Tuning into dolphin chatter could boost conservation efforts
April 29, 2020
Tuning in to the signature ‘whistles’ of dolphins could prove a game-changer in being able to accurately track the movements of this much-loved protected species.
Researchers from Edith Cowan University (ECU) and Curtin University in Australia have moved an important step closer to using sound rather than sight to track individual dolphin activity.
Their study, which has potential implications for dolphin communities around the world, investigated whether there was a way to attribute unique whistles to individual bottlenose dolphins living in Western Australia’s Swan River.
It is the first time researchers have attempted acoustic tracking dolphins in the Swan River, which is a complicated marine ecosystem due to its high volume of activity and noise.
ECU researcher Associate Professor Chandra Salgado Kent said the project could have significant implications for dolphin conservation.
“Our ultimate aim is to track the movements of individual dolphins through underwater acoustic recorders,” Professor Salgado Kent said.
“Until now researchers around the world have relied on laborious and expensive visual surveys on boats to track individual dolphins.
“These surveys can only be conducted during the day and rely on photographing the unique nicks and notches in dorsal fins when they come to the surface.
“We aimed to design a new approach to monitor individual dolphin activity through matching unique sounds, known as signature whistles, to individual dolphins.”
A challenging process
From April to September 2013 the researchers systemically monitored an area within the eastern part of the Fremantle Inner Harbour where the Swan River narrows.
Acoustic recordings were made throughout all observation times with handheld hydrophones deployed over the side of the small craft jetty lowered to 1.5m depth.
More than 500 whistles were matched to dolphin photos over the period of the study.
Curtin University Professor Christine Erbe said the process presented some unique challenges.
“Dolphins are social creatures and very frequently seen in groups, which makes the process of matching the whistles to particular individuals very challenging,” she said.
“Based on the presence and absence of dolphins when whistles were recorded, most whistle types were narrowed down to a range of possible dolphins that could have produced it.
“Our next goal will be to narrow this down to individuals.”
This 9 April 2020 video from Australia says about itself:
Illuminating Biodiversity of the Ningaloo Canyons – Amazing New Discoveries
An estimated 150-foot siphonophore— seemingly the longest animal ever recorded was discovered during the #NingalooCanyons expedition exploring the submarine canyons near Ningaloo. Additionally, up to 30 new underwater species were made by researchers from the Western Australian Museum aboard Schmidt Ocean Institute’s research vessel Falkor.
Each sample we take is done so with thoughtfulness, respect, and care. The technology – combining high-definition imagery, manipulator tools, and eDNA sensing – means that we can be very selective about what we need to get eat science done.
“We suspected these deep-sea areas would be diverse but we have been blown away by the significance of what we have seen”, Dr. Nerida Wilson.
New species discovered during exploration of abyssal deep sea canyons off Ningaloo
April 12, 2020
Summary: Unique fauna of the Cape Range and Cloates Canyons off of Ningaloo have been documented at unexplored depths. Seemingly the longest animal ever recorded, glass sponges, and octopus squid are among species seen for the first time in Western Australia.
An estimated 150-foot siphonophore — seemingly the longest animal ever recorded was discovered during a month-long scientific expedition exploring the submarine canyons near Ningaloo. Additionally, up to 30 new underwater species were made by researchers from the Western Australian Museum aboard Schmidt Ocean Institute’s research vessel Falkor.
The discovery of the massive gelatinous string siphonophore — a floating colony of tiny individual zooids that clone themselves thousands of times into specialized bodies that string together to work as a team — was just one of the unique finds among some of the deepest fish and marine invertebrates ever recorded for Western Australia. Scientists from the Western Australian Museum, led by Chief Scientist Dr. Nerida Wilson, were joined by researchers from Curtin University, Geoscience Australia and Scripps Institution of Oceanography in exploring the Ningaloo Canyons in the Indian Ocean. Using an underwater robot, ROV SuBastian, they completed 20 dives at depths of up to 4,500 meters over 181 hours of exploration.
During the expedition, scientists collected the first giant hydroids in Australia, discovered large communities of glass sponges in Cape Range Canyon, and observed for the first time in Western Australia the bioluminescent Taning’s octopus squid, long-tailed sea cucumber, and a number of other mollusc, barnacle and squat lobster species. Some of the species collected will be exhibited at the Western Australian Museum.
The team also found the largest specimen of the giant siphonophore Apolemia ever recorded. “We suspected these deep-sea areas would be diverse but we have been blown away by the significance of what we have seen,” Wilson said. Added Dr. Lisa Kirkendale, head of aquatic zoology at the Western Australian Museum and co-principal investigator, “These specimens represent so many extensions in depth and range records for so many species, and will form an important new part of WA Museum collections.”
The expedition is part of Schmidt Ocean Institute’s year-long initiative in Australia and the Pacific to conduct a number of science and engineering expeditions with teams of scientists and researchers from around the world. Using the underwater robot SuBastian, scientists for the first time are able to explore deep-sea canyons and coral reefs around Australia that have never been seen before. The footage and samples collected from the oceans that surround Australia will have important implications for the sustainability and protection of these underwater ecosystems — and for similar habitats worldwide that are in peril because of rising ocean temperatures and other environmental threats.
Owned and operated by Schmidt Ocean Institute, a philanthropic non-profit established by Eric and Wendy Schmidt in 2009, Falkor is the only year-round seagoing philanthropic research vessel in the world. The vessel is equipped with a state-of-the-art 4,500 meter-capable underwater robotic system, ROV SuBastian, that was used to visually explore and collect samples from critical deep ocean areas that had not been explored before. The ship and ROV are both made available to the international science community at no cost, and the scientists agree to make their discoveries publicly available.
“There is so much we don’t know about the deep sea, and there are countless species never before seen,” said Wendy Schmidt, co-founder of Schmidt Ocean Institute. “Our planet is deeply interconnected — what happens in the deep sea impacts life on land — and vice versa. This research is vital to advance our understanding of that connection — and the importance of protecting these fragile ecosystems. The Ningaloo Canyons are just one of many vast underwater wonders we are about to discover that can help us better understand our planet.”
Over the course of a month, the “Great Australian Deep-Sea Coral and Canyon Adventure” research team explored and visited never-before-seen areas of submarine canyon systems off South West Australia, including in the Perth Canyon. Watch some of the amazing scenery and beautiful animal life they encountered in this 4K highlight video.
Deep-sea coral gardens discovered in the submarine canyons off south Western Australia
February 28, 2020
Summary: Stunning ‘gardens’ of deep-sea corals have been discovered in the Bremer Canyon Marine Park by Australian and international scientists during an oceanographic expedition.
Bremer Canyon Marine Park is already known as a biodiversity hotspot for marine species such as whales and dolphins, however, a recent expedition focused on the deep sea has now revealed rich and diverse ecosystems inhabiting the cold waters deep within the canyon. Led by researchers from the University of Western Australia (UWA), these discoveries were only made possible by the philanthropic Schmidt Ocean Institute’s (SOI) deep-sea remotely operated vehicle, SuBastian, which is capable of sampling depths to 4,500 meters.
The team strategically collected deep-sea corals, associated fauna, seawater, and geological samples from the abyssal depths (~4,000 meters) to the continental shelf (~200 meters). “We have already made a number of remarkable discoveries from the Bremer Canyon”, said Dr Julie Trotter, the Chief Scientist from UWA who led the expedition. “The vertical cliffs and ridges support a stunning array of deep-sea corals that often host a range of organisms and form numerous mini-ecosystems.”
These new discoveries are being integrated into a comprehensive package of biological, geological, and bathymetric data. Such rare records of these deep-sea habitats are a new and very important contribution to the Marine Parks, which will help managers as well as the broader community to better understand and protect these previously unknown ecosystems.
This 27 February 2020 video shows some of the discoveries.
The deeper waters in the three oceans that surround Australia, including the world’s largest barrier reef and submarine canyons, are largely unexplored. The expedition explored the Bremer, Leeuwin and Perth canyons, all of which have extensive fossil coral deposits, with the Leeuwin especially notable for a massive pedestal-like coral graveyard.
“This has global implications given these waters originate from around Antarctica which feed all of the major oceans and regulate our climate system”, said Professor Malcolm McCulloch from UWA.
Facing the Southern Ocean, the Bremer Canyon provides important information on the recent and past histories of climate change and ocean conditions in this region, as well as global scale events. Because the Southern Ocean completely encircles Antarctica, it is the main driver of the global climate engine and regulates the supply of heat and nutrient-rich waters to the major oceans. “A particular species of solitary cup coral was found during the expedition. This is significant because we are working on the same coral in the Ross Sea on the Antarctic shelf, in much colder waters,” said collaborator and co-Chief Scientist Dr Paolo Montagna from the Institute of Polar Sciences in Italy. “This is an important connection between disparate sites across the Southern Ocean, which helps us trace changes in water masses forming around Antarctica and dispersing northward into the Indian and other oceans.”
This is a short video about a few of the rock art paintings of the Bradshaw (aka Gwion Gwion) and Wandjina styles that we found in Emma Gorge on El Questro Station in Western Australia. Our video is neither a comprehensive nor professional production. Our purpose in creating it was to supplement what we wrote about it on our website, and to share the visual pleasure of the art, and our excitement in finding it.
University of Melbourne and ANSTO scientists put the Gwion Gwion art period around 12,000 years old.
“This is the first time we have been able to confidently say Gwion style paintings were created around 12,000 years ago,” said PhD student Damien Finch, from the School of Earth Sciences at the University of Melbourne. “No one has been able to present the scientific evidence to say that before.”
One wasp nest date suggested one Gwion painting was older than 16,000 years, but the pattern of the other 23 dates is consistent with the Gwion Gwion period being 12,000 years old.
The rock paintings, more than twice as old as the Giza Pyramids, depict graceful human figures with a wide range of decorations including headdresses, armbands, and anklets. Some of the paintings are as small as 15cm, others are more than two metres high.
The details of the breakthrough are detailed in the paper 12,000-year-old Aboriginal rock art from the Kimberley region, Western Australia, now published in Science Advances.
More than 100 mud wasp nests collected from Kimberley sites, with the permission of the Traditional Owners, were crucial in identifying the age of the unique rock art.
“A painting beneath a wasp nest must be older than the nest, and a painting on top of a nest must be younger than the nest,” Mr Finch said. “If you date enough of the nests, you build up a pattern and can narrow down an age range for paintings in a particular style.”
Lack of organic matter in the pigment used to create the art had previously ruled out radiocarbon dating. But the University of Melbourne and ANSTO scientists were able to use dates on 24 mud wasp nests under and over the art to determine both maximum and minimum age constraints for paintings in the Gwion style.
The project was initiated by Professor Andy Gleadow and Professor Janet Hergt, from the School of Earth Sciences, and started in 2014 with funding from the Australian Research Council and the Kimberley Foundation. It is the first time in 20 years scientists have been able to date a range of these ancient artworks.
“The Kimberley contains some of the world’s most visually spectacular and geographically extensive records of Indigenous rock art, estimated to include tens of thousands of sites, only a small fraction of which have been studied intensively,” said Professor Gleadow.
Professor Hergt said being able to estimate the age of Gwion art is important as it can now be placed into the context of what was happening in the environment and what we know from excavations about other human activities at the same time.
Dr Vladimir Levchenko, an ANSTO expert in radiocarbon dating and co-author, said rock art is always problematic for dating because the pigment used usually does not contain carbon, the surfaces are exposed to intense weathering and nothing is known about the techniques used thousands of years ago.
“Beeswax or resin have also been used — usually on more modern samples,” Dr Levchenko said.
“Although soil is full of carbon, most of it is easily degradable. However, charcoal is more likely to survive for longer periods. There is lots of black carbon in Australian soil because of bushfires.”
When a new baby dolphin is born, his family reunites around him to welcome him as one of them.
In a stunning new insight into the lives of wild dolphins, this film follows six remarkable months in the life of the ‘Beachies’: a family of six dolphins led by mother-to-be Puck, who live in the shark-infested waters of Western Australia‘s Shark Bay. Using the latest miniature cameras to eavesdrop on the Beachies’ underwater lives, this moving story follows Puck and the challenges she faces bringing up her newborn calf Samu. From learning to fish, to the ever-present threat of a shark attack, no day is ever the same. Including rarely seen footage of young dolphins and revelatory new behaviour, this is a heart-warming and emotional portrayal of one of the ocean’s most revered creatures.
Lead author Claire Ross said the study was carried out over two years in Western Australia’s Bremer Bay, 515km south-east of Perth in the Great Southern region. Bremer Bay is a renowned diving, snorkelling and tourism hot spot due to its stunning crystal clear waters, white sand and high marine biodiversity.
“For two years we used cutting-edge geochemical techniques to link the internal chemistry of the coral with how fast the corals were growing in a high-latitude reef”, Ms Ross said.
“These high-latitude reefs (above 28 degrees north and below 28 degrees south) have lower light and temperatures compared to the tropics and essentially provide natural laboratories for investigating the limits for coral growth.”
Ms Ross said the researchers expected the corals to grow slower during winter because the water was colder and light levels lower but they were surprised to find the opposite pattern.
“We were able to link the remarkable capacity for temperate corals to maintain high growth during winter to the regulation of their internal chemistry,” she said.
“We also found that there was more food in the water for corals during winter compared to summer, indicating that (in addition to internal chemical regulation) corals may feed more to sustain growth.”
Coral reefs are one of world’s most valuable natural resources, providing a habitat for many ocean species, shoreline protection from waves and storms, as well as being economically important for tourism and fisheries.
However, studies have shown that the important process by which corals build their skeletons is under threat due to CO2-driven climate change. The effects of climate change on coral reefs are likely to vary geographically, but relatively little is known about the growth rates of reefs outside of the tropics.
“Our study is unique because it is among the first to fully decipher the corals’ internal chemistry”, Ms Ross said. “The findings of this study help better understand and predict the future of high-latitude coral reefs under CO2-driven climate change.”
“However, the biggest surprise was photographic evidence of the black-footed tree rat.
“We were a bit unsure at first, we tried to explain it away and said ‘no, it can’t be, it can’t be, it’s got to be this or it’s got to be that’ but the images speak for themselves which was really exciting.
“It had not been seen in the Kimberley since 1987, despite considerable survey efforts during this period.”
3.5 billion year old fossils hint life evolved in pond, not sea
It’s the age-old question: where do we come from? New fossil evidence suggests the first spark of life may have occurred in a hot spring on land rather than a hydrothermal vent in the deep sea.
Charles Darwin proposed in 1871 that life originated in a “warm little pond”. But the dominant theory nowadays is that primitive microorganisms first assembled in hot, chemical-rich water at hydrothermal vents at the bottom of the ocean.
One reason for favouring this marine model is that fossil evidence of early land-based microbial life has been lacking. Until recently, the oldest evidence of life on land was only 2.8 billion years old, whereas the oldest evidence from the sea was 3.7 billion years old.
Now, a team led by Tara Djokic at the University of New South Wales in Australia has discovered fossils of land-based microorganisms. They were found in 3.5-billion-year-old rocks in an extinct volcano in the Dresser Formation in the hot, dry, remote Pilbara region of Western Australia.
The fossils include stromatolites – layered rock structures created by microorganisms – and circular holes left in the rock by gas bubbles that look like they were once trapped by sticky microbial substances. Both types of structures are preserved in geyserite, a type of rock that is only found in and around freshwater hot springs in volcanic areas on land.
Land-based launch pad?
The findings suggest that microbes were present on land and in the ocean around the same time, says Djokic. The question is – which came first?
“There are now a number of converging lines of evidence that point to terrestrial hot springs over hydrothermal vents for the origin of life,” says Djokic.
Small bodies of water like hot springs may have been more conducive to the formation of life because they can evaporate and concentrate the building blocks of life, says Djokic. “In hot springs, you’ve also got a nutritious concoction of elements because hot fluids circulate through the underlying rocks and bring up different minerals,” she says.
Recent research suggests that the element mix in ancient hot springs would have been more likely to give rise to life than that of deep sea vents.
Primitive microorganisms formed in the springs could have then spread to the sea, where they could have adapted and continued to evolve, Djokic says.
The findings are compelling, says Gregory Webb at the University of Queensland in Australia. “There are lots of microbes that live in terrestrial hot springs today, so it’s not a stretch to believe that an ancient hot spring could have accommodated life,” he says.
Then again, making assertions about life on early Earth is tricky, says Webb. “Microbial life isn’t easy to see, even today, so rocks that preserve evidence of ancient bacteria are hard to find and hard to study.” He is not ruling out the deep sea model of the origin of life.
Djokic and her colleagues believe the research could have implications for the search for ancient life on Mars. Earth and Mars both formed around 4.5 billion years ago and had volcanoes and hot springs dotted across their surfaces.
“If life can be preserved in hot springs so far back in Earth’s history, then there is a good chance it could be preserved in Martian hot springs too,” says Djokic.
One of the three potential landing sites for NASA’s Mars 2020 rover mission is Columbia Hills, a rocky formation that is thought to have once been a hot spring environment.
A paradigm-shifting hypothesis could reshape our idea about the origin of life
July 18, 2017
Summary: A new discovery pushes back the time for the emergence of microbial life on land by 580 million years and also bolsters a paradigm-shifting hypothesis that life began, not in the sea, but on land.
For three years, Tara Djokic, a Ph.D. student at the University of New South Wales Sydney, scoured the forbidding landscape of the Pilbara region of Western Australia looking for clues to how ancient microbes could have produced the abundant stromatolites that were discovered there in the 1970s.
Stromatolites are round, multilayered mineral structures that range from the size of golf balls to weather balloons and represent the oldest evidence that there were living organisms on Earth 3.5 billion years ago.
Scientists who believed life began in the ocean thought these mineral formations had formed in shallow, salty seawater, just like living stromatolites in the World Heritage-listed area of Shark Bay, which is a two-day drive from the Pilbara.
The discovery pushed back the time for the emergence of microbial life on land by 580 million years and also bolstered a paradigm-shifting hypothesis laid out by UC Santa Cruz astrobiologists David Deamer and Bruce Damer: that life began, not in the sea, but on land.
Djokic’s discovery — together with research carried out by the UC Santa Cruz team, Djokic, and Martin Van Kranendonk, director of the Australian Centre for Astrobiology — is described in an eight-page cover story in the August issue of Scientific American.
“What she (Djokic) showed was that the oldest fossil evidence for life was in fresh water,” said Deamer, a lanky 78-year-old who explored the region with Djokic, Damer, and Van Kranendonk in 2015. “It’s a logical continuation to life beginning in a freshwater environment.”
The model for life beginning on land rather than in the sea could not only reshape our idea about the origin of life and where else it might be, but even change the way we view ourselves.
The right conditions for life
For four decades, ever since the research vessel Alvin discovered deep-sea hydrothermal vents that were habitats for specialized bacteria and worms that looked like something out of a science-fiction novel, scientists have theorized that these mineral- and gas-pumping vents were just what was needed for life to begin.
But Deamer, who describes himself as a scientist who loves playing with new ideas, thought the theory had flaws. For instance, molecules essential for the origin of life would be dispersed too quickly into a vast ocean, he thought, and salty seawater would inhibit some of the processes he knew are necessary for life to begin.
Deamer had spent the early part of his career studying the biophysics of membranes composed of soap-like molecules that form the microscopic boundaries of all living cells. Later, given a piece of the Murchison meteorite that had landed in Australia in 1969, Deamer found that the space rock also contained soap-like molecules nearly 5 billion years old that could form stable membranes. Still later, he demonstrated that membranes helped small molecules join together to form longer information-carrying molecules called polymers.
Trekking to volcanoes from Russia to Iceland and hiking through the Pilbara desert, Deamer and his colleagues observed volcanic activity that suggested the idea that hot springs provided the right environment for the beginning of life. Deamer even built a machine that simulated the heat, acidity, and wet-and-dry cycles of hot springs and installed it in his lab on the UC Santa Cruz campus.
“I think, every once in awhile, you have to be brave enough and bold enough to try new ideas,” Deamer said. “Of course, some of my colleagues think even ‘foolish enough.’ But that’s the chance you take.”
Rethinking the timeline
In Deamer’s vision, ancient Earth consisted of a huge ocean spotted with volcanic land masses. Rain would fall on the land, creating pools of fresh water that would be heated by geothermal energy and then cooled by runoff. Some of the key building blocks of life, created during the formation of our solar system, would have fallen to Earth and gathered in these pools, becoming concentrated enough to form more complex organic compounds.
The edges of the pools would go through periods of wetting and drying as water levels rose and fell. During these periods of wet and dry, lipid membranes would first help stitch together the organic compounds called polymers and then form compartments that encapsulated different sets of these polymers. The membranes would act like incubators for the functions of life.
Deamer and his team believe the first life emerged from the natural production of vast numbers of such membrane-encased “protocells.”
While there is still debate about whether life began on land or in the sea, the discovery of ancient microbial fossils in a place like the Pilbara shows that these geothermal areas — full of energy and rich in the minerals necessary for life — harbored living microorganisms far earlier than believed.
The search for life on other planets
According to Deamer and his colleagues, this discovery and their hot-springs-origins model also have implications for the search for life on other planets. If life began on land, then Mars, which was found to have a 3.65-billion-year-old hot spring deposits similar to those found in the Pilbara region of Australia, might be a good place to look.
For Damer, the new “end-to-end hypothesis” of how life began on land offers something else: that the origin of life was not just a simple story of individual, competing cells. Rather that a plausible new vision of life’s start could be a communal unit of protocells that survived and evolved through collaboration and sharing of innovation rather than strict competition.
“That,” he said, “is a fundamental shift that might impact how we think of our world, ourselves, and our future: as dependent on collaboration as much as being driven by competition.”
Sitting in his fourth-floor office on campus, Deamer smiled as he recounted the letter Charles Darwin wrote to a friend in 1871, which speculated that life might have begun in “some warm little pond.”
That’s not far off the mark, Deamer said, “except we call ours ‘hot little puddles.'”
Conventional scientific wisdom has it that plants and other creatures have only lived on land for about 500 million years, but a new study is pointing to evidence for life on land that is four times as old — at 2.2 billion years ago and almost half way back to the inception of the planet: here.
The earliest example of an organism living on land — an early type of fungus — has been identified. The organism, from 440 million years ago, likely kick-started the process of rot and soil formation, which encouraged the later growth and diversification of life on land: here.
A team of Tasmanian researchers has uncovered rare, living stromatolites deep within the Tasmanian Wilderness World Heritage Area: here.
Western Australia’s famous 3.5-billion-year-old stromatolites contain microbial remains of some of the earliest life on Earth, scientists have found: here.
Earth could have supported continental crust, life earlier than thought. Scientists studying ancient rocks say crust could have formed when Earth was just 350 million years old: here.
All living things use the genetic code to “translate” DNA-based genetic information into proteins, which are the main working molecules in cells. Precisely how the complex process of translation arose in the earliest stages of life on Earth more than four billion years ago has long been mysterious, but two theoretical biologists have now made a significant advance in resolving this mystery: here.
An unprecedented 21 different types of dinosaur tracks have been identified on a 25-kilometre stretch of the Dampier Peninsula coastline dubbed “Australia’s Jurassic Park.”
A team of palaeontologists from The University of Queensland’s School of Biological Sciences and James Cook University‘s School of Earth and Environmental Sciences braved sharks, crocodiles, massive tides and the threat of development to unveil the most diverse assemblage of dinosaur tracks in the world in 127 to 140 million-year-old rocks in the remote Kimberley region of Western Australia.
Lead author Dr Steve Salisbury said the diversity of the tracks around Walmadany (James Price Point) was globally unparalleled and made the area the “Cretaceous equivalent of the Serengeti.”
“It is extremely significant, forming the primary record of non-avian dinosaurs in the western half the continent and providing the only glimpse of Australia’s dinosaur fauna during the first half of the Early Cretaceous Period,” Dr Salisbury said.
“It’s such a magical place — Australia’s own Jurassic Park, in a spectacular wilderness setting.”
In 2008, the Western Australian Government selected Walmadany as the preferred site for a $40 billion liquid natural gas processing precinct.
The area’s Traditional Custodians, the Goolarabooloo people, contacted Dr Salisbury and his team, who dedicated more than 400 hours to investigating and documenting the dinosaur tracks.
“We needed the world to see what was at stake,” Goolarabooloo Law Boss Phillip Roe said.
The dinosaur tracks form part of a song cycle that extends along the coast and then inland for 450 km, tracing the journey of a Dreamtime creator being called Marala, the Emu man.
“Marala was the Lawgiver. He gave country the rules we need to follow. How to behave, to keep things in balance,” Mr Roe said said.
“It’s great to work with UQ researchers. We learnt a lot from them and they learnt a lot from us.”
Dr Salisbury said the surrounding political issues made the project “particularly intense,” and he was relieved when National Heritage listing was granted to the area in 2011 and the gas project collapsed in 2013.
“There are thousands of tracks around Walmadany. Of these, 150 can confidently be assigned to 21 specific track types, representing four main groups of dinosaurs, ” Dr Salisbury said.