2. French cave art researchers had identified two distinct forms of bison depicted in the artwork of our ancestors, one type resembled the hump-backed, massive Steppe bison, whilst the other depiction was of a more evenly shaped animal with reduced horns, much like a modern-day Wisent.

Depicted in Prehistoric Cave Art – the Newly Discovered Species of Bison

820 examples of bison depicted in European cave art are known, two distinct forms have been identified, representing two different species.

Picture: D. Viat/Tourismeoccitanie

Radiocarbon Dating of Cave Art

Radiocarbon dating of the artworks showed that the wedge-shaped form was drawn when Steppe bison were present on the landscape (around 18,000 years ago), while the small-horned version was drawn when the newly discovered species dominated Europe (after 17,000 years ago).  Each species appears to have dominated Europe for long periods of time, alternating in response to major climate changes.

Thanks to the accurate artwork of Stone Age people, scientists have a good understanding of what this new species of bison looked like.  It had been hiding in plain sight all along.

This study has thrown up a number of surprises.  Apparently, mammals can form new species by hybridisation, even if only rarely.  It also shows that despite the huge bison fossil record the depictions of these ancient creatures made many thousands of years ago, still have a lot to tell us about life in the past.

Everything acknowledges the help and support of “The Lead South Australia” in the compilation of this article.

The scientific paper: Soubrier, J. et al. Early cave art and ancient DNA record the origin of European bison. Nat. Commun. 7, 13158 doi: 10.1038/ncomms13158 (2016).

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The Evolution of Spiny Plants Holds Key to the Establishment of the Savannah

The continent of Africa contains a wide diversity of habitats, dominating the south, central part of Africa are the grasslands, the extensive savannahs that are home to a great diversity of iconic animals.  A team of international scientists writing in the academic journal “The Proceedings of the National Academy of Sciences United States”, have mapped the origins of the African savannah and concluded that the emergence of this ecosystem is, at least in part, down to the grazing habits of antelopes and their kin.

Ancient Bovids Influenced Habitat Formation in Africa

Honking to communicate in the hot savannah.

Picture credit: Todd Marshall

The picture above shows an illustration of Rusingoryx atopocranion a wildebeest from the Pleistocene Epoch.  Grazing bovids and antelopes may have had a remarkable impact on the evolution of plant communities.

Spiny Defences

In a study that plotted flora/faunal relationships on a continental scale, the researchers identified which mammal browsers are most closely associated with spiny communities of trees.  The team were able to show that over the last sixteen million years or so, plants from unrelated taxa developed spiny defences against being eaten a total of fifty-five times.  This pattern of convergent evolution suggests that the arrival and diversification of bovids in Africa changed the rules for persisting in woody communities.

Contrary to current understanding, this new data indicates that browsers predate fire by millions of years as agents driving the origin of the African savannah.

The study was conducted in an unorthodox manner.  The researchers, which included biologists from McGill University (Montreal, Quebec, Canada), started by observing fauna and flora relationships in Africa today and then working backwards in time to the middle of the Miocene Epoch.

For models and replicas of prehistoric mammals and other extinct creatures: Mojo Fun Prehistoric and Extinct Figures.

An Arms Race Between Plants and Animals

Many browsers like gazelles, delicately pick leaves off branches full of wicked-looking spines that are several centimetres long.  The scientists were able to uncover what happened in the past by mapping the distribution and evolution of the spiny plants on which gazelles and their relatives like to feed today.

Research team member, Jonathan Davies, (McGill University) commented:

“It’s been difficult to get a picture of how savannah ecosystems evolved because the conditions needed to preserve animal and plant fossils are very different from one another.  By working with the African Centre for DNA Bar-coding at the University of Johannesburg, we were able to sequence and compare DNA from nearly two thousand trees, and show that African plants only developed spines about fifteen million years ago. That was about the same time that a new type of mammal, antelope and their relatives, spread across the continent following the collision between the continental plates of Africa and Eurasia.”

Prior to this collision, the African continent had been dominated by the large, now extinct, ancestors of browsing elephants and hyrax.  These large herbivores would have bull-dozed trees and trampled vegetation, so spines were an ineffective defence against them according to the lead author of the study, Tristan Charles-Dominique (University of Cape Town).  However, antelopes and their relatives that arrived in Africa after the continental plate collision were highly efficient browsers, often using their delicate lips and prehensile tongue to remove leaves from branches.  It is likely that plants developed spines to defend themselves against these new plant “predators”.

Evolving a Spiny Defence Against Browsers

The study suggests a remarkable “arms race” between the trees and plant-eaters.  The arrival of new and efficient herbivores on the continent of Africa led to the evolution of more and more elaborate defences, including longer and longer spines.  One of the implications of this research is that the loss of large mammals like antelopes today, through human activities such as the bush meat trade, may have a substantial impact on the African landscape, with present day open savannahs being converted into thicket or brush.  Extensive forests may also make a comeback.

The Paper:  “Spiny Plants, Mammal Browsers and the Origin of the African Savannahs”.

Everything Dinosaur acknowledges the support of McGill University in the compilation of this article.

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Ancient Beast “Honked Like a Hadrosaur”

Convergent evolution throws up strange bedfellows from time to time.  Scientists studying an ancient bone bed have uncovered extensive fossil material from an ancient wildebeest that shows that this hoofed mammal had a raised nasal dome, reminiscent of a hollow crested duck-billed dinosaur.  Researchers have suggested that the bizarre anatomical structures helped these herd animals communicate more effectively.  It’s a question of what evolution did for the likes of Corythosaurus some 75 million years ago has been repeated in a Pleistocene bovine from around 75,000 years ago.

A Trumpeting Wildebeest – Rusingoryx atopocranion

Honking to communicate in the hot savannah.

Picture credit: Todd Marshall

The ancient ungulate (hoofed mammal), was poorly known until a bone bed containing the remains of at least twenty-four individuals was discovered on Kenya’s Rusinga Island.  The fossilised remains, which includes juveniles as well as adult animals, has enabled scientists to piece together a much more comprehensive picture of the anatomy of this grazing mammal, part of a diverse African bovine fauna that flourished on the hot, dry savannah of southern Africa during the Pleistocene Epoch.

Stone tool marks on the bones indicate that these animals were butchered and it has been suggested that Middle Stone Age people had driven the animals into a river and ambushed them, or perhaps, a tribe benefited from a chance discovery of a group of these creatures who had recently drowned in a flood event.

Hollowed-out Headgear

The wildebeest is known as Rusingoryx atopocranion, but until now it had only been known from partial remains, including incomplete skulls.  The Rusinga excavation, supported by the National Geographic Society’s Committee for Research and Exploration has uncovered a total of six skulls, most of them complete.  Thanks to these fossils, scientists have a much better idea of what these animals actually looked like.

Commenting on the new evidence, lead author of the study, Haley O’Brien (Ohio University) stated:

“The first time I saw them my jaw completely dropped”.

Previous studies based on much less complete fossil material had speculated that Rusingoryx possessed a proboscis, but the new skulls discount this idea.  Instead, they reveal that R. atopocranion had a high nasal dome in front of its eyes, a sort of “cow with a Roman nose”.  The raised naris was hollow, encasing a winding, circuitous nasal passage.

The Skull of Rusingoryx (R. atopocranion)

The dome shaped skull (raised nasal bones).

Picture credit: Haley O’Brien

Strange Nasal Apparatus

PhD student Haley explained:

“There aren’t any living animals with a nasal apparatus like this, but there are some fossil ones.  Outside and in, the nose of Rusingoryx resembles the hollow crests of the “duck-billed” dinosaurs, animals like Corythosaurus and Lambeosaurus, which lived about 75 million years earlier.  Both groups essentially push the nasal part of their airway into the crest and they’re using similar suites of bones to form the crest itself.”

The Skull of the Mexican Lambeosaurine Velafrons (Velafrons coahuilensis)

Raised nasals – an example of convergent evolution.

Picture credit: Paul Fraughton/Salt Lake Tribune

Commenting on the similarities between Rusingoryx and Late Cretaceous duck-billed dinosaurs, palaeontologist David Evans (Royal Ontario Museum, Toronto), stated that he was “blown away” by the skulls of Rusingoryx, he added:

“The resemblance between Rusingoryx and some hollow-crested dinosaurs in the form of the nasal structures is truly striking.”

Convergent Evolution

The dome shaped nasal area of Rusingoryx is an example of convergent evolution, whereby unrelated organisms evolve independently similar features, such as the streamlined bodies and tail flukes of dolphins and ichthyosaurs.  These are adaptations to similar habitats or ecological niches.

However, faced (no pun intended), with this strange-faced wildebeest, the big question is what sort of function did these domed noses have?

A number of ideas have been put forward:

• The expanded naris played a role in cooling or warming incoming air

The large nose of Rusingoryx may certainly have been able to undertake this function and all mammals have some ability to do this, thanks to scroll-like bones called turbinates that increase the surface area of the nose.  As Rusingoryx lived in a very hot, dry environment this theory is plausible, but the dome’s internal anatomy did not support this conclusion.

• The raised domes were used in ritual combat

A number of bovines use their skulls as battering rams to settle disputes and as defensive weapons.  However, the skull bones of Rusingoryx are very thin, much thinner than those of extant Artiodactyls (even-toed hoofed mammals) that indulge in such behaviour.

• The nasal area acted as a resonating chamber for sound

A Resonating Chamber?

Social, hoofed, herd-dwelling herbivores tend to be quite vocal.  They have ways to modulate their vocal tracts to increase the variety and range of sounds that they can make.  The skull anatomy suggests that the big dome-faced wildebeest used this structure to vocalise.

Student O’Brien explained:

“We calculated a frequency of between 250 and 750 hertz, which is not only pretty low, it also overlaps with the sonic frequencies of a vuvuzela.  Rusingoryx could very likely make a low trumpeting sound but there’s a good chance it could also vocalise in stealth mode.”

Being able to communicate at a low frequency making it difficult for some predators to hear, has a distinct evolutionary advantage, human hunters for example would have had difficulty picking up these sounds.  In addition, a herd of these animals would have been capable of making a lot of noise, much like a stadium full of South African football fans waving their vuvuzelas.

Everything Dinosaur stocks a range of duck-billed dinosaur models and replicas including many lambeosaurines.  To view the model’s section of the company’s award-winning website: Dinosaur and Prehistoric Animal Replicas.