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A QUT-led collaboration with University of Adelaide reveals that Australia's pint-sized banded hare-wallaby is the closest living relative of the giant short-faced kangaroos which roamed the continent for millions of years, but died out about 40,000 years ago.

The diminutive banded hare-wallaby linked to the giant Sthenurinae kangaroos [Credit: Queensland University of Technology]

Published in Systematic Biology, the research involved the first near-complete mitochondrial (mt) genome sequencing from extinct Australian megafauna.

- DNA was sequenced from inner ear bones (petrous bones) of a 45,000-year-old giant short-faced kangaroo, Simosthenurus occidentalis, part of the Sthenurinae sub-family, found at Mt Cripps in Tasmania

- These are the longest DNA sequences ever recovered from Australia's extinct megafauna, with more than 16,000 base pairs of mtDNA, which is used to help understand evolutionary relationships

- The results support an evolutionary link between giant short-faced kangaroos (Sthenurinae) and the threatened banded hare-wallaby, Lagostrophus fasciatus

- The study also combined the DNA evidence with fossil and anatomical data to trace body size change over the evolutionary history of kangaroos and wallabies

The analysis was conducted by QUT evolutionary biologists Ph.D. researcher Manuela Cascini and Associate Professor Matthew Phillips, from the Science and Engineering Faculty, in collaboration with University of Adelaide's Professor Alan Cooper and Dr. Kieren Mitchell, who undertook the DNA sequencing at the Australian Centre for Ancient DNA.

Credit: Queensland University of Technology

Lead author Ms Cascini, a molecular biologist who moved from Italy to undertake her Ph.D. research with Associate Professor Phillips, said her project also involved analysis of mtDNA sequenced from the inner ear bones of another ancient extinct macropod that was found in Tasmania – the giant wallaby, Protemnodon anak, which weighed up to 150 kilograms.

Small fragments of ancient DNA sequenced from this giant wallaby species and from the giant short-faced kangaroo were first reported on by University of Adelaide scientists in 2015.

"Our analysis confirmed their conclusion that the giant wallabies are close relatives of the iconic living Macropus genus of kangaroos and wallabies," Ms Cascini said.

"However that earlier study provided insufficient DNA to confidently place the giant short-faced kangaroos on the evolutionary tree.

"We've now been able to show the strongest evidence yet that the closest living relative of these massive Sthenurinae kangaroos, which weighed up to about 240 kilograms, is the tiny, 2-kilogram banded hare-wallaby. These wallabies live in the wild only on islands off Western Australia and are classified as vulnerable."

Largest of the extinct giant short-faced kangaroos, Procoptodon goliah, featured on an Australia Post stamp  [Credit: Queensland University of Technology]

Associate Professor Phillips said the larger amount of mtDNA sequenced in this study by the University of Adelaide collaborators helped enable the strong finding on the banded hare-wallaby link.

"This is by far the most genetic data that anyone has extracted out of Australian megafauna, and it was taken from the petrous bones which are denser and often seem to hold DNA better," he said.
"You find a lot of ancient DNA studies of megafauna from permafrost in northern Europe and northern America because the cold helps preserve the DNA. But in Australia the hotter climate and older age of the megafauna is far less favourable for DNA preservation."

Dr. Mitchell said Tasmania's cooler climate and higher-altitude caves "make for much better DNA preservation than we find elsewhere in Australia, so we focused our hunt for high-quality megafaunal DNA there".

Associate Professor Phillips said other findings of the study on the evolution of kangaroos and wallabies (macropods) included:

- The macropod ancestors diverged from tree-living possums around 41 to 46 million years ago

- They remained small, in the 2-15 kg range, while Australia was more dominated by rainforest

- As the climate cooled and dried, and as the forests opened up over the past 10 million years, at least four different kangaroo lineages independently evolved to megafaunal size (more than 44 kg)

- This includes the short-faced kangaroos, the giant Protemnodon wallabies, and the living red and grey kangaroos.

Author: Rose Trapnell | Source: Queensland University of Technology [December 10, 2018]

Rivaling the evolution of feathers in dinosaurs, one of the most extraordinary transformations in the history of life was the evolution of baleen--rows of flexible hair-like plates that blue whales, humpbacks and other marine mammals use to filter relatively tiny prey from gulps of ocean water. The unusual structure enables the world's largest creatures to consume several tons of food each day, without ever chewing or biting. Now, Smithsonian scientists have discovered an important intermediary link in the evolution of this innovative feeding strategy: an ancient whale that had neither teeth nor baleen.

Carlos Mauricio Peredo, National Museum of Natural History predoctoral fellow and lead author of the study, with the 33 million-year-old early baleen whale Maiabalaena nesbittae. The fossil is the first of its species to be described by scientists and will now serve as the exemplar of this species for the scientific community. Because of its age, Peredo said, paleontologists suspected Maiabalaena might hold important clues about baleen's evolution. The fossil comes from a period of massive geological change during the second major phase of whale evolution, around the time the Eocene epoch was transitioning to the Oligocene. With continents shifting and separating, ocean currents were swirling around Antarctica for the first time, cooling the waters significantly. The fossil record indicates that whales' feeding styles diverged rapidly during this timeframe, with one group leading to today's filter-feeding whales and the other leading to echolocating ones [Credit: Smithsonian]

In the recent issue of the journal Current Biology, scientists at the Smithsonian's National Museum of Natural History and colleagues describe for the first time Maiabalaena nesbittae, a whale that lived about 33 million years ago. Using new methods to analyze long-ago discovered fossils housed in the Smithsonian's national collection, the team, which includes scientists at George Mason University, Texas A&M University and the Burke Museum of Natural History and Culture in Seattle, have determined that this toothless, 15-foot whale likely had no baleen, showing a surprising intermediary step between the baleen whales that live today and their toothed ancestors.

"When we talk about whale evolution, textbooks tend to focus on the early stages, when whales went from land to sea," said National Museum of Natural History's curator of fossil marine mammals. "Maiabalaena shows that the second phase of whale evolution is just as important for evolution over big scales. For the first time, we can now pin down the origin of filter-feeding, which is one of the major innovations in whale history."

When whales first evolved, they used teeth to chew their food, just like their land-dwelling ancestors. As time went on, many descendants of these early whales continued to chew their food, inheriting this trait from their predecessors. But as the oceans around them changed and animals evolved, entirely new feeding strategies arose, including baleen filter feeding, says National Museum of Natural History predoctoral fellow Carlos Mauricio Peredo, the lead author of the study who analyzed the Maiabalaena fossils.

Baleen is the soft, hair-like structure on the upper mouth of whales, such as the humpback whale in this photo, which allows  them to trap prey in their mouth. When whales first evolved, they used teeth to chew their food, just like their land-dwelling ancestors. As time went on, many descendants of these early whales continued to chew their food, inheriting this trait from  their predecessors. But as the oceans around them changed and animals evolved, entirely new feeding strategies arose,  including baleen filter feeding. Peredo and Pyenson see studying whale evolution as key to understanding their survival  in today's rapidly changing oceans. Like the emergence of baleen, tooth loss in whales is evidence of adaptability, suggesting that whales might be able to adapt to challenges posed in the ocean today. Still, Peredo cautions,  evolutionary change may be slow for the largest whales, which have long life spans and take a long time  to reproduce [Credit: Ari S. Friedlaender/University of California, Santa Cruz/NOAA]

Whales were the first mammals to evolve baleen, and no other mammal uses any anatomical structure even remotely similar to it to consume its prey. But frustratingly, baleen, whose chemical composition is more like that of hair or fingernails than bone, does not preserve well. It is rarely found in the fossil record, leaving paleontologists without direct evidence of its past or origins. Instead, scientists have had to rely on inferences from fossils and studies of fetal-whale development in the womb to piece together clues about how baleen evolved.

As a result, it has not been clear whether, as they evolved, early baleen whales retained the teeth of their ancestors until a filter-feeding system had been established. An early initial assumption, Peredo said, was that ocean-dwelling mammals must have needed teeth or baleen to eat--but several living whales contradict that idea. Sperm whales have teeth in their bottom jaw, but none on the top, so they cannot bite or chew. Narwhals' only teeth are their long tusks, which they do not use for feeding. And some species of beaked whales, despite being classified as toothed whales, have no teeth at all.

Because of its age, Peredo said, paleontologists suspected Maiabalaena might hold important clues about baleen's evolution. The fossil comes from a period of massive geological change during the second major phase of whale evolution, around the time the Eocene epoch was transitioning to the Oligocene. With continents shifting and separating, ocean currents were swirling around Antarctica for the first time, cooling the waters significantly. The fossil record indicates that whales' feeding styles diverged rapidly during this timeframe, with one group leading to today's filter-feeding whales and the other leading to echolocating ones.

The upper jaw and skull of Maiabalaena nesbittae. Whales were the first mammals to evolve baleen, and no other mammal  uses any anatomical structure even remotely similar to it to consume its prey. But frustratingly, baleen, whose chemical composition is more like that of hair or fingernails than bone, does not preserve well. It is rarely found in the fossil record, leaving paleontologists without direct evidence of its past or origins. Instead, scientists have had to rely on inferences from fossils and studies of fetal-whale development in the womb to piece together clues about how baleen evolved. "When we talk about whale evolution, textbooks tend to focus on the early stages, when whales went from land to sea," said Nicholas Pyenson, the National Museum of Natural History's curator of marine mammals. "Maiabalaena shows that the second phase of whale evolution is just as important for evolution over big scales. For the first time, we can now pin down  the origin of filter-feeding, which is one of the major innovations in whale history" [Credit: Smithsonian]

Consequently, Maiabalaena had received plenty of scrutiny since its discovery in Oregon in the 1970s, but the rock matrix and material that the fossil was collected in still obscured many of its features. It was not until Peredo finally cleaned the fossil and then examined it with state-of-the-art CT scanning technology that its most striking features became clear. Maiabalaena's lack of teeth was readily apparent from the preserved bone, but the CT scans, which revealed the fossil's internal anatomy, told the scientists something new: Maiabalaena's upper jaw was thin and narrow, making it an inadequate surface from which to suspend baleen.

"A living baleen whale has a big, broad roof in its mouth, and it's also thickened to create attachment sites for the baleen," Peredo said. "Maiabalaena does not. We can pretty conclusively tell you this fossil species didn't have teeth, and it is more likely than not that it didn't have baleen either."

While Maiabalaena would not have been able to chew or to filter feed, muscle attachments on the bones of its throat indicate it likely had strong cheeks and a retractable tongue. These traits would have enabled it to suck water into its mouth, taking up fish and small squid in the process. The ability to suction feed would have rendered teeth, whose development requires a lot of energy to grow, unnecessary. The loss of teeth, then, appears to have set the evolutionary stage for the baleen, which the scientists estimate arose about 5 to 7 million years later.

An artistic reconstruction of a mother and calf of Maiabalaena nesbittae nursing offshore of Oregon during the Oligocene, about 33 million years ago. While Maiabalaena would not have been able to chew or filter feed, muscle attachments on the bones of its throat indicate it likely had strong cheeks and a retractable tongue. These traits would have enabled it to suck water into its mouth, taking up fish and small squid in the process. The ability to suction feed would have rendered teeth, whose development requires a lot of energy to grow, unnecessary. The loss of teeth, then, appears to have set the evolutionary stage for the baleen, which the scientists estimate arose about 5 to 7 million years later [Credit: Alex Boersma]

Peredo and Pyenson see studying whale evolution as key to understanding their survival in today's rapidly changing oceans. Like the emergence of baleen, tooth loss in whales is evidence of adaptability, suggesting that whales might be able to adapt to challenges posed in the ocean today. Still, Peredo cautions, evolutionary change may be slow for the largest whales, which have long life spans and take a long time to reproduce.

"Given the scale and rate of changes in the ocean today, we don't exactly know what that will mean for all of the different species of filter-feeding whales," he said. "We know that they've changed in the past. It's just a matter of whether they can keep up with whatever the oceans are doing--and we're changing the oceans pretty quickly right now."

Source: Smithsonian [November 29, 2018]

Scientists are worried about the platypus, with a national risk assessment led by UNSW Professor Richard Kingsford suggesting declines of up to 30 percent.

A UNSW-led project has raised concerns about the decline of platypus populations [Credit: Taronga Zoo: G Anderson]

Mounting evidence that platypus populations are falling has concerned scientists who are nearing the end of a three-year national survey of the iconic species.

The UNSW-led Australian Research Council-funded project has compiled a comprehensive database of the distribution and abundance of the platypus over the last two centuries, combining this with data from systematic capture surveys to conduct a national risk assessment for the species.

"We have great concerns about the future survival of this unique species," says project leader Professor Richard Kingsford, director of the UNSW Centre for Ecosystem Science.

New research has shed light on the origin and extinction of a giant, shaggy Ice Age rhinoceros known as the Siberian unicorn because of its extraordinary single horn.

Australian scientists believe the Siberian unicorn was a victim of climate change [Credit: WikiCommons]

An international team of researchers from Adelaide, Sydney, London, the Netherlands, and Russia, have settled a long-standing debate about the relationship of the Siberian unicorn to living rhinos, and revealed that it survived much later than previously believed, overlapping in time with modern humans.

Published in the journal Nature Ecology and Evolution and led by London's Natural History Museum, the researchers say the Siberian unicorn became extinct around 36,000 years ago. This was most likely because of reduction in steppe grassland where it lived – due to climate change rather than the impact of humans.

Today there are just five surviving species of rhino, although in the past there have been as many as 250 species.

Weighing up to 3.5 tonnes with a single enormous horn, the Siberian unicorn (Elasmotherium sibiricum), which roamed the steppe of Russia, Kazakhstan, Mongolia, and Northern China, was undoubtedly one of the most impressive.

Skeleton of the rhino at the Stavropol Museum [Credit: Igor Doronin]

Genetic analyses performed at the University of Adelaide's Australian Centre for Ancient DNA (ACAD), however, have shown that the Siberian unicorn was the last surviving member of a unique family of rhinos.

"The ancestors of the Siberian unicorn split from the ancestors of all living rhinos over 40 million years ago," says co-author and ACAD researcher Dr. Kieren Mitchell, who analysed the DNA of the Siberian unicorn. It is the first time DNA has ever been recovered from E. sibiricum.

"That makes the Siberian unicorn and the African white rhino even more distant cousins than humans are to monkeys."

This new genetic evidence overturns previous studies that suggested the Siberian unicorn was a very close relative of the extinct woolly rhino and living Sumatran rhino.

It had long been assumed that the Siberian unicorn went extinct well before the last Ice Age, perhaps as much as 200,000 years ago.

Artist’s impression of Elasmotherium [Credit: © W. S. Van der Merwe/Natural History Museum]

In this study 23 Siberian unicorn bone specimens were dated, confirming that the species survived until at least 39,000 years ago, and possibly as late as 35,000 years ago. The Siberian unicorn's final days were shared with early modern humans and Neanderthals.

"It is unlikely that the presence of humans was the cause of extinction," says co-author Professor Chris Turney, climate scientist at the University of New South Wales.

"The Siberian unicorn appears to have been badly hit by the start of the ice age in Eurasia when a precipitous fall in temperature led to an increase in the amount of frozen ground, reducing the tough, dry grasses it lived on and impacting populations over a vast region."

Other species that shared the Siberian unicorn's environment were either less reliant on grass – like the woolly rhino – or more flexible in their diet – like the saiga antelope – and escaped the Siberian unicorn's fate, though the woolly rhino eventually became extinct 20,000 years later.

Author: Robyn Mills | Source: University of Adelaide [November 27, 2018]