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News Article | April 19, 2017
Site: www.chromatographytechniques.com

An analysis of the microscopic wear on the teeth of the legendary "man-eating lions of Tsavo" reveals that it wasn't desperation that drove them to terrorize a railroad camp in Kenya more than a century ago. "Our results suggest that preying on people was not the lions' last resort, rather, it was simply the easiest solution to a problem that they confronted," said Larisa DeSantis, assistant professor of earth and environmental studies at Vanderbilt University. The study, which she performed with Bruce Patterson, MacArthur Curator of Mammals at The Field Museum of Natural History in Chicago, is described in a paper titled "Dietary behavior of man-eating lions as revealed by dental microwear textures" published online Apr. 19 by the journal Scientific Reports. "It's hard to fathom the motivations of animals that lived over a hundred years ago, but scientific specimens allow us to do just that," said Patterson, who has studied the Tsavo lions extensively. "Since The Field Museum preserves these lions' remains, we can study them using techniques that would have been unimaginable a hundred years ago." In order to shed light on the lion's motivations, DeSantis employed state-of-the-art dental microwear analysis on the teeth of three man-eating lions from the Field Museum's collection: the two Tsavo lions and a lion from Mfuwe, Zambia which consumed at least six people in 1991. The analysis can provide valuable information about the nature of animal's diet in the days and weeks before its death. DeSantis and Patterson undertook the study to investigate the theory that prey shortages may have driven the lions to man-eating. At the time, the Tsavo region was in the midst of a two-year drought and a rinderpest epidemic that had ravaged the local wildlife. If the lions were desperate for food and scavenging carcasses, the man-eating lions should have dental microwear similar to hyenas, which routinely chew and digest the bones of their prey. "Despite contemporary reports of the sound of the lion's crunching on the bones of their victims at the edge of the camp, the Tsavo lion's teeth do not show wear patterns consistent with eating bones," said DeSantis. "In fact, the wear patterns on their teeth are strikingly similar to those of zoo lions that are typically provisioned with soft foods like beef and horsemeat." The study provides new support for the proposition that dental disease and injury may play a determining role in turning individual lions into habitual man eaters. The Tsavo lion which did the most man-eating, as established through chemical analysis of the lions' bones and fur in a previous study, had severe dental disease. It had a root-tip abscess in one of its canines--a painful infection at the root of the tooth that would have made normal hunting impossible. "Lions normally use their jaws to grab prey like zebras and buffalos and suffocate them," Patterson explained. "This lion would have been challenged to subdue and kill large struggling prey; humans are so much easier to catch." The diseased lion's partner, on the other hand, had less pronounced injuries to its teeth and jaw--injuries that are fairly common in lions which are not man eaters. According to the same chemical analysis, it consumed a lot more zebras and buffalos, and far fewer people, than its hunting companion. The fact that the Mfuwe lion also had severe structural damage to its jaw provides additional support for the role of dental problems in triggering man-eating behavior, as do a number of reports of man-eating incidents by tigers and leopards in colonial India that cite similar infirmities, the researchers pointed out. "Our data suggests that these man-eating lions didn't completely consume the carcasses of their human or animal prey," said DeSantis. "Instead, people appear to have supplemented their already diverse diet. Anthropological evidence suggests that humans have been a regular item on the menu of not only lions, but also leopards and the other great cats. Today, lions seldom hunt people but as human populations continue to grow and the numbers of prey species decline, man-eating may increasingly become a viable option for many lions."


News Article | April 19, 2017
Site: phys.org

"Our results suggest that preying on people was not the lions' last resort, rather, it was simply the easiest solution to a problem that they confronted," said Larisa DeSantis, assistant professor of earth and environmental studies at Vanderbilt University. The study, which she performed with Bruce Patterson, MacArthur Curator of Mammals at The Field Museum of Natural History in Chicago, is described in a paper titled "Dietary behavior of man-eating lions as revealed by dental microwear textures" published online Apr. 19 by the journal Scientific Reports. "It's hard to fathom the motivations of animals that lived over a hundred years ago, but scientific specimens allow us to do just that," said Patterson, who has studied the Tsavo lions extensively. "Since The Field Museum preserves these lions' remains, we can study them using techniques that would have been unimaginable a hundred years ago." In order to shed light on the lion's motivations, DeSantis employed state-of-the-art dental microwear analysis on the teeth of three man-eating lions from the Field Museum's collection: the two Tsavo lions and a lion from Mfuwe, Zambia which consumed at least six people in 1991. The analysis can provide valuable information about the nature of animal's diet in the days and weeks before its death. DeSantis and Patterson undertook the study to investigate the theory that prey shortages may have driven the lions to man-eating. At the time, the Tsavo region was in the midst of a two-year drought and a rinderpest epidemic that had ravaged the local wildlife. If the lions were desperate for food and scavenging carcasses, the man-eating lions should have dental microwear similar to hyenas, which routinely chew and digest the bones of their prey. "Despite contemporary reports of the sound of the lion's crunching on the bones of their victims at the edge of the camp, the Tsavo lion's teeth do not show wear patterns consistent with eating bones," said DeSantis. "In fact, the wear patterns on their teeth are strikingly similar to those of zoo lions that are typically provisioned with soft foods like beef and horsemeat." The study provides new support for the proposition that dental disease and injury may play a determining role in turning individual lions into habitual man eaters. The Tsavo lion which did the most man-eating, as established through chemical analysis of the lions' bones and fur in a previous study, had severe dental disease. It had a root-tip abscess in one of its canines—a painful infection at the root of the tooth that would have made normal hunting impossible. "Lions normally use their jaws to grab prey like zebras and buffalos and suffocate them," Patterson explained. "This lion would have been challenged to subdue and kill large struggling prey; humans are so much easier to catch." The diseased lion's partner, on the other hand, had less pronounced injuries to its teeth and jaw—injuries that are fairly common in lions which are not man eaters. According to the same chemical analysis, it consumed a lot more zebras and buffalos, and far fewer people, than its hunting companion. The fact that the Mfuwe lion also had severe structural damage to its jaw provides additional support for the role of dental problems in triggering man-eating behavior, as do a number of reports of man-eating incidents by tigers and leopards in colonial India that cite similar infirmities, the researchers pointed out. "Our data suggests that these man-eating lions didn't completely consume the carcasses of their human or animal prey," said DeSantis. "Instead, people appear to have supplemented their already diverse diet. Anthropological evidence suggests that humans have been a regular item on the menu of not only lions, but also leopards and the other great cats. Today, lions seldom hunt people but as human populations continue to grow and the numbers of prey species decline, man-eating may increasingly become a viable option for many lions." Explore further: Upper Paleolithic humans may have hunted cave lions for their pelts More information: Larisa R. G. DeSantis et al, Dietary behaviour of man-eating lions as revealed by dental microwear textures, Scientific Reports (2017). DOI: 10.1038/s41598-017-00948-5


News Article | May 3, 2017
Site: www.eurekalert.org

Climate plays a key role in determining what animals can live where. And while human-induced climate change has been causing major problems for wildlife as of late, changes in the Earth's climate have impacted evolution for millions of years--offering tantalizing clues into how to protect animals facing climate change today. In a new paper in Ecology and Evolution, scientists have delved into the effects of Ice Age climate change upon the evolution of tiny, hand-standing skunks. "By analyzing western spotted skunk DNA, we learned that Ice Age climate change played a crucial role in their evolution," says lead author Adam Ferguson, Collections Manager of Mammals at The Field Museum in Chicago and affiliate of Texas Tech University. "Over the past million years, changing climates isolated groups of spotted skunks in regions with suitable abiotic conditions, giving rise to genetic sub-divisions that we still see today." Western spotted skunks are really stinkin' cute-- at two pounds, they're smaller than the striped Pepe Le Pew variety, their coats are an almost maze-like pattern of black and white swirls, and when they spray, they often do a hand-stand, hind legs and fluffy tail in the air as they unleash smelly chemicals to ward off predators. They're found throughout the Western US and Mexico, in a wide variety of climates-- they thrive everywhere from Oregon's temperate rainforests to the Sonoran, the hottest desert in Mexico. There are three genetic sub-groups, called clades, of western spotted skunks. Often, clades develop when a species is split up by geography. If a species is separated by, say, a mountain range, the groups on either side of the mountain may wind up splitting off from each other genetically. However, the division of the skunks into three clades doesn't seem to have been driven solely by geographical barriers-- populations separated by mountains are more or less genetically identical. Instead, the skunks vary genetically from one historic climate region to another, due to Ice Age climate change. "Western spotted skunks have been around for a million years, since the Pleistocene Ice Age," explains Ferguson. "During the Ice Age, western North America was mostly covered by glaciers, and there were patches of suitable climates for the skunks separated by patches of unsuitable climates. These regions are called climate refugia. When we analyzed the DNA of spotted skunks living today, we found three groups that correspond to three different climate refugia." "That means that for spotted skunk evolution, climate change appears to have been a more important factor than geographical barriers," says Ferguson. In the study, scientists used DNA samples from 97 skunks from a variety of regions and climates in the American Southwest. Upon sequencing the DNA, the scientists were surprised to see that the skunks split into three clades based on pockets of suitable climate present during the Pleistocene. "Small carnivores like skunks haven't been well-studied when it comes to historical climate change," says Ferguson. "We know how small mammals like rodents respond to changing climates, and we know how bigger carnivores like wolves respond, but this study helps bridge the gap between them." Ferguson also notes that skunks don't deserve the bad rap they get. "Skunks are a really interesting family of North American carnivores-- they're well-known, but not well-studied. And studying them comes with a cost-- they stink, even their tissues stink, and you run the risk of getting sprayed. But they're important to their ecosystems-- for example, they eat insects and rodents that damage our crops," he says. Moreover, Ferguson says, the study can illuminate the bigger picture of biodiversity in the face of climate change-- an issue that grows increasingly relevant as human-driven climate change affects more and more of the world's animals. "What we know about the past can inform what we expect to see in the future," says Ferguson. "Understanding these genetic subdivisions that happened as a result of changing climatic conditions can help us conserve skunks and other animals in the future." Before working at The Field Museum, Adam Ferguson was affiliated with Texas Tech University and completed this research there. Ferguson's co-authors are affiliated with Angelo State University, the National Museum of Natural History, the National Zoological Park, the US Fish and Wildlife Service, and the University of New Mexico.


"By analyzing western spotted skunk DNA, we learned that Ice Age climate change played a crucial role in their evolution," says lead author Adam Ferguson, Collections Manager of Mammals at The Field Museum in Chicago and affiliate of Texas Tech University. "Over the past million years, changing climates isolated groups of spotted skunks in regions with suitable abiotic conditions, giving rise to genetic sub-divisions that we still see today." Western spotted skunks are really stinkin' cute— at two pounds, they're smaller than the striped Pepe Le Pew variety, their coats are an almost maze-like pattern of black and white swirls, and when they spray, they often do a hand-stand, hind legs and fluffy tail in the air as they unleash smelly chemicals to ward off predators. They're found throughout the Western US and Mexico, in a wide variety of climates— they thrive everywhere from Oregon's temperate rainforests to the Sonoran, the hottest desert in Mexico. There are three genetic sub-groups, called clades, of western spotted skunks. Often, clades develop when a species is split up by geography. If a species is separated by, say, a mountain range, the groups on either side of the mountain may wind up splitting off from each other genetically. However, the division of the skunks into three clades doesn't seem to have been driven solely by geographical barriers— populations separated by mountains are more or less genetically identical. Instead, the skunks vary genetically from one historic climate region to another, due to Ice Age climate change. "Western spotted skunks have been around for a million years, since the Pleistocene Ice Age," explains Ferguson. "During the Ice Age, western North America was mostly covered by glaciers, and there were patches of suitable climates for the skunks separated by patches of unsuitable climates. These regions are called climate refugia. When we analyzed the DNA of spotted skunks living today, we found three groups that correspond to three different climate refugia." "That means that for spotted skunk evolution, climate change appears to have been a more important factor than geographical barriers," says Ferguson. In the study, scientists used DNA samples from 97 skunks from a variety of regions and climates in the American Southwest. Upon sequencing the DNA, the scientists were surprised to see that the skunks split into three clades based on pockets of suitable climate present during the Pleistocene. "Small carnivores like skunks haven't been well-studied when it comes to historical climate change," says Ferguson. "We know how small mammals like rodents respond to changing climates, and we know how bigger carnivores like wolves respond, but this study helps bridge the gap between them." Ferguson also notes that skunks don't deserve the bad rap they get. "Skunks are a really interesting family of North American carnivores— they're well-known, but not well-studied. And studying them comes with a cost— they stink, even their tissues stink, and you run the risk of getting sprayed. But they're important to their ecosystems— for example, they eat insects and rodents that damage our crops," he says. Moreover, Ferguson says, the study can illuminate the bigger picture of biodiversity in the face of climate change— an issue that grows increasingly relevant as human-driven climate change affects more and more of the world's animals. "What we know about the past can inform what we expect to see in the future," says Ferguson. "Understanding these genetic subdivisions that happened as a result of changing climatic conditions can help us conserve skunks and other animals in the future." Before working at The Field Museum, Adam Ferguson was affiliated with Texas Tech University and completed this research there. Ferguson's co-authors are affiliated with Angelo State University, the National Museum of Natural History, the National Zoological Park, the US Fish and Wildlife Service, and the University of New Mexico. Explore further: Study finds climate, landscape changes may lead to more rabid skunks


News Article | April 20, 2017
Site: www.gizmag.com

Colonel John Patterson, who shot the two Tsavo man-eaters and wrote a book about them, posing with one of the lions (Credit: The Field Museum of Natural History) In 1898, in what served as the inspiration for the movie The Ghost and the Darkness, a pair of lions in Kenya killed and devoured about 135 railway workers building the Kenya-Uganda Railway before being shot by project leader Lieutenant-Colonel John Henry Patterson. Now known as the man-eating lions of Tsavo, the reason why the animals developed a taste for human flesh has been a mystery, but microscopic analysis of their remains by a Vanderbilt University team puts the blame on bad teeth. The construction of the railway linking Uganda with the Indian Ocean would be of little interest outside of railway buff circles if it hadn't been for the frightening events of March through December of 1898. During that time, the British were building a bridge for the line over the Tsavo River, but two male lions started to stalk the Indian workmen, attacking them and dragging them off to be eaten. Despite attempts to frighten the lions off, trap them, or build defenses against them, the death toll mounted until Patterson managed to hunt down and shoot the killers. The remains of the lions eventually ended up the the Chicago Field Museum of Natural History, where they are on display, but why these animals started to attack humans instead of their normal prey was never determined. Until now, the favored theory was that a severe drought and a rinderpest epidemic had so deprived the lions of food that they were reduced to scavenging and then attacking the railway camp. However, modern science has provided another explanation. "It's hard to fathom the motivations of animals that lived over a hundred years ago, but scientific specimens allow us to do just that," says Bruce Patterson, MacArthur Curator of Mammals. "Since The Field Museum preserves these lions' remains, we can study them using techniques that would have been unimaginable a hundred years ago." Larisa DeSantis, assistant professor of earth and environmental studies at Vanderbilt University, took the skulls of the Tsavo lions, plus a third man eater from Mfuwe, Zambia that ate six people in 1991, and used state-of-the-art dental microwear analysis to examine the wear patterns on their teeth. What they found was that the lions didn't show any evidence that they had been consuming normal prey in the time before their death, nor were they scavenging. If they had, their teeth would have shown the distinct pattern caused by gnawing and breaking bones. Instead, the wear patterns resembled those of zoo lions, which usually eat soft foods like beef and horsemeat. In addition, Patterson and DeSantis say that previous chemical analysis of the Tsavo lions' remains indicates that they suffered from severe dental disease and one had a root-tip abscess in one of its canines. Anyone who's had toothache or a case of gum infection and can't handle a tough steak can sympathize with the animals, who would have found it impossible to catch and kill zebras and buffalos by running them down and suffocating them with their teeth clamped about their prey's windpipe. The team say that the lions probably switched to attacking humans because they were easier to catch and more tender to eat. This is partly supported by the fact that the Tsavo lion with less dental injuries still supplemented its anthropophagous diet with zebras and buffalos. In addition, the Mfume lion showed dental problems, as have written accounts of man-eating lions and leopards in colonial India. "Our data suggests that these man-eating lions didn't completely consume the carcasses of their human or animal prey," says DeSantis. "Instead, people appear to have supplemented their already diverse diet. Anthropological evidence suggests that humans have been a regular item on the menu of not only lions, but also leopards and the other great cats. Today, lions seldom hunt people, but as human populations continue to grow and the numbers of prey species decline, man eating may increasingly become a viable option for many lions." The results were published in Nature: Scientific Reports. The video below discusses the Tsavo Man Eaters.


News Article | April 19, 2017
Site: www.eurekalert.org

In 1898, Lieutenant Colonel John Patterson shot two man-eating lions that killed dozens of workers building a railroad in Tsavo, Kenya. He wrote, "I have a very vivid recollection of one particular night when the brutes seized a man from the railway station and brought him close to my camp to devour. I could plainly hear them crunching the bones, and the sound of their dreadful purring filled the air and rang in my ears for days afterwards." But new research into those lions' teeth suggests that he might have been a little flowery with his words: the man-eaters' teeth don't show the wear and tear you'd expect if they'd been chowing down on bones. "It's hard to fathom the motivations of animals that lived over a hundred years ago, but scientific specimens allow us to do just that," says Bruce Patterson, a co-author of the study in Scientific Reports and MacArthur Curator of Mammals at The Field Museum. (And no, no relation to the Colonel Patterson who shot the lions. The lions themselves have a claim to fame, though--their story was popularized in three Hollywood movies, including the 1996 film The Ghost and the Darkness.) "Since The Field Museum preserves these lions' remains, we can study them using techniques that would have been unimaginable a hundred years ago." In this study, lead author Larisa DeSantis of Vanderbilt University and Patterson investigated a hypothesis suggesting that the Tsavo man-eaters turned to human prey because they couldn't find other food to eat. The region was in the midst of a two-year drought at the end of a viral epidemic that ravaged local wildlife. Some scientists have speculated that prey shortages may have driven the lions to man-eating. The lions' teeth could be the key to determining whether this hypothesis was true. If the teeth showed lots of wear and tear from crunching bones, that would be a sign that pickings were slim enough that the lions had to eat entire carcasses instead of just the fresh meat. DeSantis used dental tools to create molds of the lions' teeth, made casts of them, then examined the microscopic wear (termed dental microwear) on the teeth in 3D, much like a topographic map, and used fractal geometric methods to characterize them. But instead of seeing heavily worn tooth surfaces expected from a bone-heavy diet, the researchers saw the opposite. "The microscopic wear of the lions' teeth were less complex and 'chewed up' than you'd see in an animal that eats lots of bone, like a hyena. Instead, their dental microwear is similar to what you'd see in a zoo lion," says DeSantis. Less complex dental microwear contradict the notion that the lions were so hard up for food that they had to eat humans, including their bones. So why then did these lions eat people? While the dental microwear didn't show bone-crunching wear and tear, the teeth were far from pristine. The Tsavo man-eater who did the most man-eating, as established through chemical analysis of the lions' bones and fur in a previous study, had severe dental disease. It had a root-tip abscess in one of its canines-- a painful infection at the root of the tooth that would have made normal hunting impossible. "Lions normally use their jaws to grab prey like zebras and wildebeests and suffocate them," explains Patterson. "This lion would have been challenged to subdue and kill large, struggling prey, and humans are so much easier to catch." It's still not clear why the lions weren't consuming the bones of their human prey. It could be that dental disease rendered them physically unable to do so, or perhaps it's because the human victims' remains were reclaimed at dawn by their fellow workers before the lions could further scavenge the carcasses. Either way, it's likely that dental disease played a major role in this unusual spate of man-eating. "It's remarkably rare for lions to attack people, but it's catastrophic when it happens," says Patterson. "When a big, dangerous predator becomes incapacitated, there's a real danger for this kind of behavior--no animal will let itself starve to death if there's another option." This paper marks the latest development in a century-long quest to figure out what led the Tsavo lions to kill humans. "There's an endless fascination with these lions. The Tsavo man-eaters were the only lions ever mentioned by the British parliament, when the British were inconvenienced by construction delays. The lions stopped the British Empire in its tracks at the height of its power," says Patterson. "We humans like to think we're at the top of the food chain, but the moment we step off our paved streets, these other animals are really on top."


Although several late Cretaceous sauropod colonial nesting sites have been discovered nearly on every continent during the last few decades, no studies have been performed to determine the factors that underpinned the choice of these specific sites. Here, we report the first definitive evidence of a group of sauropods that nested repetitively and purposely at a Cretaceous hydrothermal site at Sanagasta, La Rioja Province, Argentina. The discovery of this new colonial nesting locality shows nest fidelity over a long time, and a symbiotic relationship between egg clutches and a peculiar hydrothermal environment that favoured their incubation. Sedimentary and geochemical analyses of 80 clutches and their large eggs with thick eggshells substantiate that the Sanagasta sauropods were specifically using the soil moisture and thermoradiance to incubate their eggs, similar to a few extant species, namely, the megapode, Megapodius pritchardii, which is known to lay its egg clutches in burrows at volcanically heated nesting grounds.


Rieppel O.,The Field Museum
Cladistics | Year: 2013

The reconstruction of the evolutionary history of animal phyla was an integral part of Othenio Abel's paleobiology (paleozoology). Abel took issue with those phylogeneticists who, following the lead of Haeckel, would draw up phylogenetic trees on the basis of transformation series of singular characters considered to be of particular importance. Abel highlighted Louis Dollo's principle of the chevauchement des spécialisations (crossing of specializations), which transformed phylogenetics from a search for ancestor-descendant sequences to research into relative degrees of relationships. This replacement resolved the conflict, much discussed at the time, between the continuity of ancestor-descendant lineages and the discontinuity inherent in the natural (phylogenetic) system. Walter Zimmermann refined Abel's methodology, which he called character-phylogenetics (Merkmalsphylogenie), an approach that was eventually adopted by Willi Hennig. © The Willi Hennig Society 2012.


Rieppel O.,The Field Museum
Cladistics | Year: 2011

The German tradition of considering species, and higher taxonomic entities, as individuals begins with the temporalization of natural history, thus pre-dating Darwin's 'Origin' of 1859. In the tradition of German Naturphilosophie as developed by Friedrich Schelling, species came to be seen as parts of a complex whole that encompasses all (living) nature. Species were comprehended as dynamic entities that earn individuality by virtue of their irreversible passage through time. Species individuality was conceived in terms of species taxa forming a spatiotemporally located relational system (complex whole), a conception of species that was easily assimilated to an evolutionary world view. However, the dynamics of an evolutionary process driven by variation and natural selection created a tension between continuity in nature as opposed to the discreteness and relative stasis of species. As a consequence, some authors such as Ernst Haeckel and Karl August Möbius denied the reality of species, while others explicitly linked the reality and individuality of species to their temporal duration. The mature conception of species as individuals, as formulated by Ludwig von Bertalanffy and adopted by Willi Hennig, is one of an historically conditioned, spatiotemporally located, causally integrated, dynamic yet transiently homeostatically stabilized relational system. © The Willi Hennig Society 2011.


Rieppel O.,The Field Museum
Cladistics | Year: 2011

Two formal assumptions implied in Willi Hennig's "phylogenetic systematics" were repeatedly criticized for not being biologically grounded. The first is that speciation is always dichotomous; the second is that the stem-species always goes extinct when its lineage splits into two daughter species. This paper traces the theoretical roots of Hennig's "principle of dichotomy". While often considered merely a methodological principle, Hennig's realist perspective required him to ground the "principle of dichotomy" ontologically in speciation. As a methodological principle, the adherence to a strictly dichotomously structured phylogenetic system allowed Hennig to be unequivocal in character analysis and precise in the rendition of phylogenetic relationships. The ontological grounding of the "principle of dichotomy" in speciation remains controversial, however. This has implications for the application of techniques of phylogeny reconstruction to populations of bisexually reproducing organisms (phylogeography). Beyond that, the "principle of dichotomy" has triggered an intensive debate with respect to phylogeny reconstruction at the prokaryote level. © The Willi Hennig Society 2010.

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