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https://paleontology.us/allosaurus-vs-stegosaurus/ Paleontology_US Sat, 30 May 2020 13:53:26 +0000 Paleontology https://paleontology.us/?p=1353 Allosaurus vs. Stegosaurus Across the plains and woodlands of late Jurassic North America, circa 150 million years ago, two dinosaurs stood out for their size and majesty: the gentle, small-brained, impressively plated Stegosaurus, and the agile, three-fingered and perpetually hungry Allosaurus. Before these dinosaurs take their corners in the Dinosaur Death Duel thunderdome, let’s look […]
Across the plains and woodlands of late Jurassic North America, circa 150 million years ago, two dinosaurs stood out for their size and majesty: the gentle, small-brained, impressively plated Stegosaurus, and the agile, three-fingered and perpetually hungry Allosaurus. Before these dinosaurs take their corners in the Dinosaur Death Duel thunderdome, let’s look at their specs. (See more Dinosaur Death Duels.)
About 30 feet long from head to tail and weighing in the neighborhood of two to three tons, Stegosaurus was built like a Jurassic tank. Not only did this plant-eater sport two rows of roughly triangular bony plates lining its back and neck, but its skin was extremely tough (and probably much harder to bite through than the epidermis of an elephant). this dinosaur’s name, “roofed lizard,†was bestowed before paleontologists properly understood the orientation of its famous “scutes,†or bony plates (and even today, there’s some controversy about what these plates were actually intended for).
Advantages . In close combat, Stegosaurus could rely on its spiked tail–sometimes called a “thagomizerâ€â€“to deter hungry theropods. We don’t know how fast the average Stegosaurus could swing this deadly weapon, but even a glancing blow might well have taken out an unlucky theropod’s eye, or inflicted some other nasty wound that would convince it to go after easier prey. The squat build of Stegosaurus, and its low center of gravity, also made this dinosaur difficult to dislodge from an advantageous position.
Disadvantages . Stegosaurus is the genus everyone has in mind when they talk about how spectacularly dumb dinosaurs were. This hippopotamus-size herbivore only possessed a brain the size of a walnut, so there’s now way it could outsmart a nimble theropod like Allosaurus (or even a giant fern, for that matter). Stegosaurus was also considerably slower than Allosaurus, thanks to its low-to-the-ground build and much shorter legs. As for its plates, they would have been virtually useless in combat–unless these structures evolved to make Stegosaurus look much bigger than it actually was, and thus prevent a fight in the first place.
Pound for pound, if we’re speaking literally, a full-grown Allosaurus would be almost an even match for an adult Stegosaurus. The largest specimens of this two-legged killing machine measured about 40 feet from head to tail and weighed about two tons. Like Stegosaurus, Allosaurus has a slightly deceptive name–Greek for “different lizard,†which didn’t impart much information to early paleontologists save for the fact that it was an entirely different dinosaur from the closely related Megalosaurus.
Advantages . The deadliest weapon in Allosaurus’ armory was its teeth. This theropod’s plentiful choppers attained lengths of three or four inches, and were continually growing, and being shed, during its lifetime–meaning they were more likely than not to be razor-sharp and ready for the kill. We don’t know quite how fast Allosaurus was able to run , but it’s a sure bet that it was speedier than the plodding, walnut-brained Stegosaurus. And let’s not forget those grasping, three-fingered hands, a more nimble implement than anything in Stegosaurus’ armory.
Disadvantages . As fearsome as it was, there’s no evidence that Allosaurus ever got the hang of hunting in packs, which would have been of considerable advantage when attempting to take down a plant-eating dinosaur the size of a Sherman tank. It’s also unlikely that Allosaurus could do much with its relatively puny arms (as opposed to its hands), which were still, however, much deadlier than the near-vestigial appendages of the much later Tyrannosaurus Rex . And then there’s the matter of weight class; although the largest Allosaurus individuals might have approached Stegosaurus in bulk, most adults weighed only one or two tons, max.
Let’s say our full-grown Allosaurus happens upon the Stegosaurus while the latter dinosaur is busy feeding on low, tasty shrubs. Allosaurus lowers its neck, builds up a head of steam, and butts the Stegosaurus in the flank with its big, bony head, imparting countless megajoules of momentum. Startled, but not quite toppled, the Stegosaurus lashes out with the thagomizer on the end its tail, inflicting only superficial wounds on Allosaurus’ hind legs; at the same time, it crouches closer to the ground, so as not to expose its soft underbelly to a well-delivered bite. Undeterred, Allosaurus charges again, lowers its massive head, and this time succeeds in flipping the Stegosaurus onto its side.
Allosaurus! Once dislodged from its defensive position, the slow-witted Stegosaurus is nearly as helpless as a flipped turtle, uselessly thrashing its head and its thagomizer and bellowing to other members of the herd. A modern tiger would mercifully bite its prey in the neck and end its misery, but Allosaurus, unencumbered by any sort of Jurassic conscience, digs into Stegosaurus’ belly and begins eating its entrails while its victim is still alive. Other hungry theropods, including small, feathered dino-birds, cluster around the scene, eager for a taste of the kill but sensible enough to let the much bigger Allosaurus have its fill first.
https://paleontology.us/10-best-dinosaur-books-in-2020/ Paleontology_US Mon, 11 May 2020 13:34:56 +0000 Paleontology http://www.paleontology.us/?p=1277 10 Best Dinosaur Books in 2020 Tons of dinosaur books are written every year for kids, but if you want the most reliable, up-to-date information it’s best to consult literature aimed at science-minded teenagers and adults (or even other scientists). Here’s our list of the 10 best, most essential, readable, and scientifically accurate books about […]
Tons of dinosaur books are written every year for kids, but if you want the most reliable, up-to-date information it’s best to consult literature aimed at science-minded teenagers and adults (or even other scientists). Here’s our list of the 10 best, most essential, readable, and scientifically accurate books about dinosaurs and prehistoric life.
Dorling-Kindersley’s Prehistoric Life qualifies as a coffee-table book, full of stunning illustrations (photographs of fossils, detailed depictions of prehistoric animals in their natural habitats) and voluminous amounts of text. This handsome book doesn’t only focus on dinosaurs, but also mammals, birds, plants and fish, ranging all the way from the Proterozoic age to the rise of modern humans; it also includes detailed descriptions of all the Earth’s geologic epochs, which helps put its vast profusion of prehistoric life into an accessible context.
Dinosaurs: A Concise Natural History is a genuine college textbook, complete with scholarly references and questions at the ends of chapters, intended as exercises for undergrads or graduate students, but fun for lay readers to tackle as well. It’s also one of the most detailed, comprehensive, and readable overviews of dinosaurs you can buy, especially notable for its detailed classification of the different types of dinosaurs of the Mesozoic Era, and its authors (David E. Fastovsky and David B. Weishampel) have an infectious sense of humor.
Over the last couple of decades, Dougal Dixon’s lavishly illustrated World Encyclopedia of Dinosaurs has been sliced and diced by its publisher into numerous smaller and less comprehensive books, and the concept has been imitated ad infinitum by lesser writers using less striking illustrators. This is the edition to get, though, if you’re looking for concise, crisply illustrated profiles of over 1,000 prehistoric animals, including  birds, crocodiles, and megafauna mammals as well as dinosaurs both well-known and extremely obscure.
With its massive head, enormous jaws, and formidable teeth, Tyrannosaurus rex has long been the young person’s favorite creepy carnivore in the Mesozoic zoo. Nor has T. rex been ignored by the scientific community, as this new collection amply demonstrates. Scientists explore such questions as why T. rex had such small forelimbs; how the dinosaur moved; what bone pathologies tell us about life in the Cretaceous; and whether T. rex was a predator, a scavenger, or both. There are reports on newly discovered skeletons, on variation and sexual dimorphism, and how the big beasts chewed. The methods used by the contributors to unlock the mysteries of T. rex range from “old fashioned†stratigraphy to contemporary computer modeling. Together they yield a wealth of new information about one of the dinosaur world’s most famous carnivores. An enclosed CD-ROM presents additional photographic and filmed reconstructions of the mighty beast.
Many people find it surprising that the fossils of so many marine reptiles, dating to the Jurassic and Cretaceous periods, have been discovered in landlocked Kansas, of all places. The evocatively titled Oceans of Kansas , by Michael J. Everhart, is an exhaustive if somewhat academic survey of the dozens of ichthyosaurs, plesiosaurs, and mosasaurs that have been discovered in the western U.S., as well as the distantly related  pterosaurs that flew above the Western Interior Sea and occasionally preyed on these marine reptiles.
The Complete Dinosaur was getting on a bit in age–the first edition of this 750-page reference book was published in 1999–but dinosaur fans will be happy to know that a second edition, subtitled Life of the Past , appeared in 2012, under the supervision of the eminent paleontologists Michael K. Brett-Surman and Thomas Holtz. Page for page, this is the most comprehensive, scholarly, and just plain fun dinosaur book out there, with meaty contributions by a veritable who’s who of famous scientists and researchers; this is the book to buy if you believe the recipient is a budding paleontologist.
As its subtitle implies, Ross Piper’s Extinct Animals : Species That Have Disappeared During Human History has nothing to do with dinosaurs, focusing instead on 50 or so notable mammals, birds, and reptiles that have gone extinct within the last 50,000 years–ranging from the Golden Toad (a very recent casualty of human civilization) to Phorusrhacos, better known as the Terror Bird. Some of the terminology in this book is a bit odd, especially regarding the names of some of the better-known animals, but it’s still a fun and informative read.
Bruce S. Lieberman and Roger Kaesler’s Prehistoric Life : Evolution and the Fossil Record puts dinosaurs (and other extinct animals) in their proper natural context, with a focus on mass extinctions, plate tectonics, continental drift and global climate change. This textbook (intended for college students, but eminently accessible to curious laypeople) drives home the point that evolution isn’t a linear process, but one that zigs and zags in response to an unpredictable and often-hostile environment, and the evidence for which crucially depends on the discovery of fossils.
The chief virtue of Gregory S. Paul’s The Princeton Field Guide to Dinosaurs is that it lists virtually every single one of the thousands of genera, and individual species, of dinosaurs that have ever been discovered, making it a handy desk reference. The problem is that Paul doesn’t go into much, if any, detail about these dinosaurs, and his illustrations, though anatomically correct, can be a bit underwhelming. This book will also drive home the point that dinosaur taxonomy is a constantly evolving process–not everyone agrees about which species deserve genus and species status.
Many people find it surprising that the fossils of so many marine reptiles, dating to the Jurassic and Cretaceous periods, have been discovered in landlocked Kansas, of all places. The evocatively titled Oceans of Kansas , by Michael J. Everhart, is an exhaustive if somewhat academic survey of the dozens of ichthyosaurs, plesiosaurs, and mosasaurs that have been discovered in the western U.S., as well as the distantly related pterosaurs that flew above the Western Interior Sea and occasionally preyed on these marine reptiles.
https://paleontology.us/fossil-eggshells-suggest-all-dinosaurs-may-have-been-warm-blooded/ Paleontology_US Sat, 25 Apr 2020 10:27:20 +0000 Paleontology http://www.paleontology.us/?p=1181 New analysis reveals body temps in same range as modern birds. Were all dinosaurs warm-blooded? Were any of them warm-blooded? The question of endothermy has long been, ahem, a hot topic in paleontology. No doubt a new study, using a recently developed method, will fire up the debate. Unlike cold-blooded ectotherms, endotherms have the ability to regulate […]
Were all dinosaurs warm-blooded? Were any of them warm-blooded? The question of endothermy has long been, ahem, a hot topic in paleontology. No doubt a new study, using a recently developed method, will fire up the debate.
Unlike cold-blooded ectotherms, endotherms have the ability to regulate their body temperature internally. They generate, conserve and shed heat in response to their environment, making them generally more adaptable to different climates and ecological niches.
Most animals, including reptiles, are ectotherms. Mammals, birds and a handful of fish are either endotherms or evolved some degree of endothermy. Because warm-blooded birds evolved from dinosaurs , and dinosaurs evolved from cold-blooded reptiles, researchers have long sought clues to just where in the reptile-to-bird story things heated up.
Over the years, researchers have come up with a number of theories about warm-blooded dinosaurs, but they’ve been based almost entirely on looking at living animals and extrapolating. Comparing the bone structure of some dinosaurs with that of modern birds, for example, suggested that at least some of the extinct animals may have evolved endothermic abilities.
These kinds of comparisons can be problematic, however, because they’re based on the assumption that dinosaurs lived, breathed and grew the same way modern animals do.
More recently, researchers have been looking for dinosaur endothermy with a method called carbonate clumped isotope paleothermometry. Paleothermometry itself is nothing new; it’s been around for decades as a way to model ancient ocean temperatures, climates and other environmental patterns using proxies.
For example: The density of the cells that form a tree’s annual growth ring varies based on the ambient temperature and humidity of the tree’s environment. Researchers have used these subtle changes to reconstruct ancient climate patterns.
Carbonate clumped isotope paleothermometry zeroes in on, yes, carbonates. Living things are one of the many sources of these chemical compounds, and tooth enamel and eggshells in particular are full of them. The exact composition and structure of the carbonate varies based on the temperature at the time it formed. By analyzing this variation, researchers are able to determine what the body temperature of the animal was.
The paleothermometry method was previously used to estimate body temperature for species in two of the major groups of dinosaurs: sauropods (the often-enormous, four-legged, long-necked plant-eaters) and theropods (the bipedal, generally carnivorous dinosaurs, including the lineage that eventually gave rise to birds).
These previous studies suggested that the animals had body temperatures of about 32-38 degrees Celsius (about 90-100 degrees Fahrenheit), which put them in the range of modern endotherms.
There were some questions about the dinosaur specimens used, however, because they were collected from sites that, back in the Mesozoic, would have been in the low to mid-latitudes. Seasonal temperatures in these locations may have reached 100 degrees or more, potentially skewing the paleothermometry data.
For example, a separate study using the method sampled eggshells from cold-blooded animals — bearded lizards and tortoises — living at the Los Angeles Zoo. The samples fell into the range of living endotherms because of the warm environment.
To avoid this problem, most of the samples in the new study came from dinosaur eggshells found in Alberta, Canada, which would have had cooler ambient temperatures. Therefore any higher paleothermometry readings would be a strong indicator of endothermy.
One of the species sampled, Maiasaura peeblesorum , is the first ornithischian dinosaur to be tested using this method. Ornithischians were the first major lineage of dinosaurs to split off onto their own branch, making them, of all dinosaurs, the most distant relatives of modern birds.
Including an ornithischian in the study is significant because of their evolutionary distance to birds, but also because it means all three major groups of dinosaurs have now been analyzed using this method of paleothermometry.
Another species in the study, the theropod Troodon formosus , is more closely related to the lineage that evolved into birds. The third sample came from eggshells collected in Romania and tentatively assigned to a sauropod, Magyarosaurus .
In the evolution of archosaurs, alligators and other crocodilians remained ectothermic, or cold-blooded. Birds adapted to be endothermic, or warm-blooded. To learn which camp dinosaurs fell into, researchers sampled material from three species representing the three major groups of Dinosauria. (Credit: Dawson et al 2020)
The researchers also tested eggshells from modern birds including emus, chickens, hummingbirds, sparrows and wrens. They included previously-collected body temperature information about alligators, mollusks and other ectotherms in their analysis.
The study’s results: All of the dinosaur material tested fell within the range of modern endotherms. The Maiasaurus sample in particular, say the authors, tested within the range of modern birds at about 44 degrees Celsius (about 111 degrees Fahrenheit). Finding evidence of warm-bloodedness in all major groups of dinosaur suggests that endothermy was an ancestral trait that evolved earlier in the archosaur lineage.
But wait, there’s a twist: The research uncovered something interesting about Troodon . One sample tested at about 38 degrees Celsius (100 degrees Fahreneheit). However, the other two samples, from two different sites, had significantly cooler body temps of around 27-28 degrees Celsius (80-82 degrees Fahrenheit). The lower Troodon temps matched those of fossil mollusks from the same deposits — because mollusks are ectotherms and cannot self-regulate their heat, the temperature in which their shells formed is considered a proxy for the environment’s ambient temperature.
The researchers’ analysis suggests that the cooler Troodon samples may be evidence of heterothermy in the dinosaurs.
Heterothermic animals have evolved the ability to essentially switch off their endothermy and become more ectothermic to conserve energy. Heterothermy typically turns up in smaller birds and mammals that have periods of high activity and extreme energy expenditure. To recoup their losses, so to speak, they may drop their body temperatures and become inactive during short daily periods of torpor, or longer stretches of hibernation.
The too-cool Troodon s may, say the authors, be a hint that at least some dinosaurs were heterothermic.
Source: discovermagazine.com/
Also read: Possible Dinosaur DNA Has Been Found
https://paleontology.us/possible-dinosaur-dna-has-been-found/ Paleontology_US Sat, 18 Apr 2020 23:42:52 +0000 Paleontology http://www.paleontology.us/?p=1159 Possible Dinosaur DNA Has Been Found New discoveries have raised the possibility of exploring dino genetics, but controversy surrounds the results. The tiny fossil is unassuming, as dinosaur remains go. It is not as big as an Apatosaurus femur or as impressive as a Tyrannosaurus jaw. The object is a just a scant shard of cartilagefrom the skull of […]
The tiny fossil is unassuming, as dinosaur remains go. It is not as big as an Apatosaurus femur or as impressive as a Tyrannosaurus jaw. The object is a just a scant shard of cartilagefrom the skull of a baby hadrosaur called Hypacrosaurus that perished more than 70 million years ago. But it may contain something never before seen from the depths of the Mesozoic era: degraded remnants of dinosaur DNA.
Genetic material is not supposed to last over such time periods—not by a long shot. DNA begins to decay at death. Findings from a 2012 study on moa bones show an organism’s genetic material deteriorates at such a rate that it halves itself every 521 years. This speed would mean paleontologists can only hope to recover recognizable DNA sequences from creatures that lived and died within the past 6.8 million years—far short of even the last nonavian dinosaurs.
But then there is the Hypacrosaurus cartilage. In a study published earlier this year , Chinese Academy of Sciences paleontologist Alida Bailleul and her colleagues proposed that in that fossil, they had found not only evidence of original proteins and cartilage-creating cells but a chemical signature consistent with DNA.
Recovering genetic material of such antiquity would be a major development. Working on more recently extinct creatures—such as mammoths and giant ground sloths—paleontologists have been able to revise family trees, explore the interrelatedness of species and even gain some insights into biological features such as variations in coloration. DNA from nonavian dinosaurs would add a wealth of new information about the biology of the “terrible lizards.†Such a find would also establish the possibility that genetic material can remain detectable not just for one million years, but for tens of millions. The fossil record would not be bones and footprints alone: it would contain scraps of the genetic record that ties together all life on Earth.
Yet first, paleontologists need to confirm that these possible genetic traces are the real thing. Such potential tatters of ancient DNA are not exactly Jurassic Park –quality. At best, their biological makers seem to be degraded remnants of genes that cannot be read—broken-down components rather than intact parts of a sequence. Still, these potential tatters of ancient DNA would be far older (by millions of years) than the next closest trace of degraded genetic material in the fossil record.
If upheld, Bailleul and her colleagues’ findings would indicate that biochemical traces of organisms can persist for tens of millions of years longer than previously thought. And that would mean there may be an entire world of biological information experts are only just getting to know. “I think exceptional preservation is really more common than what we think, because, as researchers, we have not looked at enough fossils yet,†Bailleul says. “We must keep looking.â€
The question is whether these proteins and other traces are really what they seem. Hot on the heels of Bailleul’s paper—and inspired by the controversy over what the biomolecules inside dinosaur bones represent—a separate team, led by Princeton University geoscientist Renxing Liang, recently reported on unexpected microbes found inside one from Centrosaurus, a horned dinosaur of similar age to Hypacrosaurus . The researchers said that they unearthed DNA inside the bone, but it was from lineages of bacteria and other microorganisms that had not been seen before. The bone had its own unique microbiome, which could cause confusion as to whether proteins and possible genetic material belonged to the dinosaur itself or to bacteria that had come to reside within it during the fossilization process.
The discovery that such fossils can harbor bacterial communities different from those in the surrounding stone complicates the search for dinosaur DNA, proteins and other biomolecules. The modern may be overlaid on the past, creating a false image. “Even if any trace organics could be preserved,†Liang says, “the identification processes would be as challenging as finding a needle in the haystack and thus will likely lead to potential false claims.â€
“Right now, molecular paleontology is controversial,†Bailleul says. The first sticking point is that when researchers look for traces of ancient biological molecules, they use technologies invented to find intact traces that have been degraded or altered by vast amounts of time. On top of that issue, there remains much experts do not know about how a dinosaur bone changes from organic tissue in a recently alive animal to a fossil hardened by minerals. “We have not figured out all of the complex mechanisms of molecular fossilization using chemistry. And we don’t know enough about the roles that microbes play,†Bailleul says. For example, it is unclear how modern microbes outside of fossils might interact with those that have been living within the bones.
These unknowns, as well as protocols that are still in development, fuel the ongoing debate over what the biological tidbits inside dinosaur bones represent. The research on the Hypacrosaurus cartilage looked at its microscopic details and used chemical stains that bind to DNA. In contrast, the study on the Centrosaurus bone used DNA sequencing to understand the nature of the genetic traces inside it—but did not look at its microstructure.
Bailleul acknowledges that considering previously unknown forms of microorganisms when studying dinosaur bone microbiology is important. But she proposes that it is unlikely bacteria would find their way into a cartilage cell and mimic its nucleus in such a way that researchers would mistake the microorganisms for the genuine article. Yet “you can never be too skeptical of your own results,†says paleogeneticist and author Ross Barnett, who was not involved in the two studies described above.
One of the largest difficulties in the ongoing debate, Barnett says, is a lack of replication. And paleogenetics has been through this problem before: Around the time the film Jurassic Park debuted in 1993, research papers heralded the discovery of Mesozoic DNA . Those claims were later overturned when other research teams could not replicate the same results. Even though the science of paleogenetics has changed since that time, the need for multiple labs to confirm the same result remains important. “If a different lab could be independently sent fossils from the same site, work up their own antibodies, do their own staining and get the same results, it would make things more believable,†Barnett says. Such collaboration has yet to take place for some of the assertions of exceptional dinosaurian preservation.
Nevertheless, molecular paleobiology is developing standards of evidence and protocols as it continues to search for clues held inside ancient bones. “I hope that many paleontologists or biologists, or both, are also trying to do this,†Bailleul says. “We can figure out the answers faster if we are all working on this together.â€
Even if proposed dinosaur organics turn out to be false, the effort could still yield unexpected benefits. Bacterial communities are thought to be involved in the preservation of bones and in their replacement with minerals, thus helping dinosaur remains become fossils. “Future studies about ancient DNA from past microbial communities that used to live inside the dinosaur bones could shed more light on the roles of microorganisms in the fossilization and preservation of bones through geological time,†Liang says.
“These are very difficult questions,†Bailleul says. “But if we keep trying, there is hope that we will figure out most answers.†As the situation stands now, nothing is written in stone.
Source: scientificamerican.com/
Also read: Paleontologists Are Trying to Understand Why the Buffalo Fossil Record Is Mostly Males
https://paleontology.us/the-oligocene-epoch-34-23-million-years-ago/ Paleontology_US Fri, 20 Mar 2020 20:30:26 +0000 Paleontology http://www.paleontology.us/?p=957 Oligocene Epoch The Oligocene epoch wasn’t especially innovative with regard to its prehistoric animals, which continued along the evolutionary paths that had been pretty much locked in during the preceding Eocene (and continued on in turn during the ensuing Miocene). The Oligocene was the last major geologic subdivision of the Paleogene period (65-23 million years ago), following the Paleocene (85-56 million years […]
The Oligocene epoch wasn’t especially innovative with regard to its prehistoric animals, which continued along the evolutionary paths that had been pretty much locked in during the preceding Eocene (and continued on in turn during the ensuing Miocene). The Oligocene was the last major geologic subdivision of the Paleogene period (65-23 million years ago), following the Paleocene (85-56 million years ago) and Eocene (56-34 million years ago) epochs; all of these periods and epochs were themselves part of the Cenozoic Era (65 million years ago to the present).
While the Oligocene epoch was still fairly temperate by modern standards, this 10-million-year stretch of geologic time saw a decrease in both average global temperatures and sea levels. All of the world’s continents were well on their way toward moving into their present positions; the most striking change occurred in Antarctica, which drifted slowly south, became more isolated from South America and Australia, and developed a polar ice cap.
Mollewide [Oval-Globe] Plate Tectonic Map of the Earth from the Oligocene [35Ma]
Giant mountain ranges continued to form, most prominently in western North America and southern Europe.
There were two major trends in mammalian evolution during the Oligocene epoch. First, the spread of newly evolved grasses across the plains of the northern and southern hemispheres opened a new ecological niche for grazing mammals. Early horses (such as Miohippus), distant rhinoceros ancestors (such as Hyracodon), and proto-camels (such as Poebrotherium) were all common sights on grasslands, often in locations you might not expect (camels, for instance, were especially thick on the ground in Oligocene North America, where they first evolved).
The other trend was mostly confined to South America, which was isolated from North America during the Oligocene epoch (the Central American land bridge would not form for another 20 million years) and hosted a bizarre array of megafauna mammals, including the elephant-like Pyrotherium and the meat-eating marsupial Borhyaena (the marsupials of Oligocene South America were every match for the contemporary Australian variety). Asia, meanwhile, was home to the largest terrestrial mammal that ever lived, the 20-ton Indricotherium, which bore an uncanny resemblance to a sauropod dinosaur!
As with the preceding Eocene epoch, the most common fossil birds of the Oligocene epoch were predatory South American “terror birds†(such as the unusually pint-sized Psilopterus) and giant penguins that lived in temperate, rather than polar, climates–Kairuku of New Zealand being a good example. Other types of birds also undoubtedly lived during the Oligocene epoch; we just haven’t identified many of their fossils yet!
To judge by the limited fossil remains, the Oligocene epoch wasn’t an especially notable time for lizards, snakes, turtles or crocodiles. However, the plenitude of these reptiles both before and after the Oligocene provides at least circumstantial evidence that they must have prospered during this epoch as well; a lack of fossils doesn’t always correspond to a lack of wildlife.
The Oligocene epoch was a golden age for whales, rich in transitional species like Aetiocetus,Janjucetus and Mammalodon (which possessed both teeth and plankton-filtering baleen plates).Prehistoric sharks continued to be the apex predators of the high seas; it was toward the end of the Oligocene, 25 million years ago, that the gigantic Megalodon first appeared on the scene. The latter part of the Oligocene epoch also witnessed the evolution of the first pinnipeds (the family of mammals that includes seals and walruses), the basal Puijila being a good example.
As remarked above, the major innovation in plant life during the Oligocene epoch was the worldwide spread of newly evolved grasses, which carpeted the plains of North and South America, Eurasia and Africa–and spurred the evolution of horses, deer, and various ruminants, as well as the meat-eating mammals that preyed on them. The process that had begun during the preceding Eocene epoch, the gradual appearance of deciduous forests in place of jungles over the earth’s spreading non-tropical regions, also continued unabated.
Source: thoughtco.com/
Also read: Mesozoic Era and Cretaceous Period
https://paleontology.us/jurassic/ Paleontology_US Thu, 12 Mar 2020 19:19:15 +0000 Paleontology http://www.paleontology.us/?p=852 The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago (Mya) to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles. The start of the period is marked by the major Triassic–Jurassic […]
The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago (Mya) to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles. The start of the period is marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Pliensbachian/Toarcian event in the Early Jurassic, and the Tithonian event at the end; however, neither event ranks among the “Big Five†mass extinctions.
The Jurassic is named after the Jura Mountains within the European Alps, where limestone strata from the period were first identified. By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, and many of the arid deserts of the Triassic were replaced by lush rainforests.
On land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds also appeared during the Jurassic, having evolved from a branch of theropod dinosaurs. Other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to an aquatic mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates.
The Jurassic period is divided into the Early, Middle, and Late epochs. The Jurassic System, in historiography, is divided into the Lower, Middle, and Upper series of rock formations, also known as Lias , Dogger and Malm in Europe. The separation of the term into three sections goes back to Leopold von Buch. The faunal stages from youngest to oldest are:
| Upper/Late Jurassic | |
| Tithonian | (152.1 ± 4 – 145 ± 4 Mya) |
| Kimmeridgian | (157.3 ± 4 – 152.1 ± 4 Mya) |
| Oxfordian | (163.5 ± 4 – 157.3 ± 4 Mya) |
| Middle Jurassic | |
| Callovian | (166.1 ± 4 – 163.5 ± 4 Mya) |
| Bathonian | (168.3 ± 3.5 – 166.1 ± 4 Mya) |
| Bajocian | (170.3 ± 3 – 168.3 ± 3.5 Mya) |
| Aalenian | (174.1 ± 2 – 170.3 ± 3 Mya) |
| Lower/Early Jurassic | |
| Toarcian | (182.7 ± 1.5 – 174.1 ± 2 Mya) |
| Pliensbachian | (190.8 ± 1.5 – 182.7 ± 1.5 Mya) |
| Sinemurian | (199.3 ± 1 – 190.8 ± 1.5 Mya) |
| Hettangian | (201.3 ± 0.6 – 199.3 ± 1 Mya) |
During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Gulf of Mexico opened in the new rift between North America and what is now Mexico’s Yucatán Peninsula. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, when Gondwana itself rifted apart. The Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of a glacier having appeared. As in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed.
The Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, and invertebrate faunas with dominantly calcitic skeletons.
The first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are also found in Russia, India, South America, Japan, Australasia and the United Kingdom.
In Africa, Early Jurassic strata are distributed in a similar fashion to Late Triassic beds, with more common outcrops in the south and less common fossil beds which are predominated by tracks to the north. As the Jurassic proceeded, larger and more iconic groups of dinosaurs like sauropods and ornithopods proliferated in Africa.
Also read: Pangea and Cretaceous Period
https://paleontology.us/the-best-dinosaur-museums-in-us/ Paleontology_US Fri, 28 Feb 2020 12:35:59 +0000 Paleontology http://www.paleontology.us/?p=674 The Best Dinosaur Museums in U.S. Natural history museums across the country are full of spectacular dinosaur fossils. But they’re usually set behind velvet ropes and glass walls, to keep small children (and their sticky fingers) at bay. If your pint-sized paleontologists are eager to get more up close and personal with their favorite giant […]
Natural history museums across the country are full of spectacular dinosaur fossils. But they’re usually set behind velvet ropes and glass walls, to keep small children (and their sticky fingers) at bay. If your pint-sized paleontologists are eager to get more up close and personal with their favorite giant lizards, here are a few Dinosaur Museums in U.S. to explore.
Littered with dinosaur bones, the 210,000 acres of this glorious national park are a junior paleontologist’s dream. The Fossil Discovery Trail, which reopens April 1, allows visitors to see dinosaur bones naturally exposed in a cliff wall. The park also has Junior Ranger and Junior Paleontology programs available for children at no cost. Kids receive booklets of age-appropriate activities and are given a Junior Ranger or Junior Paleontologist badge upon completion.
Kids can dig for fossils on the 500-acre Warm Springs Ranch, where the dino center is located. Sediments here are from the Late Jurassic—meaning they are more than 140 million years old. These hold many of the most famous dinosaurs: Allosaurus, Apatosaurus (also known as Brontosaurus), Camarasaurus, Diplodocus, and Stegosaurus. Eight- to 12-year-olds can go on a daylong, guided Kids’ Dig in a nearby canyon to look for fossils. Bones from apatosaurs, barosaurs, and six other species have been uncovered. Children of any age can take part in family digs. The center exhibits 30 full-size dinosaur mounts and has the only skeleton of an Albertaceratops (a horn-faced, plant-eating dino) on display in the world.
Kids can clamber on top of dinosaur replicas at the three outdoor museums of Dinosaur World. The park has a walking trail with more than 150 life-size casts of dinosaurs, as well as several sculptures to play on. Nearby signs explain the names of the dinosaurs and offer interesting facts about them. Tucked among a lush assortment of native vegetation, the dinosaurs are so lifelike that some visitors have claimed to see them moving. The parks also offer classes, birthday parties, and digs (kids can keep the fossils they find!).
A giant Tyrannosaurus rex greets visitors to this museum, which has a lab where kids can watch scientists prepping dinosaur fossils. Skeletons of more than 30 species are on display in the Dinosaur Hall and a hands-on exhibit allows kids to dig for dino bones. On the third weekend in February the Academy hosts the annual Paleopalooza, a weekend filled with crafts, fossil hunts, dino tours, and games. Children can also talk with real paleontologists.
This state park is home to one of the largest dinosaur track sites in North America, which includes early Jurassic footprints made 200 million years ago. Five hundred of the tracks are enclosed within the Exhibit Center’s geodesic dome and another 1,500 are buried for preservation. The tracks were discovered in 1966 when the area was excavated. Guided walks, dinosaur arts and crafts, and an outdoor scavenger hunt are also available.
If there’s one dinosaur your kid absolutely has to see at a museum, it’s Sue, the largest, most complete, and best-preserved Tyrannosaurus rex skeleton in the world. The 42-foot-long, 67-million-year-old dinosaur (named after the paleontologist who found her) is on display here. If that’s not enough for your little ones, they can participate in Dozin’ with the Dinos, a program that allows kids to have a sleepover with Sue and her friends. The evening includes tours and activities and sleeping under the belly of the beast.
Sources: Parents.com
Also Read: 10 Places Every Dinosaur Fan Needs To Visit
https://paleontology.us/devonian-period-facts-information/ Paleontology_US Fri, 28 Feb 2020 10:04:43 +0000 Curiosities Paleontology http://www.paleontology.us/?p=665 Devonian Period The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 419.2 Mya (million years ago), to the beginning of the Carboniferous Period, about 358.9. It is named after Devon, England, where rocks from this period were first studied. The Devonian period experienced the first significant adaptive […]
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period , about 419.2 Mya (million years ago), to the beginning of the Carboniferous Period, about 358.9. It is named after Devon, England, where rocks from this period were first studied. The Devonian period experienced the first significant adaptive radiation of terrestrial life. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the “Age of Fishâ€. The first ray-finned and lobe-finned bony fish appeared, while the placoderms began dominating almost every known aquatic environment.
Early Devonian Earth
The ancestors of all tetrapods began adapting to walking on land, their strong pectoral and pelvic fins gradually evolving into legs. In the oceans, primitive sharks became more numerous than in the Silurian and the late Ordovician. The first ammonite mollusks appeared. Trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction which started about 375 million years ago severely affected marine life, killing off all placoderms, and all trilobites, save for a few species of the order Proetida.
The supercontinent Gondwana occupied most of the Southern Hemisphere, although it began significant northerly drift during the Devonian Period. Eventually, by the later Permian Period, this drift would lead to collision with the equatorial continent known as Euramerica, forming Pangaea .
The mountain building of the Caledonian Orogeny, a collision between Euramerica and the smaller northern continent of Siberia, continued in what would later be Great Britain, the northern Appalachians and the Nordic mountains. Rapid erosion of these mountains contributed large amounts of sediment to lowlands and shallow ocean basins. Â Sea levels were high with much of western North America under water. Climate of the continental interior regions was very warm during the Devonian Period and generally quite dry.
Plants, which had begun colonizing the land during the Silurian Period, continued to make evolutionary progress during the Devonian. Lycophytes, horsetails and ferns grew to large sizes and formed Earth’s first forests.  By the end of the Devonian, progymnosperms such as Archaeopteris were the first successful trees. Archaeopteris could grow up to 98 feet (30 meters) tall with a trunk diameter of more than 3 feet. It had a softwood trunk similar to modern conifers that grew in sequential rings. It did not have true leaves but fern-like structures connected directly to the branches (lacking the stems of true leaves). There is evidence that they were deciduous, as the most common fossils are shed branches. Reproduction was by male and female spores that are accepted as being the precursors to seed-bearing plants. By the end of the Devonian Period, the proliferation of plants increased the oxygen content of the atmosphere considerably, which was important for development of terrestrial animals. At the same time carbon dioxide (CO 2 ), a greenhouse gas, was depleted from earlier levels. This may have contributed to the cooling climate and the extinction event at the end of the Devonian.
Arthropod fossils are concurrent with the earliest plant fossils of the Silurian. Millipedes, centipedes and arachnids continued to diversify during the Devonian Period. The earliest known insect, Rhyniella praecusor, was a flightless hexapod with antennae and a segmented body. Fossil Rhyniella are between 412 million and 391 million years old.
Early tetrapods probably evolved from Lobe-finned fishes able to use their muscular fins to take advantage of the predator-free and food-rich environment of the new wetland ecosystems. The earliest known tetrapod is Tiktaalik rosae. Dated from the mid-Devonian, this fossil creature is considered to be the link between the lobe-finned fishes and early amphibians. Tiktaalik was probably mostly aquatic, “walking†on the bottom of shallow water estuaries. It had a fish-like pelvis, but its hind limbs were larger and stronger than those in front, suggesting it was able to propel itself outside of an aquatic environment. It had a crocodile-like head, a moveable neck, and nostrils for breathing air.
Also read: Paleozoic Era: Facts & Information
https://paleontology.us/what-is-a-paleontologist/ Paleontology_US Mon, 17 Feb 2020 08:24:26 +0000 Paleontology http://www.paleontology.us/?p=519 What is a Paleontologist? Paleontology is the science dealing with the fossils of long-deceased animals and plants that lived up to billions of years ago. It’s an interdisciplinary field involving geology, archaeology, chemistry, biology, archaeology and anthropology. But What is a Paleontologist? A paleontologist studies the history and process of evolution by examining fossils, the […]
Paleontology is the science dealing with the fossils of long-deceased animals and plants that lived up to billions of years ago. It’s an interdisciplinary field involving geology, archaeology, chemistry, biology, archaeology and anthropology. But What is a Paleontologist? A paleontologist studies the history and process of evolution by examining fossils, the preserved traces of long dead animals and plants. Using data from fossilized bones, ancient pollen, and other clues, paleontologists dig up the details on past climates and past extinctions. They tell us about the history of the earth, the evolution of life, and our own place in the world.
Paleontologists plan, direct, and conduct fieldwork projects to search for fossils or collect samples. They document the work site and dig up fossils or take core samples from lakes, soil, or ice sheets. They then need to preserve the specimens and prepare them for transport to the institution where they’ll be cleaned and studied. Some work in laboratories, using chemical techniques to analyze fossilized samples and ancient pollen. They share their research by writing journal articles and presenting to colleagues at professional conferences. Most need to write applications for grants to support their research. Many teach and conduct research as faculty members at colleges and universities.
Paleontologists usually specialize in a particular research area. For example, micropaleontologists study microscopic fossils. Paleobotanistsconduct research on fossil plants, including algae and fungi. Palynologists study pollen and spores. Invertebrate paleontologists study fossils of invertebrate animals like mollusks and worms. Vertebrate paleontologists focus on the fossils of vertebrate animals, including fish. Human paleontologists or paleoanthropologists focus on the fossils of prehistoric humans and pre-human hominids. Taphonomists study the process that creates fossils. Ichnologists hunt for fossil tracks, trails, and footprints, such as the dinosaur tracks found in Arkansas in 2011. Paleoecologists use fossils, spores, pollen, and other information to study the ecologies and climates of the past.
The revelations they uncover can help us understand the past, so that we don’t repeat it. They can also provide context for comparison between the current state of our environment and biodiversity, and those of ancient and turbulent epochs.
Most paleontologists are faculty members in the geology departments of colleges and universities. Some work in museums. A handful are employed by government geological surveys, where they make geological maps or investigate geological issues. A few help oil companies search for petroleum.
Paleontologists spend most of their time in offices while teaching, writing, or analyzing their finds. However, some conduct research in laboratories. When conducting fieldwork, paleontologists work outdoors, where they do rigorous physical work in all kinds of weather.
Indeed listed the average annual salary of paleontologists as $74,000.
| State | Total Employment | Bottom 25% | Median Salary | Top 75% |
|---|---|---|---|---|
| Alabama | 310 | $51,060 | $66,160 | $81,240 |
| Alaska | 610 | $72,940 | $101,580 | $146,260 |
| Arizona | 410 | $50,920 | $61,230 | $82,450 |
| Arkansas | 110 | $38,020 | $57,410 | $81,320 |
| California | 5,170 | $71,940 | $97,170 | $116,000 |
| Colorado | 2,490 | $77,440 | $100,300 | $138,280 |
| Connecticut | 140 | $54,240 | $67,850 | $81,000 |
| Delaware | 80 | $65,890 | $73,380 | $85,440 |
| District of Columbia | 70 | – | – | – |
| Florida | 650 | $52,910 | $70,170 | $95,150 |
| Georgia | 300 | $51,830 | $62,620 | $73,990 |
| Hawaii | 80 | $67,800 | $90,910 | $121,720 |
| Idaho | 130 | $59,310 | $68,880 | $80,280 |
| Illinois | 340 | $65,050 | $85,550 | $103,640 |
| Indiana | 190 | $46,250 | $59,290 | $81,040 |
| Iowa | 50 | – | – | – |
| Kansas | 230 | $52,690 | $71,090 | $91,950 |
| Kentucky | 200 | $46,600 | $60,400 | $77,990 |
| Louisiana | 910 | $61,880 | $90,420 | $116,830 |
| Maine | 100 | $56,100 | $64,220 | $72,130 |
| Maryland | 580 | $62,910 | $76,840 | $105,070 |
| Massachusetts | 190 | $56,850 | $75,450 | $98,390 |
| Michigan | 350 | $54,700 | $66,080 | $78,550 |
| Minnesota | 130 | $59,700 | $77,440 | $98,490 |
| Mississippi | 430 | $68,060 | $89,440 | $106,360 |
| Missouri | 160 | $46,520 | $67,950 | $83,480 |
| Montana | 230 | $49,780 | $72,410 | $103,310 |
| Nebraska | 150 | $44,700 | $59,300 | $94,990 |
| Nevada | 740 | $63,930 | $85,770 | $109,250 |
| New Hampshire | 70 | $56,000 | $75,390 | $107,370 |
| New Jersey | 630 | $61,970 | $78,300 | $97,750 |
| New Mexico | 280 | $53,530 | $66,500 | $89,450 |
| New York | 940 | $54,310 | $67,780 | $88,180 |
| North Carolina | 560 | $53,890 | $65,190 | $78,310 |
| North Dakota | – | $67,600 | $74,740 | $84,850 |
| Ohio | 290 | $58,440 | $71,440 | $84,800 |
| Oklahoma | 1,210 | $71,140 | $118,110 | $173,660 |
| Oregon | 410 | $53,560 | $62,540 | $80,280 |
| Pennsylvania | 1,030 | $50,940 | $63,630 | $84,200 |
| Puerto Rico | – | $43,130 | $51,860 | $58,630 |
| Rhode Island | 110 | $49,600 | $64,610 | $85,770 |
| South Carolina | 150 | $30,890 | $41,630 | $75,330 |
| South Dakota | 60 | $45,350 | $54,870 | $66,190 |
| Tennessee | 200 | $43,260 | $55,050 | $78,940 |
| Texas | 10,470 | $91,400 | $139,870 | – |
| Utah | 340 | $55,810 | $68,350 | $84,860 |
| Vermont | 30 | $56,520 | $76,700 | $92,560 |
| Virginia | 450 | $59,390 | $89,450 | $127,130 |
| Washington | 1,120 | $61,190 | $79,110 | $102,690 |
| West Virginia | 130 | $40,480 | $49,900 | $74,670 |
| Wisconsin | 190 | $60,200 | $73,630 | $90,590 |
| Wyoming | 220 | $58,340 | $72,120 | $96,330 |
Data taken from BLS https://www.bls.gov/
Paleontologist jobs deal primarily with the study of animal and plant fossils from various eras of earth’s prehistory. While jobs vary significantly, most paleontologists would call the below list of tasks a basic outline of their scope of work:
A lead paleontologist, chief researcher, or project manager may have the following or similar additional responsibilities, depending on the project and its goals:
What Is the Job Demand for Paleontologists?
While the government projects that employment of geoscientists as a whole will grow quickly, the outlook for paleontologists specifically is more conservative. The Paleontological Research Institution notes that there are fewer jobs in this area in the U.S. than there were a few years ago, but a few good jobs still become available each year.
How Do I Get a Paleontology Degree?
A Ph.D. is usually necessary for paleontological careers, particularly in academia. Aspiring paleontologists should have extensive knowledge of biology and geology. A double-major with full training in both is the best educational option. Chemistry, physics, calculus, statistics, and computer science are also very important. Undergraduate geology classes typically include mineralogy, stratigraphy, sedimentary petrology, vertebrate and invertebrate paleontology, ecology, evolutionary biology, and genetics.
Field and lab experience are also vital. Paleontologists will need to know professional standards and procedures for surveying work sites and unearthing their finds. Look for volunteer opportunities at nearby museums, or join a mineral or fossil club at your university.
What Kind of Societies and Professional Organizations Do Paleontologists Have?
Also read: How much does a paleontologist get paid?
https://paleontology.us/earth-was-stressed-even-before-dinosaur-extinction/ Paleontology_US Wed, 18 Dec 2019 12:26:43 +0000 Paleontology http://www.paleontology.us/?p=171 New evidence gleaned from Antarctic seashells confirms that Earth was already unstable before the asteroid impact that wiped out the dinosaurs. The study, led by researchers at Northwestern University, is the first to measure the calcium isotope composition of fossilized clam and snail shells, which date back to the Cretaceous-Paleogene mass extinction event. The researchers […]
The study, led by researchers at Northwestern University, is the first to measure the calcium isotope composition of fossilized clam and snail shells, which date back to the Cretaceous-Paleogene mass extinction event. The researchers found that — in the run-up to the extinction event — the shells’ chemistry shifted in response to a surge of carbon in the oceans.
This carbon influx was likely due to long-term eruptions from the Deccan Traps, a 200,000-square-mile volcanic province located in modern India. During the years leading up to the asteroid impact, the Deccan Traps spewed massive amounts of carbon dioxide (CO 2 ) into the atmosphere. The concentration of CO 2 acidified the oceans, directly affecting the organisms living there.
“Our data suggest that the environment was changing before the asteroid impact,†said Benjamin Linzmeier, the study’s first author. “Those changes appear to correlate with the eruption of the Deccan Traps.â€
“The Earth was clearly under stress before the major mass extinction event,†said Andrew D. Jacobson, a senior author of the paper. “The asteroid impact coincides with pre-existing carbon cycle instability. But that doesn’t mean we have answers to what actually caused the extinction.â€
The study will be published in the January 2020 issue of the journal Geology , which comes out later this month.
Jacobson is a professor of Earth and planetary sciences in Northwestern’s Weinberg College of Arts and Sciences. Linzmeier was a postdoctoral researcher with the Ubben Program for Climate and Carbon Science at the Institute for Sustainability and Energy at Northwestern when the research was conducted. He is now a postdoctoral fellow at the University of Wisconsin-Madison in the Department of Geoscience.
‘Each shell is a snapshot’
Previous studies have explored the potential effects of the Deccan Traps eruptions on the mass extinction event, but many have examined bulk sediments and used different chemical tracers. By focusing on a specific organism, the researchers gained a more precise, higher-resolution record of the ocean’s chemistry.
“Shells grow quickly and change with water chemistry,†Linzmeier said. “Because they live for such a short period of time, each shell is a short, preserved snapshot of the ocean’s chemistry.â€
Seashells mostly are composed of calcium carbonate, the same mineral found in chalk, limestone and some antacid tablets. Carbon dioxide in water dissolves calcium carbonate. During the formation of the shells, CO 2 likely affects shell composition even without dissolving them.
For this study, the researchers examined shells collected from the Lopez de Bertodano Formation, a well-preserved, fossil-rich area on the west side of Seymour Island in Antarctica. They analyzed the shells’ calcium isotope compositions using a state-of-the-art technique developed in Jacobson’s laboratory at Northwestern. The method involves dissolving shell samples to separate calcium from various other elements, followed by analysis with a mass spectrometer.
“We can measure calcium isotope variations with high precision,†Jacobson said. “And those isotope variations are like fingerprints to help us understand what happened.â€
Using this method, the team found surprising information.
“We expected to see some changes in the shells’ composition, but we were surprised by how quickly the changes occurred,†Linzmeier said. “We also were surprised that we didn’t see more change associated with the extinction horizon itself.â€
A future warning
The researchers said that understanding how the Earth responded to past extreme warming and CO 2 input can help us prepare for how the planet will respond to current, human-caused climate change.
“To some degree, we think that ancient ocean acidification events are good analogs for what’s happening now with anthropogenic CO 2 emissions,†Jacobson said. “Perhaps we can use this work as a tool to better predict what might happen in the future. We can’t ignore the rock record. The Earth system is sensitive to large and rapid additions of CO 2 . Current emissions will have environmental consequences.â€
Brad Sageman and Matthew Hurtgen, both professors of Earth and planetary sciences at Northwestern, are co-senior authors of the paper.
Also read: Dinosaur-Killing Asteroid Rapidly Turned Oceans to Acid, Disrupted Climate
The study, “Calcium isotope evidence for environmental variability before and across the Cretaceous-Paleogene mass extinction,†was supported by the Ubben Program for Climate and Carbon Science at Northwestern University, the David and Lucile Packard Foundation (award number 2007-31757) and the National Science Foundation (award numbers EAR-0723151, ANT-1341729, ANT-0739541 and ANT-0739432.