‘Plants caused end-Ordovician mass extinction’


This 12 May 2020 video says about itself:

How Plants Caused the First Mass Extinction

In the middle of the Cambrian, life on land was about to get a little more crowded. And those newcomers would end up changing the world. The arrival of plants on land would make the world colder, drain much of the oxygen out of the oceans and eventually, it would help cause a massive extinction event.

Ancient trilobites’ social life, new research


This June 2017 video from the USA says about itself:

Trilobites are famous not just because they were so beautifully functional, or because they happened to preserve so well. They’re known the world over because they were everywhere!

From the CNRS in France:

Arthropods formed orderly lines 480 million years ago

October 17, 2019

Researchers studied fossilized Moroccan Ampyx trilobites, which lived 480 million years ago and showed that the trilobites had probably been buried in their positions — all oriented in the same direction. Scientists deduced that these Ampyx processions may illustrate a kind of collective behavior adopted in response to cyclic environmental disturbances.

Though our understanding of the anatomy of the earliest animals is growing ever more precise, we know next to nothing about their behaviour. Did group behaviour arise recently or is it primeval? To answer this question, researchers from the CNRS, the University of Poitiers, UBO, Claude Bernard Lyon 1 University*, Cadi Ayyad University (Marrakech, Morocco), and the University of Lausanne (Switzerland) studied fossilized Moroccan Ampyx trilobites, which lived 480 million years ago. They showed that the trilobites had probably been buried in their positions — all oriented in the same direction, in orderly lines, maintaining close contact with each other through their long spines — during storms.

By comparing this observation with the behaviour of living animals such as North American spiny lobsters, the scientists deduced that these Ampyx processions may illustrate a similar kind of collective behaviour — adopted in response to cyclic environmental disturbances like storms or to chemical signals associated with reproduction.

This example would seem to suggest that group behaviour is of ancient origin and, from an early date, likely conferred an evolutionary advantage on the first animals, allowing them to survive environmental stress and improve their reproductive chances.

*- From the Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement (CNRS / ENS de Lyon / Université Claude Bernard Lyon 1), the Laboratoire Géosciences Océan (CNRS / Université Bretagne Occidentale / Université Bretagne Sud), and the Institute of Chemistry of Materials and Media of Poitiers (IC2MP (CNRS / Université de Poitiers).

Ordovician age biodiversity increase, new study


This November 2017 video says about itself:

Climatic cooling during the Ordovician caused explosion of marine diversity

Read more here.

From Ohio University in the USA:

Early species developed much faster than previously thought

Landmark review of Great Ordovician Biodiversification Event

When Earth’s species were rapidly diversifying nearly 500 million years ago, that evolution was driven by complex factors including global cooling, more oxygen in the atmosphere, and more nutrients in the oceans. But it took a combination of many global environmental and tectonic changes occurring simultaneously and combining like building blocks to produce rapid diversification into new species, according to a new study by Dr. Alycia Stigall, Professor of Geological Sciences at Ohio University.

She and fellow researchers have narrowed in a specific time during an era known as the Ordovician Radiation, showing that new species actually developed rapidly during a much shorter time frame than previously thought. The Great Biodiversification Event where many new species developed, they argue, happened during the Darriwilian Stage about 465 million years ago. Their research, “Coordinated biotic and abiotic change during the Great Ordovician Biodiversification Event: Darriwilian assembly of early Paleozoic building blocks”, was published in Palaeogeography, Palaeoclimatology, Palaeoecology as part of a special issue they are editing on the Great Ordovician Biodiversification Event.

New datasets have allowed them to show that what previously looked like species development widespread over time and geography was actually a diversification pulse. Picture a world before the continents as we know them, when most of the land mass was south of the equator, with only small continents and islands in the vast oceans above the tropics. Then picture ice caps forming over the southern pole. As the ice caps form, the ocean recedes and local, isolated environments form around islands and in seas perched atop continents. In those shallow marine environments, new species develop.

Then picture the ice caps melting and the oceans rising again, with those new species riding the waves of global diversification to populate new regions. The cycle then repeats producing waves of new species and new dispersals.

Lighting the Spark of Diversification

The early evolution of animal life on Earth is a complex and fascinating subject. The Cambrian Explosion (between about 540 to 510 million years ago) produced a stunning array of body plans, but very few separate species of each, notes Stigall. But nearly 40 million years later, during the Ordovician Period, this situation changed, with a rapid radiation of species and genera during the Great Ordovician Biodiversification Event.

The triggers of the GOBE and processes that promoted diversification have been subject to much debate, but most geoscientists haven’t fully considered how changes like global cooling or increased oxygenation would foster increased diversification.

A recent review paper by Stigall and an international team of collaborators attempts to provide clarity on these issues. For this study, Stigall teamed up with Cole Edwards (Appalachian State University), a sedimentary geochemist, and fellow paleontologists Christian Mac Ørum Rasmussen (University of Copenhagen) and Rebecca Freeman (University of Kentucky) to analyze how changes to the physical earth system during the Ordovician could have promoted this rapid increase in diversity.

In their paper, Stigall and colleagues demonstrate that the main pulse of diversification during the GOBE is temporally restricted and occurred in the Middle Ordovician Darriwilian Stage (about 465 million years ago). Many changes to the physical earth system, including oceanic cooling, increased nutrient availability, and increased atmospheric oxygen accumulate in the interval leading up to the Darriwilian.

These physical changes were necessary building blocks, but on their own were not enough to light the spark of diversification.

The missing ingredient was a method to alternately connect and isolate populations of species through cycles of vicariance and dispersal. That spark finally occurs in the Darriwilian Stage when ice caps form over the south pole of the Ordovician Earth. The waxing and waning of these ice sheets caused sea level to rise and fall (similar to the Pleistocene), which provided the alternate connection and disconnection needed to facilitate rapid diversity accumulation.

Stigall and her collaborators compared this to the assembly of building blocks required to pass a threshold.

Ordovician age marine animal fossils discovery


This October 2014 video says about itself:

The Hidden Secrets of the Ordovician Age

The origins of advanced forms of life began 500 million years ago during the Ordovician period ending with the Silurian extinction event.

Australian biologist Richard Smith travels across the continent to study the fossil record of living things that continued to flourish at this time as it did in the earlier Cambrian period. Invertebrates, namely molluscs and arthropods, dominated the oceans and fish, the world’s first true vertebrates, continued to evolve, with jaws appearing late in the period, not yet to diversifying onto land.

About 100 times as many meteorites struck the Earth during the Ordovician compared with today.

From the University of Kansas in the USA:

Rare fossils provide more detailed picture of biodiversity during Middle Ordovician

June 4, 2019

A clutch of marine fossil specimens unearthed in northern Portugal that lived between 470 and 459 million years ago is filling a gap in understanding evolution during the Middle Ordovician period.

The discovery, explained in a new paper just published in The Science of Nature, details three fossils found in a new “Burgess Shale-type deposit.” (The Burgess Shale is a deposit in Canada renowned among evolutionary biologists for excellent preservation of soft-bodied organisms that don’t have a biomineralized exoskeleton.)

“The paper describes the first soft-body fossils preserved as carbonaceous films from Portugal”, said lead author Julien Kimmig, collections manager at the University of Kansas Biodiversity Institute and Natural History Museum. “But what makes this even more important is that it’s one of the few deposits that are actually from the Ordovician period — and even more importantly, they’re from the Middle Ordovician, a time were very few soft-bodied fossils are known.”

Kimmig and his KU Biodiversity Institute colleagues, undergraduate researcher Wade Leibach and senior curator Bruce Lieberman, along with Helena Couto of the University of Porto in Portugal (who discovered the fossils), describe three marine fossil specimens: a medusoid (jellyfish), possible wiwaxiid sclerites and an arthropod carapace.

“Before this, there had been nothing found on the Iberian Peninsula in the Ordovician that even resembled these,” Kimmig said. “They close a gap in time and space. And what’s very interesting is the kind of fossils. We find Medusozoa — a jellyfish — as well as animals which appear to be wiwaxiids, which are sluglike armored mollusks that have big spines. We found these lateral sclerites of animals which were actually thought to have gone extinct in the late Cambrian. There might have been some that survived into the Ordovician in a Morocco deposit, but nothing concrete has been ever published on those. And here we have evidence for the first ones actually in the middle of the Ordovician, so it extends the range of these animals incredibly.”

Kimmig said the discovery of uncommon wiwaxiids fossils in this time frame suggests the animals lived on Earth for a far greater span of time than previously understood.

“Especially with animals that are fairly rare that we don’t have nowadays like wiwaxiids, it’s quite nice to see they lived longer than we ever thought,” he said. “Closely after this deposit, in the Upper Ordovician, we actually get a big extinction event. So, it’s likely the wiwaxiids survived up to that big extinction event and didn’t go extinct earlier due to other circumstances. But it might have been whatever caused the big Ordovician extinction event killed them off, too.”

According to the researchers, the soft-bodied specimens fill a gap in the fossil record for the Middle Ordovician and suggest “many soft-bodied fossils in the Ordovician remain to be discovered, and a new look at deep-water shales and slates of this time period is warranted.”

“It’s a very interesting thing with these discoveries — we’re actually getting a lot of information about the distribution of animals chronologically and geographically,” Kimmig said. “Also, this gives us a lot of information on how animals adapted to different environments and where they actually managed to live. With these soft-body deposits, we get a much better idea of how many animals there were and how their environment changed over time. It’s something that applies to modern days, with changing climate and changing water temperatures, because we can see how animals over longer periods of time in the geologic record have actually adapted to these things.”

Co-author Couto discovered the fossils in the Valongo Formation in northern Portugal, an area famed for containing trilobites. When the animals were alive, the Valongo Formation was part of a shallow sea on the margin of northern Gondwana, the primeval supercontinent.

“Based on the shelly fossils, the deposit looks like it was a fairly common Ordovician community,” Kimmig said. “And now we know that in addition to those common fossils jellyfish were floating around, we had sluglike mollusks roaming on the ground, too, and we had bigger arthropods, which might have been predatory animals. So, in that regard, we’re getting a far better image with these soft-bodied fossils of what these communities actually looked like.”

According to the KU researcher, scientists didn’t grasp until recently that deposits from this period could preserve soft-bodied specimens.

“For a long time, it was just not known that these kinds of deposits survived in to the Ordovician,” Kimmig said. “So, it is likely these deposits are more common in the Ordovician than we know of, it’s just that people were never looking for them.”

Kimmig led analysis of the fossils at KU’s Microscopy and Analytical Imaging Laboratory to ensure the fossils were made of organic material. Leibach, the KU undergraduate researcher, conducted much of the lab work.

“We analyzed the material and looked at the composition because sometimes you can get pseudo fossils — minerals that create something that looks like a fossil,” Kimmig said. “We had to make sure that these fossils actually had an organic origin. And what we found is that they contain carbon, which was the big indication they would actually be organic.”

Ordovician animals, marine or terrestrial?


This 2014 video says about itself:

The origins of advanced forms of life began 500 million years ago during the Ordovician period ending with the Silurian extinction event. Australian biologist Richard Smith travels across the continent to study the fossil record of living things that continued to flourish at this time as it did in the earlier Cambrian period.

Invertebrates, namely mollusks and arthropods, dominated the oceans and fish, the world’s first true vertebrates, continued to evolve, with jaws appearing late in the period, not yet to diversifying onto land. About 100 times as many meteorites struck the Earth during the Ordovician compared with today.

From the Geological Society of America:

Early animals: Death near the shoreline, not life on land

December 13, 2018

Our understanding of when the very first animals started living on land is helped by identifying trace fossils — the tracks and trails left by ancient animals — in sedimentary rocks that were deposited on the continents.

Geoscientists Anthony P. Shillito and Neil S. Davies of the University of Cambridge studied the site of what has widely been accepted as the earliest set of non-marine trackways, in Ordovician (ca. 455 million-year-old) strata from the Lake District, England.

What they discovered is that the trackways occur within volcanic ash that settled under water, and not within freshwater lake and sub-aerial sands (as previously thought). This means that the site is not the oldest evidence for animal communities on land, but instead “is actually a remarkable example of a ‘prehistoric Pompeii‘”, says Shillito — a suite of rocks that preserve trails made by distressed and dying millipede-like arthropods as they were overcome by ash from volcanic events.

Shillito and Davies directed their research at this site in particular because it seemed unusual — at every other known trackway site in the world the evidence for when animals came onto land dates to the latest Silurian (ca. 420 million years ago), so something about the Borrowdale site didn’t seem right. Further investigation proved that this was the case. In the course of their study, they found 121 new millipede trackways, all within volcanic ash with evidence for underwater or shoreline deposition.

Volcanic ash is known to cause mass death in some modern arthropod communities, particularly in water, because ash is so tiny it can get inside arthropod exoskeletons and stick to their breathing and digestive apparatus. Shilllito and Davies noticed that most of the trails were extremely tightly looping — a feature which is commonly associated with “death dances” in modern and ancient arthropods.

This study, published in Geology, overturns what is known about the earliest life on land and casts new light onto one of the key evolutionary events in the history of life on Earth. Shillito notes, “It reveals how even surprising events can be preserved in the ancient rock record, but — by removing the ‘earliest’ outlier of evidence — suggests that the invasion of the continents happened globally at the same time.”

Understanding how life engineered major evolutionary advances within environments, and the rate and impact of these advances on the functioning of the Earth system, provides vital context for understanding global change at the present day, and underlines the inseparable relationship between life and the planet.

Unique Ordovician fossil discovery


Hummelstown Fossils. A) Typical specimen reconstruction showing body mass (white) poking out of the 'spindle'-shaped cone (patterned). Note the presence of 'spikes' on the sides of the exposed body. B) Typical fossil specimen with body mass (with at least one spike) and 'spindle'-shaped cone. C) Surface of rock slab showing numerous Hummelstown fossils. Credit: University of Leicester

From the University of Leicester in England:

Rare 450-million-year-old ‘cone-shaped’ fossil discovery

January 23, 2018

Researchers from the University of Leicester, working with an international team of geologists, have discovered an enigmatic fossil of a 450 million year-old creature resembling a tiny ice-cream cone.

Fossils of the creature, in which the ‘body’ resembles a scoop of ice cream atop the cone, was located in the Appalachian Mountains, near Hummelstown in Pennsylvania from the Ordovician period.

Intriguingly, the rocks in which the fossil was found have been ‘cooked’ during mountain building, which usually hinders fossil preservation.

Discovered by consulting geologist Bob Ganis, who obtained his PhD from the University of Leicester, and Mike Meyer of the Carnegie Institute of Science, it has now been described in a paper published in the journal Palaios by them and co-authors Professor Jan Zalasiewicz of the University of Leicester, Jacalyn Wittmer of the State University of New York, Geneseo and Kenneth de Baets of Geozentrum Nordbayern in Erlangen Germany.

The paper discusses the possibilities of this newly found soft-bodied creature, which lived among the plankton before being carried to the sea floor and buried within mud slurries.

Professor Jan Zalasiewicz from the University of Leicester’s School of Geography, Geology and the Environment, said: “The ancient world of the Ordovician, some 450 million years ago, was one of a huge expansion of life in the seas of our planet.

“Fossils abound in Ordovician strata, but almost all of them are of creatures with hard shells or support structures, and so our understanding of booming Ordovician life is almost completely based on skeleton-bearing animals. There are few of those rare, precious localities where softer-bodied animals might be found, to give a wider insight into the life of those times.

“Was this creature an important but usually unpreserved part of ocean life, or just a bit player among the Ordovician animal communities? It is a new puzzle for palaeontologists.”

Mike Meyer, of the Carnegie Institute of Science, said: “That this fossil still has the soft bits preserved, even though the rocks that hold it have been squeezed and twisted, is remarkable. This enigmatic organism has major implications for how we look for well-preserved fossils.”

Bob Ganis added: “It’s a small fossil with a big story.”

The events that triggered the Late Ordovician Mass Extinction or LOME of marine animals and plants has largely remained a mystery until now. The Ordovician was a dynamic time interval in Earth history that recorded a major increase in marine biologic diversity and a greenhouse-to-icehouse climatic transition. Researchers believe this cooling period, which culminated in the first Phanerozoic glaciation led to the Late Ordovician Mass Extinction: here.

‘Asteroids not cause of Ordovician biodiversification’


This video says about itself:

30 May 2013

Few people have heard of the Ordovician Period, but it was one of the most important periods in Earth’s history. Many familiar sea creatures evolved, and life took first steps onto land.

From Science News:

Asteroid barrage, ancient marine life boom not linked

New dating debunks idea that bombardment created eco-niches needed to diversify

By Thomas Sumner

11:00am, January 24, 2017

An asteroid bombardment that some say triggered an explosion of marine animal diversity around 471 million years ago actually had nothing to do with it.

Precisely dating meteorites from the salvo, researchers found that the space rock barrage began at least 2 million years after the start of the Great Ordovician Biodiversification Event. So the two phenomena are unrelated, the researchers conclude January 24 in Nature Communications.

Some scientists had previously proposed a causal link between the two events: Raining debris from an asteroid breakup (SN: 7/23/16, p. 4) drove evolution by upsetting ecosystems and opening new ecological niches. The relative timing of the impacts and biodiversification was uncertain, though.

Geologist Anders Lindskog of Lund University in Sweden and colleagues examined 17 crystals buried alongside meteorite fragments. Gradual radioactive decay of uranium atoms inside the crystals allowed the researchers to accurately date the sediment layer to around 467.5 million years ago. Based in part on this age, the researchers estimate that the asteroid breakup took place around 468 million years ago. That’s well after fossil evidence suggests that the diversification event kicked off.

Other forces such as climate change and shifting continents instead promoted biodiversity, the researchers propose.