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Giant lemurs went extinct at some point in the last 2,000 years—but in a newly-discovered “lemur graveyard," they're still a jaw-dropping presence. A team of divers found hundreds of giant lemur skeletons—along with fossils from other extinct species—in an underwater cave deep beneath a Madagascar national park.
Scientists think that the giant lemurs found in the cave washed in over time, National Geographic reports. There, they decomposed in a relatively peaceful environment that left the skeletons marvelously intact. Because the skeletons are so well-preserved, they offer an “unprecedented look” at a species—lemurs so huge, they are being compared to gorillas.
Scientists hope to use the information yielded by the giant lemur cache to shed new light on the now-extinct species. It is estimated that there were up to 50 species of lemur living on Madagascar when the island became populated by humans, but only 33 survive. And while some believe humans hunted giant lemurs into oblivion, recent research on their DNA suggests a small population size may have been to blame—which means the underwater find is even more precious to researchers.
And the lemur bones represent only one find in the underwater graveyard. Scientists also uncovered the bones of an extinct elephant bird and representatives of a long list of other species, from rodents to ancient crocodiles. They believe even more skeletons might be buried under the sea floor. Alfred Rosenberger, an anthropologist and archaeologist who led the international team of cave divers and paleontologists, said in a release that the project is only just getting started:
This is the success of just phase one.…[The discovery is] the beginning of a complex international project that has a lot of long, hard work in store.
The human-driven extinction of fruit-eating lemurs on Madagascar has created multiple "orphan" plant species with precarious futures because their primary seed dispersers are gone, scientists say.
The findings, detailed in this week's issue of the journal of the Proceedings of the National Academy of Sciences, could have implications for conservation efforts not only in Madagascar, but around the world.
Among the world’s most unique primates, lemurs play a vital role in Madagascar as seed dispersers for many plants and are essential for maintaining healthy and diverse forests on the island. Fruits make up a large part of many lemurs' diets, and the animals will often ingest whole seeds and then poop them out far from the parent tree, thus helping the plants spread.
"In other tropical areas, the primary seed dispersers are birds, but in Madagascar, that's not the case," says study first-author Sarah Federman, a graduate student at Yale University. "The burden of seed dispersal falls mainly on lemurs, of which there are very few."The researchers examined lemur features, like the skull of this mouse lemur, to identify what seeds the primates may have had a role in dispersing. (Courtesy Sarah Federman)
That number is dwindling even further. Scientists estimate that in the past few thousand years, at least 17 lemur species on Madagascar have been driven to extinction by human activity, through either direct hunting or loss of habitat.
To investigate how these extinctions have affected Madagascar's forests, Federman and her team matched the diets of extinct lemurs with the seeds of plants on the island, including some plant species that scientists suspected were “orphans”--plants that did not have any existing animal seed dispersers.
To infer whether the extinct lemurs were capable of eating and dispersing the seeds, the group analyzed the animals' gape sizes–how wide their jaws could open–as well as other clues, such as their tooth shapes and dental wear.
The scientists concluded that many of the extinct lemur species they examined had once indeed been seed dispersers. Furthermore, one large extinct lemur in particular, called Pachylemur, was likely the primary disperser for a group of orphan plants on the island called Canarium. More than 30 Canarium tree species are found on Madagascar, and the largest of these have seeds that resemble large olives and are too big for Madagascar's existing lemurs to eat.
Bereft of their main seed dispersers, today's Canariums must rely on less-effective secondary dispersers such as strong winds and rodents to spread their seeds, but their days could be numbered, Federman and her team concluded.A golden-crowned sifaka, one of Madagascar's rarest lemurs. (Courtesy Sarah Federman)
The group also identified living lemur species–including several endangered species–that occupy essential dispersal niches. If these lemurs also disappear, the scientists warn, the health and diversity of Madagascar’s forests could be jeopardized.
Mauro Galetti, an ecologist at Paulo State University in Brazil, says the new findings foreshadow what could happen in many other regions, such as continental Africa, Asia and South America, as large fruit-eating animals such as elephants, gorillas, and rhinos are driven to extinction.
"More and more we find evidence for the importance of large frugivores [(fruit-eaters)]to our planet," says Galetti, who was not involved in the study.
Federman says her group's findings have practical and even philosophical ramifications for species conservation.
"Traditionally, conservation tended to be species-specific ... but now people are moving toward more ecosystem-level projects because we’ve realized that you can't protect a species in a vacuum," she says. "Our analysis facilitates thinking about how Madagascar’s lemurs fit into their ecosystems, but it also raises the question of what do you do with a tree that can no longer disperse its seeds. Do we intervene? Or do we just let it go extinct?"
It sounds like something out of a crime show: police pouring through data from surveillance cameras, using facial recognition software to nab the perp. But now, researchers have adapted this software for use in the forests of Madagascar, identifying and tracking the whereabouts of endangered lemurs.
As the BBC reports, the software, known as LemurFaceID, allows scientists to more effectively track and protect the primates. The software can distinguish individual lemurs from digital photographs with greater than 97-percent accuracy. Researchers hope the tool will improve conservation of the species while providing a more humane, noninvasive way to identify individual lemurs. The team recently published their work in the journal BioMed Central Zoology.
To track lemurs, scientists traditionally trapped and tagged individual animals. They cataloged their physical characteristics—body size, markings, notable scars or injuries. But tracking these lemurs as their appearance changes over time is both time consuming and challenging, hampering long-term studies.
“[We] weren’t particularly satisfied with the common approaches used in lemur research,” Rachel Jacobs, a co-author on the paper, tells the BBC. “[S]o we aimed to do something different with red-bellied lemurs, and we sought the expertise of our computer science collaborators.”
To develop the software, Jacobs, a biological anthropologist from George Washington University, turned Anil Jain, a biometrics expert and distinguished professor at Michigan State University.
Jain and his students in the computer science department created a dataset comprising 462 images of 80 red-bellied lemurs primarily taken in Ranomafana National Park in Madagascar. The researchers also included an additional 190 images of other lemur species to help expand the software’s capacity. To identify an individual, LemurFaceID first identifies its eyes and then analyzes the characteristics of each surrounding pixel in the image.
“Like humans, lemurs have unique facial characteristics that can be recognized by this system,” Jain tells MSU Today.
The new software will give lemur researchers and conservationists a new tool for tracking lemurs over time. Long-term data provides researchers with crucial metrics to measure population growth and decline, like the rates of infant and juvenile mortality.
The software could also aid in the fight against illegal captures of the big-eyed primates. With only a clear digital image, locals and tourists can report sightings to law enforcement and researchers to quickly identify captive lemurs.
The researchers believe LemurFaceID could be adapted to protect other mammals with variable facial and skin patterns as well. Jain tells MSU Today that he believes the software could work for bears, red pandas, raccoons and sloths.
The National Zoological Park’s 23-year-old male red-ruffed lemur, Joven, enjoys a tasty St. Patrick’s Day frozen treat made of apples, pears, cucumbers, honeydew and diluted […]
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