Researchers from Syracuse University’s College of Arts and Sciences are pairing chemical analyses with micropalaeontology- the study of tiny fossilised organisms- to obtain a better understanding of how global marine life was affected by a rapid warming event over 55 million years ago.
Their findings are the subject of an article published in the journal Paleocenography (John Wiley & Sons, 2014).
“Global warming impacts marine life in complex ways, of which the loss of dissolved oxygen [a condition known as hypoxia] is a growing concern,” says Zunli Lu, assistant professor of Earth sciences and a member of Syracuse’s Water Science and Engineering Initiative. “Moreover, it’s difficult to predict future deoxygenation that is induced by carbon emissions, without a good understanding of our geologic past.”
Lu says this type of deoxygenation results in larger and thicker oxygen minimum zones (OMZs) in the wold’s oceans. An OMZ is the layer of water in an ocean where oxygen saturation is at its lowest.
Much of Lu’s work revolves around the Paleocene-Eocene Thermal Maximum (PETM), a well-studied analogue for modern climate warming. Documenting the expansion of OMZs during the PETM is problematic due to the lack of a sensitive, widely applicable indicator of dissolved oxygen.
In order to address the problem, Lu and his colleagues have started working with iodate, a type of iodine that is apparent in oxygenated waters only. By analysing the iodine-to-calcium ratios in microfossils, they are able to estimate the oxygen levels because of the lack of sensitive widely applicable indicator of dissolved oxygen.
Fossil skeletons of a group of protists known as foraminiferas have long been used for palaeo-environmental reconstructions. Developing an oxygenated proxy for foraminifera is important to Lu because it could allow him to study the extent of OMZs “in 3-D,” since these popcorn-like organisms have been abundant in ancient and modern oceans.
“By comparing our fossil data with oxygen levels simulated in climate models, we think OMZs were much more prevalent 55 million years ago than they are today,” he says, adding that OMZs likely expanded in the PETM, prompting mass extinction on the seafloor.”
Lu thinks analytical facilities that combine climate modeling with micropalaeontology will aid scientists in anticipating trends in ocean deoxygenation. Already, it’s been reported that modern-day OMZs, such as those in the Eastern Pacific Ocean, are beginning to expand. “They’re natural laboratories for research,” he says, regarding the interactions between oceanic oxygen levels and climate changes.
Contributing Source: Syracuse University
Header Image Source: Flickr
These, now extinct, giant kangaroos were most likely unable to hop and used a more rigid body posture to move their hindlimbs one at a time, says a study published October 15th, 2014 in the open-access journal PLOS ONE by Christine Janis from Brown University and colleagues.
The “short-faced”, large bodied sthenurine kangaroos- a now extinct relative to modern-day kangaroos- first appeared in the middle Miocene and became extinct in the late Pleistocene. The largest of these kangaroos had an estimated body mass of 240 kg, almost three times larger than that of the biggest currently living kangaroos. Scientists think that kangaroos of this size may not have had the physical ability to hop. Analysis of different sthenurine species limb bone when compared to other kangaroos indicates various anatomical differences, especially in the larger species.
The physical differences the authors of this study discovered suggest that the large kangaroo species lacked various specialised features for rapid hopping, but had anatomy suggesting they supported their body weight with an upright posture and were able to support their weight on one leg at a time using their larger hips, knees, and stabilised ankle joints. Previous studies described that sthenurines’ specialised forelimbs and rigid lumbar spine would limit their ability to move slowly, using the tail as a fifth limb, as is typical in smaller kangaroos.
Instead, the authors propose that sthenurines adopted a walking gait on two hind legs, in the smaller and earlier forms, this gait may have been used as an alternative gait to using the tails as fifth limb at slower speeds. Larger Pleistocene kangaroos may have used this gait exclusively as they evolved larger body sizes, where hopping quickly was no longer possible.
“People often interpret the behavior of extinct animals as resembling that of the ones known today, but how would we interpret a giraffe or an elephant known only from the fossil record? We need to consider that extinct animals may have been doing something different from any of the living forms, and the bony anatomy provides great clues,” said Christine Janis.
If you would like to read the full paper, free access is available: http://dx.plos.org/10.1371/journal.pone.0109888
Contributing Source: PLOS
Header Image Source: WikiPedia
Archaeologist Anna Ihr’s research has led to fascinating discoveries in two completely different regions of the world – in the old Swedish trade centre Old Lödöse along the Göta Älv river and in Qalhāt, the former capital of the Hormuz Kingdom in Oman. Ihr’s research shows that primary glass was produced in Sweden 300 years before the reign of King Gustav Vasa. It also shows that dried fish was once used to fuel ceramic kilns in Oman.
In Old Lödöse, Ihr has found pieces of a cracked clay crucible with glass remains inside and attached stones underneath. Nearly 100 kilos of this material has been uncovered.
‘The dating of my finds shows that glass was produced in Old Lödöse prior to 1260. That’s 300 years earlier than the previously oldest known written sources, which are from 1556. This means that Sweden’s history of glass production now has to be revised,’ she says.
The thesis describes how different vitrified, or glassy, materials can be interpreted and analysed. It can be very difficult to interpret how a piece of glass was made. It could have been made intentionally or unintentionally. Glaze is an example of intentionally produced glassy material. Glass describes a state of a processed material. Vitrified slag from blast furnaces is one example of unintentionally material.
‘In order to determine the difference between intentionally and unintentionally processed materials, you need a certain type of scientific analysis which is very rarely performed in Scandinavia. This is the reason why glass never has been studied in this perspective in Sweden,’ says Ihr.
Three ceramic kilns have been located and excavated in Qalhāt. The analyses show that they were fuelled with dried fish, and the ashes and the minerals in the sand fused and formed a glassy slag, vitrifying the inside of the kilns.
‘The use of dried fish was a conscious choice, though.’
Ihr hopes that her doctoral thesis will contribute to a broader understanding of how certain societies were organised. In glass artefacts which reflect a well-structured community, as in Old Lödöse, archaeologists can extract traces of trade specialisation, technology, rituals and decision making – so called advanced societies. In other cases, vitrified assemblages may reveal a community which-was not advanced. One example of this is the vitrified dung found in an old settlement in South Africa.
‘My studies show that glass production may be used as an indicator of an advanced society. From processed materials it is possible to extrat imanent social information, which may say much of a lost society’ says Anna Ihr.
The fossils belong to 500-million-year-old blind water creatures, known to scientists as “vetulicolians” (pronounced: ve-TOO-lee-coal-ee-ans).
These marine creatures, which have been described as alien-like in appearance, were “filter-feeder” creatures, shaped like a figure-of-8. Their odd anatomy has meant that they have not been placed correctly in the tree of life, that is, until now.
In a new paper published in BMC Evolutionary Biology, researchers at the University of Adelaide and the South Australian Museum argue for an alteration in the way that these creatures are viewed, placing them in the same group as vertebrate animals, such as humans.
“Although not directly related to humans in the evolutionary line, we can confirm that these ancient water creatures are among our distant cousins,” says the lead author of the paper, Dr. Diego Garcia-Bellido, ARC Future Fellow with the University’s Environment Institute.
“They are close relatives of vertebrates- animals with backbones, such as ourselves. Vetulicolians have a long tail supported by a stiff rod. This rod resembles a notochord, which is the precursor of the backbone and is unique to vertebrates and their relatives,” he says.
The first specimens were studied back in 1911, but it took until 1997 for the fossils to be classified as a group on their own: the vetulicolians. These fossils have now been discovered across the world including: Canada, Greenland, China and Australia.
The latest insights to vetulicolians have derived from new fossils found on Kangaroo Island off the coast of South Australia, which have been named Nesonektris (Greek for “Island Swimmer).
“Vetulicolians are further evidence that life was very rich in diversity during the Cambrian period, in some aspects more than it is today, with many extra branches on the evolutionary tree,” Dr. Diego Garcia-Bellido says. “They were simple yet successful creatures, large in number and in distribution across the globe, and one of the first representations of our cousins, which include sea squirts and salps.”
Contributing Source: University of Adelaide
Header Image Source: University of Adelaide/South Australian Museum
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