Herbivores, displaced by ocean warming, threaten subtropical seagrass meadows

Tropical herbivores are on the move, and that could spell trouble for subtropical seagrass meadows.

As the ocean warms, marine species often travel poleward in search of suitable habitats and food.

This phenomenon, known as tropicalization, can expand the range of tropical herbivores such as sea turtles and manatees -- which prefer warmer waters -- to subtropical regions that have historically supported few marine herbivores.

A new study published in Nature Ecology & Evolution describes how subtropical seagrasses are at risk as tropical herbivores move in response to warming oceans.

"Ocean warming poses multiple threats to marine ecosystems," said Tom Frazer, co-author of the study, and professor and dean of the University of South Florida College of Marine Science.

"Seagrass meadows, which provide forage for herbivores and nursery habitat for many recreational and commercially important fishery species, are already threatened by degraded water quality. This study suggests that the tropicalization of marine ecosystems in response to warming temperatures could further contribute to the decline of these vital habitats."

The study's authors used turtlegrass, a foundational seagrass species found throughout the Western Atlantic, Caribbean Sea and Gulf of Mexico, as a model for seagrass meadows.

Researchers conducted a series of coordinated experiments in seagrass beds spanning 23 degrees of latitude (including sites in Bonaire, Panama, Belize, Mexico, the Cayman Islands, and the United States) and found that turtlegrass populations at higher latitudes had lower productivity in response to simulated grazing than populations at lower latitudes.

The findings suggest that subtropical seagrasses are less resilient to heavy grazing from marine herbivores, in part because they receive less sunlight relative to their tropical counterparts.

As tropical herbivores move into subtropical waters, overgrazing may prevent subtropical seagrass meadows from persisting in these environments.

There's hope, though, for subtropical seagrasses and the many species they sustain.

What's key, according to the study's authors, is making sure seagrasses have what they need to thrive.

"If we want to give these meadows the best chance of enduring the anticipated increases in grazing, we need to get them as much light as possible," said Justin Campbell, lead author and marine biologist at Florida International University.

"That means protecting the water quality."

While overgrazing is not yet a widespread occurrence across the Western Atlantic, it already occurs in subtropical to temperate waters around Australia and in the Mediterranean.

This recent study can serve as a clarion call to protect subtropical seagrass meadows before grazing pressure from tropical herbivores increases.

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To restore ecosystems, think about thwarting hungry herbivores

Re-establishing plantings of trees, grasses and other vegetation is essential for restoring degraded ecosystems, but a new survey of almost 2,600 restoration projects from nearly every type of ecosystem on Earth finds that most projects fail to recognize and control one of the new plants' chief threats: hungry critters that eat plants.

"While most of the projects took steps to exclude competing plant species, only 10% took steps to control or temporarily exclude herbivores, despite the fact that in the early stages these plants are like lollipops -- irresistible little treats for grazers," said Brian Silliman, Rachel Carson Distinguished Professor of Marine Conservation Biology at Duke University's Nicholas School of the Environment.

By not protecting plants in their early states, conservationists are missing out on great opportunity to significantly speed restoration, improve its outcomes, and lower its costs, he said.

"Our analysis of the surveyed projects shows that introducing predators to keep herbivore populations in check or installing barriers to keep them at bay until plantings become more established and less vulnerable, can increase plant re-growth by 89% on average," said Silliman, who helped conceptualize the study and was one of its coauthors.

Those gains are equal to or greater than the gains realized by excluding competing plant species, the new survey shows.

"This begs the question: Why aren't we doing it more?" he asks.

The new survey was conducted with input from an international team of researchers affiliated with 20 universities and institutions. They published their peer-reviewed findings Nov. 3 in Science.

Qiang He, professor of coastal ecology at Fudan University and a former postdoctoral research associate of Silliman's at Duke, co-led the study with Changlin Xu, a member of He's Coastal Ecology Lab at Fudan.

The survey's findings have far-reaching implications for efforts to restore vegetation at a time of climate change, He said.

"Herbivores' effects were particularly pronounced in regions with higher temperatures and lower precipitation," He noted.

All of which leads to one inescapable conclusion, Silliman said.

"If we want more plants, we have to let more predators in or restore their populations," Silliman said. "Indeed, the decline of large predators, like wolves, lions, and sharks, that normally keep herbivore populations in check, is likely an important indirect cause of high grazing pressures."

"Conventional restoration is slowing our losses, but it's not expanding vegetation in many places, and climate change could make that even more difficult," he said.

Using predators to keep herbivores in check at restored sites is a relatively untapped approach that could help us boost plant diversity and restore ecosystems that are vital to human and environmental health, in less time and at lower costs," Silliman said. "It's like learning a new gardening trick that doubles your yield."

Once a planting is established, the herbivores are essential too, he added. "Plants just need a small break from being eaten to get restarted making ecosystems. Once they establish, herbivores are key to maintaining plant ecosystem diversity and function."

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Climate change played key role in dinosaur success story

Climate change, rather than competition, played a key role in the ascendancy of dinosaurs through the Late Triassic and Early Jurassic periods.

According to new research, changes in global climate associated with the Triassic-Jurassic mass extinction -- which wiped out many large terrestrial vertebrates such as the giant armadillo-like aetosaurs -- actually benefitted the earliest dinosaurs.

In particular, sauropod-like dinosaurs, which became the giant herbivore species of the later Jurassic like Diplodocus and Brachiosaurus, were able to thrive and expand across new territories as the planet warmed up after the extinction event, 201 million years ago.

The new evidence is published in Current Biology, by an international team of palaeontologists led by the Universities of Birmingham and Bristol, in the UK, Friedrich-Alexander University Erlangen-Nu?rnberg (FAU), in Germany, and the University of São Paulo in Brazil.

The team compared computer models of prehistoric global climate conditions such as temperature and rainfall with data on the different locations of dinosaurs taken from sources such as the Paleobiology Database. They showed how the sauropods, and sauropod-like animals, with their long tails and necks and small heads, were the runaway success story of a turbulent period of evolution.

Dr Emma Dunne, now a lecturer in palaeontology at FAU, carried out the research while at the University of Birmingham. She said: "What we see in the data suggests that instead of dinosaurs being outcompeted by other large vertebrates, it was variations in climate conditions that were restricting their diversity. But once these conditions changed across the Triassic-Jurassic boundary, they were able to flourish.

"The results were somewhat surprising, because it turns out that sauropods were really fussy from the get-go: later in their evolution they continue to stay in warmer areas and avoid polar regions."

Co-author on the paper, Professor Richard Butler, at the University of Birmingham, said: "Climate change appears to have been really important in driving the evolution of early dinosaurs. What we want to do next is use the same techniques to understand the role of climate in the next 120 million years of the dinosaur story."

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Unprecedented levels of insects damaging plants

Insects today are causing unprecedented levels of damage to plants, even as insect numbers decline, according to new research led by University of Wyoming scientists.

The first-of-its-kind study compares insect herbivore damage of modern-era plants with that of fossilized leaves from as far back as the Late Cretaceous period, nearly 67 million years ago. The findings appear in the  journal Proceedings of the National Academy of Sciences.

"Our work bridges the gap between those who use fossils to study plant-insect interactions over deep time and those who study such interactions in a modern context with fresh leaf material," says the lead researcher, UW Ph.D. graduate Lauren Azevedo-Schmidt, now a postdoctoral research associate at the University of Maine. "The difference in insect damage between the modern era and the fossilized record is striking."

Azevedo-Schmidt conducted the research along with UW Department of Botany and Department of Geology and Geophysics Professor Ellen Currano, and Assistant Professor Emily Meineke of the University of California-Davis.

The study examined fossilized leaves with insect feeding damage from the Late Cretaceous through the Pleistocene era, a little over 2 million years ago, and compared them with leaves collected by Azevedo-Schmidt from three modern forests. The detailed research looked at different types of damage caused by insects, finding marked increases in all recent damage compared to the fossil record.

"Our results demonstrate that plants in the modern era are experiencing unprecedented levels of insect damage, despite widespread insect declines," wrote the scientists, who suggest that the disparity can be explained by human activity.

More research is necessary to determine the precise causes of increased insect damage to plants, but the scientists say a warming climate, urbanization and introduction of invasive species likely have had a major impact.

"We hypothesize that humans have influenced (insect) damage frequencies and diversities within modern forests, with the most human impact occurring after the Industrial Revolution," the researchers wrote. "Consistent with this hypothesis, herbarium specimens from the early 2000s were 23 percent more likely to have insect damage than specimens collected in the early 1900s, a pattern that has been linked to climate warming."

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Dinosaur extinction changed plant evolution

With the extinction of large, non-flying dinosaurs 66 million years ago, large herbivores were missing on Earth for the subsequent 25 million years. Since plants and herbivorous animals influence each other, the question arises whether, and how this very long absence and the later return of the so-called "megaherbivores" affected the evolution of the plant world.

To answer this question, a research team led by iDiv and Leipzig University analysed fossil and living palms today. Genetic analyses enabled the researchers to trace the evolutionary developments of plants during and after the absence of megaherbivores. Thus, they first confirmed the common scientific assumption that many palm species at the time of the dinosaurs bore large fruits and were covered with spines and thorns on their trunks and leaves.

However, the research team found that the "evolutionary speed" with which new palm species with small fruits arose during the megaherbivore gap decreased, whereas the evolutionary speed of those with large fruits remained almost constant. The size of the fruits themselves, however, also increased. So, there were palms with large fruits even after the extinction of the dinosaurs. Apparently, much smaller animals could also eat large fruits and spread the seeds with their excretions. "We were thus able to refute the previous scientific assumption that the presence of large palm fruits depended exclusively on megaherbivores," says the study's first author Dr Renske Onstein from iDiv and Leipzig University. "We therefore assume that the lack of influence of large herbivores led to denser vegetations in which plants with larger seeds and fruits had an evolutionary advantage."

However, the defence traits of the plants; spines and thorns on leaves and stems, showed a different picture: the number of palm species with defence traits decreased during the megaherbivore gap. "Defence traits without predators apparently no longer offered evolutionary advantages," says Onstein, who heads the junior research group Evolution and Adaptation at iDiv. "However, they returned in most palm species when new megaherbivores evolved, in contrast to the changes in fruits, which persisted."

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Large new titanosaurian dinosaur from the Pyrenees

Researchers from the Institut Català de Paleontologia Miquel Crusafont (ICP), the Conca Dellà Museum (MCD), the Universitat Autònoma de Barcelona (UAB), the University of Zaragoza (UNIZAR) and the NOVA University of Lisbon (UNL) have described the new species of titanosaur dinosaur Abditosaurus kuehnei from the remains excavated at the Orcau-1 site, in the southern Pyrenees (Catalonia, Spain). The semiarticulated 70.5-million-year-old skeleton is the most complete specimen of this herbivorous group of dinosaurs discovered so far in Europe. Moreover, Abditosaurus is the largest titanosaur species found in the Ibero-Armorican island -- an ancient region nowadays comprising Iberia and the south of France -- representing a senescent individual estimated to be 17,5 meters in length with body mass of 14,000 kg.

The size of this giant is one of the most surprising facts to researchers. "Titanosaurs from the Upper Cretaceous of Europe tend to be small or medium-sized due to their evolution in insular conditions," explained Bernat Vila, paleontologist at the ICP leading the research. During the Upper Cretaceous (between 83 and 66 million years ago), Europe was a large archipelago made up of dozens of islands. The species that evolved there tend to be relatively small, or even dwarves compared to their relatives living in large landmasses, due primarily to the limitation of food resources in islands. "It is a recurring phenomenon in the history of life on Earth, we have several examples worldwide in the fossil record of this evolutionary trend. That's why we were astonished by the large dimensions of this specimen," said Vila.

The fieldwork conducted over several decades unearthed 53 skeletal elements of the specimen. These include several teeth, vertebrae, ribs, and limb, scapular and pelvic bones, as well as a semiarticulated fragment of the neck formed by 12 cervical vertebrae. "We were really lucky, it is unusual to find such complete specimens in the Pyrenees due to its troubled geologic history," explains Àngel Galobart, ICP researcher and director of the Conca Dellà Museum (Isona, Catalonia).

The excavation of the neck in 2014 was a technical challenge. Once prepared for extraction, the neck was encased in a large block of polyurethane foam, becoming one of the largest jackets ever excavated in Europe.

The history of the research that has led to the description of the new species dates back to 1954, when German paleontologist Walter Kühne collected the first remains and sent them to Madrid. The site fell into oblivion until 1986, when some more remains began to be extracted until a great storm forced the cancellation of the excavation. Subsequently, fieldwork on the site fell again into oblivion until a paleontologist from the ICP resumed systematic excavations in Orcau-1. The story of this finding was featured in the 2017 documentary "Europe's last giant." The generic name Abditosaurus means 'forgotten reptile' and the specific epithet kuehnei is a tribute to its discoverer.

A migrating dinosaur

In their article published in Nature Ecology & Evolution, researchers conclude that Abditosaurus belongs to a group of saltasaurine titanosaurs from South America and Africa, different from the rest of European titanosaurs that are characterized by a smaller size. These authors hypothesize that the Abditosaurus lineage reached the Ibero-Armorican island taking advantage of a global drop in sea level that reactivated ancient migration routes between Africa and Europe.

"Other evidence support the migration hypothesis," explains Albert Sellés, paleontologist at the ICP and co-author of the article. "In the same site we have found eggshells of dinosaur species known to have inhabited Gondwana, the southernmost continent."

The new finding is a major advance in the understanding of the evolution of sauropod dinosaurs at the end of the Cretaceous and brings a new perspective to the phylogenetic and paleobiogeographic puzzle of sauropods in the last 15 million years before their extinction.

In addition to Vila, Sellés and Galobart, Novella Razzolini (Institut Català de Paleontologia Miquel Crusafont and Conca Dellà Museum), Miguel Moreno (Museu de Lurinhã and NOVA University of Lisbon), Iñaki Canudo (Aragosaurus-IUCA Group, University of Zaragoza) and Alejandro Gil (Universitat Autònoma de Barcelona) participated in this study.

"During the Jurassic and Cretaceous, Iberia was the point of connection between Eurasia, Africa and North America. Studying how Abditosaurus relates to the fauna of these continents helps us to understand when there were connections between them, and when they became isolated," says Miguel Moreno, researcher at the Museu de Lurinhã and NOVA University of Lisbon that has performed the paleobiogeographic study.

The large Cretaceous herbivores

Titanosaurs are a group of sauropod dinosaurs that become very diverse and abundant in the terrestrial ecosystems of the Cretaceous. All of them were quadrupeds and phytophagous. Titanosaurs had a small and pointed skull, with small nail-shaped teeth used to uproot vegetation. Their body was robust, with forelimbs shorter than the hindlimbs and a long necks and tails. Some species sported a skin covered with bony plates named osteoderms that may have served as a protective shield or as a reserve of calcium.

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'Cold bone': Researchers discover first dinosaur species that lived on Greenland 214 million years ago

The two-legged dinosaur Issi saaneq lived about 214 million years ago in what is now Greenland. It was a medium-sized, long-necked herbivore and a predecessor of the sauropods, the largest land animals ever to live. It was discovered by an international team of researchers from Portugal, Denmark and Germany, including the Martin Luther University Halle-Wittenberg (MLU). The name of the new dinosaur pays tribute to Greenland's Inuit language and means "cold bone." The team reports on its discovery in the journal Diversity.

The initial remains of the dinosaur -- two well-preserved skulls -- were first unearthed in 1994 during an excavation in East Greenland by palaeontologists from Harvard University. One of the specimens was originally thought to be from a Plateosaurus, a well-known long-necked dinosaur that lived in Germany, France and Switzerland during the Triassic Period. Only a few finds from East Greenland have been prepared and thoroughly documented. "It is exciting to discover a close relative of the well-known Plateosaurus, hundreds of which have already been found here in Germany," says co-author Dr Oliver Wings from MLU.

The team performed a micro-CT scan of the bones, which enabled them to create digital 3D models of the internal structures and the bones still covered by sediment. "The anatomy of the two skulls is unique in many respects, for example in the shape and proportions of the bones. These specimens certainly belong to a new species," says lead author Victor Beccari, who carried out the analyses at NOVA University Lisbon.

The plant-eating dinosaur Issi saaneq lived around 214 million years ago during the Late Triassic Period. It was at this time that the supercontinent Pangaea broke apart and the Atlantic Ocean began forming. "At the time, the Earth was experiencing climate changes that enabled the first plant-eating dinosaurs to reach Europe and beyond," explains Professor Lars Clemmensen from the University of Copenhagen.

The two skulls of the new species come from a juvenile and an almost adult individual. Apart from the size, the differences in bone structure are minor and only relate to proportions. The new Greenlandic dinosaur differs from all other sauropodomorphs discovered so far, however it does have similarities with dinosaurs found in Brazil, such as the Macrocollum and Unaysaurus, which are almost 15 million years older. Together with the Plateosaurus from Germany, they form the group of plateosaurids: relatively graceful bipeds that reached lengths of 3 to 10 metres.

The new findings are the first evidence of a distinct Greenlandic dinosaur species, which not only adds to the diverse range of dinosaurs from the Late Triassic (235-201 million years ago) but also allows us to better understand the evolutionary pathways and timeline of the iconic group of sauropods that inhabited the Earth for nearly 150 million years.

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Ecosystems worldwide are disrupted by lack of large wild herbivores – except in Africa

Biological research has repeatedly demonstrated that the relationship between the producer and the consumer is governed by a scaling law. An international research team has now looked into whether this law of nature can be reproduced in the relationship between the production of plants in an area and the number of large herbivores that graze on them. The study reveals that Africa is the only continent where the scaling law holds true.

June 2021 saw the start of the United Nations Decade on Ecosystem Restoration. A total of 115 countries have committed themselves to restoring up to a billion hectares of nature worldwide.

According to a group of researchers from Aarhus University and the University of Sussex, one of biggest challenges will be restoring the historical and prehistoric grazing of large mammals. What level of restoration should we aim for? How many large herbivores will we need? And how are we going to co-exist with these large animals?

A baseline in Africa

The researchers examined the current low densities of large herbivores in a scientific article in the Journal of Applied Ecology. In the article, they calculated a baseline for large animals based on the ratio between producer and consumer, i.e. plants and herbivores, in nature reserves in Africa.

They stress that this relationship between producers and consumers applies across ecosystems and biomes implying a close correlation between the biomass produced and the biomass of dependent consumers.

However, after investigating the density of large herbivores in nature reserves throughout the world, the researchers were only able to find such a close correlation on one continent: Africa. On the other continents, they found strong indications of impoverished fauna, even in protected natural areas.

"African ecosystems have species-rich mammal fauna and a large biomass of big herbivores that are significantly linked to plant productivity," says Camilla Fløjgaard from the Department of Ecoscience at Aarhus University and head of the research group.

"But we can't find this pattern on other continents, and in general the large herbivore biomass is much lower than we would expect considering the level of productivity," she adds.

Far fewer animals in European nature

The survey includes data from protected areas, reserves and several rewilding projects in Europe. The researchers found significant differences, as the biomass for large herbivores in natural areas was less than one-tenth of the biomass observed in fenced rewilding areas with restored herbivore fauna.

"It's thought-provoking that, even in many protected areas, the number of large herbivores is only a fraction of what the areas can actually sustain," says Camilla Fløjgaard.

Another and lower baseline

In the article, the researchers argue that large herbivores are still being displaced, hunted and eradicated, and that there is a widespread perception, even among game managers, that there are plenty of herbivores in the wild, perhaps even too many. This perception is not supported by the new study.

On the contrary, efforts to decrease populations of large herbivores can reflect a shifting baseline.

"Even though large herbivores have been wandering the landscape for millions of years, it seems that we have become accustomed to landscapes almost completely devoid of them, and we have come to accept this as the natural state of things," says Camilla Fløjgaard.

Large animals are 'troublesome'

In the EU alone, there is a plan is to allocate 30% of marine and land areas to the restoration of natural areas and ecosystems.

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‘Raptor-like’ dinosaur discovered in Australian mine, actually uncovered as a timid vegetarian

Fossil footprints found in an Australian coal mine around 50 years ago have long been thought to be that of a large 'raptor-like' predatory dinosaur, but scientists have in fact discovered they were instead left by a timid long-necked herbivore.

University of Queensland palaeontologist Dr Anthony Romilio recently led an international team to re-analyse the footprints, dated to the latter part of the Triassic Period, around 220 million-year-ago.

"For years it's been believed that these tracks were made by a massive theropod predator that was part of the dinosaur family Eubrontes, with legs over two metres tall," Dr Romilio said.

"This idea caused a sensation decades ago because no other meat-eating dinosaur in the world approached that size during the Triassic period."

However, findings made by a team of international researchers, published today in the peer-reviewed journal Historical Biology, in fact shows the tracks were instead made by a dinosaur known as a Prosauropod - a vegetarian dinosaur that were smaller, with legs about 1.4 metres tall and a body length of six metres.

The research team suspected there was something not-quite-right with the original size estimates and there was a good reason for their doubts.

"Unfortunately, most earlier researchers could not directly access the footprint specimen for their study, instead relying on old drawings and photographs that lacked detail," Dr Romilio said.

The dinosaur fossils were discovered more than half a century ago around 200 metres deep underground at an Ipswich coal mine, just west of Brisbane.

"It must have been quite a sight for the first miners in the 1960s to see big bird-like footprints jutting down from the ceiling," Dr Romilio said.

Hendrik Klein, co-author and fossil expert from Saurierwelt Paläontologisches Museum in Germany, said the footprints -- referred to as 'Evazoum', scientifically, the footprint type made by prosauropod dinosaurs -- were made on the water-sodden layers of ancient plant debris with the tracks later in-filled by silt and sand.

"This explains why today they occur in an upside-down position right above our heads," Mr Klein said.

"After millions of years, the plant material turned into coal which was extracted by the miners to reveal a ceiling of siltstone and sandstone, complete with the natural casts of dinosaur footprints."

The mine has long since closed, but fortunately, in 1964, geologists and the Queensland Museum mapped the trackway and made plaster casts, now used in current research.

"We made a virtual 3D model of the dinosaur footprint that was emailed to team members across the world to study," Mr Klein said.

"The more we looked at the footprint and toe impression shapes and proportions, the less they resembled tracks made by predatory dinosaurs -- this monster dinosaur was definitely a much friendlier plant-eater.

"This is still a significant discovery even if it isn't a scary Triassic carnivore.

"This is the earliest evidence we have for this type of dinosaur in Australia, marking a 50-million-year gap before the first quadrupedal sauropod fossils known."

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