Ediacaran dinner party featured plenty to eat, adequate sanitation, computer model shows

By: Thomas Schmitt Attorney on June 19, 2019 / comment : 0 Fossils, Namibia, Palaeontology

Earth's first dinner party wasn't impressive, just a bunch of soft-bodied Ediacaran organisms sunk into sediment on the ocean floor, sharing in scraps of organic matter suspended in the water around them.

Artistic reconstruction of a gregarious community of Ernietta [Credit: Dave Mazierski]

But sorting out the way the 570-540-million-year-old, enigmatic creatures ate supports the argument that they behaved like more modern-looking animals and evolved into shapes that helped them feed.

Paleontologist Simon A.F. Darroch, assistant professor of earth and environmental sciences at Vanderbilt University, and Brandt M. Gibson, a Ph.D. student, developed a series of computational fluid dynamics simulations demonstrating that not only were some of the Ediacara biota suspension feeders, trapping nutrients in deep cavities, but that they oriented themselves within flow currents to amplify eddies as water moved around them. That meant more food being sent into each creature's cavity.

Well preserved Ernietta with bottom suture and individual modules visible [Credit: Charlotte Kenchington]

"They were enhancing the amount of nutrients going from individual to individual, and they were also exporting waste down-current and away from the one making it," Gibson said. "So it was a good dinner party in that they got to eat a lot and didn't have to sit in their own waste."

The team used fossil evidence gathered near Bethanie, Namibia, and plans to return to the African nation this summer to study and photograph other samples. Their recent work builds on Darroch's findings last year that Ediacara biota were forming complex communities tens of millions of years before the Cambrian explosion.

Artistic reconstruction of a cross section of Ernietta. Note the laminations of sediment within the cavity, and the particles within the surrounding water that settles into the cavity [Credit: Dave Mazierski]

Because Ediacarans fed similarly to modern sea creatures, the work helps place them on the tree of life, Darroch said.

"For hundreds of years, we've just stared at the fossils themselves and made judgments on what we believe they're related to," he said. "But Brandt is focused on these unusual bizarre shapes and morphologies and said, 'What if these evolved as a way of dealing with life in moving fluids.'

Turbulent energy flowlines in multi-model CFD simulation showing recirculating turbulent patterns within and downstream of Ernietta cavities [Credit: Dave Mazierski]

One of the reasons things evolve strange shapes is to help them feed.

"They are behaving like animals, and that's a link between them and what we recognize as animals."

The research is published in the journal Science Advances.

Source: Vanderbilt University [June 19, 2019]

Germany returning 15th century stone cross to Namibia

By: Thomas Schmitt Attorney on May 20, 2019 / comment : 0 Africa, Archaeology, Germany, Heritage, Namibia

The German Historical Museum in Berlin announced Friday that it is returning to Namibia a 15th century artifact known as the Stone Cross of Cape Cross. The country has called for the object's return since June 2017.

The Cape Cross was originally put up by the Portuguese [Credit: Picture-Alliance/dpa/P. Zinken]

"The rapprochement with Namibia is clearly, and visibly taking place," said Monika Grütters, Germany's State Secretary for Culture and Media. She said that dealing with its colonial legacy in Namibia had been a "blind spot" for Germany for too long.

For Grütters, the restitution planned for August, is a "clear signal that we want words to be followed by deeds."

Namibia's Ambassador to Germany, Andreas Guibeb, sees the return as a "significant progress" which however, does not end the chapter. "The origin of the column is inseparably connected with the history of Namibia," said Guibeb in Berlin. He said that this reconciliation for the colonial era would allow his country to concentrate on its future.

The restitution, sparked in part by a 2018 symposium the museum held on the history of the object, is part of Germany's desire to face up to the moral responsibility of its colonial past.

The museum says that although the object is not an African artwork, it nevertheless highlights how "descendants from Europe and Africa can engage in dialogue that does historical justice" to it.

The museum acknowledged the "outstanding significance which an artifact like this pillar has to the people of Namibia and the special contribution it can make on site in the future to understanding Namibia's history."

Marking Portuguese territorial claims

The artifact was originally erected by explorer Diogo Cao in 1486 on the coastline of present-day Namibia to signify Portuguese territorial claims, as well as serve as a navigational marker.

The Stone Cross was placed by the Portuguese in 1486 and features the country's crest [Credit: AFP/Getty]

The 1.1 ton, 3.5-meter (11-foot) Stone Cross is emblazoned with the Portuguese coat of arms as well as inscriptions in Portuguese and Latin. Its presence, alongside other such crosses, was so significant that maps at the time — such as Martin Waldseemüller's world map from 1500 — featured images of them. The crosses also gave rise to the coast's present-day name, Cape Cross.

The artifact came into Germany's possession in 1893, when seafarer Gottlieb Becker discovered it and ordered it removed and returned with it to Germany, where it made its way from Wilhelmshaven to Berlin.

The object was presented to Kaiser Wilhelm II, who used it to serve his propaganda purposes regarding the empire's naval superiority. The kaiser also ordered a new cross, emblazoned this time with the German imperial eagle and a German inscription, to replace the original.

The object entered the collection of East Germany's Museum of German History in 1953, and then the German Historical Museum after reunification. It has been part of the museum's permanent exhibition since 2006.

Namibia, which was previously known as German South-West Africa, was a German colony from 1884 to 1915.

Researcher unearths an ice age in the African desert

By: Thomas Schmitt Attorney on February 04, 2019 / comment : 0 Africa, Earth Science, Geology, Namibia, Palaeontology

A field trip to Namibia to study volcanic rocks led to an unexpected discovery by West Virginia University geologists Graham Andrews and Sarah Brown.

Drumlins, hills formed in places once covered by glaciers, were discovered in Namibia by WVU's Graham Andrews [Credit: WVU]

While exploring the desert country in southern Africa, they stumbled upon a peculiar land formation -- flat desert scattered with hundreds of long, steep hills. They quickly realized the bumpy landscape was shaped by drumlins, a type of hill often found in places once covered in glaciers, an abnormal characteristic for desert landscapes.

"We quickly realized what we were looking at because we both grew up in areas of the world that had been under glaciers, me in Northern Ireland and Sarah in northern Illinois," said Andrews, an assistant professor of geology. "It's not like anything we see in West Virginia where we're used to flat areas and then gorges and steep-sided valleys down into hollows."

After returning home from the trip, Andrews began researching the origins of the Namibian drumlins, only to learn they had never been studied.

The drumlins were formed by fast-moving ice floes instead of slow melting ice [Credit: WVU]

"The last rocks we were shown on the trip are from a time period when southern Africa was covered by ice," Andrews said. "People obviously knew that part of the world had been covered in ice at one time, but no one had ever mentioned anything about how the drumlins formed or that they were even there at all."

Andrews teamed up with WVU geology senior Andy McGrady to use morphometrics, or measurements of shapes, to determine if the drumlins showed any patterns that would reflect regular behaviors as the ice carved them.

While normal glaciers have sequential patterns of growing and melting, they do not move much, Andrews explained. However, they determined that the drumlins featured large grooves, which showed that the ice had to be moving at a fast pace to carve the grooves.

Megawhalebacks oriented NW/SE covered by sand and termite mounds [Credit: WVU]

These grooves demonstrated the first evidence of an ice stream in southern Africa in the late Paleozoic Age, which occurred about 300 million years ago.

"The ice carved big, long grooves in the rock as it moved," Andrews said. "It wasn't just that there was ice there, but there was an ice stream. It was an area where the ice was really moving fast."

McGrady used freely available information from Google Earth and Google Maps to measure their length, width and height.

Megawhalebacks oriented NW/SE covered by sand, trees and shrubs [Credit: WVU]

"This work is very important because not much has been published on these glacial features in Namibia," said McGrady, a senior geology student from Hamlin. "It's interesting to think that this was pioneer work in a sense, that this is one of the first papers to cover the characteristics of these features and gives some insight into how they were formed."

Their findings also confirm that southern Africa was located over the South Pole during this period.

"These features provide yet another tie between southern Africa and south America to show they were once joined," Andrews said.

Zoomed in photo shows striations in the megawhaleback, or carvings in the bedrock made by moving ice [Credit: WVU]

The study, "First description of subglacial megalineations from the late Paleozoic ice age in southern Africa" is published in the Public Library of Science's PLOS ONE journal.

"This is a great example of a fundamental discovery and new insights into the climatic history of our world that remain to be discovered," said Tim Carr, chair of the Department of Geology and Geography.

Source: West Virginia University [February 04, 2019]

Earth's oldest animals formed complex ecological communities

By: Thomas Schmitt Attorney on September 17, 2018 / comment : 0 Fossils, Namibia, Palaeontology

A new analysis is shedding light on the earth's first macroscopic animals: the 570-million-year-old, enigmatic Ediacara biota.

Paleontologist Simon A.F. Darroch examines fossils in Namibia [Credit: Simon A.F. Darroch]

Ediacaran fossils have a slightly bizarre appearance not shared by any modern animal groups. For decades, researchers believed these enigmatic fossils were ecologically simple. However, borrowing a method from modern ecology - fitting species to relative abundance distributions - Vanderbilt University paleontologist Simon A.F. Darroch and his team learned that these organisms were more like modern animals than once thought.

The analyses showed that a majority of fossil assemblages bear the hallmarks of being ecologically complex, and Ediacara biota were forming complex communities tens of millions of years before the Cambrian explosion. The creatures lived partially submerged in what was once the ocean floor, some of them suspension feeding, others filter feeding, still others passively absorbing nutrition. A few were even mobile.

Ediacara biota fossil found during Darroch's latest field work in Namibia  [Credit: Simon A.F. Darroch]

Complex communities are ones that comprise species competing for numerous different resources or species that create niches for others (as in many modern-day ecosystems). The team found that the signature of complex communities extends all the way back to the oldest Ediacaran fossils. In other words, as soon as macroscopic life evolved, it began forming diverse ecological communities not unlike those in the present day.

"The main impact of our work was testing between the simple and complex models for Ediacaran ecosystems," said Darroch, an assistant professor in Vanderbilt's Earth and Environmental Sciences Department.

Ediacara biota fossils found during Darroch's latest research in Namibia  [Credit: Simon A.F. Darroch]

"Supporting a simple model would suggest that these mysterious organisms were universally primitive, sharing the same basic ecology and all competing for the same resources," he said. "Support for the complex model would instead suggest that they likely competed for a variety of different resources, just like modern animals. Our analyses support the complex model, illustrating that - even though they may look bizarre - these mysterious fossils may have far more in common with modern animals than we thought."

The team first compiled all Ediacaran fossil data from the published literature then added a dataset collected during fieldwork in southern Namibia. These Namibian fossils are the some of the youngest from anywhere in the world and record communities that were living immediately prior to the onset of the Cambrian explosion.


The fossils formed one of the few simple communities in the analysis, suggesting that these organisms were ecologically stressed. That lends support to the idea that the Ediacara biota were gradually going extinct in the run-up to the Cambrian explosion. Although it's an exciting idea, Darroch said, it's only one data point and will need much more research to prove.

The team is also using 3D modeling based on the fossil record to better characterize Ediacara biota, which completely disappeared 540 million years ago - as early arthropods, mollusks and sponges began to appear.

The study is published in Nature Ecology & Evolution.

Source: Vanderbilt University [September 17, 2018]

Earth's oxygen increased in gradual steps rather than big bursts

By: Thomas Schmitt Attorney on August 31, 2018 / comment : 0 Earth Science, Fossils, Geology, Namibia, Palaeontology

A carbon cycle anomaly discovered in carbonate rocks of the Neoproterozoic Hüttenberg Formation of north-eastern Namibia follows a pattern similar to that found right after the Great Oxygenation Event, hinting at new evidence for how Earth's atmosphere became fully oxygenated.

An oxygenated Earth is vital for the evolution of complex life [Credit: NASA]

By using the Hüttenberg Formation, which formed between a billion and half a billion years ago, to study the time between Earth's change from an anoxic environment (i.e. one lacking oxygen) to a more hospitable environment that heralded the animal kingdom, a team of researchers led by Dr. Huan Cui of the NASA Astrobiology Institute at the University of Wisconsin–Madison discovered a sustained, high level of carbon. This influx of carbon, coupled with changes in other elements, indicates how changing levels of oceanic oxygen may have lent a helping hand to early animal evolution.

The study, published in the journal Precambrian Research,paired new oxygen, sulfur, and strontium isotope data, with carbon isotope data published in 2009, obtained from drill core samples from the Hüttenberg Formation. Together, the data provides further evidence that Earth's oxygen increased in a stepwise fashion, as opposed to being constrained to two major events capping the Proterozoic (a geological epoch that lasted between 2.5 billion and 541 million years ago). The resulting pattern of changing redox reactions (i.e. reactions involving oxygenation and reduction via the exchange of electrons) was named the Hüttenberg Anomaly, after the rock formation in which it was found.

The University of Maryland's Dr. Alan J. Kaufman, who is the second author of the study and the lead author of the 2009 carbon isotope study, says that the paired data "suggest that the rise of oxygen was oscillatory through this 50- to 75-million year intervalassociated with the Hüttenberg Anomaly and the Neoproterozoic Oxidation Event or NOE at the end of the Proterozoic."

The anomaly shows how the carbon isotope ratios (13C/12C) experienced a sustained 12 to 14 parts per thousand increase in abundance for roughly 15 million years before returning to prior low levels. As oxygen levels in the ocean increased, sulfides were converted to sulfates, which some microbes use in their metabolism to digest and recycle organic carbon on the seafloor. The isotopes of oxygen, carbon, and sulfur moved in tandem during the Hüttenberg Anomaly, convincing the scientists that what they were seeing wasn't just a coincidence.

Wild fluctuations

Although it has long been accepted that high levels of atmospheric oxygen paved the way for animals to populate the Earth, global carbon and oxygen cycles fluctuated wildly during the Proterozoic, between the time when oxygen first accumulated in the atmosphere during the Great Oxygenation Event (GOE) around 2.4 billion years ago, and the time in which they stabilized near to modern levels once animals took the world stage following the NOE, around 500 million years ago.

Lead researcher Huan Cui analyzing isotopes in the wet lab at the University of Wisconsin–Madison. Oxygen, carbon,  strontium and sulfur isotopes during the Neoproterozoic reveal a step-wise pattern of atmospheric oxygen, crucial to the evolution of complex life [Credit: Huan Cui]

During the time between those two events, pulses of unicellular life and variable levels of oxygen in the oceans are thought to have stimulated the evolution of more complex life. These ancient oxygen swings were crucial to the evolution of multicellular life at the Precambrian–Cambrian boundary (541 million years ago; the Cambrian is a geological period that marked the origin and diversification complex animal life on Earth). As pools of oxygenated water grew in the ocean, life was given the opportunity to develop towards a future when oxygen would be at stable and high levels. The Hüttenberg Anomaly represents one such window of opportunity for life.

Kaufman compares the jump in oxygen to another oxygen oasis in time, the Lomagundi event right after the GOE. The Lomagundi event has been described as a false start, when oxygen concentrations rose to levels that could support some life, before decreasing again. It wouldn't be until the NOE that oxygen would rise to modern-day levels.

"Here's an isotope anomaly in the Neoproterozoic that is associated broadly in time with the NOE, but which has a rise and fall structure that looks very similar to the GOE," Kaufman tells Astrobiology Magazine. "At both ends of the Proterozoic Eon there was continental rifting, glaciations, and profound carbon fluctuations; just as the GOE was likely responsible for the evolution of simple eukaryotes, the NOE was involved in the evolution of multicellularity."

So the GOE ushered in eukaryotes, which are microbes with cells containing a nucleus wrapped by a membrane, and the NOE ushered in even more complex animals. These exceptional events in Earth's history each harbored an evolutionary test pool that fostered new lifeforms. How exactly the Hüttenberg Anomaly fits into these events or exactly what evolutionary consequence it had still remains to be seen.

Temporary habitability

During the period between the GOE and the NOE, pockets or bubbles of habitability in a mostly uninhabitable planet would pop up, but these blips on the radar were reversible. Shifting ice sheets or the absence of erosion would decrease elements such as nitrogen and phosphorus required by photosynthesizing life, causing the oxygen and carbon signatures to disappear. The tipping point would appear in the Cambrian Period when the planet was consistently oxygenated.

Drill core samples from the Tsumeb mine in the Huttenberg Formation in north-eastern Namibia. A carbon anomaly  found in the samples holds clues as to the early oxygenation of Earth’s oceans [Credit: Huan Cui]

We see similar effects of anomalies today; in our mostly well-oxygenated atmosphere, there are still oxygen-depleted environments where life struggles to persist or takes an alternative evolutionary pathway: inland seas, underground caves and oceanic dead zones where sulfate- or nitrate-breathers persist while the rest of the world breathes oxygen.

"There are still anoxic environments in the modern Earth," Huan Cui, first author of the paper, says. "If you go to the Black Sea, you can still find local anoxic environments in the modern ocean."

In this study the anomaly was oxygen. Today, the anomaly is a lack of oxygen.

While rocks in other areas of Namibia have been well-studied, the rock strata containing the Hüttenberg Anomaly have been eroded out in many sections, leaving the crucial data piece missing for decades.

Taking another look

Dr. Paul Myrow, a geology professor at Colorado College who was not involved with the study, says that given the time constraints this study provides, more researchers will now take a closer look at other ancient rock formations and re-examine whether this anomaly exists elsewhere on the planet.

Parsing out whether the rise in oxygen was restricted or widespread throughout the ancient ocean or on different ancient continents is something every isotopic study has to take into account.

"One of the ways that we can get that answer is to see if the signal of the Hüttenberg Anomaly can be matched to places around the world," Myrow, who also studies Precambrian ocean conditions, says. "If there is this shift that took place in different continents at the same time, then we can be more confident about this being global."

At a time when the planet's oceanic chemistry, tectonic plates and inhabitants were in such a state of disequilibrium, the Earth's low-oxygen and unstable atmosphere could be considered wildly dangerous by today's standards. As the Earth was changing, its teenage awkwardness manifested as smelly, sulfuric pits, hairy living situations, moody shifts in its accommodations, and irreverence towards its co-inhabitants. The Hüttenberg Anomaly is one small step towards the Earth airing out its dirty laundry, cleaning up and becoming presentable for the lifeforms that evolved later.

Author: Emily Moskal | Source: Astrobiology Magazine [August 31, 2018]