New study shows a carnivorous dinosaur species regrew all its teeth every few months

By: Thomas Schmitt Attorney on November 27, 2019 / comment : 0 Dinosaurs, Fossils, Madagascar, Palaeontology

A meat-eating dinosaur species that lived in Madagascar some 70 million years ago replaced all its teeth every couple of months or so, a new study has found, surprising even the researchers.

Credit: Sae Bom Ra

In fact, Majungasaurus grew new teeth roughly two to 13 times faster than those of other carnivorous dinosaurs, says paper lead author Michael D. D'Emic, an assistant professor of biology at Adelphi University. Majungasaurus would form a new tooth in each socket every couple of months.

"This meant they were wearing down their teeth quickly, possibly because they were gnawing on bones," D'Emic says. "There is independent evidence for this in the form of scratches and gouges that match the spacing and size of their teeth on a variety of bones - bones from animals that would have been their prey."

Some animals today, too, will gnaw on bones, including rodents, D'Emic explains. It's a way for them to ingest certain nutrients. It also requires exceptionally strong teeth - but Majungasaurus did not have those.

"That's our working hypothesis for why they had such elevated rates of replacement," D'Emic says. The rapid-fire tooth growth puts Majungasaurus in same league with sharks and big, herbivorous dinosaurs, he adds.

CT scan-generated models of the jaws of Majungasaurus (left), Ceratosaurus (center) and Allosaurus (right), with microscopic views of the interior of their teeth below each model. Stripes running from upper left to lower right in each microscopic image are daily deposited incremental lines, which allow the amount of time it took for a tooth to grow to be reconstructed [Credit: D’Emic et al. 2019]

Although at least a few hundred meat-eating dinosaur species roamed the Earth, researchers have analyzed tooth-replacement rates for only about a half-dozen of them, D'Emic says. He also has looked into tooth-replacement patterns in plant-eating dinosaurs.

"I'm hoping this latest project spurs more people to study other species. I bet that will reveal further surprises," he says. "And hopefully that will lead to a better understanding of how dinosaurs evolved to be successful for so long."

Importantly, the recent study examined two additional species of predatory dinosaur (Allosaurus and Ceratosaurus), providing an opportunity to consider tooth-growth patterns at a broader scale.

In collaboration with Patrick O'Connor, professor of anatomy at Ohio University, and Ph.D. student Eric Lund, D'Emic used a collection of isolated fossil teeth to examine microscopic growth lines in the teeth. These growth lines are similar to tree rings, but instead of being deposited once a year, they were deposited daily. At the same, the team used computerized tomography (CT) on intact jaws to visualize unerupted teeth growing deep inside the bones. That allowed them to estimate tooth-replacement rates in a large number of individual jaws so they could cross-check their results.

The importance of Madagascar's lowland rainforest for lemur conservation

By: Thomas Schmitt Attorney on November 06, 2019 / comment : 0 Ecosystems, Endangered Species, Environment, Madagascar, Natural Heritage, Wildlife

Throughout their evolutionary history, animals in regions with limited lowland habitat have evolved to adapt to higher elevations. Although lemurs--among the most endangered mammals on earth--are flexible and can persist at intermediate and high elevations in the Madagascar's eastern rainforest, a new Mammal Review study shows that the few remaining patches of lowland rainforest host the highest levels of lemur abundance for several species.

A new study shows that the few remaining patches of lowland rainforest host the highest levels of lemur abundance for several species [Credit: Marco Campera]

The findings suggest that the rapid human encroachment occurring in Madagascar's coastal areas has disproportionately threatened these primates.

"Very few lowland forests remain in Madagascar, and most of them have been poorly studied compared with areas at mid-elevations," said lead author Marco Campera, PhD, of Oxford Brookes University, in the UK. "Our research group found that the few remaining forests at low elevations host the highest abundance of lemurs,"

"It is crucial to promote research and conservation management in the few remaining patches of lowland rainforests to reconstruct the evolutionary history of the lemurs and to ensure the best possible protection of these unique primates," added senior author Giuseppe Donati, PhD, of Oxford Brookes University, in the UK.

Source: Wiley [November 06, 2019]

Researchers confirm timeline of human presence on Madagascar

By: Thomas Schmitt Attorney on October 08, 2019 / comment : 0 Africa, Archaeology, Madagascar

A team of researchers has confirmed that humans arrived on Madagascar about 11,000 years ago, much earlier than commonly accepted estimates of 2,000 years.

Kristina Douglass and her team systematically reviewed all of the archaeological radiocarbon dates for Madagascar and confirmed the timeline of human presence on Madagascar [Credit: Roland Schmitt/SIPA]

Kristina Douglass, assistant professor of anthropology in the College of the Liberal Arts and a faculty member in the Institutes of Energy and the Environment, led the team of researchers who worked on this project. She said the debate over when people came to Madagascar has long been contentious.

For example, in 2018, two papers by different teams of researchers presented wildly different estimates of when people first arrived on the island, one estimating that Madagascar was settled 11,000 years ago, and the other arguing that people first arrived only 1,500 years ago.

To settle this debate, Douglass and her team collected all of the radiocarbon dates that have ever been generated for archaeological sites on the African island. Their work resulted in the most comprehensive database of radiocarbon dates for the island.

"The African continent has some of the oldest human remains on record, some of which are millions of years old," Douglass said. "Yet, previous research suggested that this huge island that is not that far off the coast of Africa doesn't get settled by people until about 2,000 years ago."

To determine the timeline of human settlement, the researchers used statistical models to rank the dates using specific criteria, including whether the dated samples were clearly associated with human activities and whether the samples came from long or short-lived species, so that both the reliability and precision of radiocarbon dates could be evaluated. This method of "chronometric hygiene" had never been done for Madagascar.

"We looked at the type of material to see whether or not there was built in error based on the type of material," Douglass said. "We took all of those criteria that we called 'quality control' for those dates, and we fed that into a system where we ranked the dates to know which dates are the most reliable based on our criteria and which are the least reliable."

What Douglass and her team suggest in their paper is that the 11,000-year estimate of human presence is reliable.

A map of sites in Madagascar used in the systematic review of archaeological radiocarbon dates by Kristina Douglass and her team [Credit: Kristina Douglass]

Despite the reliability of this early arrival estimate, it is still unclear whether the evidence from 11,000 years ago is from permanent human settlements or if humans just visited the island temporarily, Douglass said.

"Somebody could have floated over to Madagascar by accident and left some remains," she said.

The team's paper also supports current evidence that cities started to emerge on Madagascar about 1,000 years ago.

Douglass said that confirming the timeline of human settlement is important for historical reasons, but it also has critical meaning for today's changing world.

"The bigger context of why this matters is because this island with some of the world's greatest biodiversity hotspots is going through significant environmental change, today and within the last 2,000 years," Douglass said. "A huge number of animals went extinct on the island about 1,000 years ago—pygmy hippos, giant elephant birds, man-sized lemurs, giant tortoises."

Douglass said it is important for understanding today's environmental challenges to determine if these animals went extinct rapidly after a short co-existence with newly arrived people or if the extinctions were a more complex, longer-term process, involving climate change and human activity.

"If people arrived 1,500 years ago, then within 500 years, all of these animals go extinct and all of these changes happen," Douglass said. "If people arrived 11,000 years ago, people have been coexisting with these environments for a much longer time, so the changes we see may be less abrupt or may have been caused by a significant shift in how people were using the landscape."

Douglass added that human presence should not be used as the only indication of whether an environment is going to change. Human activity should be considered within a constellation of human-environment-climate dynamics.

"If people were there 11,000 years ago and practicing a certain kind of subsistence, that might be very different from 1,000 years ago when Madagascar is swept into booming Indian Ocean trade networks and people start building ports and cities," Douglass said. "That is when we start to see the extinctions happen."

The paper was published in Quaternary Science Reviews.

Author: Kevin Sliman | Source: Pennsylvania State University [October 08, 2019]

New species of lizard found in stomach of microraptor

By: Thomas Schmitt Attorney on July 11, 2019 / comment : 0 Dinosaurs, Early Birds, Fossils, Madagascar, Palaeontology

A team of paleontologists led by Prof. Jingmai O'Connor from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences, together with researchers from the Shandong Tianyu Museum of Nature, have discovered a new specimen of the volant dromaeosaurid Microraptor zhaoianus with the remains of a nearly complete lizard preserved in its stomach. Their findings were published in Current Biology.

A new lizard species in the abdomen of a specimen of Microraptor [Credit: Jingmai O'Connor]

The lizard is unlike any previously known from the Cretaceous and represents a new species, Indrasaurus wangi. The lizard was named after Prof. WANG Yuan from IVPP, who is also director of the Paleozoological Museum of China. Prof. WANG is an expert on the paleoherpetofauna of China and has been in charge of numerous exhibitions of Chinese fossils.

The name Indrasaurus was inspired by a Vedic legend in which the god Indra was swallowed by a dragon during a great battle (the dragon here referring to Microraptor).

Dr. DONG Liping, a former student of Prof. WANG's, ran the most extensive phylogenetic analysis of Cretaceous lizards ever conducted and showed that all known Cretaceous species were more closely related to each other than to any modern lineage. The new lizard had teeth unlike any other previously known from the Jehol Biota, thus expanding the diversity of this clade and possibly suggesting a unique diet for this new species.

This is the fourth documented occurrence of a Microraptor preserving stomach contents - this dinosaur is now known to have fed on mammals, birds, fish, and lizards, supporting the interpretation that it was an opportunistic predator.

Illustration of the lizard-swallowing Microraptor [Credit: Doyle Trankina]

The lizard is nearly complete and articulated, showing that it was swallowed whole and head first, meaning that Microraptor fed in a manner similar to living carnivorous birds and lizards.

Although the Jurassic troodontid Anchiornis has been recently demonstrated to have egested pellets similar to extant carnivorous birds (most famously documented in owls), this ability was apparently absent in Microraptor, further adding to the evidence that the evolutionary transition from dinosaur to bird was characterized by extreme homoplasy - that is, numerous traits evolved multiple times independently in closely related groups.

Over the past 20 years, direct evidence of trophic interactions in the Jehol Biota has slowly accumulated. There are now 20 predator-prey relationships documented through direct evidence of stomach contents.

The authors used these relationships to reconstruct the first Jehol food web. Although certainly preliminary, this food web indicates that fish formed the most important food source for secondary and tertiary consumers. This food web can be used in the future to better understand the Jehol ecosystem.

Source: Chinese Academy of Sciences [July 11, 2019]

Severely disturbed habitats impacting health of Madagascar's lemurs

By: Thomas Schmitt Attorney on July 11, 2019 / comment : 0 Ecosystems, Endangered Species, Madagascar, Natural Heritage, Wildlife

A new study led by Mitch Irwin and Karen Samonds of Northern Illinois University finds that degraded rainforest habitats are having an unhealthy impact on at least one species of Madagascar's treasured lemurs, the most endangered mammal group in the world.

A diademed sifaka lemur in Madagascar's Tsinjoarivo forest [Credit: Mitch Irwin, Northern Illinois University]

Irwin, Samonds and other research team members captured, measured and released 113 critically endangered diademed sifakas over the course of 19 years. They then compared the health of the animals living in intact continuous rainforest versus those in habitats disturbed and fragmented by human encroachment.

Working with a veterinarian to ensure animal safety, the scientists recorded the body mass, length and body condition of the stunning silken-furred primates, which grow to be roughly a meter in length and weigh in at about 6.5 kilograms. The results actually revealed that sifakas in some fragmented rainforest environments were doing fine--their bodies were identical to those animals in the richest environments. But significant differences were found in the two most disturbed habitats.

"Below a critical threshold in the most degraded of all fragments, there were key differences--adults were skinnier, and the growth of immatures was delayed both in their height and weight," said Irwin, an NIU professor of anthropology and lead author of the study. The study was published in Scientific Reports, an open access journal of the Nature Research family.

Notably, the 11 lemurs living in the three lowest-quality habitats, representing three separate groups of the animals, died or disappeared during the study duration. The authors said it is unclear whether the habitats will be recolonized.

"Although anecdotal, the loss of these three groups would seem to corroborate the interpretation that their health was impacted by their low-quality habitat," Irwin said. "It's sad to actually witness a species' range shrink - it's a small step toward extinction."

A 2003 photo of three sub-adult lemurs resting in a pristine area of Madagascar's Tsinjoarivo rainforest [Credit: Mitch Irwin, Northern Illinois University]

For groups of sifakas in the remaining fragmented areas, both nutritional inputs and body measurements showed little distinction from groups living in optimal continuous forest, despite a noticeable degree of habitat fragmentation and disturbance.

"This suggests substantial resilience to moderate levels of habitat change," Irwin said. "If no further degradation occurs, the remaining long-term viability of groups in these fragmented areas may depend more on whether juveniles can disperse to find new groups than on nutritional inputs. If they are stuck in small isolated fragments they may die out due to inbreeding."

The study also presents the first detailed data on body proportions and dimensions of wild diademed sifakas. The animals are among the largest living lemur varieties, live in groups of two to 10 individuals and have life spans that typically exceed 20 years. Foliage is usually the major component of sifaka diets, although fruits and seeds can play a major role.

"Sifakas are long-lived animals, so they may not rapidly go extinct in these degraded habitats, but over time these threats can add up and cause these populations to be lost," Irwin said. "This research not only helps identify which groups are at risk, but identifies ways to monitor their health directly through these measurements of size and growth."

The study was conducted on sifakas living in Madagascar's Tsinjoarivo forest, part of the newly-created Tsinjoarivo-Ambalaomby protected area. Located 80 kilometers south and southeast of the capital city of Antananarivo, the rainforest is home to many spectacular varieties of lemurs, a group of primates only found in the island country.

Over the past 35 years in Tsinjoarivo’s forests, limited economic options in poor rural areas have often led to uncontrolled and unsustainable natural resource exploitation, degrading lemur habitat [Credit: Mitch Irwin, Northern Illinois University]

Its preservation is being spearheaded by the NGO SADABE, a Malagasy organization created by Irwin and Samonds with Malagasy colleagues. Each year, Irwin and Samonds, a husband-and-wife team of scientists, spend a large portion of their summer conducting research in the region.

Though the Malagasy care deeply for the forest, limited economic options in poor rural areas often lead to uncontrolled and unsustainable natural resource exploitation. Over roughly the past 35 years, much of Tsinjoarivo's forests were turned to agricultural plots and trees chopped down for lumber, disturbing habitats. The rainforest's western half has been fragmented and degraded by settlers, while the eastern half is minimally disturbed.

Many studies have examined how human-caused habitat change can affect wildlife populations. But wild animals, especially highly intelligent primates, are very flexible. "They can change their diet and movement patterns to respond to changing conditions," Irwin said. "You really need direct indicators of health to know if those changes reflect an underlying threat to the population."

Samonds and Irwin continue to collect data this summer.

"For this kind of research, you need a long-term database," said Samonds, an NIU professor of biological sciences. "Basic health parameters such as body size and condition are perhaps the best tools for judging population viability, but getting the measurements typically requires captures, which are often challenging."

Source: Northern Illinois University [July 11, 2019]

The bird that came back from the dead

By: Thomas Schmitt Attorney on May 09, 2019 / comment : 0 Early Birds, Endangered Species, Evolution, Fossils, Madagascar, Wildlife

New research has shown that the last surviving flightless species of bird, a type of rail, in the Indian Ocean had previously gone extinct but rose from the dead thanks to a rare process called 'iterative evolution'.

White-throated rail [Credit: Charles J Sharp]

The research, from the University of Portsmouth and Natural History Museum, found that on two occasions, separated by tens of thousands of years, a rail species was able to successfully colonise an isolated atoll called Aldabra and subsequently became flightless on both occasions. The last surviving colony of flightless rails is still found on the island today.

This is the first time that iterative evolution (the repeated evolution of similar or parallel structures from the same ancestor but at different times) has been seen in rails and one of the most significant in bird records.

The white-throated rail is a chicken-sized bird, indigenous to Madagascar in the south-western Indian Ocean. They are persistent colonisers of isolated islands, who would have frequent population explosions and migrate in great numbers from Madagascar. Many of those that went north or south drowned in the expanse of ocean and those that went west landed in Africa, where predators ate them. Of those that went east, some landed on the many ocean islands such as Mauritius, Reunion and Aldabra, the last-named is a ring-shaped coral atoll that formed around 400,000 years ago.

With the absence of predators on the atoll, and just like the Dodo of Mauritius, the rails evolved so that they lost the ability to fly. However, Aldabra disappeared when it was completely covered by the sea during a major inundation event around 136,000 years ago, wiping out all fauna and flora including the flightless rail.

Wing bones fossils of flighted (right) and flightless Dryolimnas rails [Credit: Dr Julian Hume]

The researchers studied fossil evidence from 100,000 years ago when the sea-levels fell during the subsequent ice age and the atoll was recolonised by flightless rails. The researchers compared the bones of a fossilised rail from before the inundation event with bones from a rail after the inundation event. They found that the wing bone showed an advanced state of flightlessness and the ankle bones showed distinct properties that it was evolving toward flightlessness.

This means that one species from Madagascar gave rise to two different species of flightless rail on Aldabra in the space of a few thousand years.

Lead researcher Dr Julian Hume, avian paleontologist and Research Associate at the Natural History Museum, said: "These unique fossils provide irrefutable evidence that a member of the rail family colonised the atoll, most likely from Madagascar, and became flightless independently on each occasion. Fossil evidence presented here is unique for rails, and epitomises the ability of these birds to successfully colonise isolated islands and evolve flightlessness on multiple occasions."

Co-author Professor David Martill, from the School of Earth and Environmental Sciences at the University of Portsmouth, said: "We know of no other example in rails, or of birds in general, that demonstrates this phenomenon so evidently. Only on Aldabra, which has the oldest palaeontological record of any oceanic island within the Indian Ocean region, is fossil evidence available that demonstrates the effects of changing sea levels on extinction and recolonisation events.

"Conditions were such on Aldabra, the most important being the absence of terrestrial predators and competing mammals, that a rail was able to evolve flightlessness independently on each occasion."

The study is published in the latest issue of the Zoological Journal of the Linnean Society.

Source: University of Portsmouth [May 09, 2019]

The last chance for Madagascar's biodiversity

By: Thomas Schmitt Attorney on April 29, 2019 / comment : 0 Biodiversity, Ecosystems, Endangered Species, Madagascar, Natural Heritage, Wildlife

Scientists from around the world have joined together to identify the most important actions needed by Madagascar's new government to prevent species and habitats being lost for ever.

Many of Madagascar's iconic lemur species such as this black and white ruffed lemur are critically endangered [Credit: Daniel Burgas]

In January, Madagascar's recently-elected president, Andry Rajoelina, began his five-year term of office. A group of scientists from Madagascar, the UK, Australia, the USA and Finland have published a paper recommending actions needed by the new government to turn around the precipitous decline of biodiversity and help put Madagascar on a trajectory towards sustainable growth.

Professor Jonah Ratsimbazafy, from the University of Antananarivo and one of the paper's co-authors said: "The United States have the Statue of Liberty, France has the Eifel tower.... For us in Madagascar it is our biodiversity (the product of millions of years of evolution), which is the unique heritage we are known for around the world. We cannot let these natural wonders, including 100 different types of lemur found nowhere else, disappear".

The group say that Madagascar's protected areas, some of the most important for biodiversity in the world, have suffered terribly in recent years from illegal mining, logging, and collection of threatened species for the pet trade. They suggest that much of this illegal activity is linked to corruption. They emphasise that the insecurity which goes alongside this illegal exploitation is bad for people as well as nature.

Dr Herizo Andrianandrasana, the first Malagasy DPhil graduate in Oxford University's 800-year history and an experienced Malagasy conservationist, commented: "the destruction of Madagascar's biodiversity benefits few; those who profit from rosewood trafficking, illegal mining in protected areas, or the prohibited trade in species like our Critically Endangered tortoises. However, the costs are widespread and affect all Malagasy."

Illegal logging in protected areas in Madagascar has damaged these globally important sites [Credit: Toby Smith]

The group has identified five priority measures for the new government's focus: investing in protected areas, strengthening local people's tenure over natural resources, ensuring new infrastructure development limits impacts on biodiversity, tackling environmental crime linked to corruption, and investing in major restoration efforts that will address the country's growing fuelwood crisis.

The team takes great care to emphasise that conservation must benefit, not harm, local communities.

Professor Julia Jones of Bangor University, who led the study said "Madagascar is one of the poorest countries on the planet. More than 40% of children under five are stunted due to malnutrition, and the country has more people living in extreme poverty than almost anywhere else on Earth. Conservation therefore needs to contribute to, and not detract from, national efforts targeting economic development. It must not make situations worse for the rural poor who are so often marginalised in decision making."

The team believe that action in the five areas could make all the difference. Professor Ratsimbazafy again: "The time has come for action-It's not too late to turn things around in Madagascar, but it soon will be."

Large scale clearance of Madagascar's dry forests (to clear land for peanuts and corn) is decimating remaining patches of this rare habitat, home to species found nowhere on the planet [Credit: copyright Tahina Roland Frederic]

Professor Jones added: "Since his election President Rajoelina has given positive indications that he recognises the importance of Madagascar's biodiversity. We will make sure that he has a copy of this paper and that the contents are well shared within Madagascar (and with the potential donors whose support will be needed). Our co-authors, and the many other active Malagasy and international scientists who care about Madagascar, are all ready to help the new president ensure that his term can deliver the turning point needed for Madagascar, and its wildlife."

The paper is published in Nature Sustainability.

Source: Bangor University [April 29, 2019]

A rare assemblage of sharks and rays from nearshore environments of Eocene Madagascar

By: Thomas Schmitt Attorney on February 27, 2019 / comment : 0 Fossils, Madagascar, Palaeontology

Eocene-aged sediments of Madagascar contain a previously unknown fauna of sharks and rays, according to a study published in the open-access journal PLOS ONE by Karen Samonds of Northern Illinois University and colleagues. This newly-described fauna is the first report of sharks and rays of this age in Madagascar.

Eocene shark teeth from northwestern Madagascar [Credit: Samonds et al, 2019]

The Mahajanga basin of northwestern Madagascar yields abundant fossil remains of terrestrial and marine ecosystems, but little is known about fossil sharks and rays during the Eocene Epoch, 55-34 million years ago, in this region. This is in contrast to the numerous shark and ray faunas known from other Eocene sites around the globe, and to shark and ray ecosystems known from older and younger sediments in the Mahajanga basin.

In this study, Samonds and colleagues collected isolated teeth, dental plates, and stingray spines from ancient coastal sediments of the Ampazony and Katsepy regions of the basin, dated to the middle to late Eocene. They identified at least 10 species of sharks and rays, including one new species, Carcharhinus underwoodi. This is the oldest named species of Carcharhinus, a genus that has been globally distributed for the past 35 million years but is known only rarely from the Eocene.

Aside from the new species, the fauna of Eocene Madagascar shares many species with Eocene ecosystems across North Africa, suggesting these animals were widespread in southern seas at that time. On the other hand, the Madagascar fauna is uniquely lacking in sandsharks and dominated by eagle rays, indicating a somewhat unusual ecosystem, unsurprising given Madagascar's long history of isolation. The authors caution that this study provides an incomplete picture given that they collected only fossils larger than 2 millimeters. They recommend that future studies target smaller material for a more complete view of the ancient ecosystem.

Source: Public Library of Science [February 27, 2019]

Detective mission to characterize and trace the history of a new African meteorite

By: Thomas Schmitt Attorney on November 26, 2018 / comment : 0 Astronomy, Geology, Madagascar, Universe

Researchers from Wits and colleagues from the University of Antananarivo in Madagascar are on a "detective mission" to describe, classify and trace the history of a meteorite that landed in and around the small town of Benenitra in southwestern Madagascar shortly before the lunar eclipse on 27 July 2018.

A fragment of the meteorite showing the black fusion crust and thumbprint-like depressions (called regmaglypts) formed by melting during its entry into the atmosphere. The small bumps on the surface are grains of nickel-iron alloy [Credit: Wits University]

News of the event in this remote area was brought to the attention of a Wits Geosciences graduate, Tim Marais, who was travelling in the area a few days after the meteorite fall. He collected some preliminary eyewitness accounts that reported a bright meteor fireball, a loud explosion and a rain of rock fragments that fell in and around Benenitra that, fortuitously, appear to have missed all people and buildings, and he was able to acquire several small fragments that residents had managed to locate.

He delivered these to Professors Roger Gibson and Lewis Ashwal in the School of Geosciences at Wits and asked them to verify their extra-terrestrial origin. The signs of a dark fusion crust and small spheres in the rock matrix that were visible on broken surfaces appeared promising and the School's Senior Technician, Caiphas Majola, was immediately commissioned to prepare a thin section of one of the fragments for microscopic analysis.

Tracing the history

Assessment of the thin section confirmed that it was, indeed, a meteorite and, more specifically, a relatively common type called a chondrite, referring to the small spherical chondrules that it contains. This established that the meteorite dates from the formation of our Solar System about 4.56 billion years ago.

At the same time, a news report appeared in the local Triatra Gazette newspaper on 4 August regarding the eyewitness reports and showing a large specimen with a similar black fusion crust. To corroborate the event scientifically, the team approached Dr Andry Ramanantsoa of the Laboratory of Seismology and Infrasound at the Institute and Observatory of Geophysics at the University of Antananarivo to investigate if there was any evidence that a significant explosion occurred in the atmosphere above Madagascar sometime in the evening of 27 July.

Ramanantsoa was able to confirm, using infrasound data from the international Comprehensive Nuclear Test Ban Treaty Infrasound Station IS33 outside Antananarivo, that there had, indeed, been an "upper atmosphere energy release event" at 5.16 p.m. GMT (7.16 p.m. local time). Furthermore, he was able to identify that it occurred in a direction south-southwest of Antananarivo - the exact bearing of Benenitra.

This is a close-up of the meteorite fragment showing the fusion crust [Credit: Wits University]

The next step was to see if the blast wave from the atmospheric detonation was sufficiently large to have caused a ground vibration that could be detected by geophysical seismometers. For this the team turned to Dr Andriamiranto (Ranto) Raveloson, a Postdoctoral Fellow and Technical Manager of the Africa Array Seismic Network that is co-ordinated from Wits. He was able to confirm a very faint seismic tremor at 5.17 p.m. GMT on the same night.

The final confirmation that the fragment was related to a fall on 27 July was obtained from Dr Matthias Laubenstein from the Laboratori Nazionali del Gran Sasso at the Istituto Nazionale di Fisica Nucleare in Italy, who measured the meteorite for rare cosmogenic nuclides that are created when an asteroid in Space is bombarded by high-energy cosmic rays. His measurements showed high levels of cosmogenic nuclides, consistent with the meteorite having entered Earth's protective atmosphere only within the past few months.

Based on these findings, the team has submitted a request to the international Meteoritical Society to officially name and register Africa's newest meteorite - Benenitra - on its database.

Classifying Africa's newest meteorite

Ashwal and Gibson have refined the meteorite classification as an L6 chondrite. The name refers to the fact that it contains a low amount of iron (the "L"), and that it contains recognizable chondrules. Chondrules are the original building blocks of rocky bodies - such as asteroids and the Inner Planets - in Space. As these bodies grew larger, heat built up inside them - partly through gravitational collapse and partly because of radioactive elements - which caused the metals and chondrules to recrystallise and maybe even melt.

Where temperatures were sufficiently high to melt the body, the denser metals were then able to settle towards the core of the body, with the less dense silicate melts rising towards the surface. Eventually the body would have cooled down sufficiently to solidify. The Benenitra meteorite appears to have got quite hot (the number "6" refers to the high amount of recrystallisation that occurred within the chondrules owing to this heating process) but only melted partially, allowing some of the chondrules to survive.

Poor Man's Space Probe

The meteorite also has a thin shock-melt vein that is most likely related to a collision with another asteroid that shattered the original body and sent the fragment spinning off on its eventual collision course with Earth.

"Meteorites are commonly called The Poor Man's Space Probe, because they deliver rocks from Outer Space to our door for free, where we can study the birth and history of other parts of our Solar System" says Gibson. The Benenitra meteorite fragment is being subjected to a range of other tests to establish properties such as its density and magnetism, and the team plans to write the results up soon in a scientific paper.

"The Benenitra meteorite is a new Space rock, but it is also a witnessed fall, which makes it part of special group of meteorites. It is part of our collective heritage as a species, planet and Solar System. It fell in a remote area that will henceforth be recognised internationally for the event on the evening of 27 July. Our project provides an opportunity to further strengthen scientific collaboration in the SADC region. Ultimately, one of our goals is to inform the people of Benenitra about the significance of what they witnessed and thus build greater awareness of science," says Gibson.

Source: University of the Witwatersrand [November 27, 2018]

Humans may have colonized Madagascar later than previously thought

By: Thomas Schmitt Attorney on October 10, 2018 / comment : 0 Archaeology, Fossils, Genetics, Madagascar

New archaeological evidence from southwest Madagascar reveals that modern humans colonized the island thousands of years later than previously thought, according to a study published in the open-access journal PLOS ONE by Atholl Anderson from the Australian National University, Canberra, Australia, and colleagues.

Taolambiby cut-marked bone dated to 1200 years ago [Credit: Anderson et al., 2018]

Madagascar's colonization is key for tracing prehistoric human dispersal across the Indian Ocean, but exactly when human settlement began in the island remains unclear. Several pieces of evidence, including archaeological findings such as chert tools and charcoal, provide a direct indication of human occupation in Madagascar from about 1500 years before present (BP).

However, recent studies have suggested that the island's early settlers made first landfall as early as 5000 years BP, based on indirect evidence from animal bones with damage (cutmarks) presumably resulting from human activity. Anderson and colleagues revisited these bone collections and excavated three new sites in southwest Madagascar to collect a larger sample of animal bone material.

They recovered 1787 bones belonging to extinct megafauna, such as hippos, crocodiles, giant lemurs, giant tortoise and elephant birds, dated between 1900 BP and 1100 years BP. Microscopic analyses revealed that potential cutmarks in bones dated before 1200 years BP were in fact animal biting and gnawing marks, root etching, or chop marks from the excavation, suggesting that cutmarking (and human activity) only appeared after that time point.

Similar results were obtained upon re-examination of bone damage previously interpreted as cutmarks in samples from old collections. The study also confirmed previous evidence of megafaunal extinction starting around 1200 years BP. These findings add to the evidence showing that prehistoric human colonization of Madagascar began between 1350 and 1100 years BP, and suggest that hunting gradually led to the extinction of the island's megafauna.

The authors add: "Recent estimates indicate human arrival in Madagascar as early as ~10,000 years ago. Diverse evidence (from bone damage, palaeoecology, genomic and linguistic history, archaeology, introduced biota and seafaring capability) indicate initial human colonization of Madagascar was later at 1350-1100 y B.P. Results have implications for decline and extinction of megafauna, a proposed early African hunter-gatherer phase, and transoceanic voyaging from Southeast Asia."

Source: Public Library of Science [October 10, 2018]

Scientists name world's largest ever bird: Vorombe titan

By: Thomas Schmitt Attorney on September 25, 2018 / comment : 0 Early Birds, Fossils, Madagascar, Palaeontology

After decades of conflicting evidence and numerous publications, scientists at international conservation charity ZSL's (Zoological Society of London) Institute of Zoology, have finally put the 'world's largest bird' debate to rest. Published in Royal Society Open Science - Vorombe titan (meaning 'big bird' in Malagasy and Greek), has taken the title reaching weights of up to 800 kg and three metres tall, with the research also discovering unexpected diversity in these Madagascan creatures.

An artist's illustration of the giant elephant bird [Credit: (c) Jaime Chirinos]

Until now, it was previously suggested that up to 15 different species of elephant birds had been identified under two genera, however research by ZSL scientists boasts new rigorous and quantitative evidence - that shows, in fact, this is not the case. Armed with a tape measure and a pair of callipers, Dr Hansford analysed hundreds of elephant bird bones from museums across the globe to uncover the world's largest bird, while also revealing their taxonomy is in fact spread across three genera and at least four distinct species; thus, constituting the first taxonomic reassessment of the family in over 80 years.

Elephant birds (belonging to the family Aepyornithidae) are an extinct group of colossal flightless birds that roamed Madagascar during the Late Quaternary, with two genera (Aepyornis and Mullerornis) previously recognised by scientists. The first species to be described, Aepyornis maximus, has often been considered to be the world's largest bird. In 1894, British scientist C.W. Andrews described an even larger species, Aepyornis titan, this has usually been dismissed as an unusually large specimen of A. maximus. However, ZSL's research reveals Andrew's 'titan' bird was indeed a distinct species. The shape and size of its bones are so different from all other elephant birds that it has now been given the new genus name Vorombe by ZSL.

Vorombe titan bones [Credit: (c) ZSL]

Lead Author at ZSL's Institute of Zoology, Dr James Hansford said: "Elephant birds were the biggest of Madagascar's megafauna and arguably one of the most important in the islands evolutionary history - even more so than lemurs. This is because large-bodied animals have an enormous impact on the wider ecosystem they live in via controlling vegetation through eating plants, spreading biomass and dispersing seeds through defecation. Madagascar is still suffering the effects of the extinction of these birds today."

Co-Author Professor Samuel Turvey from ZSL's Institute of Zoology said: "Without an accurate understanding of past species diversity, we can't properly understand evolution or ecology in unique island systems such as Madagascar or reconstruct exactly what's been lost since human arrival on these islands. Knowing the history of biodiversity loss is essential to determine how to conserve today's threatened species."

Analysing this data in a novel combination of machine learning combined with Bayesian clustering, Dr Hansford applied modern techniques to solve a 150-year-old taxonomic knot, that will form the modern understanding of these enigmatic avian megafauna. The revelation that the biggest of these birds was forgotten by history is just one part of their remarkable story.

Source: Zoological Society of London [September 25, 2018]

Ancient bird bones redate human activity in Madagascar by 6,000 years

By: Thomas Schmitt Attorney on September 12, 2018 / comment : 0 Africa, Archaeology, Early Humans, Madagascar

Analysis of bones, from what was once the world's largest bird, has revealed that humans arrived on the tropical island of Madagascar more than 6,000 years earlier than previously thought -- according to a study published in the journal Science Advances.

Disarticulation marks on the base of the tarsometatarsus. These cut marks were made when removing the toes from the foot [Credit: ZSL]

A team of scientists led by international conservation charity ZSL (Zoological Society of London) discovered that ancient bones from the extinct Madagascan elephant birds (Aepyornis and Mullerornis) show cut marks and depression fractures consistent with hunting and butchery by prehistoric humans. Using radiocarbon dating techniques, the team were then able to determine when these giant birds had been killed, reassessing when humans first reached Madagascar.

Previous research on lemur bones and archaeological artefacts suggested that humans first arrived in Madagascar 2,400-4,000 years ago. However, the new study provides evidence of human presence on Madagascar as far back as 10,500 years ago -- making these modified elephant bird bones the earliest known evidence of humans on the island.

This chop mark would have been made with a large sharp tool. The clear straight line of the cut with no continued cracks indicate the mark was made on fresh bone and chopped into different cuts of meat [Credit: ZSL]

Close up of the disarticulation marks on the base of the tarsometatarsus. Here you can see the v-shaped tool mark and rough edges indicating a stone tool was used [Credit: ZSL]

Lead author Dr James Hansford from ZSL's Institute of Zoology said: "We already know that Madagascar's megafauna -- elephant birds, hippos, giant tortoises and giant lemurs -- became extinct less than 1,000 years ago. There are a number of theories about why this occurred, but the extent of human involvement hasn't been clear.

"Our research provides evidence of human activity in Madagascar more than 6,000 years earlier than previously suspected -- which demonstrates that a radically different extinction theory is required to understand the huge biodiversity loss that has occurred on the island. Humans seem to have coexisted with elephant birds and other now-extinct species for over 9,000 years, apparently with limited negative impact on biodiversity for most of this period, which offers new insights for conservation today."

Illustration of a Vorompatra (Elephant bird) skeleton [Credit: Alain Rasolo, Wildlife Artist, Madagascar]

Co-author Professor Patricia Wright from Stony Brook University said: "This new discovery turns our idea of the first human arrivals on its head. We know that at the end of the Ice Age, when humans were only using stone tools, there were a group of humans that arrived on Madagascar. We do not know the origin of these people and won't until we find further archaeological evidence, but we know there is no evidence of their genes in modern populations. The question remains -- who these people were? And when and why did they disappear?"

The bones of the elephant birds studied by this project were originally found in 2009 in Christmas River in south-central Madagascar -- a fossil 'bone bed' containing a rich concentration of ancient animal remains. This marsh site could have been a major kill site, but further research is required to confirm.

Source: Zoological Society of London [September 12, 2018]

Enigmatic African fossils rewrite story of when lemurs got to Madagascar

By: Thomas Schmitt Attorney on August 21, 2018 / comment : 0 Early Mammals, Kenya, Madagascar, Palaeontology

Discovered more than half a century ago in Kenya and sitting in museum storage ever since, the roughly 20-million-year-old fossil Propotto leakeyi was long classified as a fruit bat.

Fossilized fragments of primate jaws and teeth from Africa are changing what researchers thought they knew about when lemurs made it to Madagascar. Shown here is 20-million-year-old Propotto leakeyi [Credit: Duke SMIF]

Now, it's helping researchers rethink the early evolution of lemurs, distant primate cousins of humans that today are only found on the island of Madagascar, some 250 miles off the eastern coast of Africa. The findings could rewrite the story of just when and how they got to the island.

In a study published in the journal Nature Communications, researchers have re-examined Propotto's fossilized remains and suggest that the strange creature wasn't a bat, but an ancient relative of the aye-aye, the bucktoothed nocturnal primate that represents one of the earliest branches of the lemur family tree.

The reassessment challenges a long-held view that today's 100-some lemur species descended from ancestors that made their way to Madagascar in a single wave more than 60 million years ago, becoming some of the first mammals to colonize the island.

Instead, the study lends support to the idea that two lineages of lemurs split in Africa before coming to Madagascar. One lineage eventually led to the aye-aye, and the other to all other lemurs. There are no lemurs left on mainland Africa. These ancestors then colonized Madagascar independently, and millions of years later than once believed.

"One implication is that lemurs have had a much less extensive evolutionary history on Madagascar than was previously thought," said study co-author Erik Seiffert, professor of anatomy at the University of Southern California.

When Propotto was first described in the 1960s, experts didn't agree about what they were looking at. They didn't have a lot to go on: just three lower jaw bones, each barely an inch long, and a handful of teeth less than three millimeters across.

These fossils could rewrite the origin story of Madagascar’s lemurs. Plesiopithecus teras, left, lived 34 million years ago in Egypt. Propotto leakeyi, right, lived 20 million years ago in Kenya [Credit: Duke SMIF]

In 1967, paleontologist George Gaylord Simpson inspected the fragments and classified the specimen as a previously unknown member of the loris family, nocturnal primates with enormous eyes. But a colleague named Alan Walker took a look and thought otherwise, eventually convincing Simpson that the bones belonged to a bat.

For nearly half a century the creature's identity appeared to have been settled, until 2016, when another paleontologist, the late Gregg Gunnell of Duke University, began taking a fresh look at the fossil. To Gunnell's eye, the creature's hind teeth were more reminiscent of a primate than a bat. He also noted the stump of a broken front tooth, just visible in cross section, which would have jutted out from its mouth like a dagger -- a trait only known in aye-ayes, the only living primates with rodent-like teeth.

"Gregg wrote to us and said, 'Tell me I'm crazy,'" Seiffert said.

To verify Propotto's place in the primate family tree, Seiffert and Steven Heritage of Duke's Division of Fossil Primates analyzed more than 395 anatomical features and 79 genes for 125 mammal species, living and extinct.

With help from Doug Boyer, associate professor of evolutionary anthropology at Duke, the team also compiled microCT scans of the lower molars of 42 living and extinct mammal groups, including bats, treeshrews and primates. They then used a computer program to compare the bumps, pits and ridges on the scans of Propotto's teeth to those of other animals.

The researchers found that Propotto shared a number of features with a similarly buck-toothed primate that lived 34 million years ago in Egypt called Plesiopithecus, and that both were ancient relatives of the aye-aye.

New analysis shows that fossilized remains found in Africa belonged to ancient relatives of the aye-aye [Credit: David Haring, Duke Lemur Center]

In the new study, Seiffert, Gunnell and colleagues propose that the ancestors of aye-ayes split from the rest of the lemur family tree roughly 40 million years ago, while still on the African continent, and the resulting two lineages didn't make their separate ways to Madagascar until later.

The findings suggest they arrived around the same time as other mammals, such as rodents, Malagasy mongooses and hedgehog- and shrew-like animals called tenrecs. Frogs, snakes and lizards may have made the trip around the same time.

Lemurs can't swim, so some scientists hypothesize that the small-bodied creatures crossed the 250-mile-wide channel that lies between Africa and Madagascar after being swept out to sea in a storm, by holding on to tree limbs or floating mats of vegetation before finally washing ashore.

But if the arrival were more recent, they might have had a shorter distance to travel, thanks to lower sea levels when the Antarctic ice sheet was much larger.

"It's possible that lemurs weren't in Madagascar at all until maybe the Miocene," as recently as 23 million years ago, Boyer said.

"Some of the lowest sea levels were also during this time," Heritage said.

Either way, "the fossils tell us something we never could have guessed from the DNA evidence about the history of lemurs on Madagascar," Boyer said.

Author: Robin A. Smith | Source: Duke University [August 21, 2018]

95% of lemur population facing extinction: conservationists

By: Thomas Schmitt Attorney on August 01, 2018 / comment : 0 Endangered Species, Madagascar, Natural Heritage, Wildlife

Ninety-five percent of the world's lemur population is "on the brink of extinction," making them the most endangered primates on Earth, a leading conservation group said Wednesday.

Out of a total of 111 lemur species and subspecies, 105 are under threat, IUCN said [Credit: ANP/AFP/Bas Czerwinsk]

The arboreal primates with pointed snouts and typically long tails are found only in Madagascar, where rainforest destruction, unregulated agriculture, logging and mining have been ruinous for lemurs, the International Union for the Conservation of Nature (IUCN) said.

"This is, without a doubt, the highest percentage of threat for any large group of mammals and for any large group of vertebrates," Russ Mittermeier of IUCN's species survival commission said in a statement.

Out of a total of 111 lemur species and subspecies, 105 are under threat, IUCN said, as it released its first update on the lemur population since 2012.

Among the most concerning trends is an "increase in the level of hunting of lemurs taking place, including larger-scale commercial hunting," Christoph Schwitzer, director of conservation at the Bristol Zoological Society, said in the statement.

He described the hunting as "unlike anything we have seen before in Madagascar."

One of the species identified as "critically endangered" is the northern sportive lemur, of which there are thought to be only 50 individuals left, IUCN said.

"Lemurs are to Madagascar what giant pandas are to China—they are the goose that laid the golden egg, attracting tourists and nature lovers," said Jonah Ratsimbazafy of the domestic primate research group known as GERP.

Madagascar is one of the most biodiverse nations in the world.

IUCN said it was launching "a major action plan for lemur conservation," to help preserve the endangered primates.

Source: AFP [August 01, 2018]

Loss of lemurs might endanger many of Madagascar's largest tree species

By: Thomas Schmitt Attorney on July 02, 2018 / comment : 0 Ecosystems, Endangered Species, Madagascar, Natural Heritage, Wildlife

Widespread logging and hunting have endangered virtually all of Madagascar's 100-plus species of iconic lemurs, and a new study by Rice University ecologists illustrates how saving the animals may also be key to saving the island's largest trees.

Black-and-white ruffed lemur [Credit: Mathias Appel]

"Forest loss is a huge problem in Madagascar right now, but our study suggests that just saving the trees is not enough," said Amy Dunham, associate professor of biosciences at Rice and co-author of a paper appearing online today in a special issue of the International Journal of Primatology. "Not only are we facing the loss of these unique, charismatic animals, we're also losing their role in the ecosystem. Without lemurs, the rainforests themselves will change because the lemurs alone disperse the seeds of many of the forests' largest hardwoods."

The study builds upon nearly a decade of collaborative work by Dunham and lead author Onja Razafindratsima at the island nation's Ranomafana National Park.

Lemurs mostly eat fruit, and for many of the largest trees in Madagascar, lemurs are the only animals large enough to ingest the seeds of their fruit. By dispersing seeds throughout the forest in their scat, lemurs serve as the unwitting gardeners of these large canopy trees.

In earlier work, Razafindratsima meticulously tracked 24 groups of lemurs for three years and showed that the seeds of one species of canopy tree had a 300 percent greater chance of sprouting and becoming a sapling when they were dispersed by lemurs as opposed to simply falling to the ground.

"That work and other studies have suggested that lemur loss is likely to reduce regeneration of trees that rely on lemurs for seed dispersal," Dunham said. "In the latest study, we wanted to take a broader approach to understanding how the forest might change with lemur loss."

In 2016, Rice undergraduate Anecia Gentles joined Dunham's research group and spent a year examining characteristics of rainforest trees and programming computational models to estimate how the forest would change if lemurs disappeared. Rice graduate student Andrea Drager also joined the effort, and the team showed that lemurs are not only important as gardeners of the forest but also likely play an important role in forest carbon sequestration.

Malagasy rainforest [Credit: A. Dunham]

"We found that lemurs are the primary seed dispersers of the largest canopy trees," said Gentles, who graduated from Rice in May. "The models suggested that the loss of lemurs and the trees they disperse could lead to increasing abundances of smaller, fast-growing tree species with lighter wood."

Dunham said, "The biggest trees in Madagascar are dense hardwoods that grow more slowly but also store more carbon. They also tend to have the biggest seeds."

The team used trait measurements from more than 7,000 trees of nearly 300 species. The data were collected as part of the Tropical Ecology Assessment and Monitoring (TEAM) Network, a yearslong effort led by study co-authors Jean-Claude Razafimahaimodison and Claude Ralazampirenena, Malagasy scientists from the Centre ValBio, a research station at Ranomafana National Park.

"We used TEAM Network data, new data and previously published data on animal seed dispersal in the park to make models that show what would happen if lemur-dispersed trees started disappearing and were replaced by trees whose seeds are dispersed by birds, the wind or other methods less affected by human activities," Dunham said.

The models explored how the makeup of the forests might change in different scenarios ranging from one in which lemur-dispersed trees declined by 25 percent to an extreme case where all lemur-dispersed trees were wiped out.

"There still would be a forest, but the makeup of trees would be quite different, and the forest's ability to sequester carbon would be greatly diminished," Dunham said. "For example, in the case where all lemur-dispersed trees disappear from just one hectare of forest, a patch of 2 1/2 acres, the average loss of above-ground biomass is 24 metric tons -- or almost 53,000 pounds."

She said the findings have implications for initiatives like the United Nations' REDD program, which incentivizes carbon sequestration through forest conservation.

"The goal of such programs is to preserve forests, because there's a lot of carbon in the biomass of trees," Dunham said. "At the same time, tropical forest ecosystems globally are threatened by the loss of large fruit-eating animals, and there's growing evidence that we need to think more holistically about conserving functioning ecosystems in order to save forests.

"For Malagasy forests, our study connects the dots and shows that integrated forest protection and lemur conservation are required in order to maximize carbon-storage potential," she said.

Author: Jade Boyd | Source: Rice University [July 02, 2018]