Articles by "Paleontology"
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The relic of King Albert I of Belgium, bought at an auction by VTM journalist Reinout Goddyn: blood-stained tree leaves collected by people living near the forest at the foot of the rocks of Marche-les-Dames. The DNA analysis has confirmed that the blood really belonged to the monarch. Credit: Copyright KU Leuven - Maarten Larmuseau
The relic of King Albert I of Belgium, bought at an auction by VTM journalist Reinout Goddyn: blood-stained tree leaves collected by people living near the forest at the foot of the rocks of Marche-les-Dames. The DNA analysis has confirmed that the blood really belonged to the monarch. Credit: Copyright KU Leuven - Maarten Larmuseau
The death of King Albert I of Belgium in 1934 -- officially a climbing accident -- still fuels speculation. Forensic geneticist Maarten Larmuseau and his colleagues at KU Leuven (University of Leuven, Belgium), have now compared DNA from blood found on the scene in 1934 to that of two distant relatives. Their analysis confirms that the blood really is that of Albert I. This conclusion is at odds with several conspiracy theories about the king's death.

On 17 February 1934, King Albert I -- the third King of the Belgians -- died after a fall from the rocks in Marche-les-Dames, in the Ardennes region of Belgium near Namur. Albert I was popular and world famous due to his role during the First World War. The fact that there were no witnesses to his death soon fuelled speculations about the king's 'real' cause of death.

Conspiracy theories are circulating to this very day, ranging from a political murder to a crime of passion: the king is said to have been murdered elsewhere, his dead body allegedly never was in Marche-les-Dames, or his fall is believed to have been staged only later. Evidence for these theories, however, has never been found.

After the death of Albert I, Marche-les-Dames virtually became a place of pilgrimage, and relics turned up with the king's trails of blood, said to have been collected during the night of 17 to 18 February by people living in the neighbourhood.

VTM journalist Reinout Goddyn, who works for the Flemish television programme Royalty, bought one of these relics: blood-stained tree leaves. He wanted to know if this could really be the blood of Albert I, given the conspiracy theories. In 2014, UGent Professor Dieter Deforce had already confirmed that the blood was definitely human.

Forensic geneticist Maarten Larmuseau and his colleagues from KU Leuven (University of Leuven, Belgium) continued the investigation and found two living relatives of Albert I: "King Simeon II of Saxe-Coburg and Gotha, the last tsar and former prime minister of Bulgaria who is related to Albert I on his father's side, and Anna Maria Freifrau von Haxthausen, a German baroness who is related to Albert I on her mother's side, were willing to cooperate. They gave up DNA samples that we compared with the DNA of the trails of blood. We found that the blood is indeed that of Albert I."

This confirmation has historical importance. "80 years after the fact, everyone involved has passed away, and most material is gone; we will probably never be able to dismiss all speculations concerning this 'cold case'. This study was one of the last possibilities to gather additional data. The authenticity of the trails of blood confirms the official account of the death of Albert I. The story that the dead body of the king has never been in Marche-les-Dames or was only placed there at night has now become very improbable. Furthermore, the results show that conducting a perfect legal investigation at the time was impossible right from the start, because souvenir hunters had disturbed the scene."

This type of genetic family-tree research confronts researchers with quite a few ethical questions, adds bioethicist Pascal Borry from the KU Leuven Interfaculty Centre for Biomedical Ethics and Law: "We have to take into account the consequences of this study for living relatives. After all, in addition to the actual identification, a genetic profile can reveal quite a bit of sensitive information, in the context of a kinship analysis or in terms of hereditary conditions. This particular case concerns someone who's deceased and has obviously never given permission for a genetic profile."

"We only focused on the identification of the trails of blood and deliberately avoided deducing unexpected results from the DNA," Larmuseau continues. "The latter was the most difficult aspect of this study. We also want to protect the privacy of everyone involved and of living relatives, and avoid commercialization of the genetic information, following international guidelines for biomedical research. Therefore, the genetic profiles have not been published, but they were double-checked by independent experts. The DNA samples of our study have been destroyed. What is left of the relic will be entrusted to an institution for cultural heritage or a scientific institution."
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Source:
The above post is reprinted from materials provided by KU Leuven. Note: Materials may be edited for content and length.

Reference:
Maarten H.D. Larmuseau, Bram Bekaert, Maarten Baumers, Tom Wenseleers, Pieter Deforce, Pascal Borry, and Ronny Decorte. Biohistorical materials and contemporary privacy concerns -- The forensic case of King Albert I. Forensic Science International: Genetics, 2016 DOI: 10.1016/j.fsigen.2016.07.008
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Metatarsal (a) and (b) surface rendered models show medullary spongy bone infill and clear focalized cortical destruction near the periosteal margin; also evident on external cortical margin directly abutting malignant neoplasm is the characteristic hair on end bone reaction in (b). Credit: Edward Odes (Wits)
Metatarsal (a) and (b) surface rendered models show medullary spongy bone infill and clear focalized cortical destruction near the periosteal margin; also evident on external cortical margin directly abutting malignant neoplasm is the characteristic hair on end bone reaction in (b). Credit: Edward Odes (Wits)
An international team of researchers led by scientists from the University of the Witwatersrand's Evolutionary Studies Institute and the South African Centre for Excellence in PalaeoSciences today announced in two papers, published in the South African Journal of Science, the discovery of the most ancient evidence for cancer and bony tumors yet described in the human fossil record.

The discovery of a foot bone dated to approximately 1.7 million years ago from the site of Swartkrans with definitive evidence of malignant cancer, pushes the oldest date for this disease back from recent times into deep prehistory. Although the exact species to which the foot bone belongs is unknown, it is clearly that of a hominin, or bipedal human relative.

In an accompanying paper appearing in the same journal, a collaborating team of scientists identify the oldest tumor ever found in the human fossil record, a benign neoplasm found in the vertebrae of the well-known Australopithecus sediba child, Karabo from the site of Malapa, and dated to almost two million years in age. The oldest previously demonstrated possible hominin tumor was found in the rib of a Neanderthal and dated to around 120,000 years old.

Edward Odes, a Wits doctoral candidate and lead author of the cancer paper, and co-author on the tumor paper, notes "Modern medicine tends to assume that cancers and tumors in humans are diseases caused by modern lifestyles and environments. Our studies show the origins of these diseases occurred in our ancient relatives millions of years before modern industrial societies existed."

The cancer in a foot bone, a metatarsal, was identified as an osteosarcoma, an aggressive form of cancer which usually affects younger individuals in modern humans, and, if untreated typically results in early death. "Due to its preservation, we don't know whether the single cancerous foot bone belongs to an adult or child, nor whether the cancer caused the death of this individual, but we can tell this would have affected the individuals' ability to walk or run," says Dr Bernhard Zipfel, a Wits scientist and an expert on the foot and locomotion of early human relatives. "In short, it would have been painful."

Lead author of the tumor paper and co-author of the cancer paper, Dr Patrick Randolph-Quinney of Wits University and the University of Central Lancashire in the UK, suggests "The presence of a benign tumor in Australopithecus sediba is fascinating not only because it is found in the back, an extremely rare place for such a disease to manifest in modern humans, but also because it is found in a child. This, in fact, is the first evidence of such a disease in a young individual in the whole of the fossil human record."

Prof. Lee Berger, an author on both papers and leader of the Malapa project where the fossil vertebra was found adds "not only has there been an assumption that these sorts of cancers and tumors are diseases of modernity, which these fossils clearly demonstrate they are not, but that we as modern humans exhibit them as a consequence of living longer, yet this rare tumor is found in a young child. The history of these types of tumors and cancers is clearly more complex than previously thought."

Both incidents of disease were diagnosed using state of the art imaging technologies including those at the European Synchrotron Research Facility in Grenoble, France, medical CT at the Charlotte Maxeke Hospital in Johannesburg, and the micro-CT facility at the Nuclear Energy Corporation of South Africa at Pelindaba.

"Researchers in South Africa are at the forefront of using various X-Ray modalities to discover new and interesting facts about ancient human relatives," notes Dr Jacqueline Smilg, a radiologist based at Charlotte Maxeke Hospital, who is an author on both papers and was involved in the clinical diagnoses. "This is another good example of how the modern clinical sciences and the science of palaeoanthropology are working together in South Africa and with international collaborators to advance our understanding of diseases in both the past and the present."

Source:
The above post is reprinted from materials provided by University of the Witwatersrand. 

References:
  • Lee R. Berger, Paul Tafforeau, Tanya Augustine, Edward J. Odes, Steven E. Churchill, Jacqueline S. Smilg, Marc R. Meyer, Maryna Steyn, Scott A. Williams, Patrick S. Randolph-Quinney. Osteogenic tumour in Australopithecus sediba: Earliest hominin evidence for neoplastic disease. South African Journal of Science, 2016; Volume 112 (Number 7/8) DOI: 10.17159/sajs.2016/20150470
  • Lee R. Berger, Ryan D. Franklin, Jakobus W. Hoffman, Frikkie de Beer, Tanya N. Augustine, Bernhard Zipfel, Jacqueline S. Smilg, Zach Throckmorton, Maryna Steyn, Patrick S. Randolph-Quinney, Edward J. Odes. Earliest hominin cancer: 1.7-million-year-old osteosarcoma from Swartkrans Cave, South Africa. South African Journal of Science, 2016; Volume 112 (Number 7/8) DOI: 10.17159/sajs.2016/20150471
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Illustration showing size comparison of Australian marsupials including new extinct species of carnivorous marsupial, Whollydooleya tomnpatrichorum, from New Riversleigh fossil site in Queensland. Credit: Illustration: Karen Black/UNSW
Illustration showing size comparison of Australian marsupials including new extinct species of carnivorous marsupial, Whollydooleya tomnpatrichorum, from New Riversleigh fossil site in Queensland. Credit: Illustration: Karen Black/UNSW
A new species of extinct flesh-eating marsupial that terrorised Australia's drying forests about 5 million years ago has been identified from a fossil discovered in remote northwestern Queensland.

The hypercarnivore, which is thought to have weighed about 20 to 25 kilograms, is a distant and much bigger cousin of Australia's largest living, flesh-eating marsupial, the Tasmanian Devil, which weighs in at about 10 kilogram.

Named Whollydooleya tomnpatrichorum, it is the first creature to be formally identified from a range of strange new animals whose remains have been found in a recently discovered fossil site in Queensland dubbed 'New Riversleigh'.

A description of the new marsupial, based on its fossil molar tooth, is published in the Memoirs of Museum Victoria.

"W. tomnpatrichorum had very powerful teeth capable of killing and slicing up the largest animals of its day," says study lead author UNSW Professor Mike Archer.

The late Miocene period between about 12 and 5 million years ago, when Australia began to dry out and the megafauna began to evolve, is one of the most mysterious and least well-understood periods in the continent's past. Fossils of land animals from this period are extremely rare, because of the increasing aridity.

"Fortunately, in 2012, we discovered a whole new fossil field that lies beyond the internationally famous Riversleigh World Heritage Area fossil deposits in north-western Queensland," says Professor Archer.

"This exciting new area - New Riversleigh - was detected by remote sensing using satellite data."

With the help of ARC funding and a grant from the National Geographic Society, Professor Archer and his colleagues began to systematically explore New Riversleigh in 2013.

The new species' highly distinctive molar was one of the first fossil teeth obtained from a particularly fossil-rich site in the area which was discovered by team member Phil Creaser and named Whollydooley Hill in honour of his partner and Riversleigh volunteer Genevieve Dooley.

"New Riversleigh is producing the remains of a bevy of strange new small to medium-sized creatures, with Whollydooleya tomnpatrichorum, the first one to be described," says Professor Archer.

"These new discoveries are starting to fill in a large hole in our understanding about how Australia's land animals transformed from being small denizens of its ancient wet forests to huge survivors on the second most arid continent on Earth."

Team member UNSW Professor Suzanne Hand says medium to large-sized Australian Late Miocene animals have previously been known from fossil deposits in the Northern Territory, such as at Alcoota.

"But those deposits give almost no information about the small to medium-sized mammals that existed at the same time, which generally provide more clues about the nature of prehistoric environments and climates," Professor Hand says.

Team member and UNSW postdoctoral researcher in palaeontology, Dr Karen Black, adds: "The small to medium-size mammals from the New Riversleigh deposits will reveal a great deal about how Australia's inland environments and animals changed between 12 and 5 million years ago - a critical time when increasing dryness ultimately led to the Ice Ages of the Pleistocene."

The Whollydooley Site deposit provides other exciting clues about how the environment was changing. For example, it contains the first signs of wind-blown sand grains, which are absent from the older Riversleigh World Heritage deposits.

And the teeth of the other animals in this deposit are unusual for Riversleigh, because they are more worn down. This suggests that the foods animals were eating in the late Miocene were perhaps tougher, more drought-resistant plants, and there was more abrasive dust in the environment.

"Although Whollydooleya terrorized the drying forests around 5 million years ago, its own days were numbered," says Archer.

"While it was at least distantly related to living and recently living carnivorous marsupials such as Devils, Thylacines and Quolls, it appears to have represented a distinctive subgroup of hypercarnivores that did not survive into the modern world.

"Climate change can be a merciless eliminator of the mightiest of mammals," he says.
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Source:
The above post is reprinted from materials provided by University of New South Wales.

Reference:
Archer, M.; Christmas, O.; Hand, S.J.; Black, K.H.; Creaser, P.; Godthelp, H.; Graham, I.; Cohen, D.; Arena, D.A.; Anderson, C.; Soares, G.; Machin, N.; Beck, R.M.D.; Wilson, L.A.B.; Myers, T.J.; Gillespie, A.K.; Khoo, B., and Travouillon, K.J. Earliest known record of a hypercarnivorous dasyurid (Marsupialia), from newly discovered carbonates beyond the Riversleigh World Heritage Area, north Queensland. Memoirs of Museum Victoria, July 2016
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Paleoparadoxia (left: Desmostylia, Paenungulata) and Ambulocetus (right: Cetacea, Cetartiodactyla) in two different ways of reconstructions -- top: terrestrial/semi-aquatic; bottom: obligate aquatic. Credit: Fujiwara
Paleoparadoxia (left: Desmostylia, Paenungulata) and Ambulocetus (right: Cetacea, Cetartiodactyla) in two different ways of reconstructions -- top: terrestrial/semi-aquatic; bottom: obligate aquatic. Credit: Fujiwara
Despite the extensive fossil record of mammals, it is often difficult to use fossil data to reconstruct the lifestyles and habitats of extinct species. The fact that some species spent all or part of their time underwater, respectively similar to modern-day whales and seals, further complicates this.

Konami Ando and Shin-chi Fujiwara, researchers at Nagoya University, addressed this by developing a new index for predicting if a species lived its entire life in the water. The index is based on how the ribs must be relatively strong for an animal to walk or crawl over land, but not for it to swim. After establishing the index via measurements of living terrestrial, semiaquatic, and exclusively aquatic species, Ando and Fujiwara used it to predict that some extinct species could not have supported themselves on land.

Although mammals originally evolved as terrestrial organisms, cladistics shows that some returned to aquatic lives, and that this sometimes occurred independently. Examples include whales, dolphins, and manatees, which never leave the water, and seals and hippopotamuses, which split time between land and water. Studies of fossils of extinct species also suggest some species spent all or some of their time in the water. However, inability to use fossil records alone to determine a species' lifestyle has made this hard to confirm.

In their study, reported in the Journal of Anatomy, Ando and Fujiwara analyzed rib cages and their resistance to vertical compression in a range of mammalian species. This important factor represents an animal's ability to support its body weight against gravity while walking or crawling; a trait aquatic organisms do not need. The researchers investigated 26 modern-day terrestrial, semiaquatic, and exclusively aquatic species, including the killer whale, polar bear, dugong, giraffe, and hippopotamus. They used their data to establish an index for differentiating between groups with different habitats. They then applied the index to four extinct mammalian species, all of which had retained their four limbs but showed signs of having been partially or completely aquatic, to shed light on their potential lifestyles.

"We selected mammals with different habitats from a range of taxa and analyzed fossils for which the bones in the thoracic region were well-preserved," Fujiwara says. "We focused on the fracture loads of ribs. We found the sum of the fracture loads of all true ribs directly connected to the sternum divided by the body weight effectively separated the extant species groups by habitat. Exclusively aquatic species were clearly differentiated."

After establishing that the index could correctly classify living species with known habitats and lifestyles, the researchers applied it to extinct groups: Ambulocetus, an early ancestor of whales, and three desmostylian species, which are the keens of elephants and sea cows. This was to confirm or reject earlier hypotheses about these groups' lifestyles, which were based on other morphological findings.

"Our index lets us conclude that Ambulocetus and two desmostylians (Paleoparadoxia and Neoparadoxia) could not have supported themselves on land; they were exclusively aquatic," Ando says. "But the findings were inconclusive for the third desmostylian (Desmostylus). We may need to perform additional studies on the intermediate group of semiaquatic species, include a bone density variable in our model, or improve our data on the body mass of extinct species to refine the index."

The new index should help in both reconstructing the lifestyles and habitats of extinct mammals and clarifying anatomical changes associated with mammals shifting to a life partly or exclusively in the water.
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Source:
The above post is reprinted from materials provided by Nagoya University.

Reference:
Konami Ando, Shin-ichi Fujiwara. Farewell to life on land - thoracic strength as a new indicator to determine paleoecology in secondary aquatic mammals. Journal of Anatomy, 2016; DOI: 10.1111/joa.12518

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This is a skull and body reconstruction of the new dinosaur species, Murusraptor barrosaensis. Credit: Coria et al (2016); CCAL
This is a skull and body reconstruction of the new dinosaur species, Murusraptor barrosaensis. Credit: Coria et al (2016); CCAL
A new species of megaraptorid dinosaur discovered in Patagonia may help discern the evolutionary origins of the megaraptorid clade, according to a study published July 20, 2016 in the open-access journal PLOS ONE by Rodolfo Coria from the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina, and Phillip Currie from the University of Alberta, Canada.

The Patagonian region of Argentina has previously proven to be rich in fossils from the Late Cretaceous epoch, including a number of megaraptorids, a clade whose carnivorous diet gave rise to their name meaning 'giant thieves'. These medium-sized theropod dinosaurs, including South American genera Megaraptor, Orkoraptor, and Aerosteon as well as genera from Australia and Japan, have characteristically large claws and air-filled, birdlike bones.

The fossilized partial skeleton of a megaraptorid dinosaur analyzed in this study was discovered in Sierra Barrosa, in northwest Patagonia and represents one of the most complete megaraptorids found, with an unusually intact braincase. With unique skull features, the dinosaur, which they named Murusraptor barrosaensis, is a new species in the megaraptorid clade. This specimen appears to be immature, but the authors suggest that the species is larger and slenderer than Megaraptor and comparable in size with Aerosteon and Orkoraptor. While sharing many features with the other species, Musuraptor has distinctive facial features not previously seen amongst megaraptorids, as well as unusually shaped hip bones.

While phylogenetic analysis could not clearly determine evolutionary relationships, the authors note that these fossils provide new anatomical information which might help to resolve current debates as to whether the megaraptorids are a clade of the allosauroid or the coelurosaurid theropods.

As lead author Rodolfo Coria states: "A new meat-eating dinosaur, Murusraptor barrosaensis, has been discovered from 80 million years old rocks from Patagonia, Argentina. Although incomplete, the beautifully preserved bones of Murusraptor unveil unknown information about the skeletal anatomy of megaraptors, a highly specialized group of Mesozoic predators."
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Source:
The above post is reprinted from materials provided by PLOS.

Reference:
Rodolfo A. Coria, Philip J. Currie. A New Megaraptoran Dinosaur (Dinosauria, Theropoda, Megaraptoridae) from the Late Cretaceous of Patagonia. PLOS ONE, 2016; 11 (7): e0157973 DOI: 10.1371/journal.pone.0157973

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A specimen of the newly identified fossil species Ticinolepis crassidens (above) and of the species Ticinolepis longaeva. Credit: Adriana López-Arbarello
A specimen of the newly identified fossil species Ticinolepis crassidens (above) and of the species Ticinolepis longaeva. Credit: Adriana López-Arbarello
A new study of fossil fishes from Middle Triassic sediments on the shores of Lake Lugano provides new insights into the recovery of biodiversity following the great mass extinction event at the Permo-Triassic boundary 240 million years ago.

The largest episode of mass extinction in the history of the Earth, which led to the demise of about 90% of marine organisms and a majority of terrestrial species, took place between the Late Permian and Early Triassic, around 240 million years ago. How long it took for biological communities to recover from such a catastrophic loss of biodiversity remains the subject of controversial debate among paleontologists. A new study of fossil fishes from Middle Triassic strata on the shores of Lake Lugano throws new light on the issue.

The study, undertaken by researchers led by Dr. Adriana López-Arbarello, who is a member of the GeoBiocenter at Ludwig-Maximilians-Universitaet (LMU) in Munich and the Bavarian State Collection for Paleontology and Geology, suggests that the process of recovery was well underway within a few million years. The authors, including Dr. Heinz Furrer of Zurich University and Dr. Rudolf Stockar of the Museo Cantonale di Storia Naturale in Lugano, who led the excavations at the sites, and Dr. Toni Bürgin of the Naturmuseum St. Gallen report their findings in the journal PeerJ.

The fossil fishes analyzed by López-Arbarello and her colleagues originate from Monte San Giorgio in the canton Ticino in Switzerland, which is one of the most important sources of marine fossils from the Middle Triassic in the world. The Monte San Giorgio rises to an altitude of 1000 m on the promontory that separates the southern arms of Lake Lugano in the Southern Swiss Alps. But in the Middle Triassic, it was part of a shallow basin dotted with islands fringed by lagoons, which were separated by reefs from the open sea. "

The particular significance of its fossil fauna lies in the careful stratigraphic work that has accompanied the excavations here. The positions of each of the fossil finds discovered here have been documented to the centimeter," says Adriana López-Arbarello. On the basis of detailed anatomical studies of new material and a taxonomic re-evaluation of previously known specimens from the locality, she and her colleagues have identified a new genus of fossil neopterygians, which they name Ticinolepis. The Neopterygii include the teleost fishes, which account for more than half of all extant vertebrate species. However, the new fossil species are assigned to the second major group of neopterygians, the Holostei, of which only a handful of species survives today. The researchers assign two new fossil species to the genus Ticinolepis, namely T. longaeva and T. crassidens, which occur in different sedimentary beds within the so-called Besano Formation on Monte San Giorgio.

The two species coexisted side by side but they occupied distinct ecological niches. T. crassidens fed on mollusks and was equipped with jaws and teeth that could handle their hard calcareous shells. T. longaeva was more of a generalist, and was found in waters in which T. crassidens could not survive. The authors interpret the different distribution patterns as a reflection of changing environmental conditions following the preceding mass extinction event. The less specialized T. longaeva was able to exploit a broader range of food items, and could thus adapt more flexibly to fluctuating conditions. On the other hand, the dietary differentiation between the two species indicates that a variety of well-established ecosystems was available in the Besano Formation at this time. "This in turn suggests that the marine biota is likely to have recovered from the great mass extinction relatively quickly," Adriana López-Arbarello concludes.
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Source:
The above post is reprinted from materials provided by Ludwig-Maximilians-Universität München.

Reference:
Adriana López-Arbarello, Toni Bürgin, Heinz Furrer, Rudolf Stockar. New holostean fishes (Actinopterygii: Neopterygii) from the Middle Triassic of the Monte San Giorgio (Canton Ticino, Switzerland). PeerJ, 2016; 4: e2234 DOI: 10.7717/peerj.2234
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A slab of rock from a study site in Nevada harbors many specimens of Metabolograptus extraordinarius, a shallow-water graptolite species, which together with some close relatives, replaced all the formerly dominant species following the end-Ordovician mass extinction. Credit: Charles E. Mitchell
A slab of rock from a study site in Nevada harbors many specimens of Metabolograptus extraordinarius, a shallow-water graptolite species, which together with some close relatives, replaced all the formerly dominant species following the end-Ordovician mass extinction. Credit: Charles E. Mitchell
A new study of nearly 22,000 fossils finds that ancient plankton communities began changing in important ways as much as 400,000 years before massive die-offs ensued during the first of Earth's five great extinctions.

The research, published July 18 in the Early Edition of the Proceedings of the National Academy of Sciences, focused on large zooplankton called graptolites. It suggests that the effects of environmental degradation can be subtle until they reach a tipping point, at which dramatic declines in population begin.

"In looking at these organisms, what we saw was a disruption of community structures -- the way in which the plankton were organized in the water column. Communities came to be less complex and dominated by fewer species well before the massive extinction itself," says co-author H. David Sheets, PhD, professor of physics at Canisius College and associate research professor in the Evolution, Ecology and Behavior graduate program at the University at Buffalo.

This turmoil, occurring in a time of ancient climate change, could hold lessons for the modern world, says co-author Charles E. Mitchell, PhD, professor of geology in the University at Buffalo College of Arts and Sciences.

The shifts took place at the end of the Ordovician Period some 450 million years ago as the planet transitioned from a warm era into a cooler one, leading eventually to glaciation and lower sea levels.

"Our research suggests that ecosystems often respond in stepwise and mostly predictable ways to changes in the physical environment -- until they can't. Then we see much larger, more abrupt, and ecologically disruptive changes," Mitchell says. "The nature of such tipping point effects are hard to foresee and, at least in this case, they led to large and permanent changes in the composition of the oceans' living communities.

"I think we need to be quite concerned about where our current ocean communities may be headed or we may find ourselves at the tail end of a similar event -- a sixth mass extinction, living in a very different world than we would like."

The study was a partnership between Canisius, UB, St. Francis Xavier University, Dalhousie University and The Czech Academy of Sciences.

A long slide toward oblivion

In considering mass extinction, there is perhaps the temptation to think of such events as rapid and sudden: At one moment in history, various species are present, and the next they are not.

This might be the conclusion you'd draw if you examined only whether different species of graptolites were present in the fossil record in the years immediately preceding and following the Ordovician extinction.

"If you just looked at whether they were present -- if they were there or not -- they were there right up to the brink of the extinction," Sheets says. "But in reality, these communities had begun declining quite a while before species started going extinct."

The research teased out these details by using 21,946 fossil specimens from areas of Nevada in the U.S. and the Yukon in Canada that were once ancient sea beds to paint a picture of graptolite evolution.

The analysis found that as ocean circulation patterns began to shift hundreds of thousands of years before the Ordovician extinction, graptolite communities that previously included a rich array of both shallow- and deep-sea species began to lose their diversity and complexity.

Deep-water graptolites became progressively rarer in comparison to their shallow-water counterparts, which came to dominate the ocean.

"There was less variety of organisms, and the rare organisms got rarer," Sheets says. "In the aftermath of a forest fire in the modern world, you might find that there are fewer organisms left -- that the ecosystem just doesn't have the same structure and richness as before. That's the same pattern we see here."

The dwindling deep-sea graptolites were species that specialized in obtaining nutrients from low-oxygen zones of the ocean. A decrease in the availability of such habitats may have sparked the creatures' decline, Sheets and Mitchell say.

"Temperature changes drive deep ocean circulations, and we think the deep-water graptolites lost their habitats as the climate changed," Sheets says. "As the nature of the oceans shifted, their way of life went away."
***

Source:
The above post is reprinted from materials provided by University at Buffalo. The original item was written by Charlotte Hsu.

Reference:
H. David Sheets, Charles E. Mitchell, Michael J. Melchin, Jason Loxton, Petr Štorch, Kristi L. Carlucci, Andrew D. Hawkins. Graptolite community responses to global climate change and the Late Ordovician mass extinction. Proceedings of the National Academy of Sciences, 2016; 201602102 DOI: 10.1073/pnas.1602102113
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Great Blue Heron (Ardea herodias) flying. Credit: © Yuval Helfman / Fotolia
Great Blue Heron (Ardea herodias) flying. Credit: © Yuval Helfman / Fotolia
Research by post-doctoral fellow Alexander Dececchi challenges long-held hypotheses about how flight first developed in birds. Furthermore, his findings raise the question of why certain species developed wings long before they could fly.

Dr. Dececchi, a William E. White Post-Doctoral Fellow in the Department of Geological Sciences and Geological Engineering, used measurements from fossil records and data from modern birds to test the evolutionary explanation for the origin of birds. Dr. Dececchi and his colleagues determined that none of the previously predicted methods would have allowed pre-avian dinosaurs to take flight.

"By disproving the idea that the predicted models led to the development of flight, our research is a step towards determining how flight developed and whether it can evolve once or developed multiple times in different evolutionary lines," he says.

Dr. Dececchi and his colleagues examined 45 specimens, representing 24 different non-avian theropod species, as well as five bird species. After determining some critical variables from the fossils -- such as body mass and wing size -- they used measurements from living birds to estimate wing beat, flap angle and muscular output.

These values were used to build a model for different behaviours linked to the origins of flight such as vertical leaping and wing-assisted incline running (WAIR) -- a method of evasion for many ground-based modern birds that has become a favoured pathway towards the origin of flapping flight in the paleontological literature. They also tested if any species met the requirements to take-off from the ground and fly under their own power.

"We know the dimensions and we know how modern birds muscles and anatomy work," Dr. Dececchi says. "Using our model, if a particular species doesn't reach the minimum thresholds for function seen in the much more derived birds -- such as the ability to take off or to generate a certain amount of power -- it's safe to say they would not have been able to perform these behaviours or fly."

The researchers found that none of the behaviours met the criteria expected in the pathway models. In fact, they found that almost all the behaviours had little or no benefit, outside of those species which evolved right before the origin of birds. When looking at WAIR specifically -- the method that has been touted as an explanation for some early wing adaptations -- the researchers found that it only was possible in a handful of large winged, small bodied species such as Microraptor, but found no evidence to suggest its use was widespread.

Dr. Dececchi says that the group's findings suggest that wings, even those with large or ornately coloured feathers, could have initially served different purposes rather than flying such as signaling or sexual selection before the development of flight.

Dr. Dececchi explains that the question of whether flight evolved once or multiple times in multiple evolutionary tracks is an ongoing topic of debate. Many of the species studied lived tens of millions of years and thousands of miles apart, with a last common ancestor that existed 50 or 100 million years earlier -- leading researchers to wonder if flight evolved once but was lost, or if different species stumbled upon the same solution.

"There is some evidence that they evolved in parallel -- there may be some differences in the details between how each taxon flew, but they tend to converge on these same answers," says Dr. Dececchi. "That, to me, is one of the most exciting questions that has come out of the past few decades of work in theropods."
***

Source:
The above post is reprinted from materials provided by Queen's University.

Reference:
T. Alexander Dececchi, Hans C.E. Larsson, Michael B. Habib. The wings before the bird: an evaluation of flapping-based locomotory hypotheses in bird antecedents. PeerJ, 2016; 4: e2159 DOI: 10.7717/peerj.2159
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Neanderthal depiction (stock image). Neanderthals lived in the Middle Paleolithic, the middle period of the Old Stone Age. This period encompasses the time from roughly 200,000 to 40,000 before our times. Credit: © procy_ab / Fotolia
Neanderthal depiction (stock image). Neanderthals lived in the Middle Paleolithic, the middle period of the Old Stone Age. This period encompasses the time from roughly 200,000 to 40,000 before our times. Credit: © procy_ab / Fotolia
Neanderthals once populated the entire European continent. Around 45,000 years ago, Homo neanderthalensis was the predominant human species in Europe. Archaeological findings show that there were also several settlements in Germany. However, the era of the Neanderthal came to an end quite suddenly.

Based on an analysis of the known archaeological sites, Professor Jürgen Richter from Collaborative Research Center 806 -- Our Way to Europe, in which the universities of Cologne, Bonn and Aachen cooperate, comes to the conclusion that Neanderthals reached their population peak right before their population rapidly declined and they eventually became extinct.

Neanderthals lived in the Middle Paleolithic, the middle period of the Old Stone Age. This period encompasses the time from roughly 200,000 to 40,000 before our times. In his article published in the Quaternary International Journal, Richter comes to the conclusion that more than 50 percent of the known Neanderthal settlement sites in Germany can be dated to the Middle Paleolithic. More precisely, they date back 60,000 to 43,000 years before our times. Thus, the Neanderthal population peak seems to lie in this period.

The number of sites, their analysis and the analysis of the artefacts found at these settlements indicate that the Neanderthal population in Germany was subject to extreme demographic fluctuations. During the Middle Paleolithic, there appear to have been several migrations, population increase and decline, extinction in certain areas and then a return of settlers to these areas.

While for the time period between 110,000 to 70,000 years ago there are only four known settlement sites, in the following period from 70,000 to 43,000 years ago there are ninety-four. In less than 1,000 years after this demographic peak, however, there was a rapid decline and the Neanderthal disappeared from the scene. Precisely why the species died out is still unclear. Perhaps it was due to low genetic diversity, perhaps to the rise of Homo sapiens. This question will continue to occupy scientists.
***

Source:
The above post is reprinted from materials provided by University of Cologne - Universität zu Köln.

Reference:
Jürgen Richter. Leave at the height of the party: A critical review of the Middle Paleolithic in Western Central Europe from its beginnings to its rapid decline. Quaternary International, 2016; DOI: 10.1016/j.quaint.2016.01.018
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Global climate change caused by soot aerosol at the K-Pg boundary. Credit: Kunio Kaiho
Global climate change caused by soot aerosol at the K-Pg boundary. Credit: Kunio Kaiho
A new hypothesis on the extinction of dinosaurs and ammonites at the end of the Cretaceous Period has been proposed by a research team from Tohoku University and the Japan Meteorological Agency's Meteorological Research Institute.

The researchers believe that massive amounts of stratospheric soot ejected from rocks following the famous Chicxulub asteroid impact, caused global cooling, drought and limited cessation of photosynthesis in oceans. This, they say, could have been the process that led to the mass extinction of dinosaurs and ammonites.

The asteroid, also known as the Chicxulub impactor, hit Earth some 66 million years ago, causing a crater more than 180 km wide. It's long been believed that that event triggered the mass extinction that led to the macroevolution of mammals and the appearance of humans.

Tohoku University Professor Kunio Kaiho and his team analyzed sedimentary organic molecules from two places -- Haiti, which is near the impact site, and Spain, which is far. They found that the impact layer of both areas have the same composition of combusted organic molecules showing high energy. This, they believe, is the soot from the asteroid crash.

Soot is a strong, light-absorbing aerosol, and Kaiho's team came by their hypothesis by calculating the amount of soot in the stratosphere estimating global climate changes caused by the stratospheric soot aerosols using a global climate model developed at the Meteorological Research Institute. The results are significant because they can explain the pattern of extinction and survival.

While it is widely accepted that the Chicxulub impact caused the mass extinction of dinosaurs and other life forms, researchers have been stumped by the process of how. In other words, they'd figured out the killer, but not the murder weapon.

Earlier theories had suggested that dust from the impact may have blocked the sun, or that sulphates may have contaminated the atmosphere. But researchers say it is unlikely that either phenomenon could have lasted long enough to have driven the extinction.

The new hypothesis raised by Kaiho's team says that soot from hydrocarbons had caused a prolonged period of darkness which led to a drop in atmospheric temperature. The team found direct evidence of hydrocarbon soot in the impact layers and created models showing how this soot would have affected the climate.

According to their study, when the asteroid hit the oil-rich region of Chicxulub, a massive amount of soot was ejected which then spread globally. The soot aerosols caused colder climates at mid-high latitudes, and drought with milder cooling at low latitudes on land. This in turn led to the cessation of photosynthesis in oceans in the first two years, followed by surface-water cooling in oceans in subsequent years.

This rapid climate change is believed to be behind the loss of land and marine creatures over several years, suggesting that rapid global climate change can and did play a major role in driving extinction.

Kaiho's team is studying other mass extinctions in the hopes of further understanding the processes behind them.
***

Source:
The above post is reprinted from materials provided by Tohoku University.

Reference:
Kunio Kaiho, Naga Oshima, Kouji Adachi, Yukimasa Adachi, Takuya Mizukami, Megumu Fujibayashi, Ryosuke Saito. Global climate change driven by soot at the K-Pg boundary as the cause of the mass extinction. Scientific Reports, 2016; 6: 28427 DOI: 10.1038/srep28427
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Image of the cave discoveries. Credit: University of Leicester
Image of the cave discoveries. Credit: University of Leicester
A project led by archaeologists from the British Museum and the University of Leicester has discovered remarkable evidence which shows how the first generations of Europeans to arrive in the Americas engaged with indigenous peoples and their spiritual beliefs deep inside the caves of a remote Caribbean island.

Recent fieldwork by a collaborative Anglo-Puerto Rican* team has uncovered new evidence in the Caribbean of an early religious dialogue between Europeans and Native Americans.

A large collection of early colonial inscriptions and commentaries written by named individuals within a cave system of pre-existing indigenous spiritual iconography provides dramatic new insights into the tone and personal context of this momentous time of encounter.

In a paper, published in Antiquity, researchers have provided new understandings about the formation of emergent cultural identities in the Caribbean that challenge historic accounts of indigenous extinction.

The island of Mona, on a key Atlantic route from Europe to the Americas, was at the heart of sixteenth-century Spanish colonial projects and was recorded by Christopher Columbus on his second voyage in AD 1494.

Communities on the island were exposed to the earliest waves of European impact during a critical period of transformation and the forging of new identities.

A team of researchers led by Dr Jago Cooper (British Museum) and Dr Alice Samson (University of Leicester) has been studying the island -- which is one of the most cavernous regions, per square kilometre, in the world.

The team, which has just completed its 2016 season, includes students from Puerto Rico and the UK carrying out dissertations in Climate Science, Archaeology, and History.

Since 2013, exploration and survey of around 70 cave systems -- part of an interdisciplinary study of past human activity on Mona Island -- has revealed that Mona's caves include the greatest diversity of preserved indigenous iconography in the Caribbean, with thousands of motifs recorded in darkzone chambers far from cave entrances.

In the astonishing cave discussed in this paper more than 30 historic inscriptions include named individuals, phrases in Latin and Spanish, dates and Christian symbols that occur within a series of connecting chambers all within the area of indigenous iconography.

This account of spiritual encounters provides a rare, personalised insight into intercultural religious dynamics in the early Americas.

Dr Alice Samson from the University of Leicester School of Archaeology and Ancient History said: "Increasing use of interdisciplinary approaches and archaeometric analyses have provided new understandings of colonial processes that are more nuanced than mere oppression, domination and, in the case of the Caribbean, indigenous extinction.

"This not only provides a counterpoint to official metropolitan histories, but also tracks the beginnings of new religious engagements and transforming cultural identities in the Americas."

Dr Jago Cooper from the British Museum added: "This research reveals a new perspective on the personal encounter between indigenous populations and the first generations of Europeans in the Americas.

"This is a unique site that helps us to understand the origins of cultural identity in the Americas, the start of a process that continues right up to the modern day."

*The British Museum, the School of Archaeology and Ancient History, University of Leicester, US Coastal Cave Survey , the Puerto Rican Ministry of Natural Resources and Environment, Institute of Puerto Rican Culture, Centre of Advanced Studies of Puerto Rico and the Caribe, and University of Puerto Rico.
***

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The above post is reprinted from materials provided by University of Leicester.
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A bonobo, formerly called a pygmy chimpanzee, is eating fruit in the Democratic Republic of the Congo. Bonobos, chimps, gorillas and humans have all evolved their own gut microbes based on an ancestral gut flora in our most recent common ancestor. Credit: Alexander Georgiev photo, courtesy of Science
A bonobo, formerly called a pygmy chimpanzee, is eating fruit in the Democratic Republic of the Congo. Bonobos, chimps, gorillas and humans have all evolved their own gut microbes based on an ancestral gut flora in our most recent common ancestor. Credit: Alexander Georgiev photo, courtesy of Science
For all the anxiety today about the bacteria in our gut being under constant assault by antibiotics, stress and bad diets, it turns out that a lot of the bacteria in our intestines have been with us for at least 15 million years, since we were pre-human apes.

A new comparison of the gut microbiomes of humans, chimps (our closest ancestor), bonobos and gorillas shows that the evolution of two of the major families of bacteria in these apes' guts exactly parallels the evolution of their hosts.

This shows that the microbes in our guts are determined in part by our evolutionary history, not just external factors like diet, medicine and geography. Obesity, cancer and some inflammatory diseases, such as diabetes and Crohn's disease, have been linked to imbalances in the mix of microbes in our stomach and intestines.

"We are showing that some human gut bacteria are the direct descendants of gut bacteria that lived within our common ancestors with apes," said lead researcher Andrew Moeller, a Miller Postdoctoral Fellow in UC Berkeley's Museum of Vertebrate Zoology. "It shows there has been an unbroken line of inheritance or transfer from one generation to another for millions of years, since the dawn of African apes."

Moeller is beginning to assemble a snapshot of the microbes in the guts of our ancient ape ancestor -- in essence, a paleo gut that fit our paleo diet -- and hopes to go even further back in time if, as seems likely, all mammals have evolved their unique microbiota from a common ancestral population in the distant past.

"We now have samples from all the major groups of mammals, and we're working on tracing the evolution of the microbiome all the way back to when we were tiny carnivorous creatures 100 million years ago," he said.

Moeller and his African and American colleagues, including corresponding author Howard Ochman at the University of Texas at Austin, will publish their findings in the July 22 issue of Science.

"It's surprising that our gut microbes, which we could get from many sources in the environment, have actually been co-evolving inside us for such a long time," said Ochman, who noted that the microbes were passed down over hundreds of thousands of host generations.

Microbes are us

The importance of the human microbiome -- the microbes that live on our skin, in our bodily orifices and in our intestines -- has become evident over the past decade as scientists have sequenced the microbial populations from healthy and unhealthy people, from newborns to seniors, and of peoples around the world. There are about as many microbial cells in our body as our own cells, and they appear to be transmitted from mother to child during birth and continually altered by the home environment, type of diet, medications and even the family pet. Gut bacteria, in particular, guide the early development of our intestines, train our immune systems to fight pathogens and may even affect our moods and behavior.

"We know that gut bacteria are really integrated with our biology, and this reseach gives us a framework for investigating how that has come to be," Moeller said.

Most researchers studying the gut microbiota of humans or animals have identified the specific microbes present based on a distinctive bit of DNA that codes for a piece of RNA in the bacterial ribosome, which manufactures proteins. This piece of DNA, called the 16S subunit of ribosomal RNA, does not change quickly over time, however, so it gives a very coarse timeline for the evolution of bacteria. Its slow rate of change does not allow researchers to determine which individual bacterial strains -- different variants of the same species -- are present, only the genus and sometimes species.

Moeller and his colleagues decided, instead, to look at a more rapidly evolving gene that varies even in different strains of bacteria, allowing them to identify individual bacterial strains. The gene, called gyrase B, codes for a variable subunit of the DNA gyrase protein, which helps DNA coil and uncoil.

He and his colleagues obtained feces from 24 gorillas living in Cameroon, 47 chimpanzees from Gombe National Park in Tanzania, 24 wild bonobos from the Democratic Republic of the Congo and 16 people from Connecticut. They isolated bacterial DNA from these samples, amplified the DNA of the gyrase B genes present and catalogued the variations within three major bacterial families to create a microbiome family tree for three families of bacteria -- Bacteroidaceae, Bifidobacteriaceae and Lachnospiraceae -- that together comprise about 20 percent of all the microbes in the human gut, including both bacteria and their cousins, the Archaea.

Only bacteria in the Bacteroidaceae and Bifidobacteriaceae families showed cospeciation with their ape hosts, with gut microbial diversity lowest in humans and highest in gorillas.

"Once we calibrated the molecular clock, we were able to date the split of human and chimp bacteria at around 5.3 million years ago, and the human-gorilla gut bacteria split at around 15.6 million years ago, which are roughly in line with what we know from fossil and genomic data of the hosts," Moeller said. "It is one more line of evidence that gut bacteria have cospeciated with humans."

"In a way, host speciation is like continental drift: When two continents drift apart, whole biotas begin to diverge," Moeller said. "Here, as the hosts are splitting, a good chunk of their microbiota is also splitting and diversifying."

The third bacterial family tree, the Lachnospiraceae, was more complicated. There were apparently at least four times when these bacteria were transferred between different host species. The researchers speculate that because these bacteria form spores and can thus survive outside their hosts for long periods, they were easily passed between species.

"We have shown that the microbiome is a composite of microbial lineages, some that have cospeciated with us, and some that have been passed around from one host species to another," he said.

They also looked at the microbial metagenomes of Africans from Malawi, and saw distinct differences between the African and the U.S. human microbiota, with some lineages seeminly lost by Americans.

"It will be interesting in the future to do a full study of human populations using this strain-level method to see whether we can use bacteria to reconstruct the history of human migrations," he said.
***

Source:
The above post is reprinted from materials provided by University of California - Berkeley. The original item was written by Robert Sanders.

Reference:
Andrew H. Moeller, Alejandro Caro-Quintero, Deus Mjungu, Alexander V. Georgiev, Elizabeth V. Lonsdorf, Martin N. Muller, Anne E. Pusey, Martine Peeters, Beatrice H. Hahn, Howard Ochman. Cospeciation of gut microbiota with hominids. Science, 2016 DOI: 10.1126/science.aaf3951
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Analysis of rocks unearthed in Oman that were formed in an ancient ocean around the time of Earth's greatest mass extinction have helped explain why life on Earth took so long to recover. Credit: D. Astratti
Analysis of rocks unearthed in Oman that were formed in an ancient ocean around the time of Earth's greatest mass extinction have helped explain why life on Earth took so long to recover. Credit: D. Astratti
Scientists have shed light on why life on Earth took millions of years to recover from the greatest mass extinction of all time.

The study provides fresh insight into how Earth's oceans became starved of oxygen in the wake of the event 252 million years ago, delaying the recovery of life by five million years.

Findings from the study are helping scientists to better understand how environmental change can have disastrous consequences for life on Earth.

The Permian-Triassic Boundary extinction wiped out more than 90 per cent of marine life and around two thirds of animals living on land. During the recovery period, Earth's oceans became starved of oxygen -- conditions known as anoxia.

Previous research suggested the mass extinction and delayed recovery were linked to the presence of anoxic waters that also contained high levels of harmful compounds known as sulphides.

However, researchers say anoxic conditions at the time were more complex, and that this toxic, sulphide-rich state was not present throughout all the world's oceans.

The team, led by researchers at the University of Edinburgh, used precise chemical techniques to analyse rocks unearthed in Oman that were formed in an ancient ocean around the time of the extinction.

Data from six sampling sites, spanning shallow regions to the deeper ocean, reveal that while the water was lacking in oxygen, toxic sulphide was not present. Instead, the waters were rich in iron.

The finding suggests that iron-rich, low oxygen waters were a major cause of the delayed recovery of marine life following the mass extinction.

The study also shows how oxygen levels varied at different depths in the ocean. While low oxygen levels were present at some depths and restricted the recovery of marine life, shallower waters contained oxygen for short periods, briefly supporting diverse forms of life.

The precise cause of the long recovery period remains unclear, but increased run-off from erosion of rocks on land -- caused by high global temperatures -- likely triggered anoxic conditions in the oceans, researchers say.

The study, published in the journal Nature Communications, was funded by the Natural Environment Research Council and the International Centre for Carbonate Reservoirs. The work is a contribution to the UNESCO International Geoscience Programme. It was carried out in collaboration with the Universities of Leeds, Gratz, Bremen and Vienna University.

Dr Matthew Clarkson, of the University of Edinburgh's School of GeoSciences, who led the study, said: "We knew that lack of oxygen in the oceans played a key role in the extinction and recovery processes, but we are still discovering how exactly it was involved. Our findings about the chemistry of the ocean at the time provide us with a clearer picture of how this complex process delayed the recovery of life for so long."

Professor Simon Poulton, of the University of Leeds, who co-authored the study, said: "The neat point about this study is that it shows just how critical an absence of oxygen, rather than the presence of toxic sulphide, was to the survival of animal life. We found that marine organisms were able to rapidly recolonise areas where oxygen became available."
***

Source:
The above post is reprinted from materials provided by University of Edinburgh.

Reference:
M. O. Clarkson, R. A. Wood, S. W. Poulton, S. Richoz, R. J. Newton, S. A. Kasemann, F. Bowyer, L. Krystyn. Dynamic anoxic ferruginous conditions during the end-Permian mass extinction and recovery. Nature Communications, 2016; 7: 12236 DOI: 10.1038/ncomms12236
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Calcite tests of extinct species of planktonic foraminifera from the Eocene epoch (>34 million years) of Tanzania. The largest is less than a millimetre in size.
Calcite tests of extinct species of planktonic foraminifera from the Eocene epoch (>34 million years) of Tanzania. The largest is less than a millimetre in size. Credit: Image courtesy of Paul N. Pearson, Cardiff University
The number of species that can exist on Earth depends on how the environment changes, according to new research led by the University of Southampton.

By analysing the fossil record of microscopic aquatic creatures called planktonic foraminifera, whose fossil remains now resemble miniaturised popcorn and date back millions of years, the research provided the first statistical evidence that environmental changes put a cap on species richness.

Lead author of the study, published in the journal Ecology Letters, Dr Thomas Ezard, an evolutionary ecologist at the University of Southampton, said: "While the idea of infinite species on a finite Earth is clearly fanciful, the relevance of upper limits to diversity is still a fractious debate amongst evolutionary biologists, ecologists and palaeontologists.

"We are the first to show statistically that this upper limit is environmentally dependent. It's intuitive that a changing environment alters how many species we see -- the spatial gradient of more species in the tropics than at the poles is pervasive evidence for its large-scale impact.

"However, analyses of how species numbers have changed over time have assumed that any limit has always been the same, even through periods of massive climate upheaval. Our data reject this idea of fixed rules for competition among species and instead show that the limit to the number of species that can co-exist on Earth is much more dynamic. Climate and geology are always changing, and the limit changes with them."

While previous research typically focused individually on either biological, climate change or geological explanations, this new research examined the co-dependence of these factors on how species interact.

Looking at the fossil history of 210 evolutionary species of macroperforate planktonic foraminifera in the Cenozoic Era from 65 million years ago to the present, the study found that the number of species was almost certainly controlled by competition among themselves and probably kept within a finite upper limit.

Dr Ezard added: "We used mathematical models to reveal how environmental changes influence both the rate of diversification among species and how many species can co-exist at once. Our results suggest that the world is full of species, but that the precise fullness varies through time as environmental changes alter the outcome of competition among species."

The study also involved Professor Andy Purvis from the Natural History Museum. He said: "Scientists have long argued that environmental changes are likely to impact the number of species that can co-exist on Earth, but the fossil record is usually too incomplete for powerful statistical testing. Microfossils -- especially planktonic foraminifera -- give us a record with almost no gaps. It's this complete evolutionary history that lets us decide between these different hypotheses of how species interacted millions of years ago."
***

Source:
The above post is reprinted from materials provided by University of Southampton.

Reference:
Thomas H. G. Ezard, Andy Purvis. Environmental changes define ecological limits to species richness and reveal the mode of macroevolutionary competition. Ecology Letters, 2016; DOI: 10.1111/ele.12626
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