‘Ancient humans left Africa once’


Human migration out of Africa, picture by P.D. deMenocal and C. Stringer/Nature 2016

From Science News:

Going global

Previous studies have used fossil, archaeological and genetic data to time humans’ colonization of the world (times shown above). New genetic studies may change that map; they suggest small numbers of people left Africa 120,000 years ago, but left little trace in the DNA of present-day people. Most non-Africans inherited their DNA from people who left Africa between about 70,000 and 50,000 years ago, new studies suggest. But a climate study indicates that was the worst possible time for an out-of-Africa migration and suggests people may have left earlier, between 80,000 and 100,000 years ago.

This video says about itself:

Predicted spread of humans around the world | Science News

21 September 2016

Earth wobbles on its axis, causing major climate shifts. Some of those shifts turned the Arabian Peninsula into lush grassland that ancient humans could have traversed as they migrated out of Africa. Researchers at the University of Hawaii at Manoa simulated climate conditions over the last 125,000 years and predicted how those changes would have allowed humans to spread around the globe (increasing intensity of red shows greater predicted migration).

Credit: Tobias Friedrich

The Science News article continues:

Single exodus from Africa gave rise to today’s non-Africans

Genetic data point to a date less than 72,000 years ago but climate scientists disagree

By Tina Hesman Saey

3:28pm, September 21, 2016

One wave of ancient human migrants out of Africa gave rise to all non-Africans alive today, three separate genetic studies conclude.

Those human explorers left Africa about 50,000 to 72,000 years ago, mixed with Neandertals and spread across the world, researchers report online September 21 in Nature. The studies present data from genetically diverse and previously unrepresented populations. Together they offer a detailed picture of deep human history and may settle some long-standing debates, but there is still room to quibble. All non-Africans stem from one major founding population, the studies agree, but earlier human migrations are also recorded in present-day people’s DNA, one study finds. And a fourth study in the same issue of Nature, this one focusing on ancient climate, also makes the case for an earlier exodus.

Scientists have long debated when anatomically modern humans first trekked out of Africa and how many waves of migration there were. Archaeological evidence indicates there were modern humans in Asia by at least 80,000 years ago. Human DNA in a Neandertal woman from Siberia indicates humans interbred with Neandertals outside Africa as long as 110,000 years ago (SN: 3/19/16, p. 6). But those people died out and didn’t contribute DNA to later generations, says Swapan Mallick, an evolutionary geneticist at Harvard Medical School and coauthor of a paper that traced the genetic history of 300 people from 142 populations around the world. The ancestors of today’s non-Africans probably left Africa about 50,000 years ago, Mallick and colleagues calculate.

Data in another study reveal remnants of a much earlier exodus from Africa that persist in the genomes of present-day Papuans, biological anthropologist Luca Pagani of the Estonian Biocentre in Tartu and colleagues report. About 2 percent of the genome of Papuans can be traced back to small bands of humans who left Africa 120,000 years ago. “This expansion was successful in leaving descendants today,” Pagani says. But a massive wave of migrants who left Africa after about 75,000 years ago probably overwhelmed that small trickle, swamping out their genetic signature.

A third study focusing on the genetic history of aboriginal Australians and Papuans from the New Guinea highlands didn’t find traces of a 120,000-year-old migration, but didn’t rule it out either, says study coauthor Eske Willerslev, an evolutionary geneticist at the University of Copenhagen.

Some previous studies have suggested that ancestors of Australians and Papuans came from an earlier wave of migration than other non-Africans did. “Australians and Papuans are descendants of some of the earliest modern human explorers,” Willerslev says. His group’s evidence suggests a single wave of migrants left Africa about 72,000 years ago and settled initially in the Middle East. Ancestors of Europeans and Asians stayed put for thousands of years before splitting into different groups. But Australian and Papuan ancestors kept going. “These guys were heading off on this marvelous journey across Asia,” ending up in Australia and Papua New Guinea about 50,000 years ago, Willerslev says.

Mallick and colleagues also found evidence of a main wave of migration into the Middle East that split into two groups after breeding with Neandertals. Those groups took different routes. One ended up in Europe, the other populated Asia. Instead of Australians and Papuans sprinting ahead of everyone else as an independent group, the researchers say they moved with the ancestors of East Asians and continued to the islands only later.

Pagani and colleagues used a method for analyzing their data that helped them pick out older chunks of DNA, says Mattias Jakobsson, an evolutionary geneticist at Uppsala University in Sweden. That method enabled them to see evidence of the older migration where the other studies couldn’t. But genetic dating methods are far from perfect; they can differ because of inaccurate mutation rates, skewed sampling, biased analyses or other reasons. Future genetic studies of present-day people added to new work on ancient DNA and archaeological evidence may help resolve some of the remaining discrepancies.

Even though results from Pagani’s study seem to disagree with the other two, “it’s a superficial disagreement,” says evolutionary geneticist Joshua Akey of the University of Washington in Seattle who was not involved in any of the studies. “One group is saying 98 percent” of DNA came from the main wave of migration, “while the other groups say it’s 100 percent. … The main conclusion is that the vast majority of ancestry in non-Africans can be traced to a single out-of-Africa dispersal.”

A study of ancient climates may create another discrepancy. It suggests the departure window geneticists propose was the absolute worst time to leave Africa. “Every 20,000 years or so, Earth’s axis wobbles caused massive shifts in climate and vegetation,” says Axel Timmermann, a climate scientist at the University of Hawaii at Manoa. Those fluctuations opened green corridors across northern Africa and the Arabian Peninsula, then turned those same areas to parched deserts.

Timmermann and University of Hawaii colleague Tobias Friedrich did computer simulations of climate and sea level changes over the last 125,000 years to predict when and where humans might have easily moved. By the scientists’ calculations, the timing of a mass human migration out of Africa 60,000 to 70,000 years ago “is the most unlikely scenario from a climate point of view, because … northeastern Africa was completely dry. It was one of the worst drought periods in the entire history, so the corridor was closed,” Timmermann says.

The researchers predict conditions were favorable for migration between 107,000 and 95,000 years ago and again 90,000 to 75,000 years ago. Another window didn’t open until 59,000 years ago, after humans were probably well on their way to Australia. “People could have chased antelope across and they wouldn’t even know they were on a different continent,” Timmermann says. That seamless landscape transition would have been mirrored in people’s mating habits, with populations moving in and out of Africa and mixing freely, he speculates.

Most genetic analyses don’t take that back-to-Africa movement into account, Timmermann says. Back-and-forth mating would make the Africans and non-Africans genetically indistinguishable from each other and obscure the real date at which people left Africa.  Allowing for cross-continent mingling puts people’s exodus from Africa at about 80,000 to 100,000 years ago. Climate shifts that turned Arabia to desert 70,000 years ago would have cut off the connection, making people already outside Africa genetically distinct from Africans. That would show up in the genetic studies as the point at which people left Africa instead of the point-of-no-return.

Some previous genetic research has found evidence of back-to-Africa migrations starting about 45,000 years ago (SN: 6/25/16, p.14).

The climate study reinforces the idea that people had spread out of Africa much sooner than the new genetic evidence indicates, says archaeologist Michael Petraglia of the Max Planck Institute for the Science of Human History in Jena, Germany. He is a coauthor of the Pagani study, but says genetics alone won’t solve all the mysteries of early human history.

Debate over when people left Africa, where they came from inside Africa and who they interbred with as they spread around the globe are far from over, says Petraglia. “I expect some fireworks in the next few years.”

Mammoth bone found on Texel island beach


The mammoth bone and its discoverers, with a woolly rhino model in the background, photo Ecomare museum

Translated from Dutch NOS TV:

Family finds mammoth bone during holiday on Texel

Today, 12:42

A family from Gouda found a mammoth bone tens of thousands of years old during a walk on the beach of Texel. Arieke Visscher and her daughters Francine and Ruth made the discovery at beach post 28, the regional broadcasting organisation NH writes.

Mother Arieke thought almost immediately that it was a mammoth bone. Her grandfather was a fisherman and fished these bones from the sea.

Fibula

A curator of Ecomare museum established that it was indeed a mammoth bone. Presumably it is a piece of a fibula. The bone is from the last ice age, about 20,000 to 40,000 years ago.

The bones of mammoths are still found at the bottom of the sea. The bones end up on the beach and North Sea sand is used for widening the beach. The discovery on the island, according to Ecomare therefore is “not very special, but still very nice.”

North American mammoths, new study


This video says about itself:

1 December 2014

Woolly Mammoth: The Autopsy

Science Documentary hosted by Steven Mackintosh, published by Channel 4 in 2014 – English narration

The 2013 discovery in Siberia of the best-preserved mammoth yet has quickened the pace of one of the most ambitious and controversial projects in science: the cloning of the woolly mammoth. This one is unlike any mammoth found before; when it was dug out of the permafrost, a dark red liquid oozed from the frozen body. Speculation is rife: could the liquid be mammoth blood? And does the freshness of the mammoth’s flesh mean that a clone is now achievable?

This documentary follows an international team of mammoth specialists and cloning scientists as they carry out a historic autopsy in Siberia, and follows those who strive to bring these iconic giants of the Ice Age back from extinction. As the animal is carefully dissected and its tusks are examined, the programme reveals the life story of this mammoth in forensic detail.

From Frontiers in Ecology and Evolution:

Mammuthus Population Dynamics in Late Pleistocene North America: Divergence, Phylogeography and Introgression

06 April 2016

After evolving in Africa at the close of the Miocene, mammoths (Mammuthus sp.) spread through much of the northern hemisphere, diversifying morphologically as they entered various habitats. Paleontologically, these morphs are conventionally recognized as species.

In Pleistocene North America alone, several mammoth species have been recognized, inhabiting environments as different as cold tundra-steppe in the north and the arid grasslands or temperate savanna-parklands of the south. Yet mammoth phylogeographic studies have overwhelmingly focused on permafrost-preserved remains of only one of these species, Mammuthus primigenius (woolly mammoth).

Here we challenge this bias by performing a geographically and taxonomically wide survey of mammoth genetic diversity across North America. Using a targeted enrichment technique, we sequenced 67 complete mitochondrial genomes from non-primigenius specimens representing M. columbi (Columbian mammoth), M. jeffersonii (Jeffersonian mammoth), and M. exilis (pygmy mammoth), including specimens from contexts not generally associated with good DNA preservation.

While we uncovered clear phylogeographic structure in mammoth matrilines, their phylogeny as recovered from mitochondrial DNA is not compatible with existing systematic interpretations of their paleontological record. Instead, our results strongly suggest that various nominal mammoth species interbred, perhaps extensively.

We hypothesize that at least two distinct stages of interbreeding between conventional paleontological species are likely responsible for this pattern – one between Siberian woolly mammoths and resident American populations that introduced woolly mammoth phenotypes to the continent, and another between ecomorphologically distinct populations of woolly and Columbian mammoths in North America south of the ice.

Columbian mammoth discovery in Oklahoma, USA


This video says about itself:

BBC: Columbian Mammoth, Death by Tar – Ice Age Death Trap

26 August 2008

With the help of CGI and animal puppetry, BBC’s Ice Age Death Trap team bring the … mammoth back to life to explain how such a giant creature could be killed by tar.

By Dominique Mosbergen, Senior Writer, The Huffington Post in the USA:

Bulldozer Operator Stumbles Upon Mammoth Skull In Oklahoma

The remains are at least 11,000 years old.

04/05/2016 05:21 am ET

Imagine being at work and stumbling, completely by chance, upon a mammoth discovery — a literal one, at that.

That’s what happened last month to a bulldozer operator in northwestern Oklahoma, who found the remains of a Columbian mammoth while on the job.

According to the Oklahoma Archeological Survey, the man was working at a sand pit near Alva when he made the surprise find. A partial mammoth skull, along with two tusks, have since been unearthed from the area.

“We don’t know the cause of death. There is no sign that people killed or butchered it,” archeologist Lee Bement told Live Science of the animal remains, which have yet to be dated. “Its skull was washed around in the river. The rest of the animal could be anywhere.”

Mammoth discoveries in the U.S. are not entirely unusual. Earlier this year, a mammoth femur was found under Oregon State University’s football field, and last September, two Michigan farmers stumbled upon mammoth remains in a soybean field.

Bement told Live Science that Oklahoma is home to about three “mammoth sightings” a year. Still, each new discovery brings hope of something new and unexpected.

“Archeological fieldwork is always exciting. You never know what you are going to find,” he said.

As The Associated Press noted, Columbian mammoths were a common sight across the Plains until they — along with many large Ice Age animals, including mastodons, giant sloths and giant bears — went extinct at the end of Pleistocene era about 11,000 years ago. Scientists are still unsure as to what prompted this mass die-off, though hunting by humans and climate change have been floated as possible culprits.

New Ice Age rhino discovery in Kazakhstan


This video says about itself:

18 August 2015

Elasmotherium” is an extinct genus of giant rhinoceros endemic to Eurasia during the Late Pliocene through the Pleistocene, documented from 2.6 Ma to as late as 50,000 years ago, possibly later, in the Late Pleistocene, an approximate span of slightly less than 2.6 million years.

Three species are recognised. The best known, “E. sibiricum”, was the size of a mammoth and is thought to have borne a large, thick horn on its forehead. This horn was used for defense, attracting mates, driving away competitors, sweeping snow from the grass in winter and digging for water and plant roots. Like all rhinoceroses, elasmotheres were herbivorous. Unlike any others, its high-crowned molars were ever-growing. Its legs were longer than those of other rhinos and were adapted for galloping, giving it a horse-like gait.

From LiveScience:

‘Unicorns’ Lumbered Across Siberia 29,000 Years Ago

by Mindy Weisberger, Senior Writer

March 29, 2016 04:24pm ET

Large, four-legged beasts, each with a single horn growing from its head, once ambled across part of western Siberia, in what is now Kazakhstan.

Sometimes referred to as “unicorns” because of their single horns, these animals were originally thought to have gone extinct 350,000 years ago. However, fossils from a new dig site place the hefty creatures in the region as recently as 29,000 years ago, according to a recent study.

In spite of their magical-sounding nickname, these bruisers share little in common with the graceful and delicate horselike creatures described in song and story and pictured in medieval tapestries. A 1923 publication by paleontologist Henry Fairfield Osborn estimated the creatures to be larger than any of the modern rhino species. Artists’ reconstructions hint at a burly build and body plan that resemble that of the animals’ extant cousins. And the beasts go by an equally cumbersome name: Elasmotherium sibiricum (ee–laz–moh–THEER–ee–um sih–BIH–rih–cum). [6 Extinct Animals That Could Be Brought Back to Life]

A well-preserved skull

The partial skull that the researchers found was well-preserved and in very good condition overall, though the teeth were missing, the scientists said. Dimensions of features in the skull fragment were considerably bigger than those in any other E. sibiricum specimen yet discovered in Eastern Europe, hinting that the skull most likely belonged to a large, older male, said study co-author Andrey Shpanski, a paleontologist at Tomsk State University in Russia.

“The dimensions of this rhino [described] today are the biggest of those described in the literature,” Shpanski said in a statement.

E. sibiricum is thought to have ranged from the Don River in southern Russia to the eastern part of Kazakhstan, and prior findings showed that the animal had long inhabited the southeastern part of the West Siberian Plain.

Other fossils found alongside the E. sibiricum skull include two upper teeth from a mammoth, the lower jaw of a steppe elephant and pieces of a bison‘s horn stem.

Dating a “unicorn”

To find out how old the fossils were, the scientists used a method known as radiocarbon dating, which they employed to analyze the amount of carbon-14 in the skull pieces. Carbon-14 is a carbon isotope, a variation of carbon with a different number of neutrons in its nucleus (14, in this case). Living plants and animals absorb carbon-14 from the atmosphere as long as they’re alive.

But once an organism dies, the carbon-14 in its body begins to decay at a regular rate that can be tracked over time, until about 60,000 years have passed and all the carbon-14 is gone. By analyzing bones to see how much carbon-14 is left, scientists can tell when the animal was still alive.

Radiocarbon dating told researchers that the E. sibiricum individual died 29,000 years ago, a dramatic divergence from previous estimates placing the species’ extinction at 350,000 years ago.

If the new calculation is correct, the “Siberian unicorn” could have crossed paths with modern humans. An earlier study suggested that humans inhabited the Siberian Arctic as far back as 45,000 years ago, based on the evidence of a butchered mammoth carcass that was likely cut up by hunters.

The new findings were published in the Feb. 2016 issue of the American Journal of Applied Sciences.

‘Neanderthal-human mating earlier than thought’


Scenario of interbreeding between modern humans and Neanderthals: Neanderthal DNA in present-day humans outside Africa originates from interbreeding that occurred 47,000 - 65,000 years ago (green arrow). Modern human DNA in Neanderthals is likely a consequence of earlier contact between the two groups roughly 100,000 years ago (red arrow). Credit: © Ilan Gronau

This video says about itself:

Neanderthals mated with modern humans much earlier than previously thought

22 December 2015

Using several different methods of DNA analysis, an international research team has found what they consider to be strong evidence of an interbreeding event between Neanderthals and modern humans that occurred tens of thousands of years earlier than any other such event previously documented.

From Cold Spring Harbor Laboratory in New York in the USA:

Neanderthals mated with modern humans much earlier than previously thought

February 17, 2016

Using several different methods of DNA analysis, an international research team has found what they consider to be strong evidence of an interbreeding event between Neanderthals and modern humans that occurred tens of thousands of years earlier than any other such event previously documented.

Today in Nature the team publishes evidence of interbreeding that occurred an estimated 100,000 years ago. More specifically the scientists provide the first genetic evidence of a scenario in which early left the African continent and mixed with archaic (now-extinct) members of the human family prior to the migration “out of Africa” of the ancestors of present-day non-Africans, less than 65,000 years ago.

“It’s been known for several years, following the first sequencing of the Neanderthal genome in 2010, that Neanderthals and humans must have interbred,” says Professor Adam Siepel, a co-team leader and Cold Spring Harbor Laboratory (CSHL) quantitative biologist. “But the data so far refers to an event dating to around 47,000-65,000 years ago, around the time that human populations emigrated from Africa. The event we found appears considerably older than that event.”

In addition to Siepel, who is Chair of CSHL’s Simons Center for Quantitative Biology, the team included several members of the Max Plank Institute for Evolutionary Anthropology, including Martin Kuhlwilm, Svante Pääbo, Matthias Meyer and co-team leader Sergi Castellano. Kuhlwilm was co-first author of the new paper with Ilan Gronau, a former member of Siepel’s Lab who is now at the Herzliya Interdisciplinary Center, Israel. Melissa Hubisz, a Ph.D. student with Siepel at Cornell University, also made major contributions to the work. The full international research team included 15 additional co-authors.

“One very interesting thing about our finding is that it shows a signal of breeding in the ‘opposite’ direction from that already known,” Siepel notes. “That is, we show human DNA in a Neanderthal genome, rather than Neanderthal DNA in .”

This finding, the result of several kinds of advanced computer modeling algorithms comparing complete genomes of hundreds of contemporary humans with complete and partial genomes of four archaic humans, has implications for our knowledge of human migration patterns.

People living today who are of European, Eurasian and Asian descent have well-identified Neanderthal-derived segments in their genome. These fragments are traces of interbreeding that followed the “out of Africa” human migration dating to about 60,000 years ago. They imply that children born of Neanderthal-modern human pairings outside of Africa were raised among the modern humans and ultimately bred with other humans, explaining how bits of Neanderthal DNA remain in human genomes.

Contemporary Africans, however, do not have detectable traces of Neanderthal DNA in their genomes. This indicates that whatever sexual contact occurred between modern humans and Neanderthals occurred among humans who left the African continent. “Ancestors of present-day African populations likely didn’t have the opportunity to interbreed with Neanderthals, who lived largely outside of Africa,” explains co-author Ilan Gronau.

The team’s evidence of “gene flow” from descendants of modern humans into the Neanderthal genome applies to one specific Neanderthal, whose remains were found some years ago in a cave in southwestern Siberia, in the Altai Mountains, near the Russia-Mongolia border. The modern human ancestor who contributed genes to this particular Neanderthal individual – called the “Altai Neanderthal,” and known from a tiny toe bone fragment – must have migrated out of Africa long before the migration that led Africans into Europe and Asia 60,000 years ago, the scientists say.

In contrast, the two Neanderthals from European caves that were sequenced for this study—one from Croatia, another from Spain—both lack DNA derived from ancestors of modern humans. The team also included in their analysis DNA from another archaic human relative, a Denisovan individual, whose remains were found in the same cave in the Altai Mountains. Denisovans, like Neanderthals, are members of the human line that eventually became extinct. Both of these archaic human cousins lived in the same cave, although at different times in the past.

The Denisovan analyzed in this study did not have traces of modern human DNA, unlike the Neanderthal found in the same cave. That doesn’t mean modern human ancestors never mated with Denisovans or European Neanderthals.

What is does mean, Siepel clarifies, is that “the signal we’re seeing in the Altai Neanderthal probably comes from an interbreeding event that occurred after this Neanderthal lineage diverged from its archaic cousins, a little more than 100,000 years ago.”

The modern human sequences in the Altai Neandertal appear to derive from a group of modern human ancestors from Africa that separated early from other humans, about the time present-day African populations diverged from one another, around 200,000 years ago. Thus, there must have been a long lag between the time when this group branched off the modern human family tree, roughly 200,000 years ago, and the time they left their genetic mark in the Altai Neandertal, about 100,000 years ago, before being lost to extinction themselves.

The team’s analysis included more than 500 genomes of contemporary Africans. “I was looking to see if I could find genomic regions where the Altai Neanderthal has sequences resembling those we see in humans,” says Martin Kuhlwilm. “We know that contemporary non-Africans have traces of Neanderthal in them, so they were not useful in this search. Instead, we used the genomes of contemporary individuals from five populations across Africa to identify mutations which most of them have in common.”

This was the data that provided evidence of “regions in the Altai Neanderthal genome that carry mutations observed in the Africans – but not in the Denisovan” or in Neanderthals found in European caves.

“This is consistent with the scenario of gene flow from a population closely related to modern humans into the Altai Neanderthal. After ruling out contamination of DNA samples and other possible sources of error, we are not able to explain these observations in any other way,” Siepel says.

Ancient DNA found in ‘Pit of Bones’ shows earliest genetic evidence of Neanderthals. The DNA is from 430,000-year-old bones found in Spain: here.

Fossil dinosaur and fossil wildebeest, discoveries and simillarities


This video says about itself:

Shared noses: Extinct wildebeest relative was remarkably dinosaur-like

5 February 2016

An artist’s interpretation of Rusingoryx atopocranion on the Late Pleistocene plains of what is now Rusinga Island, Lake Victoria.

From the Christian Science Monitor in the USA:

Weird convergence: Extinct wildebeest cousin and dinosaur shared noses

Scientists discover two unrelated, extinct animals had the same strange nose.

By Eva Botkin-Kowacki, Staff writer February 5, 2016

You might not expect to find many similarities between a mammal and a reptile, particularly if they lived millions of years apart. But scientists have found that two such extinct beasts share a rare, distinctive facial feature.

An extinct relative of the wildebeest and a duck-billed dinosaur both had bizarre crests on their heads. But it wasn’t the protruding bump that has most intrigued scientists, it’s what they found beneath.

The bony crest is hollow, forming a trumpet-shaped nasal passage unlike any seen outside these two species. No other animal, living or dead, has been found with such a feature.

So how did two beasts from two very different taxa come to have such a mysterious commonality? Convergent evolution, scientists say in a paper published Thursday in the journal Current Biology.

“We have an animal that its skeleton looks a lot like a wildebeest – it’s actually very closely related to modern wildebeests – but its face looks a lot more like something you would see if you went way back in time to the Cretaceous and looked at hadrosaur dinosaurs,” study lead author Haley O’Brien tells The Christian Science Monitor in an interview.

Rusingoryx atopocranion, the mammal, lived about 65 thousand years ago, during the late Pleistocene, while Lambeosaurine hadrosaurs, the dinosaur, lived closer to 65 million years ago, during the late Cretaceous – and yet both animals evolved the same strange nose.

And not only do their nasal passages look alike, she said, the feature also appears to develop the same way as the animals grow up from juveniles to adults, as a variety of fossils display.

“When I first saw the complete skulls, I was blown away,” vertebrate paleontologist David C. Evans, who was not part of the study, writes in an email to the Monitor. “The resemblance between Rusingoryx and some hollow-crested dinosaurs in the form of their nasal structures is truly striking, and there are clear parallels in how they evolved and grew. Both groups elongated their noses to such a degree that they evolved highly domed skulls to house their nasal passages on top of their heads, above their eyes.”

Different origins, same result

“It’s probably one of the best examples of convergence in large animals that I’ve seen in a long time,” Ali Nabavizadeh, a researcher in evolutionary biology and anatomy at the University of Chicago, who was not involved in the study, tells the Monitor.

One was a mammal and the other a reptile, and millions of years elapsed between their tenure on Earth, but still, these animals developed the same adaptation.

Convergent evolution occurs when two species along different lineages independently evolve the same, or similar, features for the same function. One example is how insects, birds, and bats can all fly.

Convergence typically occurs when different species face the same ecological pressures. So what did Rusingoryx and the hadrosaurs have in common?

Both animals were herbivores and lived in herds. Rusingoryx was a ruminant and hadrosaurs have been called the cows of the Cretaceous, but the similarities, besides the shared nose, stop there.

Rusingoryx lived on the savanna, a dry wide open plain, while Lambeosaurine hadrosaurs were thought to have lived in a tropical rainforest.

Understanding this mysterious convergence might hinge on the purpose that these strange nasal passages served.

Inner trumpets

Without looking inside the animals’ skulls, the crest might appear to be simply for visual display or some other external use.

“We have known for decades that visual display and physical combat have strongly shaped skull evolution in many groups of animals with elaborate horns and crests,” Dr. Evans says. But the long, trumpet-shaped interior suggests a more complex purpose.

The hollow cavity, part of the respiratory tract, loops up over the animal’s head and seems to connect to the vocal tract.

To determine the purpose behind this strange nose, scientists focused on the mammal’s living cousins, wildebeests and antelopes. While researchers can look at their soft tissue for clues, all that’s left of the dinosaurs is bone.

The unusual nose could have helped the animals smell, bugle, or even regulate their temperature, Evans says. “The case for vocalization as the primary function of the nasal dome in Rusingoryx is by far the most convincing, as the authors advocate.”

The Rusingoryx are very social, says Ms. O’Brien. “They live in herds and they use a lot of vocal signals to communicate. When we looked into the function of what this skull type might be doing in Rusingoryx, we really couldn’t prescribe a function outside of that social vocalization.”

“There are obviously a lot of things that animals do with their faces,” she says. “But we don’t think that this crazy nasal dome would have really changed those more normal functions for this animal. We think that it was using the nasal crest to modify the way that it’s producing these vocalizations and communicating.”

That makes sense, says Thomas E. Williamson, curator of paleontology at the New Mexico Museum of Natural History and Science, who was not part of the study.

“When you have any kind of a tubing, it becomes naturally resonant,” he explains. “So the idea that it’s being used somehow to amplify certain frequencies of sound, it will do that,”

Not your average moo

O’Brien and her colleagues suggest that Rusingoryx, and perhaps the dinosaurs by extension, used this bizarre nasal dome to communicate at frequencies other animals cannot hear. This is called infrasound, and animals like elephants and cassowaries use it to communicate under the radar.

That’s possible, says Dr. Nabavizadeh. “If you have a very gregarious group of animals and they’re in a big arid, open environment, as these bovids are, then you are under the selective pressure to start to create more lower bellowing sounds that are possibly outside of the hearing range of carnivores, so they can communicate without being found in big open environments.”

But the environment doesn’t preclude the dinosaurs from needing this ability too, says Dr. Williamson. “Infrasound … is able to travel over great distances and open areas and in closed environments. It pretty much goes everywhere,” he says. And cassowaries, the living birds thought to communicate in infrasound, live in dense tropical rainforests.