Lithophaga punctata

Many <a href="https://www.earth.com/news/dinosaurs-self-regulated-their-body-temperature/">dinosaurs</a> replaced their teeth as they fell out - a trait that is shared with modern crocodilians and sharks. Tooth replacement is useful for predatory animals whose teeth are used to hold struggling prey animals and are often broken off.&nbsp;



Now, new research shows that spinosaurids (a group that includes spinosaurus) replaced their teeth even faster than many other dinosaurs. This helps explain why so many spinosaurid teeth have been found littering dinosaur digs.&nbsp;&nbsp;&nbsp;



A team of scientists led by the <a href="https://www.ehu.eus/en">University of the Basque Country</a> assessed a partial spinosaurid jaw from the Late Cretaceous found in La Rioja, Spain. The jaw contained eight alveoli or tooth sockets and tooth remains. Indeed, the researchers found up to three teeth in a single alveolus.&nbsp;



“We recognized up to three generations of teeth in the same alveolus: the functional tooth of the animal, another tooth being formed and which would replace the first, and the germ of the one that would end up replacing the second,” explained Pablo Navarro, co-author of the research published in the journal <a href="https://www.tandfonline.com/doi/full/10.1080/08912963.2022.2069019">Historical Biology</a>.



“This suggests very rapid tooth replacement and is probably one of the reasons why so many spinosaurid teeth can be&nbsp; found on the Iberian Peninsula during the Lower Cretaceous."



Previous research showed that some species of spinosaurids were able to quickly replace their conical teeth, with an estimated time of 60 to 68 days. This research not only verifies the trait for the entire group, but also explains the mechanism of how this regeneration is possible.&nbsp;&nbsp;&nbsp;



“Throughout their lives these animals grew new teeth that gradually replaced the original ones and caused them to fall out. This means that the same animal could generate multiple teeth,” said Navarro.



“These teeth, more or less conical in shape and a centimetre in size, were transported by rivers, accumulated in lake areas and, over time, became fossilised,” said the researcher. They are one of the most common vertebrate remains in Iberian sites of the Lower Cretaceous (between 145 and 113 million years ago)”.



Although scientists aren’t entirely sure why spinosaurid teeth were replaced so quickly, it’s likely this ability gave them an edge over other predators.&nbsp;



The study is published in the journal <a href="https://dx.doi.org/10.1080/08912963.2022.2069019">Historical Biology&nbsp;</a>



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By <a href="mailto:nire518@gmail.com">Erin Moody </a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Spinosaurids rapidly replaced their teeth

Many dinosaurs replaced their teeth as they fell out -...

A new study from <a href="https://www.ncsu.edu/">North Carolina State University</a> explores the connection between hearing loss and dementia in geriatric <a href="https://www.earth.com/news/playfulness-is-a-key-personality-trait-of-gifted-dogs/">dogs</a>. These findings could support treatment of aging dogs and advance our understanding of the relationship between sensory loss and cognitive function.



“In humans, we know that age-related hearing loss is estimated to affect one-third of people over age 65,” said study co-author Natasha Olby.&nbsp;



“We also know that the rate of cognitive decline is approximately 30-40% faster in people with age-related hearing loss and that hearing loss is a greater contributor to dementia risk than other factors such as hypertension or obesity. But we don’t understand whether the same holds true for dogs.”



The researchers evaluated 39 senior or geriatric dogs. Auditory and cognitive tests were performed and owners were asked to fill out questionnaires focused on cognitive ability and quality of life. Cognitive testing, questionnaire scores and age were compared between hearing groups.



The “average” dog can hear tones at 50 decibels (dBs) with no difficulty. Of the study cohort, 19 of the dogs could hear at 50 dBs, 12 at 70 dBs, and eight at 90 dBs (roughly equivalent to the noise made by a jet plane at takeoff).&nbsp;



When the hearing results were compared with quality of life questionnaire responses, scores related to vitality and companionship declined significantly as hearing deteriorated. The results from cognitive testing were similar - as hearing declined, so did the dog’s ability to perform tasks.



“Hearing loss is one of the biggest predictors of dementia in people,” said Olby. “Hearing loss also contributes to falls in elderly people, as sensory decline contributes to a loss in motor skills. So the connection between physical and neurological decline is clear for humans.”



These findings suggest that the same connection happens with aging dogs. Understanding these changes in elderly dogs enhances the ability to identify and treat these issues in pets, but also improves the understanding of the same issues among humans.



The study appears in the <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/jvim.16510">Journal of Veterinary Internal Medicine</a>.&nbsp;



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By <a href="mailto:katherinebucko@gmail.com">Katherine Bucko</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Hearing loss linked to dementia in aging dogs

A new study from North Carolina State University explores the...

Oak savannas are grassy and shrubby areas, featuring oaks as the dominant <a href="https://www.earth.com/news/heat-makes-pine-trees-more-susceptible-to-disease/">tree</a> species. Since oaks require a dry environment, in North America these savannas are frequently found in the rain shadow of the West Coast’s mountain range. Oaks host a vast diversity of insect species, such as oak gall wasps, which form striking growths known as galls. However, the expansion of this invasive wasp species has usually been kept in check by a wide range of parasitoid wasps, which lay their eggs inside the galls, and, after hatching, their larvae feed upon the oak gall wasp larvae.&nbsp;



According to a new study led by <a href="https://www.binghamton.edu/">Binghamton University</a> in New York, climate change has led to warming temperatures in the Pacific Northwest, leading some insect species – including the oak gall wasps - to expand their range into more northerly oak savannas, where they encounter less competition and they can proliferate. “In the native range, you might find a handful of galls on a single leaf. In the expanded range, sometimes you’re finding thousands on a single tree,” said study senior author Kirsten Prior, an assistant professor of Biological Sciences at Binghamton. “This is pretty prevalent throughout Vancouver Island.”



Biodiversity tends to work on a latitudinal gradient: while there is a vast multitude of species closer to the equator, their numbers gradually decrease at higher latitudes. Thus, when species expand their range northwards due to warming temperatures, they often move into areas without a diversity of predators and competitors, eventually overwhelming the ecosystems they encounter.



“When species undergo poleward range expansions in response to anthropogenic change, they likely encounter less diverse communities in new locations. If low diversity communities provide weak biotic interactions, such as reduced competition or predation, range-expanding species may experience high niche opportunities,” the study authors explained.



This seems to happen currently with oak gall wasps, which exhibit unusual population growths at higher latitudes, where they need to face less competition – a phenomenon highlighting the importance of biodiversity for keeping invasive species in check, as well as the potential long-term ramifications of climate change.



“Biodiversity can be really important in potentially protecting areas from invading species. If we have strong competitors and predators, this might make areas less susceptible to invading species,” concluded study lead author Dylan Jones, a doctoral student in Biology at Binghamton.



The study is published in the <a href="http://dx.doi.org/10.1111/1365-2656.13780">Journal of Animal Ecology</a>.&nbsp;



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer&nbsp;&nbsp;

Invasive wasps are expanding northward on the West Coast

Oak savannas are grassy and shrubby areas, featuring oaks as...

A new study led by <a href="https://www.cornell.edu/">Cornell University</a> has examined how the geographical characteristics of the world’s islands influence the seasonal variation in the number of <a href="https://www.earth.com/news/new-report-confirms-that-bird-species-are-steadily-declining/">bird species</a>. The experts have shown that the seasonal species richness of birds is affected by the size of an island, how isolated it is from the mainland, and the latitude at which it is located.&nbsp;



“We used 21 years of bird observations on 690 islands from the Cornell Lab of Ornithology’s eBird program,” said study lead author Frank La Sorte, an expert in Avian Ecology and Behavior. “In addition to resident bird species that occur year-round on islands, islands can also host migratory bird species during the breeding or non-breeding seasons, or as transients during migration.”



The analysis revealed that species numbers peaked on islands located in the Northern Hemisphere at mid-latitudes during migration seasons. However, during non-breeding periods, the number of bird species increased on tropical islands, reflecting the fact that the majority of bird species breed in the Northern Hemisphere and migrate towards the tropics to spend their autumns and winters.



Moreover, the researchers found an unmistakable correlation between the size of an island and the number of species present there: the bigger the island, the more bird species. By contrast, islands that are more distant from the mainland usually host a smaller number of species.&nbsp;&nbsp;



“These findings emphasize the importance of evolutionary processes on the largest islands and the unique ecology of the world’s most remote islands,” Dr. La Sorte explained. “Overall, species richness was lowest across all four seasons on the smallest, most remote islands and species richness was highest across all four seasons on the largest islands located at intermediate distances from the mainland.”



However, the scientists stress that there are significant variations in these relationships. For instance, even though large islands usually contain more species of birds, if these islands are very remote, they host fewer species, much like the extremely remote small islands.



“Our findings show that islands play a pivotal role as stopover sites and as wintering grounds for the world’s migratory birds. A better understanding of the geographical relationships between migratory birds and islands across seasons will improve our ability to practice effective bird conservation in these unique places,” Dr. La Sorte concluded.



The study is published in the journal <a href="http://dx.doi.org/10.1098/rspb.2022.1105">Proceedings of the Royal Society B Biological Sciences</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer&nbsp;&nbsp;

What types of islands attract migratory birds?

A new study led by Cornell University has examined how...

Bats are known to have relatively long lifespans, with some common species living an astonishing 30–40 years. Longevity in mammals is usually related to body size, with larger species living for longer, but <a href="https://www.earth.com/news/wild-bats-have-a-long-term-memory-of-sounds/">bats</a> as a group fall above the regression line for mammals as they live longer than other mammals of similar body size. House mice, which have a weight similar to that of some bats, live only two years in captivity.&nbsp;



Scientists have long wondered why there is this difference, and a new study led by <a href="https://www.umd.edu/">University of Maryland</a> researchers has identified one of the potential reasons; it has to do with genes involved in hibernation.&nbsp;



“Hibernation has allowed bats, and presumably other animals, to stay in northerly or very southerly regions where there’s no food in the winter,” said study senior author Professor Gerald Wilkinson. “Hibernators tend to live much longer than migrators. We knew that,&nbsp;but we didn’t&nbsp;know if we would detect changes in epigenetic age due to hibernation.”



The researchers worked on big brown bats (Eptesicus fuscus) kept in a research colony at McMaster University. These are the most common bats in the United States and they can live up to 19 years of age. The research colony contained individuals of between one and ten years old. Data was collected by taking a small sample of wing tissue from the 20 captive bats on two occasions. One sample was taken in summer when the bats were active, and the other in winter, when the bats were hibernating.&nbsp;



During the genetic analysis, the researchers investigated changes in DNA methylation between samples taken from the same animal during active and hibernating periods. Methylation is a process whereby methyl groups are added to a DNA molecule, thereby changing the activity of a gene. Their results, published in the Proceedings of the Royal Society B, Biological Sciences, showed that changes in DNA methylation occurred at certain sites in the bat’s genome, particularly sites involved in regulating metabolism during hibernation.&nbsp;



“It’s pretty clear that the sites that decrease methylation in the winter are the ones that appear to be having an active effect,” said Professor Wilkinson. “Many of the genes that are nearest to them are known to be involved in regulating metabolism, so they presumably keep metabolism down.”



Some of these genes are the same ones that Wilkinson and fellow researchers identified as “longevity genes” in a&nbsp;<a href="https://cmns.umd.edu/news-events/features/4745">previous study</a>. Wilkinson said that there is significant overlap between the hibernation genes and the longevity genes, further highlighting the link between hibernation and longer lifespans.&nbsp;



The earlier study also established the first epigenetic clock for bats, capable of accurately predicting the age of any bat in the wild. That clock was applied in this latest study, enabling the researchers to demonstrate that hibernation reduces a bat’s epigenetic age in comparison to a non-hibernating animal of the same age. In fact, the researchers found that by hibernating over just one winter, a big brown bat’s epigenetic clock – a biological marker of aging – extends by three-quarters of a year.&nbsp;



This, say the researchers, may be one of the secrets to the extraordinary longevity found in some species of bats.&nbsp;



“We still don’t have a very good understanding of why some bats can live a really long time and other ones don’t,” said Professor Wilkinson. “We’ve shown that the ones that live a really long time all share the ability to hibernate, or to go into torpor frequently. That seems to be a corollary, but it’s not sufficient because hibernating rodents don’t live 20 years.”



Wilkinson said he is planning a follow-up study to compare epigenetic aging in big brown bats in Canada, where they hibernate, with the same species in Florida, where they do not hibernate. In doing so, Wilkinson hopes to get an even clearer picture of the role that hibernation plays in prolonging lifespans.&nbsp;



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Hibernation may be key to extraordinary longevity in bats

Bats are known to have relatively long lifespans, with some...

A tiny robot has helped researchers understand more about how ants learn from each other. Researchers at the <a href="https://www.bristol.ac.uk/">University of Bristol</a> designed the robot to mimic the teaching <a href="https://www.earth.com/video/how-does-the-climate-affect-the-behavior-of-migratory-birds/">behavior</a> of rock ants.



"Teaching is so important in our own lives that we spend a great deal of time either instructing others or being taught ourselves. This should cause us to wonder whether teaching actually occurs among non-human animals. And, in fact, the first case in which teaching was demonstrated rigorously in any other animal was in an ant," explained Professor Nigel Franks of Bristol's <a href="http://www.bristol.ac.uk/biology/">School of Biological Sciences</a>.



The researchers explored a learning process called tandem running, in which a teacher ant leads a pupil to a new nest, the pupil ant finds their way back to the old nest, then becomes the teacher for a new pupil. The process continues throughout the colony.



The team created an arena with one low-quality nest and one high-quality nest. They built a robot teacher, which led an ant from a low-quality to a high-quality nest.&nbsp;



The experts applied a worker scent to the robot so ants could recognize the robot as a teacher. Sometimes the robot would take a direct path to the superior nest; other times, it would take a windy route.&nbsp;



"We waited for an ant to leave the old nest and put the robot pin, adorned with attractive pheromones, directly ahead of it. The pinhead was programmed to move towards the new nest either on a straight path or on a beautifully sinuous one. We had to allow for the robot to be interrupted in its journey, by us, so that we could wait for the following ant to catch up after it had looked around to learn landmarks," explained Professor Franks.



"When the follower ant had been led by the robot to the new nest, we allowed it to examine the new nest and then, in its own time, begin its homeward journey. We then used the gantry automatically to track the path of the returning ant."



"Crucially, we could compare the performance of the ants that the robot had taught with ones that we carried to the site of the new nest and that had not had an opportunity to learn the route. The taught ants found their way home much more quickly and successfully."



The study can be found in the <a href="https://journals.biologists.com/jeb/article-lookup/doi/10.1242/jeb.244106">Journal of Experimental Biology</a>.



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By <a href="mailto:nire518@gmail.com">Erin Moody </a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Robot sheds light on how ants learn from each other

A tiny robot has helped researchers understand more about how...

In an attempt to re-establish vital ecological processes, a research team led by <a href="https://oregonstate.edu/">Oregon State University</a> (OSU) has recently proposed a series of management changes on western federal lands that would result in significant increase in <a href="https://www.earth.com/news/wisconsin-gray-wolf-population-dropped-by-30-percent-in-one-year/">gray wolf</a> and beaver populations – two currently endangered species that play a large number of critical ecological roles.&nbsp;



Gray wolves – apex predators able to trigger powerful, widespread ecological effects by controlling native ungulates such as elk, and facilitating the regrowth of vegetations species like aspen - were hunted to near extinction in the American West. Since the 1990s, wolves have been reintroduced to several regions of the Rocky Mountains and the Southwest through measures made possible by the <a href="https://www.worldwildlife.org/pages/the-us-endangered-species-act">Endangered Species Act</a>.&nbsp;



“Still, the gray wolf’s current range in those 11 states is only about 14 percent of its historical range,” said study co-lead author Christopher Wolf, a postdoctoral scholar in Forestry at OSU. “They probably once numbered in the tens of thousands, but today there might only be 3,500 wolves across the entire West.”



Similarly, beaver populations, once widespread in the West, have declined by 90 percent after the beginning of settler colonialism and have now vanished from many streams, leaving a large number of ecosystem services unprovided. By falling trees and shrubs to build their dams, beavers play a critical role in enriching fish habitats, increasing water quality as well as water and sediment retention, maintaining water flows through droughts, boosting carbon sequestration, and generally improving the habitats of a variety of riparian plant and animal species.



“Beaver restoration is a cost-effective way to repair degraded riparian areas,” said study co-author Robert Beschta, a professor emeritus of Forestry at OSU. “Riparian areas occupy less than two percent of the land in the West but provide habitat for up to 70 percent of wildlife species.”



In their study, the researchers included a catalogue of 92 threatened and endangered plant and animal species which have at least ten percent of the ranges within their proposed “Western Rewilding Network.” The most common threat for these species is livestock grazing, which can cause stream and wetland degradation, affect wildfire regimes, and make it increasingly harder for woody species, such as willow, to regenerate.



“We suggest the removal of grazing on federal allotments from approximately 285,000 square kilometers within the rewilding network, representing 29 percent of the total 985,000 square kilometers of federal lands in the 11 western states that are annually grazed. That means we need an economically and socially just federal compensation program for those who give up their grazing permits. Rewilding will be most effective when participation concerns for all stakeholders are considered, including Indigenous people and their governments,” Professor Beschta concluded.



The study is published in the journal <a href="http://dx.doi.org/10.1093/biosci/biac069">BioScience</a>.&nbsp;&nbsp;



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer&nbsp;&nbsp;

Wolves and beavers needed to "rewild" the American West

In an attempt to re-establish vital ecological processes, a research...

Lithophaga punctata

Taxonomic tree: