Mammals: Strength Through Diversity

When it comes to adapting to climate change, diversity is the mammal's best defense.

That is one of the conclusions of the first study of how mammals in North America adapted to climate change in "deep time" – a period of 56 million years beginning with the Eocene and ending 12,000 years ago with the terminal Pleistocene extinction when mammoths, saber-toothed tigers, giant sloths and most of the other "megafauna" on the continent disappeared.

"Before we can predict how mammals will respond to climate change in the future, we need to understand how they responded to climate change in the past," said Larisa R. G. DeSantis, the assistant professor of earth and environmental studies at Vanderbilt who directed the study. "It is particularly important to establish a baseline that shows how they adapted before humans came on the scene to complicate the picture."

Establishing such a baseline is particularly important for mammals because their ability to adapt to environmental changes makes it difficult to predict how they will respond. For example, mammals have demonstrated the ability to dramatically alter their size and completely change their diet when their environment is altered. In addition, mammals have the mobility to move as the environment shifts. And their ability to internally regulate their temperature gives them more flexibility than cold-blooded organisms like reptiles.

The study, which was published on Apr. 23 in the journal PLoS ONE, tracked the waxing and waning of the range and diversity of families of mammals that inhabited the continental United States during this extended period. In taxonomy, species are groups of individuals with common characteristics that (usually) can mate; genera are groups of species that are related or structurally similar and families are collections of genera with common attributes.

Scientists consider the fossil record of mammals in the U.S. for the study period to be reasonably complete. However, it is frequently impossible to distinguish between closely related species based on their fossil remains and it can even be difficult to tell members of different genera apart. Therefore the researchers performed the analysis at the family level. They analyzed 35 different families, such as Bovidae (bison, sheep, antelopes); Cricetidae (rats, mice, hamsters, voles); Equidae (horses, donkeys); Ursidae (bears); Mammutidae (mammoths); and Leporidae (rabbits and hares).

The study found that the relative range and distribution of mammalian families remained strikingly consistent throughout major climate changes over the past 56 million years. This period began with an extremely hot climate, with a global temperature about six degrees hotter than today (too hot for ice to survive even at the poles) and gradually cooled down to levels only slightly higher than today. It was followed by a dramatic temperature drop and a similarly abrupt warming and finished off with the Ice Ages that alternated between relatively cold glacial and warm interglacial periods.

"These data clearly show that most families were extremely resilient to climate and environmental change over deep time," DeSantis said.

Horses were consistently the most widely distributed family from the Eocene to the Pliocene (and remained highly dominant, just not number one, in the Pleistocene). In contrast, families with more restricted ranges maintained lower range areas. Thus, their work demonstrates that mammals maintained similar niches through deep time and is consistent with the idea that family members may inherit their ranges from ancestral species. The idea that niches are conserved over time is a fundamental assumption of models that predict current responses of mammals to climate change.

The analysis also found a link between a family's diversity and its range: Family's with the greater diversity were more stable and had larger ranges than less diverse families.

"Diversity is good. The more species a family has that fill different niches, the greater its ability to maintain larger ranges regardless of climate change," said DeSantis.

While most families during certain periods of time yielded either gains in species/genera (e.g., Oligocene to Miocene) or losses (Miocene to Pliocene), these changes were remarkably consistent through time with overall gains or losses in one genera typically yielding a gain or loss in of about two species.

Although the extent of family ranges remained relatively constant, the study found that these ranges moved south and east from the Eocene to the Pleistocene. That is most likely a response to the general climate cooling that took place during the period. However, southeastern movement of ranges from the Pliocene to the Pleistocene may also be complicated by the influx of South American animals when the Isthmus of Panama was formed. This triggered a tremendous exchange of species that has been labeled "The Great American Interchange." As a result, some of the southern movement of families' ranges may have been due to the influx of South American mammals, like the sloth and armadillo, moving north, the researchers cautioned.

The study also looked for evidence that families containing megafauna or other species that went extinct during the terminal Pleistocene extinction (also known as the Quaternary or Ice Age extinction) might have been in decline beforehand, but failed to find any evidence for any such "extinction prone" families. If climate change was the culprit, DeSantis and her team expect to see differences between families containing megafauna and those composed of smaller animals. However, the fact that they didn't find such evidence cannot completely rule out this possibility.

Link here.

Strange and Fascinating Ordovician Fossil Found

Around 450 million years ago, shallow seas covered the Cincinnati region and harbored one very large and now very mysterious organism. Despite its size, no one has ever found a fossil of this "monster" until its discovery by an amateur paleontologist last year.

The fossilized specimen, a roughly elliptical shape with multiple lobes, totaling almost seven feet in length, will be unveiled at the North-Central Section 46th Annual Meeting of the Geological Society of America, April 24, in Dayton, Ohio. Participating in the presentation will be amateur paleontologist Ron Fine of Dayton, who originally found the specimen, Carlton E. Brett and David L. Meyer of the University of Cincinnati geology department, and Benjamin Dattilo of the Indiana University Purdue University Fort Wayne geosciences faculty.

Fine is a member of the Dry Dredgers, an association of amateur paleontologists based at the University of Cincinnati. The club, celebrating its 70th anniversary this month, has a long history of collaborating with academic paleontologists.

"I knew right away that I had found an unusual fossil," Fine said. "Imagine a saguaro cactus with flattened branches and horizontal stripes in place of the usual vertical stripes. That's the best description I can give."

The layer of rock in which he found the specimen near Covington, Kentucky, is known to produce a lot of nodules or concretions in a soft, clay-rich rock known as shale.

"While those nodules can take on some fascinating, sculpted forms, I could tell instantly that this was not one of them," Fine said. "There was an 'organic' form to these shapes. They were streamlined."

Fine was reminded of streamlined shapes of coral, sponges and seaweed as a result of growing in the presence of water currents.

"And then there was that surface texture," Fine said. "Nodules do not have surface texture. They're smooth. This fossil had an unusual texture on the entire surface."

For more than 200 years, the rocks of the Cincinnati region have been among the most studied in all of paleontology, and the discovery of an unknown, and large, fossil has professional paleontologists scratching their heads.

"It's definitely a new discovery," Meyer said. "And we're sure it's biological. We just don't know yet exactly what it is."

To answer that key question, Meyer said that he, Brett, and Dattilo were working with Fine to reconstruct a timeline working backward from the fossil, through its preservation, burial, and death to its possible mode of life.

"What things had to happen in what order?" Meyer asked. "Something caused a directional pattern. How did that work? Was it there originally or is it post-mortem? What was the burial event? How did the sediment get inside? Those are the kinds of questions we have."

It has helped, Meyer said, that Fine has painstakingly reassembled the entire fossil. This is a daunting task, since the large specimen is in hundreds of pieces.

"I've been fossil collecting for 39 years and never had a need to excavate. But this fossil just kept going, and going, and going," Fine said. "I had to make 12 trips, over the course of the summer, to excavate more material before I finally found the end of it."

Even then he still had to guess as to the full size, because it required countless hours of cleaning and reconstruction to put it all back together.

"When I finally finished it was three-and-a-half feet wide and six-and-a-half feet long," Fine said. "In a world of thumb-sized fossils that's gigantic!"

Meyer, co-author of A Sea without Fish: Life in the Ordovician Sea of the Cincinnati Region, agreed that it might be the largest fossil recovered from the Cincinnati area.

"My personal theory is that it stood upright, with branches reaching out in all directions similar to a shrub," Fine said. "If I am right, then the upper-most branch would have towered nine feet high. "

As Meyer, Brett and Dattilo assist Fine in studying the specimen, they have found a clue to its life position in another fossil. The mystery fossil has several small, segmented animals known as primaspid trilobites attached to its lower surface. These small trilobites are sometimes found on the underside of other fossilized animals, where they were probably seeking shelter.

"A better understanding of that trilobite's behavior will likely help us better understand this new fossil," Fine said.

Although the team has reached out to other specialists, no one has been able to find any evidence of anything similar having been found. The mystery monster seems to defy all known groups of organisms, Fine said, and descriptions, even pictures, leave people with more questions than answers.

The presentation April 24 is a "trial balloon," Meyer said, an opportunity for the team to show a wide array of paleontologists what the specimen looks like and to collect more hypotheses to explore.

hmmm. Uber sized, late surviving Ediacaran? hmm.

Link is here because the new interface of blogger sucks.

Los Alamos of the 1940s

Yosemite, dancing in light

A New Study of the Ordovician Mass Extinction

The second-largest mass extinction in Earth's history coincided with a short but intense ice age during which enormous glaciers grew and sea levels dropped. Although it has long been agreed that the so-called Late Ordovician mass extinction—which occurred about 450 million years ago—was related to climate change, exactly how the climate change produced the extinction has not been known. Now, a team led by scientists at the California Institute of Technology (Caltech) has created a framework for weighing the factors that might have led to mass extinction and has used that framework to determine that the majority of extinctions were caused by habitat loss due to falling sea levels and cooling of the tropical oceans.

The work—performed by scientists at Caltech and the University of Wisconsin, Madison—is described in a paper currently online in the early edition of the Proceedings of the National Academy of Sciences.

The researchers combined information from two separate databases to overlay fossil occurrences on the sedimentary rock record of North America around the time of the extinction, an event that wiped out about 75 percent of marine species alive then. At that time, North America was an island continent geologists call Laurentia, located in the tropics.

Comparing the groups of species, or genera, that went extinct during the event with those that survived, the researchers were able to figure out the relative importance of several variables in dictating whether a genus went extinct during a 50-million-year interval around the mass extinction.

"What we did was essentially the same thing you'd do if confronted with a disease epidemic," says Seth Finnegan, postdoctoral scholar at Caltech and lead author of the study. "You ask who is affected and who is unaffected, and that can tell you a lot about what's causing the epidemic."

As it turns out, the strongest predictive factors of extinction on Laurentia were both the percentage of a genus's habitat that was lost when the sea level dropped and a genus's ability to tolerate broader ranges of temperatures. Groups that lost large portions of their habitat as ice sheets grew and sea levels fell, and those that had always been confined to warm tropical waters, were most likely to go extinct as a result of the rapid climate change.

"This is the first really attractive demonstration of how you can use multivariate approaches to try to understand extinctions, which reflect amazingly complex suites of processes," says Woodward Fischer, an assistant professor of geobiology at Caltech and principal investigator on the study. "As earth scientists, we love to debate different environmental and ecological factors in extinctions, but the truth is that all of these factors interact with one another in complicated ways, and you need a way of teasing these interactions apart. I'm sure this framework will be profitably applied to extinction events in other geologic intervals."

The analysis enabled the researchers to largely rule out a hypothesis, known as the record-bias hypothesis, which says that the extinction might be explained by a significant gap in the fossil record, also related to glaciation. After all, if sea levels fell and continents were no longer flooded, sedimentary rocks with fossils would not accumulate. Therefore, the last record of any species that went extinct during the gap would show up immediately before the gap, creating the appearance of a mass extinction.

Finnegan reasoned that this record-bias hypothesis would predict that the duration of a gap in the record should correlate with higher numbers of extinctions—if a gap persisted longer, more groups should have gone extinct during that time, so it should appear that more species went extinct all at once than for shorter gaps. But in the case of the Late Ordovician, the researchers found that the duration of the gap did not matter, indicating that a mass extinction very likely did occur.

"We have found that the Late Ordovician mass extinction most likely represents a real pulse of extinction—that many living things genuinely went extinct then," says Finnegan. "It's not that the record went bad and we just don't recover them after that."

Alaskan Hadrosaurs Stayed Through the Winter

Duck-billed dinosaurs that lived within Arctic latitudes approximately 70 million years ago likely endured long, dark polar winters instead of migrating to more southern latitudes, a recent study by researchers from the University of Cape Town, Museum of Nature and Science in Dallas and Temple University has found.

The researchers published their findings, "Hadrosaurs Were Perennial Polar Residents," in the April issue of the journal The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology. The study was funded through a grant from the National Science Foundation.

Anthony Fiorillo, a paleontologist at the Museum of Nature and Science, excavated Cretaceous Period fossils along Alaska's North Slope. Most of the bones belonged to Edmontosaurus, a duck-billed herbivore, but some others such as the horned dinosaur Pachyrhinosaurus were also found.

Fiorillo hypothesized that the microscopic structures of the dinosaurs' bones could show how they lived in polar regions. He enlisted the help of Allison Tumarkin-Deratzian, an assistant professor of earth and environmental science, who had both expertise and the facilities to create and analyze thin layers of the dinosaurs' bone microstructure.

Another researcher, Anusuya Chinsamy-Turan, a professor of zoology at the University of Cape Town, was independently pursuing the same analysis of Alaskan Edmontosaurus fossils. When the research groups discovered the similarities of their studies, they decided to collaborate and combine their data sets to provide a larger sampling. Half of the samples were tested and analyzed at Temple; the rest were done in South Africa.

"The bone microstructure of these dinosaurs is actually a record of how these animals were growing throughout their lives," said Tumarkin-Deratzian. "It is almost similar to looking at tree rings."

What the researchers found was bands of fast growth and slower growth that seemed to indicate a pattern.

"What we found was that periodically, throughout their life, these dinosaurs were switching how fast they were growing," said Tumarkin-Deratzian. "We interpreted this as potentially a seasonal pattern because we know in modern animals these types of shifts can be induced by changes in nutrition. But that shift is often driven by changes in seasonality."

The researchers questioned what was causing the dinosaurs to be under stress at certain times during the year: staying up in the polar region and dealing with reduced nutrition during the winter or migrating to and from lower latitudes during the winter.

They did bone microstructure analysis on similar duck-billed dinosaur fossils found in southern Alberta, Canada, but didn't see similar stress patterns, implying that those dinosaurs did not experience regular periodic seasonal stresses. "We had two sets of animals that were growing differently," said Tumarkin-Deratzian.

Since the Alaska fossils had all been preserved in the same sedimentary horizon, Fiorillo examined the geology of the bonebeds in Alaska where the samples were excavated and discovered that these dinosaurs had been preserved in flood deposits.

"They are very similar to modern flood deposits that happen in Alaska in the spring when you get spring melt water coming off the Brooks Mountain Range," said Fiorillo. "The rivers flood down the Northern Slope and animals get caught in these floods, particularly younger animals, which appear to be what happened to these dinosaurs.

"So we know they were there at the end of the dark winter period, because if they were migrating up from the lower latitudes, they wouldn't have been there during these floods," he said.

There's not a lot of endotherms of size in the very northern latitudes that winter over.

Another Northern Lights Video

Did the Great Unconformity Cause the Cambrian Explosion?

The oceans teemed with life 600 million years ago, but the simple, soft-bodied creatures would have been hardly recognizable as the ancestors of nearly all animals on Earth today.

Then something happened. Over several tens of millions of years – a relative blink of an eye in geologic terms – a burst of evolution led to a flurry of diversification and increasing complexity, including the expansion of multicellular organisms and the appearance of the first shells and skeletons.

The results of this Cambrian explosion are well documented in the fossil record, but its cause – why and when it happened, and perhaps why nothing similar has happened since – has been a mystery.

New research shows that the answer may lie in a second geological curiosity – a dramatic boundary, known as the Great Unconformity, between ancient igneous and metamorphic rocks and younger sediments.

"The Great Unconformity is a very prominent geomorphic surface and there's nothing else like it in the entire rock record," says Shanan Peters, a geoscience professor at the University of Wisconsin–Madison who led the new work. Occurring worldwide, the Great Unconformity juxtaposes old rocks, formed billions of years ago deep within the Earth's crust, with relatively young Cambrian sedimentary rock formed from deposits left by shallow ancient seas that covered the continents just a half billion years ago.

Named in 1869 by explorer and geologist John Wesley Powell during the first documented trip through the Grand Canyon, the Great Unconformity has posed a longstanding puzzle and has been viewed – by Charles Darwin, among others – as a huge gap in the rock record and in our understanding of the Earth's history.

But Peters says the gap itself – the missing time in the geologic record – may hold the key to understanding what happened.

In the April 19 issue of the journal Nature, he and colleague Robert Gaines of Pomona College report that the same geological forces that formed the Great Unconformity may have also provided the impetus for the burst of biodiversity during the early Cambrian.

"The magnitude of the unconformity is without rival in the rock record," Gaines says. "When we pieced that together, we realized that its formation must have had profound implications for ocean chemistry at the time when complex life was just proliferating."

"We're proposing a triggering mechanism for the Cambrian explosion," says Peters. "Our hypothesis is that biomineralization evolved as a biogeochemical response to an increased influx of continental weathering products during the last stages in the formation of the Great Unconformity."

Peters and Gaines looked at data from more than 20,000 rock samples from across North America and found multiple clues, such as unusual mineral deposits with distinct geochemistry, that point to a link between the physical, chemical, and biological effects.

During the early Cambrian, shallow seas repeatedly advanced and retreated across the North American continent, gradually eroding away surface rock to uncover fresh basement rock from within the crust. Exposed to the surface environment for the first time, those crustal rocks reacted with air and water in a chemical weathering process that released ions such as calcium, iron, potassium, and silica into the oceans, changing the seawater chemistry.

The basement rocks were later covered with sedimentary deposits from those Cambrian seas, creating the boundary now recognized as the Great Unconformity.

Evidence of changes in the seawater chemistry is captured in the rock record by high rates of carbonate mineral formation early in the Cambrian, as well as the occurrence of extensive beds of glauconite, a potassium-, silica-, and iron-rich mineral that is much rarer today.

The influx of ions to the oceans also likely posed a challenge to the organisms living there. "Your body has to keep a balance of these ions in order to function properly," Peters explains. "If you have too much of one you have to get rid of it, and one way to get rid of it is to make a mineral."

The fossil record shows that the three major biominerals – calcium phosphate, now found in bones and teeth; calcium carbonate, in invertebrate shells; and silicon dioxide, in radiolarians – appeared more or less simultaneously around this time and in a diverse array of distantly related organisms.

The time lag between the first appearance of animals and their subsequent acquisition of biominerals in the Cambrian is notable, Peters says. "It's likely biomineralization didn't evolve for something, it evolved in response to something – in this case, changing seawater chemistry during the formation of the Great Unconformity. Then once that happened, evolution took it in another direction." Today those biominerals play essential roles as varied as protection (shells and spines), stability (bones), and predation (teeth and claws).

Together, the results suggest that the formation of the Great Unconformity may have triggered the Cambrian explosion.

I'll post a link to the paper later.

Mesosaur Embryos Found

Yes, there is a reason for this

On the Rocket Front

USN/BAe Railgun Test Fire

A Martian Ice Cave?

Early Permian Lagerstatte in China

Permian vegetational Pompeii from Inner Mongolia and its implications for landscape paleoecology and paleobiogeography of Cathaysia

1. Jun Wang (a,*)
2. Hermann W. Pfefferkorn (b,*)
3. Yi Zhang (c)
4. Zhuo Feng (d)

a. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China;

b. Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316;

c. Institute of Palaeontology, Shenyang Normal University, Shenyang 110034, China; and

d. Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China

*. To whom correspondence may be addressed. E-mail: jun.wang@nigpas.ac.cn or hpfeffer@sas.upenn.edu

Abstract

Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m2 of forest growing on peat could be reconstructed based on the actual location of individual plants. Tree ferns formed a lower canopy and either Cordaites, a coniferophyte, or Sigillaria, a lycopsid, were present as taller trees. Noeggerathiales, an enigmatic and extinct spore-bearing plant group of small trees, is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community. Landscape heterogenity is apparent, including one site where Noeggerathiales are dominant. This peat-forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval. This Permian flora demonstrates both similarities and differences to floras of the same age in Europe and North America and confirms the distinct character of the Cathaysian floral realm. Therefore, this flora will serve as a baseline for the study of other fossil floras in East Asia and the early Permian globally that will be needed for a better understanding of paleoclimate evolution through time.

Now if only someone would find one for the LATE Permian. I am also stoked to see what tetrapod fossils come out of this.

Back to Reality: 760 Million Year Old Sponge, Oldest Known Animal?

XenoPermian Biota of the Ural Sea: Graviloricanasus roma, a pseudochelonid

THE XENOPERMIAN OF THE URAL SEA

The Xenopermian is a collaborative effort between Scott, Raven, Zach and myself to outline a very different, speculative world. In some ways this is not all that different than the exercises of Dougal Dixon, After Man and The New Dinosaurs. Rather than speculating on what the dinosaurs would be like if they had not gone extinct, much like his New Dinosaurs or the Spec World project , or project into the future with After Man or The Future is Wild, our team asked the question of ‘what if the Permian Extinction did not happen?

This is the first post about the fauna of the Xenopermian in the Ural Sea region. We have talked about a ‘fossil’ and a faux controversy associated it with. We have talked about the geological staging differences in the XenoPermian timeline, and have even talked about the differences in the world in general under such a different period. We have generalized about the fauna, but now we want to get into specifics.

Despite the fact that the world is largely dominated by the different clades of therapsids, other major lineages are major participants in the ecology of the XenoPermian. Rather than start with a therapsid, we decided to talk about a parareptile first. That first critter is a pareiasaur. That begs the questions of what is a parareptile and what is a pareiasaur?

What are the parareptiles?

Parareptiles are a clade of amniotes that have been in the past often labeled ‘anapsids.’ Amniotes, vertebrate animals that have an amniotic sack and, for the most part, are terrestrial, were divided into different groups based on the shape and structure of their skulls. Synapsids are those that had a single hole in the skull for muscle to attach. Modern mammals are the only current survivors of that clade. Diapsids are the second group and currently comprise reptiles and birds except perhaps turtles. That will be explained later. Diapsids have two holes in their skulls for anchoring their jaw muscles. Finally, there was another large traditional group, the anapsids. These amniotes had no holes in their skulls. Traditionally, this included turtles as the sole surviving members of the clade, but with a vast number of extinct relatives. There was another group, the euryapsids, but they were a smaller group that was largely centered around the extinct marine reptiles.



It turns out that the shape and number of holes in the skull were not quite the best, most accurate way to group the different clades of animals. It is possible for diapsids to redevelop, for whatever reason, the anapsid (no hole) cranial condition. This was discovered when cladistics became the tool of choice by paleontologists to determine evolutionary relationships between fossils.

A number of families and genuses were shuffled around. Interestingly, the synapsids were untouched as a group. The diapsids largely held together, but the anapsids were slaughtered as far as a ‘natural group’ (meaning closely related and descended from a common ancestor). Some ‘anapsids’ were actually diapsids that had evolved or re-evolved the anapsid condition. When the arguing was done, the skull type that has been referred to as ‘anapsid’ applied to some species that were actually descended from the diapsids and many that were not. The proposal was made to rename the remaining anapsids that were not closely related to diapsids ‘parareptiles’ (next to reptiles) and accepted by the community as a whole.

The placement of turtles is fairly contentious. The pour critters are fought over whether they are members of a group that went through parallel evolution and evolved the anapsid condition from a diapsid ancestor or actually belonged back as a sole surviving members of the parareptiles. There is strong evidence that they are actually diapsids now from studying microRNA, but cladistic analysis by and large, well, almost consistently shows them to be parareptiles. This argument, as far as I can tell, has yet to be resolved.

Other than turtles, parareptiles comprise many fascinating and interesting groups. The seemingly first bipedal animals, the bolosaurs, are members of the group. The procolonphids are another interesting member. The nycoleters and their relatives are the first amniotes, it appears, to have evolved the middle ear from the apparently deaf ancestral condition. (Yes, the basal amniotes were deaf it seems, but that is another discussion for another time) Finally, most importantly for the Xenopermian and this post, the clade that we care about most is the pareiasaurs.

What were the pareiasaurs?



The pareiasaurs were one of the earliest large megafauna. They were herbivores that grew to be as large as ten feet long and were built like tanks. In fact, the pareiasaurs were the largest herbivores of their time and were built such that they housed a massive gut for digesting the tough plants of their era. Their teeth looked leaf like and not unlike those of iguanas

They were also tanks, as noted, and had scutes, osteoderms, in their skin. Most likely this was to deal with the very large and deadly gorgonopsids. Some have projected that the gorgons and pareiasarus were in an arms race where the armor of these critters built up to deal with the ever increasing size and viciousness of the canines of the gorgons.

If you want to know more, we recommend the basics at Wikipedia and the more extensive website at the University of California at Berkeley.

In our time line, they went extinct during the Permian Extinction. However, our timeline iwe actually live in s not that of the Xenopermian. The Xenopermian didn’t have a PT Event to wipe out all life. True, the Siberian Traps did erupt, but more gradually and over the course of millions of years instead of violently in a relatively short burst. This caused a period of evolutionary innovation and turnover, but did not wipe out many of the large clades. The pareiasaurs benefitted from that time of innovation and went on to develop into interesting clades.

Elginiformes, Scutosauroformes and Therischia, oh my!

Xenopermian Pareiasauria cladogram

Technically, all of the surviving pareiasaurian of the Xenopermian are from Therischia. This is a particular clade within the pareiasaurian lineage. In paleontology, cladistics dictates that the different fossils found are evaluated as relatives rather than ancestors. Its highly unlikely, honestly, that any one fossil species found gave rise to others that are related since the fossil record is infamously and enormously incomplete. However, in our world that the Xenopermian, we know exactly who is descended from whom. Or rather what from what. In our timeline we have two different lineages of pareiasaurs that have survived through to the 15 million year mark before the Xenopermian-Jurassic Mass Extinction.

The first derives from the dwarf pareiasaur, Elginia, and is very common as solitary animals scattered about the more marginal habitats. There are several species and genuses in the Megavongo, for example. The Barred Quillosaur being an excellent example. They all have a generally sprawled stance and are heavy armored, but in a manor reminiscent of the thorny devils of modern day Australia. Though with some parallels to the styracaosaurian ceraptopsians (sans nasal and brow horns). However, while being very species and even somewhat genera diverse the elginiformes are not the most diverse nor “dominant” of the two pareiasaur lineages. That would be the scutosauriformes.

Scutosaurus was a rather large beast by modern standards. With being around ten feet long and a chest like a barrel, it weighed in over 1000 lbs. It had several innovations that made it – without the Permian Extinction – a potential founder of a new and important lineage. Some of these were the stance changes, massive expansion of the digestive tract, probable homeothermy and extensive increases in the armoring scutes. With the power of the massive selectivity of being the creators of this timeline, Scutosaurus went forth and begat several new clades. Three of those clades have survived into the late XenoPermian.

The most basal of them is Deimocephalia. These are large, sometimes up to 4.5m (15 ft) animals. They move in bull dominated herds over vast distances. They give some basic parental care to their young although this is pretty limited to guarding the nest and forming a protective barrier while en route between the young and the outside world. Their name, terror heads, derives from the fact that they have very fanciful, species specific, crown and frill ornamentation. This is more extreme in the males than females, but present in both. Additionally their skulls have thickened for further protection. They retain the ancestral scute armor of the scutosauriformes. This clade is most common in the plains and other open territories, but also present in smaller forms in the more open forests of the Xenopermian world that permit herding.

The next most derived clade is that of the Juggernautids. These are massive animals that in terms of mass, if not length, rival the sauropods of our time line. Between 6 meters (20 ft) and some species being as long as 10m (over 32 ft), they have developed the brachiosaurian layout with the forelegs being much longer than the hind. They tower over the landscape with heights between 4.5m (15ft) to as much as 6m (20ft) in the largest species. They do NOT have the extended long neck of the sauropods while one somewhat longer than the standard pareiasaurs in proportion. The juggernautids did not just get their name from their size, but also from the fact that they radically shape the environment from which they live. The bulldoze paths for food and often reduce forests to copses that are either inaccessible to the juggernautid, or ‘managed’ such that there is not an interior that the juggernautid cannot reach for feeding. Forests where juggernautids exist have a strange almost garden like appearance what seem like streets when viewed from above. Juggernautids are not noted for their parenting skills even if they mate for life. Their young are heavily armoured and their scutes tend to still be present but more scattered across the body as the animal grows, these primary scutes are surrounded by thinner, but still tough secondary scutes, which in turn are followed by tertiary scute development between those with straight scaly skin separating the rosarettes of the largest creatures.

Neither of the above clades is present around the Ural Sea. However, the final clade is.

The Pseudochelonids are a large, heavy herbivores. They are called the pseudochelonids (false turtles) because of their heavily armored carapaces. They have some elements that are convergent on turtles in that regard, with the scutes often fusing with the broad ribs in some genuses. Visually, most look closer to anklyosaurs rather than turtles, but the first example found of the clade was the most extreme in its armour development and set the nomenclature for the whole group.

Some of the unifying characteristics are that the ribs are broad and flat, almost forming a fused shell dorsally. This is often covered by scutes that are interlocking. The skulls are extremely thick and heavy: even their eyelids are armoured. The brain case is relatively small for an animal of their relative size as well. However, the olfactory and aural regions are relatively developed to support what is a very good sense of smell and moderately developed middle ear. They all have vestigal or nonexistent tails. Their scutes cover more than their torso region and extend down onto the legs. Like all scutosauriformes, they have a parasagittal stance.

They are by and large solitary animals, but do not have defined ranges except during mating season and tolerate one another quite well otherwise. They do not give parental care to their young, building a rocky nest and then abandoning them. The newly hatched young once their skin dries and hardens become what some atl paleontologists call ‘jaw breakers’ (fractognathine stage) because their scutes are so thick and dense. Their main sources of mortality once they have become jaw breakers are not predators, but rather disease and drowning. Post fractgnathinous stage starts when the animal reaches 1 meter (40 inches) in length because of the inability of the body to continue to scale up with such armor. When the animal has reached 1.5m (five feet) in length, it often is sexually mature, but while still heavily armoured, in danger from its primary predator: the gorgonopsids. In fact, the pseudochelonids and the gorgonopsids are in something of an arms race: heavier armour vs stronger bites and better piercing saber teeth.

Graviloricanasus roma



In the Ural Sea region the dominant member, both most common and largest, is Graviloricanasus roma (Roman’s heavily armored nose). Named for the discoverer, Thomas Roman, it became a bit of an in-joke because the olfactory organ – nose – was quite impressive and the great Roman Nose was too good to pass up. The belief is that the olfactory sense was highly developed for two reasons. The first was that it allowed G. roma to smell its primary predators and locate when particular foods were present.

Predation Around the Ural Sea

The gorgonopsids of the Ural Sea region were G roma's primary predators and were noted for scent marking their territories. A cross genera territorial struggle between the Baurbarops millerensis and Dispathadontis gracilis, the two large top predators in the Ural Sea left some very impressive olfactory battlefields. B. millerensis was rarer and larger gorgon largely preying on dicynodonts, especially, but definitely not exclusively, what has been popularly called the ‘Walrodonts.’ Other preferred dicynodonts included the other less specialized aquatic dicynodonts, such has the so called "Hippodonts," "desmodonts," and others. However, given the beach front territory of adult B milernensis and the sea weed dining habits of G roma, B millerensis will opportunistically predate this pseudochelonid. The sheer size and strength of B millernesis makes this predation possible despite the extensive armor of G roma.

Dispathadontis, while it could and would take other prey, was largely a specialist in pseudochelonids. In the Ural Sea region, this specifically means G roma. While B millerensis is noted for its brute force hunting style, D gracilis is more finessed. D gracilis is noted for hunting in mated pairs. The pairing will corner a G roma and then attempt to rip out its wind wipe through the use of their sabre teeth.

The only other predator of note of G roma is the ambush predator crurodont, Venofirodens macbethii, a member of the clade descended from the therocephalian Euchambersia. V macbethii relies, like all of its clade, on the delivery of a poisonous bite to its prey for it take-down mechanism rather than traumatic damage to an organism.

Of course, as eggs, G roma is at risk from a variety of potential predators. The cynodont genus, Acerdens, the small Xenopermian theropods, niictodonts, and even opportunistic raids from the trees by suminids and foliosensids can and do take their toll on the unhatched.

Diet Peculiarities

One of the benefits of the nasal system of G roma was that it also allowed for scenting food sources other than the norm for consumption. One of those is seaweed. The seaweeds that swept up from the very mixed waters of the Ural Sea are a nutritious addition to the normal diet. When the tide goes out, G roma often comes out of the coastal forest to dine, as pictured here. This is, however, the point that G roma is most in risk of predation from B millerensis.

However, for the majority of its nutritional needs, G roma browses within the Ural Sea coastal forests. Its diet is largely comprised of ferns and seed plant leaves. Its preference is not for horsetails or their allies, but will consume these during hard times.

Ecological Impact

G roma's impact on the local ecology is moderate, but appreciable. Its nothing like its remote cousins, the Juggernautids, but it is far from trivial. Within the Ural Sea coastal forests, wide avenues are present from the passage of G roma to and from certain locales, especially watering holes. This in turn, has stimulated seed baring plants to develop into upper canopy participants by leaving potential places for trees with wide boughs to collect light where the horsetails are unable to. Ginkgoes and others have taken advantage of this.

Other significant impacts are the specialization of Dispathadontis and the development of scatosporic ferns (dug heaps often sprout ferns in a massive way from consuming through an odd life cycle of certain fern species in the Ural Sea region).

Legacy

Graviloricanasus roma would last as a species for approximately three million years. Its genus would last to nearly the Xenopermian-Jurassic Extinction. All parieasaurs would go extinct during the XJ Event and take with them their "tormentors" and largely specialist carnivores, the gorgonopsids. It would be over 100 million years before another walking tank would arise, but it would not be another parareptile and it would happen outside the Xenopermian, well within the Mesozoic and embedded in the alternate Cretaceous. And thus, outside the scope of this project as yet.


Author's note: Here's our first critter. I hope that you folks enjoyed it. My apologies for the delay. Next up will be a therapsid. A notable little tree hugger for that matter. It will be a bit before it appears here, but hopefully not too long. I need yet another cladogram and its a far more complicated one than the above!

First Plants Caused Ice Age During the Ordovician?

New research reveals how the arrival of the first plants 470 million years ago triggered a series of ice ages. Led by the Universities of Exeter and Oxford, the study is published today (1 February 2012) in Nature Geoscience.

The team set out to identify the effects that the first land plants had on the climate during the Ordovician Period, which ended 444 million years ago. During this period the climate gradually cooled, leading to a series of 'ice ages'. This global cooling was caused by a dramatic reduction in atmospheric carbon, which this research now suggests was triggered by the arrival of plants.

Among the first plants to grow on land were the ancestors of mosses that grow today. This study shows that they extracted minerals such as calcium, magnesium, phosphorus and iron from rocks in order to grow. In so doing, they caused chemical weathering of the Earth's surface. This had a dramatic impact on the global carbon cycle and subsequently on the climate. It could also have led to a mass extinction of marine life.

The research suggests that the first plants caused the weathering of calcium and magnesium ions from silicate rocks, such as granite, in a process that removed carbon dioxide from the atmosphere, forming new carbonate rocks in the ocean. This cooled global temperatures by around five degrees Celsius.

In addition, by weathering the nutrients phosphorus and iron from rocks, the first plants increased the quantities of both these nutrients going into the oceans, fuelling productivity there and causing organic carbon burial. This removed yet more carbon from the atmosphere, further cooling the climate by another two to three degrees Celsius. It could also have had a devastating impact on marine life, leading to a mass extinction that has puzzled scientists.

The team used the modern moss, Physcomitrella patens for their study. They placed a number of rocks, with or without moss growing on them, into incubators. Over three months they were able to measure the effects the moss had on the chemical weathering of the rocks.

They then used an Earth system model to establish what difference plants could have made to climate change during the Ordovician Period.

I've heard this put forward for the Devonian, but not the Ordovician. For that matter, the Azolla Event is another proposed biologically driven climate change. We'll see how this plays out. The timing is...tough...to prove, but we do know that life even nonsapient/sophont does impact climate.

Volcanoes, Not the Maunder Minimum Caused the Little Ice Age?

A mysterious, centuries-long cool spell, dubbed the Little Ice Age, appears to have been caused by a series of volcanic eruptions and sustained by sea ice, a new study indicates.

The research, which looked at chemical clues preserved in Arctic vegetation as well as other data, also pinpointed the start of the Little Ice Age to the end of the 13th century.

During the cool spell, which lasted into the late 19th century, advancing glaciers destroyed northern European towns and froze the Thames River in London and canals in the Netherlands, places that are now ice-free. There is also evidence it affected other continents.

"This is the first time anyone has clearly identified the specific onset of the cold times marking the start of the Little Ice Age," said Gifford Miller, a geological sciences professor at the University of Colorado, Boulder, and the lead study researcher. "We also have provided an understandable climate feedback system that explains how this cold period could be sustained for a long period of time."

The cause appears to have been massive tropical volcanic eruptions, which spewed tiny particles called aerosols into the atmosphere. While suspended in the air, the aerosols reflect solar radiation back into space, cooling the planet below.

The cooling was sustained after the aerosols had left the atmosphere by a sea-ice feedback in the North Atlantic Ocean, the researchers believe. Expanding sea ice would have melted into the North Atlantic Ocean, interfering with the normal mixing between surface and deeper waters. This meant the water flowing back to the Arctic was colder, helping to sustain large areas of sea ice, which, in turn, reflect sunlight back into the atmosphere. The result was a self-sustaining feedback loop.

Miller and colleagues came to these conclusions by looking at radiocarbon dates — based on how much of the radioactive form of carbon they contain — from dead plants revealed by melting ice on Baffin Island, in the Canadian Arctic. Their analysis found that many plants at both high and low altitudes died between A.D. 1275 and A.D. 1300 — evidence that Baffin Island froze over suddenly. Many plants also appeared to have died at around A.D. 1450, an indication of a second major cooling.

These periods coincide with two of the most volcanically active half centuries in the past millennium, according to the researchers.

Let's see if they can provide more support. Its intriguing, but caution is in order.

What Happened Prior to the Carbon Prior to the Marinoan Glaciations (Snowball Earth)

In a study published in the journal Geology, scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science suggest that the large changes in the carbon isotopic composition of carbonates which occurred prior to the major climatic event more than 500 million years ago, known as 'Snowball Earth,' are unrelated to worldwide glacial events.

"Our study suggests that the geochemical record documented in rocks prior to the Marinoan glaciation or 'Snowball Earth' are unrelated to the glaciation itself," said UM Rosenstiel professor Peter Swart, a co-author of the study. "Instead the changes in the carbon isotopic ratio are related to alteration by freshwater as sea level fell."

In order to better understand the environmental conditions prior to 'Snowball Earth', the research team analyzed geochemical signatures preserved in carbonate rock cores from similar climactic events that happened more recently — two million years ago — during the Pliocene-Pleistocene period.

The team analyzed the ratio of the rare isotope of carbon (13C) to the more abundant carbon isotope (12C) from cores drilled in the Bahamas and the Enewetak Atoll in the Pacific Ocean. The geochemical patterns that were observed in these cores were nearly identical to the pattern seen prior to the Marinoan glaciation, which suggests that the alteration of rocks by water, a process known as diagenesis, is the source of the changes seen during that time period.

Prior to this study, scientists theorized that large changes in the cycling of carbon between the organic and inorganic reservoirs occurred in the atmosphere and oceans, setting the stage for the global glacial event known as 'Snowball Earth'.

"It is widely accepted that changes in the carbon isotopic ratio during the Pliocene-Pleistocene time are the result of alteration of rocks by freshwater," said Swart. "We believe this is also what occurred during the Neoproterozoic. Instead of being related to massive and complicated changes in the carbon cycle, the variations seen in the Neoproterozoic can be explained by simple process which we understand very well."

Scientists acknowledge that multiple sea level fluctuations occurred during the Pliocene-Pleistocene glaciations resulting from water being locked up in glaciers. Similar sea-level changes during the Neoproterozoic caused the variations in the global carbon isotopic signal preserved in the older rocks, not a change in the distribution of carbon as had been widely postulated.

I don't see the paper online as yet...

All These Worlds...

Purty Bird: X-47 From Above

Archetype: Robocop Nouveau

Greenhouse Gases Postpone (Cancel?) Next Glacial Cycle

Unprecedented levels of greenhouse gases in the Earth's atmosphere are disrupting normal patterns of glaciation, according to a study co-authored by a University of Florida researcher and published online Jan. 8 in Nature Geoscience.

The Earth's current warm period that began about 11,000 years ago should give way to another ice age within about 1,500 years, according to accepted astronomical models. However, current levels of carbon dioxide are trapping too much heat in the atmosphere to allow the Earth to cool as it has in its prehistoric past in response to changes in Earth's orbital pattern. The research team, a collaboration among University College London, University of Cambridge and UF, said their data indicate that the next ice age will likely be delayed by tens of thousands of years.

That may sound like good news, but it probably isn't, said Jim Channell, distinguished professor of geology at UF and co-author.

"Ice sheets like those in western Antarctica are already destabilized by global warming," said Channell. "When they eventually slough off and become a part of the ocean's volume, it will have a dramatic effect on sea level." Ice sheets will continue to melt until the next phase of cooling begins in earnest.

The study looks at the prehistoric climate-change drivers of the past to project the onset of the next ice age. Using astronomical models that show Earth's orbital pattern with all of its fluctuations and wobbles over the last several million years, astronomers can calculate the amount of solar heat that has reached the Earth's atmosphere during past glacial and interglacial periods.

"We know from past records that Earth's orbital characteristics during our present interglacial period are a dead ringer for orbital characteristics in an interglacial period 780,000 years ago," said Channell. The pattern suggests that our current period of warmth should be ending within about 1,500 years.

However, there is a much higher concentration of greenhouse gases trapping the sun's heat in the Earth's atmosphere now than there was in at least the last several million years, he said. So the cooling that would naturally occur due to changes in the Earth's orbital characteristics are unable to turn the temperature tide.

Over the past million years, the Earth's carbon dioxide levels, as recorded in ice core samples, have never reached more than 280 parts per million in the atmosphere. "We are now at 390 parts per million," Channell said. The sudden spike has occurred in the last 150 years.

For millions of years, carbon dioxide levels have ebbed and flowed between ice ages. Orbital patterns initiate periods of warming that cause ocean circulation to change. The changes cause carbon dioxide-rich water in the deep ocean to well up toward the surface where the carbon dioxide is released as a gas back into the atmosphere. The increase in atmospheric carbon dioxide then drives further warming and eventually the orbital pattern shifts again and decreases the amount of solar heat that reaches the Earth.

"The problem is that now we have added to the total amount of CO2 cycling through the system by burning fossil fuels," said Channell. "The cooling forces can't keep up."

1. Duh.

2. This may well be a permanent off ramp for Ice Age we have been in.

3. There might have been interglacial ending on-ramps we missed before and are missing right now.

4. Keep in mind it took over 50k years for the last time there was a huge build up in CO2 like the modern one took over 50k years for the environment to recover...and it didn't go back to what it was before.

5. The main question is whether or not we are going to have a Neo-Eocene (hot, wet) or Neo-Oligocene (hot dry).

NorAm Mammalian Fauna Diversity Shifts with Climate

(original artist here)

History often seems to happen in waves – fashion and musical tastes turn over every decade and empires give way to new ones over centuries. A similar pattern characterizes the last 65 million years of natural history in North America, where a novel quantitative analysis has identified six distinct, consecutive waves of mammal species diversity, or "evolutionary faunas." What force of history determined the destiny of these groupings? The numbers say it was typically climate change.

"Although we've always known in a general way that mammals respond to climatic change over time, there has been controversy as to whether this can be demonstrated in a quantitative fashion," said Brown University evolutionary biology Professor Christine Janis. "We show that the rise and fall of these faunas is indeed correlated with climatic change – the rise or fall of global paleotemperatures – and also influenced by other more local perturbations such as immigration events."

Specifically, of the six waves of species diversity that Janis and her Spanish collaborators describe online this week in the Proceedings of the National Academy of Sciences, four show statistically significant correlations with major changes in temperature. The two transitions that show a weaker but still apparent correlation with the pattern correspond to periods when mammals from other continents happened to invade in large numbers, said Janis, who is the paper's senior and second author.

Previous studies of the potential connection between climate change and mammal species evolution have counted total species diversity in the fossil record over similar time periods. But in this analysis, led by postdoctoral scholar Borja Figueirido, the scientists asked whether there were any patterns within the species diversity that might be significant. They were guided by a similar methodology pioneered in a study of "evolutionary faunas" in marine invertebrates by Janis' late husband Jack Sepkoski, who was a paleontologist at the University of Chicago.

What the authors found is six distinct and consecutive groupings of mammal species that shared a common rise, peak and decline in their numbers. For example, the "Paleocene fauna" had largely given way to the "early-middle Eocene fauna" by about 50 million years ago. Moreover, the authors found that these transfers of dominance correlated with temperature shifts, as reflected in data on past levels of atmospheric oxygen (determined from the isotopes in the fossilized remains of deep sea microorganisms).

By the numbers, the research showed correlations between species diversity and temperature change, but qualitatively, it also provided a narrative of how the traits of typical species within each wave made sense given the changes in vegetation that followed changes in climate. For example, after a warming episode about 20 million years in the early Miocene epoch, the dominant vegetation transitioned from woodland to a savannah-like grassland. It is no surprise, therefore, that many of the herbivores that comprised the accompanying "Miocene fauna" had high-crowned teeth that allowed them to eat the foods from those savannah sources.

Original paper here.

Tasmanian Triassic Dicynodont Found

A Tasmanian couple on a quiet walk down to the beach a few years ago discovered a fossil that scientists say is 250 million years old.

Bob and Penny Tyson found the fossilised remains of a dicynodont, a tusked plant-eating animal that's believed to be a distant ancestor of modern mammals.

Roughly the size of a cow, it had two tusks and a horny beak.

Queensland Museum palaeontologist Andrew Rozefelds says the dicynodont lived on every continent, including Antarctica.

The ABC reports that until now, the only specimen previously found in Australia was in Queensland almost 30 years ago.

He describes the dicynodont as a ''strange-looking beast''.

''They had tusks at the front of their skull, which makes you think maybe they were a carnivore, but in fact they were a plant eater.

''They had slightly splayed legs, so their posture was quite different to say some of the modern mammals you see and they're very, very distantly related to modern mammals.''

I don't see a paper at the JVP. However, considering the journal is a little outdated from the last time they updated what's online, I'm not surprised. Previously, in Tasmania the predominant fossils were temnospondyls. And not much else.

Even Nastier Siberian Traps

Around 250 million years ago, at the end of the Permian geologic period, there was a mass extinction so severe that it remains the most traumatic known species die-off in Earth's history. Although the cause of this event is a mystery, it has been speculated that the eruption of a large swath of volcanic rock in Russia called the Siberian Traps was a trigger for the extinction. New research from Carnegie's Linda Elkins-Tanton and her co-authors offers insight into how this volcanism could have contributed to drastic deterioration in the global environment of the period. Their work is published January 9 in Earth and Planetary Science Letters.

The end-Permian mass extinction saw the sudden loss of more than 90 percent of marine species and more than 70 percent of terrestrial species. The fossil record suggests that ecological diversity did not fully recover until several million years after the main pulse of the extinction. This suggests that environmental conditions remained inhospitable for an extended period of time.

Volcanic activity in the Siberian Traps has been proposed as one of the mechanisms that may have triggered the mass extinction. Gases released as a result of Siberian magmatism could have caused environmental damage. For example, perhaps sulfur particles in the atmosphere reflected the sun's heat back into space, cooling the planet; or maybe chlorine and other chemically similar nonmetal elements called halogens significantly damaged the ozone layer in the stratosphere.

The team designed experiments to examine these possibilities.

Led by Benjamin Black of the Massachusetts Institute of Technology, the group included Elkins-Tanton, formerly of MIT and now director of Carnegie's Department of Terrestrial Magnetism, Michael C. Rowe of Washington State University, and Ingrid Ukstins Peate of the University of Iowa.

The geology of the Siberian Traps is comprised of flood basalts, which form when giant lava eruptions coat large swaths of land or ocean floor with basaltic lava. This lava hardens into rock formations. The team investigated concentrations of sulfur, chlorine and fluorine (another halogen) that were dissolved in tiny samples of ancient magma found within basalt samples from the Siberian Traps. These small frozen droplets, which preserve a record of volcanic gases from the time of the eruption 250 million years ago, are called melt inclusions.

Sulfur, chlorine, and fluorine gasses could have been released into the atmosphere from eruptions spewing out of large fissures, which is common in basalt flood formation. Plumes escaping from these cracks could have reached the stratosphere. If sulfur, chlorine, and fluorine made it to the upper atmosphere, these gasses could have cause a wide array of adverse climate events, including temperature change and acid rain.

Based on their findings, the team estimated that between 6,300 and 7,800 gigatonnes of sulfur, between 3,400 and 8,700 gigatonnes of chlorine, and between 7,100 and 13,700 gigatonnes of fluorine were released from magma in the Siberian Traps during the end of the Permian period.

Anyone have the paper itself? I've not been able to find it on the server.

Siberian Traps Were Meaner Than We Knew

Explosive eruption of coal and basalt and the end-Permian mass extinction

1. Darcy E. Ogden (a)
2. Norman H. Sleep (b,*)


a. Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, 1156 Gilman Drive, La Jolla, CA 92093-0225; and

b. Department of Geophysics, Mitchell Building, 397 Panama Mall, Stanford University, Stanford CA 94305

* To whom correspondence should be addressed. E-mail: norm@stanford.edu.

Abstract:

The end-Permian extinction decimated up to 95% of carbonate shell-bearing marine species and 80% of land animals. Isotopic excursions, dissolution of shallow marine carbonates, and the demise of carbonate shell-bearing organisms suggest global warming and ocean acidification. The temporal association of the extinction with the Siberia flood basalts at approximately 250 Ma is well known, and recent evidence suggests these flood basalts may have mobilized carbon in thick deposits of organic-rich sediments. Large isotopic excursions recorded in this period are potentially explained by rapid venting of coal-derived methane, which has primarily been attributed to metamorphism of coal by basaltic intrusion. However, recently discovered contemporaneous deposits of fly ash in northern Canada suggest large-scale combustion of coal as an additional mechanism for rapid release of carbon. This massive coal combustion may have resulted from explosive interaction with basalt sills of the Siberian Traps. Here we present physical analysis of explosive eruption of coal and basalt, demonstrating that it is a viable mechanism for global extinction. We describe and constrain the physics of this process including necessary magnitudes of basaltic intrusion, mixing and mobilization of coal and basalt, ascent to the surface, explosive combustion, and the atmospheric rise necessary for global distribution.

Explosive coal eruptions and mass mercury poisoning. Halogen emitting lakes and ozone layer depletion. Its definitely time for a rewrite of my PT Extinction post.

...in my copious amounts of spare time.

On Titan the Rain Mainly Falls on the Plains in Spring and Fall

Saturn's largest moon, Titan, is an intriguing, alien world that's covered in a thick atmosphere with abundant methane. With an average surface temperature of a brisk -297 degrees Fahrenheit (about 90 kelvins) and a diameter just less than half of Earth's, Titan boasts methane clouds and fog, as well as rainstorms and plentiful lakes of liquid methane. It's the only place in the solar system, other than Earth, that has large bodies of liquid on its surface.

The origins of many of these features, however, remain puzzling to scientists. Now, researchers at the California Institute of Technology (Caltech) have developed a computer model of Titan's atmosphere and methane cycle that, for the first time, explains many of these phenomena in a relatively simple and coherent way.

In particular, the new model explains three baffling observations of Titan. One oddity was discovered in 2009, when researchers led by Caltech professor of planetary science Oded Aharonson found that Titan's methane lakes tend to cluster around its poles—and noted that there are more lakes in the northern hemisphere than in the south.

Secondly, the areas at low latitudes, near Titan's equator, are known to be dry, lacking lakes and regular precipitation. But when the Huygens probe landed on Titan in 2005, it saw channels carved out by flowing liquid—possibly runoff from rain. And in 2009, Caltech researchers discovered raging storms that may have brought rain to this supposedly dry region.

Finally, scientists uncovered a third mystery when they noticed that clouds observed over the past decade—during summer in Titan's southern hemisphere—cluster around southern middle and high latitudes.

Scientists have proposed various ideas to explain these features, but their models either can't account for all of the observations, or do so by requiring exotic processes, such as cryogenic volcanoes that spew methane vapor to form clouds. The Caltech researchers say their new computer model, on the other hand, can explain all these observations—and does so using relatively straightforward and fundamental principles of atmospheric circulation.

"We have a unified explanation for many of the observed features," says Tapio Schneider, the Frank J. Gilloon Professor of Environmental Science and Engineering. "It doesn't require cryovolcanoes or anything esoteric." Schneider, along with Caltech graduate student Sonja Graves, former Caltech graduate student Emily Schaller (PhD '08), and Mike Brown, the Richard and Barbara Rosenberg Professor and professor of planetary astronomy, have published their findings in the January 5 issue of the journal Nature.

Schneider says the team's simulations were able to reproduce the distribution of clouds that's been observed—which was not the case with previous models. The new model also produces the right distribution of lakes. Methane tends to collect in lakes around the poles because the sunlight there is weaker on average, he explains. Energy from the sun normally evaporates liquid methane on the surface, but since there's generally less sunlight at the poles, it's easier for liquid methane there to accumulate into lakes.

But then why are there more lakes in the northern hemisphere? Schneider points out that Saturn's slightly elongated orbit means that Titan is farther from the sun when it's summer in the northern hemisphere. Kepler's second law says that a planet orbits more slowly the farther it is from the sun, which means that Titan spends more time at the far end of its elliptical orbit, when it's summer in the north. As a result, the northern summer is longer than the southern summer. And since summer is the rainy season in Titan's polar regions, the rainy season is longer in the north. Even though the summer rains in the southern hemisphere are more intense—triggered by stronger sunlight, since Titan is closer to the sun during southern summer—there's more rain over the course of a year in the north, filling more lakes.

In general, however, Titan's weather is bland, and the regions near the equator are particularly dull, the researchers say. Years can go by without a drop of rain, leaving the lower latitudes of Titan parched. It was a surprise, then, when the Huygens probe saw evidence of rain runoff in the terrain. That surprise only increased in 2009 when Schaller, Brown, Schneider, and then–postdoctoral scholar Henry Roe discovered storms in this same, supposedly rainless, area.

No one really understood how those storms arose, and previous models failed to generate anything more than a drizzle. But the new model was able to produce intense downpours during Titan's vernal and autumnal equinoxes—enough liquid to carve out the type of channels that Huygens found. With the model, the researchers can now explain the storms. "It rains very rarely at low latitudes," Schneider says. "But when it rains, it pours."

The new model differs from previous ones in that it's three-dimensional and simulates Titan's atmosphere for 135 Titan years—equivalent to 3,000 years on Earth—so that it reaches a steady state. The model also couples the atmosphere to a methane reservoir on the surface, simulating how methane is transported throughout the moon.

The model successfully reproduces what scientists have already seen on Titan, but perhaps what's most exciting, Schneider says, is that it also can predict what scientists will see in the next few years. For instance, based on the simulations, the researchers predict that the changing seasons will cause the lake levels in the north to rise over the next 15 years. They also predict that clouds will form around the north pole in the next two years. Making testable predictions is "a rare and beautiful opportunity in the planetary sciences," Schneider says. "In a few years, we'll know how right or wrong they are.

Its a frozen Tanith!

A Few Xmas Pix

Its been a while since I put up some family pix. Here's my daughter, Avrora, now age 6, and my son, Orest, now 2.

Another PT Extinction Factor: Mercury Poisoning

Scientists have uncovered a lot about the Earth's greatest extinction event that took place 250 million years ago when rapid climate change wiped out nearly all marine species and a majority of those on land. Now, they have discovered a new culprit likely involved in the annihilation: an influx of mercury into the eco-system.

"No one had ever looked to see if mercury was a potential culprit. This was a time of the greatest volcanic activity in Earth's history and we know today that the largest source of mercury comes from volcanic eruptions," says Dr. Steve Grasby, co-author of a paper published this month in the journal Geology. "We estimate that the mercury released then could have been up to 30 times greater than today's volcanic activity, making the event truly catastrophic." Grasby is a research scientist at Natural Resources Canada and an adjunct professor at the University of Calgary.

[...]

During the late Permian, the natural buffering system in the ocean became overloaded with mercury contributing to the loss of 95 per cent of life in the sea.

"Typically, algae acts like a scavenger and buries the mercury in the sediment, mitigating the effect in the oceans," says lead-author Dr. Hamed Sanei, research scientist at Natural Resources Canada and adjunct professor at the University of Calgary. "But in this case, the load was just so huge that it could not stop the damage."

[...]

The mercury deposition rates could have been significantly higher in the late Permian when compared with today's human-caused emissions. In some cases, levels of mercury in the late Permian ocean was similar to what is found near highly contaminated ponds near smelters, where the aquatic system is severely damaged, say researchers

Looking more and more like my PT Extinction post needs an update. It has been almost 6 years. (wow) And I have STILL not finished my other paleo posts. :(

6th Generation US Fighter Concepts

Lockheed Martin(snark: Hey! look! Its am YF-23!)

Northrop Grumman

Boeing