These shrew-sized, early Jurassic mammals were thought to have been confined to the ecological margins, eating whatever insects they could find. However, this was also the time when new mammal characteristics – such as better hearing and teeth capable of precise chewing – were developing. So, if the earliest mammals were all small generalized insectivores, where was the competition driving the evolution of such features?
To answer this question, the researchers studied fossils of these early mammals found in Glamorgan, South Wales which 200 million years ago consisted of a series of small islands in a shallow continental sea.
By analysing jaw mechanics and fossil teeth, the team were able to determine that two of the earliest mammals, Morganucodon and Kuehneotherium, were not generalized insectivores but had already evolved specialised diets, feeding on distinct types of insects.
Lead author, Dr Pamela Gill of the University of Bristol said: “None of the fossils of the earliest mammals have the sort of exceptional preservation that includes stomach contents to infer diet, so instead we used a range of new techniques which we applied to our fossil finds of broken jaws and isolated teeth. Our results confirm that the diversification of mammalian species at the time was linked with differences in diet and ecology.”
The team used synchrotron X-rays and CT scanning to reveal in unprecedented detail the internal anatomy of these tiny jaws, which are only 2cm in length. As the jaws are in many pieces, the scans were ‘stitched together’ to make a complete digital reconstruction. Finite element modelling, the same technique used to design hip joints and bridges, was used to perform a computational analysis of the strength of the jaws. This showed that Kuehneotherium and Morganucodon had very different abilities for catching and chewing prey.
Using an analysis previously carried out on the teeth of present-day, insect-eating bats, the researchers found that the teeth of Morganucodon and Kuehneotherium had very different patterns of microscopic pits and scratches, known as ‘microwear’. This indicated they were eating different things with Morganucodon favouring harder, crunchier food items such as beetles while Kuehneotherium selected softer foods such as scorpion flies which were common at the time.
Professor Mark Purnell of the University of Leicester said: “This is the first time that tooth wear patterns have been used to analyse the diet of mammals this old. That their tooth wear compares so closely to bats that specialise on different kinds of insects gives us really strong evidence that these early mammals were not generalists when it came to diet, but were quite definite in their food choices.”
Team leader, Professor Emily Rayfield from the University of Bristol added: “This study is important as it shows for the first time that the features that make us unique as mammals, such as having only one set of replacement teeth and a specialised jaw joint and hearing apparatus, were associated with the very earliest mammals beginning to specialise their teeth and jaws to eat different things.”
Scientists who study tuberculosis have long debated its origins. New research shows that tuberculosis likely spread from humans in Africa to seals and sea lions that brought the disease to South America and transmitted it to Native people there before Europeans landed on the continent.
The paper, “Pre-Columbian Mycobacterial Genomes Reveal Seals as a Source of New World Human Tuberculosis,” was published in Nature.
“We found that the tuberculosis strains were most closely related to strains in pinnipeds, which are seals and sea lions,” said researcher Anne Stone, Arizona State University School of Human Evolution and Social Change professor. Stone and Johannes Krause of the University of Tubingen in Germany are co-principal investigators on the project. Research teams from the Wellcome Trust Sanger Institute in the United Kingdom and the Swiss Institute for Tropical and Public Health were collaborators on the study.
“What we found was really surprising. The ancient strains are distinct from any known human-adapted tuberculosis strain,” Stone added.
Modern strains of tuberculosis currently circulating are most closely related to those found in Europe, and there was a complete replacement of the older strains when European disease reached the Americas during the age of exploration. Researchers found that genomes from humans in Peru dating from about 1,000 year ago provide unequivocal evidence that a member of the tuberculosis strain caused disease in South America before Europeans arrived, so the question among the scientists was, “What types of tuberculosis strains were present before contact?”
“The age of exploration is a time when people are moving really long distances around the world and coming into contact with others. It’s a time when a lot of disease spread,” Stone said. “This opens up a lot of new questions. It fits the bioarcheological evidence that shows the oldest evidence for tuberculosis in South America.”
“The connection to seals and sea lions is important to explain how a mammalian-adapted pathogen that evolved in Africa around 6,000 years ago could have reached Peru 5,000 years later,” Krause said.
In the study, researchers collected genetic samples from throughout the world and tested those for tuberculosis DNA while utilizing advances in technology during the past five years that enable more accurate genome capture from ancient samples. Of 76 DNA samples from New World pre- and post-contact sites, three from Peru around 750 to 1350 AD had tuberculosis DNA that could be used. The researchers then focused on these three samples and used array-based capture to obtain and map the complete genome.
These were compared against a larger dataset of modern genomes and animal strains. Research results showed the clear relationship to animal lineages, specifically seals and sea lions.
“Our results show unequivocal evidence of human infection caused by pinnipeds (sea lions and seals) in pre-Columbian South America. Within the past 2,500 years, the marine animals likely contracted the disease from an African host species and carried it across the ocean to coastal people in South America,” Stone said.
Africa has the most diversity among tuberculosis strains, implying that the pathogen likely originated from the continent and spread. After tuberculosis was established in South America, it may have moved north and infected people in North America before European settlers brought new strains in.
“We hypothesize that when the more virulent European strains came, they quickly replaced the pinniped strains,” Stone said.
“It was a surprise for all of us to find that tuberculosis, formerly believed to have spread around the world with ancient human migration events, is in fact a relatively young disease,” said Kelly Harkins, one of the study’s first authors and recent doctoral graduate from ASU’s Center for Bioarchaeological Research.
“A compelling prospect for future research will be to determine the relationship of these older forms to those currently circulating, and those isolated from other ancient remains,”said Kirsten Bos, postdoctoral fellow at the University of Tuebingen and another first author on the study.
Study implications include a greater understanding of the speed and process of adaptation when a disease changes hosts. This is especially of interest when considering diseases that are transmitted between species – MERS, SARS and HIV – and how these are spread, Stone added.
“Tuberculosis is a disease that is on the rise again worldwide. This study and further research will help us understand how the disease is transmitted and how the disease may evolve,” said Jane Buikstra, a collaborator on the study who identified tuberculosis in most of the cases utilized in the research. Buikstra is an ASU Regents’ Professor and Director of the Center for Bioarchaeological Research.
Snails were widespread in the Late Pleistocene and Holocene, but it is still unknown when and how they were incorporated into human diets. The authors of this study found land snail shell remains from ~30,000 years ago at a recently discovered site in Cova de la Barriada, Spain.
To better understand if the inhabitants may have eaten snails, the researchers investigated patterns of land snail selection, consumption, and accumulation at the site, and then analyzed the shells’ decay, fossilization process, composition, and age at death by measuring the shell size.
Scientists found groupings of complete shells from a large land snail species at three areas of the site, corresponding to different time points ~30,000 years ago.
The adult snails were close to prehistoric human-constructed structures that may have been used to cook the snails, along with stone tools, and other animal remains that were likely roasted in ambers of pine and juniper at 375 C.
The authors posit that these results point to previously undiscovered patterns of invertebrate use and may highlight a broadening of the human diet in the Upper Paleolithic in the Mediterranean basin. In neighboring Mediterranean areas, eating land snails didn’t appear until about 10,000 years later, which may make these newly found snail shells the oldest known evidence that ancient human populations used them as a food resource in Europe ~30,000 years ago.
But despite this, two millenia after he bestrode the world, his mausoleum lies in disrepair under piles of rubbish while his celebrated stables, only discovered five years ago, are to be reburied due to lack of funds.
There’s a rich agenda of special and extravagant events in Rome as it celebrates the 2000th anniversary of the death of Augustus. The city is packed with cultural events, from special exhibitions to the re-enactment of ancient Roman rites. But the restoration of these important monuments are a step too far – one that simply can’t be afforded.
The mausoleum of Augustus is the monument that should be a star of the celebrations. Their restoration works, which are part of a larger project that aims to convert the square surrounding the monument into a pedestrian area, began in 2006, but have been interrupted for years. The work was a project of the local government and the negligence of the city council appears to be the cause of the progressive degradation of the area. Rubbish piled up against the pillars of the portico and eventually the restoration site became first a toilet and then a shelter for a group of homeless people.
These inhabitants of Augustus’s burial place converted the fences into clothes hangers and one of them even built a shop for his artworks. Since this spring the situation improved as the square has been partially cleaned; but the mausoleum is still closed to visitors. There are hopes for its reopening at the end of 2014, but I’m certainly not holding my breath.
And then there are Augustus’s fabled stables, discovered during the construction of a new underground car park in the heart of Rome. The plan was to have them open to visitors by the time of the current celebrations, but now they are to be reburied due to lack of funding.
Their discovery in 2009 was deemed an extremely important archaeological find, making for a unique opportunity to study the structure of the stables in the Roman era and the organisation of the games held in the Circus Maximus. But despite the value of this project, the efforts of the society in charge of the excavations have the tragic futility of Sisyphus’ curse.
Five years of work and €5m are to be buried under a thick layer of “pozzolana”, a material made of volcanic ash. The stables will be left to rest there, protected from erosion, until new funds become available – perhaps for the rediscovery of future generations. The car park will be built, but its new location has yet to be decided upon.
There are no public funds for such restorations and there are unlikely to be. But Ialy’s minister of cultural heritage, Dario Franceschini, has been inviting foreign investors to help the country to preserve its artistic and historical beauties. The minister told the New York Times:
Our doors are wide open for all the philanthropists and donors who want to tie their name to an Italian monument … We have a long list, as our heritage offers endless options, from small countryside churches to the Colosseum … Just pick.
Italian luxury shoe brand Tod’s was certainly happy to finance the restoration of the Coliseum – gaining copyrights and incomparible visibility along the way. And Fendi didn’t miss the opportunity to sponsor the Trevi Fountain, where beauty and fashion icon Anita Ekberg took a bath in Fellini’s La Dolce Vita.
But the recently discovered and less famous stables did not attract local or foreign sponsors. Despite its historical importance, the site is not so appealing to corporate brands who look for prestige and visibility in such ventures. The stables require a massive investment of time and money, they cannot be open to visitors before the completion of a long process of excavation and restoration – and they won’t make for a good film location anytime soon.
Worryingly, the growing power of the corporate sector in arts and heritage funding very possibly may bring a serious change in our conception of cultural heritage – from majestic symbols of our past, to expensive advertising gimmicks.
And so the bimillenary of Augustus takes us on a bizarre tour from car parks to cardboard boxes. As we celebrate Rome’s past grandeur we find the Divus Augustus’s tomb covered in not very divine garbage, and consign an archaeological gem to rest under the streets. Until, perhaps, a mega fashion brand from the future decides to dig it up for some fabulous campaign or other.Written by Alice Borchi
CC – The Conversation
The research, led by Jeremy Martin from the Université de Lyon, France and formerly form the University of Bristol, UK will be published this week in Nature Communications.
Today, crocodiles are ‘cold-blooded’ animals that usually reside in fresh water but with two notable exceptions, Crocodylus porosus and Crocodylus acutus occasionally venture into the sea. Crocodiles reside in tropical climates, and they are frequently used as markers of warm conditions when they are found as fossils.
Only 23 species of crocodiles exist today but once there were hundreds of species. On four occasions in the past 200 million years, major crocodiles groups entered the seas and proceeded to become extinct. It remains a mystery why they made these moves, and equally why they all eventually went extinct. This new study implies that crocodiles repeatedly colonized the oceans at times of global warming.
Lead author of the report, Dr. Jeremy Martin said: “We thought each of these evolutionary events might have had a different cause. However, there seems to be a common pattern.”
Dr. Martin, accompanied by a team of palaeontologists and geochemists from the Université de Lyon and the University of Bristol, compared the evolution of the number of marine crocodilian fossil species to the sea temperature curve during the past 200 million years. This temperature curve, established using an isotopic thermometer, is widely applied for reconstruction of past environmental condition and in this case, is based on the isotopic composition of the oxygen contained in the fossilized remains of fossil marine fish (bone, teeth, scales).
Co-author of the study, Christophe Lécuyer explained: “According to this method, it is possible to calculate the temperature of the water in which these fish lived by applying an equation linking the isotopic composition of the fossilized remains to the temperature of mineralization of their skeleton. The seawater temperatures derived from the composition of fish skeleton thus corresponds to the temperature of water in which the marine crocodiles also lived.”
The results display that colonization of the marine environment about 180 million years ago was accompanied by a period of global warming of the oceans. These first marine crocodilians became extinct approximately 25 million years later, during a period of global freezing. Then, another crocodilian lineage appeared and colonized the marine environment during another period of global warming.
The evolution of marine crocodilians is therefore closely linked to the temperature of their medium and provides information about their evolution and lifestyle, as in modern crocodilians, is constrained by environmental temperatures.
Nevertheless, one fossil lineage does not seem to follow this trend. Jurassic metriorhynchoids did not go extinct during the cold spells of the early Cretaceous, unlike the teleosaurids, another group of marine crocodilians. Surprisingly, metriorhynchoids only disappeared a few million years later. This exception will certainly provide new grounds for novel research, particularly into how the biology of this group adapted to life in the pelagic environment.
Professor Michael Benton from the University of Bristol, who also co-authored the study, said: “This work illustrates a case of the impact of climate change on the evolution of animal biodiversity, and shows that for crocodilians, warming phases of our earth’s history constitute ideal opportunities to colonise new environments.”
Contributing Source: University of Bristol
Header Image Source: WikiPedia
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