WFS News: Palaeocene–Eocene Thermal Maximum prolonged by fossil carbon oxidation

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 Palaeocene–Eocene Thermal Maximum prolonged by fossil carbon oxidation

A rapid rise in temperature on ancient Earth triggered a climate response that may have prolonged the warming for many thousands of years, according to scientists.

Their study, published online in Nature Geoscience, provides new evidence of a climate feedback that could explain the long duration of the Paleocene-Eocene Thermal Maximum (PETM), which is considered the best analogue for modern climate change.

The findings also suggest that climate change today could have long-lasting impacts on global temperature even if humans are able to curb greenhouse gas emissions.

Fossiliferous core from a drilling site in Maryland. Credit: Rosie Oakes / Penn State

Fossiliferous core from a drilling site in Maryland.Credit: Rosie Oakes / Penn State

“We found evidence for a feedback that occurs with rapid warming that can release even more carbon dioxide into the atmosphere,” said Shelby Lyons, a doctoral student in geosciences at Penn State. “This feedback may have extended the PETM climate event for tens or hundreds of thousands of years. We hypothesize this is also something that could occur in the future.”

Increased erosion during the PETM, approximately 56 million years ago, freed large amounts of fossil carbon stored in rocks and released enough carbon dioxide, a greenhouse gas, into the atmosphere to impact temperatures long term, researchers said.

Scientists found evidence for the massive carbon release in coastal sediment fossil cores. They analyzed the samples using an innovative molecular technique that enabled them to trace how processes like erosion moved carbon in deep time.

“This technique uses molecules in a really innovative, out-of-the-box way to trace fossil carbon,” said Katherine Freeman, Evan Pugh University Professor of Geosciences at Penn State. “We haven’t really been able to do that before.”

Global temperatures increased by about 9 to 14.4 degrees Fahrenheit during the PETM, radically changing conditions on Earth. Severe storms and flooding became more common, and the warm, wet weather led to increased erosion of rocks.

As erosion wore down mountains over thousands of years, carbon was released from rocks and transported by rivers to oceans, where some was reburied in coastal sediments. Along the way, some of the carbon entered the atmosphere as greenhouse gas.

“What we found in records were signatures of carbon transport that indicated there were massive erosion regimes occurring on land,” Lyons said. “Carbon was locked on land and during the PETM it was moved and reburied. We were interested in seeing how much carbon dioxide that could release.”

Lyons was studying PETM core samples from Maryland, in a location that was once underwater, when she discovered traces of older carbon that must have once been stored in rocks on land. She initially believed the samples were contaminated, but she found similar evidence in sediments from other Mid-Atlantic sites and Tanzania.

Carbon in these samples did not share common isotope patterns of life from the PETM and appeared oily, as if it been heated over long periods of time in a different location.

“That told us what we were looking at in the records was not just material that was formed during the PETM,” Lyons said. “It was not just carbon that had been formed and deposited at that time, but likely represented something older being transported in.”

The researchers developed a mixing model to distinguish the sources of carbon. Based on the amount of older carbon in the samples, scientists were able to estimate how much carbon dioxide was released during the journey from rock to ocean sediment.

They estimated the climate feedback could have released enough carbon dioxide to explain the roughly 200,000-year duration of the PETM, something that has not been well understood.

The researchers said the findings offer a warning about modern climate change. If warming reaches certain tipping points, feedbacks can be triggered that have the potential to cause even more temperature change.

“One lesson we can learn from this research is that carbon is not stored very well on land when the climate gets wet and hot,” Freeman said. “Today, we’re pushing the system out of equilibrium and it’s not going to snap back, even when we start reducing carbon dioxide emissions.”

  1. Shelby L. Lyons, Allison A. Baczynski, Tali L. Babila, Timothy J. Bralower, Elizabeth A. Hajek, Lee R. Kump, Ellen G. Polites, Jean M. Self-Trail, Sheila M. Trampush, Jamie R. Vornlocher, James C. Zachos, Katherine H. Freeman. Palaeocene–Eocene Thermal Maximum prolonged by fossil carbon oxidationNature Geoscience, 2018; 12 (1): 54 DOI: 10.1038/s41561-018-0277-3
Source: Penn State. “Ancient climate change triggered warming that lasted thousands of years.” ScienceDaily. ScienceDaily, 22 January 2019. <www.sciencedaily.com/releases/2019/01/190122104515.htm>.
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WFS News: Eretmorhipis carrolldongi,Early Triassic marine reptile

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No animal alive today looks quite like a duckbilled platypus, but about 250 million years ago something very similar swam the shallow seas in what is now China, finding prey by touch with a cartilaginous bill. The newly discovered marine reptile Eretmorhipis carrolldongi from the lower Triassic period is described in the journal Scientific Reports Jan. 24.

Apart from its platypus-like bill, Eretmorhipis was about 70 centimeters long with a long rigid body, small head and tiny eyes, and four flippers for swimming and steering. Bony plates ran down the animal’s back.

First nearly complete specimen of the rare hupehsuchian Eretmorhipis carrolldongi (YAGM V 1401), revealing an unusually small skull. (a) photograph. (b) outlines of the bones and impressions. (c) skeletal reconstruction, with flippers from the holotype. The ruler is 5 cm long.

First nearly complete specimen of the rare hupehsuchian Eretmorhipis carrolldongi (YAGM V 1401), revealing an unusually small skull. (a) photograph. (b) outlines of the bones and impressions. (c) skeletal reconstruction, with flippers from the holotype. The ruler is 5 cm long.

Eretmorhipis was previously known only from partial fossils without a head, said Professor Ryosuke Motani, a paleontologist at the University of California, Davis Department of Earth and Planetary Sciences and coauthor on the paper.

“This is a very strange animal,” Motani said. “When I started thinking about the biology I was really puzzled.”

The two new fossils show the animal’s skull had bones that would have supported a bill of cartilage. Like the modern platypus, there is a large hole in the bones in the middle of the bill. In the platypus, the bill is filled with receptors that allow it to hunt by touch in muddy streams.

In the early Triassic, the area was covered by a shallow sea, about a meter deep, over a carbonate platform extending for hundreds of miles. Eretmorhipis fossils were found at what were deeper holes, or lagoons, in the platform. There are no fossils to show what Eretmorhipis ate, but it likely fed on shrimp, worms and other small invertebrates, Motani said.

The skull and mandible of Eretmorhipis carrolldongi in two new specimens. (a) and (b) YAGM V 1401, in dorsal view. (c) and (d) WGSC V 1601, in ventral view. Scale bars are 20 mm long. Symbols: at, atlas; atns, atlantal neural spine; ax, axis; axnp, axial neural spine; bh, basihyal lingual process; ch, ceratohyal; f, frontal; j, jugal; l, lacrimal; lg, labial groove for labial cartilage; m, maxilla; mand, mandibular rami; n, nasal; os, bone resembling os paradoxum; p, parietal; palatal, unidentified palatal bones; pl, palatine; pm, premaxilla; pob, postorbital; prf, prefrontal; ps-bs, parasphenoid-basisphenoid complex; pt, pterygoid; ptf, postfrontal; q, quadrate; sq, squamosal; st, supratemporal; v, vomer.

The skull and mandible of Eretmorhipis carrolldongi in two new specimens. (a) and (b) YAGM V 1401, in dorsal view. (c) and (d) WGSC V 1601, in ventral view. Scale bars are 20 mm long. Symbols: at, atlas; atns, atlantal neural spine; ax, axis; axnp, axial neural spine; bh, basihyal lingual process; ch, ceratohyal; f, frontal; j, jugal; l, lacrimal; lg, labial groove for labial cartilage; m, maxilla; mand, mandibular rami; n, nasal; os, bone resembling os paradoxum; p, parietal; palatal, unidentified palatal bones; pl, palatine; pm, premaxilla; pob, postorbital; prf, prefrontal; ps-bs, parasphenoid-basisphenoid complex; pt, pterygoid; ptf, postfrontal; q, quadrate; sq, squamosal; st, supratemporal; v, vomer.

Its long, bony body means that Eretmorhipis was probably a poor swimmer, Motani said.

“It wouldn’t survive in the modern world, but it didn’t have any rivals at the time,” he said.

Related to the dolphin-like ichthyosaurs, Eretmorhipis evolved in a world devastated by the mass extinction event at the end of the Permian era. The fossil provides more evidence of rapid evolution occurring during the early Triassic, Motani said.

Preorbito-external-narial region of Eretmorhipis carrolldongi and a bone resembling os paradoxum. (a) ‘Os paradoxum’ of WGSC V 1601, in ventral view with unfinished surface. (b) Same of YAGM V 1401, in dorsal view revealing a median ridge; (c)-(d) Preorbito-external-narial region of YAGM V 1401. Scales for (a) and (b) are 1 mm, and each square in (c) has a side length of 1 mm. See Fig. 4 for symbols.

Preorbito-external-narial region of Eretmorhipis carrolldongi and a bone resembling os paradoxum. (a) ‘Os paradoxum’ of WGSC V 1601, in ventral view with unfinished surface. (b) Same of YAGM V 1401, in dorsal view revealing a median ridge; (c)-(d) Preorbito-external-narial region of YAGM V 1401. Scales for (a) and (b) are 1 mm, and each square in (c) has a side length of 1 mm. See Fig. 4 for symbols.

Co-authors on the study are Long Cheng and Chun-bo Yan, Wuhan Centre of China Geological Survey, Wuhan; Da-yong Jiang, Peking University; Andrea Tintori, Università degli Studi di Milano, Italy; and Olivier Rieppel, The Field Museum, Chicago. The work was supported by grants from the China Geological Survey, the National Natural Science Foundation of China and the Ministry of Science and Technology.

Journal Reference:

  1. Long Cheng, Ryosuke Motani, Da-yong Jiang, Chun-bo Yan, Andrea Tintori, Olivier Rieppel. Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detectionScientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-018-37754-6

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WFS News: T. rex fossil leads researchers to new species of shark

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T. rex fossil leads researchers to new species of shark

Scientists examining rock left over from the discovery of a fossilized Tyrannosaurus rex recently came across a surprise: shark teeth.

The huge meat-eating dinosaur, the remains of which were extricated in the 1990s, was not killed by a shark. But, scientists said on Monday, when the 12.3-metre beast, known these days as Sue, died some 67 million years ago, it fell into a South Dakota river teeming with sharks — albeit small ones — thriving in the freshwater environment.

The skeleton of Sue, the largest, most complete and best-preserved T. rex ever unearthed, is displayed at the Field Museum in Chicago, which kept the leftover rock for years in underground storage. That rock has now yielded fossils from other creatures that were Sue’s neighbours including a shark species called Galagadon nordquistae.

Galagadon, related to a group called carpet sharks found in Indo-Pacific seas today, measured 0.3 to 0.6 metres long, with teeth the size of a sand grain, about one millimetre. Tyrannosaurus teeth were up to 30 centimetres long.

If the sharks ever interacted with Sue, it may have been when the thirsty dinosaur came to the river for a gulp of water.

“It would not surprise me at all if a T. rex individual scared a little Galagadon as it lowered its head to drink,” said North Carolina State University paleontologist Terry “Bucky” Gates, lead author of the research published in the Journal of Paleontology.

If the prehistoric shark resembled its existing relatives, it was a blunt-faced bottom-dweller with barbels by its mouth like a catfish and camouflage patterning.

Researchers hypothesize that the prehistoric shark Galagadon nordquistae was a bottom–dweller with barbels by its mouth, like a catfish, with camouflage patterning. (Velizar Simeonovski/Field Museum/Reuters)

Researchers hypothesize that the prehistoric shark Galagadon nordquistae was a bottom–dweller with barbels by its mouth, like a catfish, with camouflage patterning. (Velizar Simeonovski/Field Museum/Reuters)

“The teeth have an unusual shape with three unequal points and a wide apron at the root. Some of the teeth bear an uncanny resemblance to the spaceship in the 1980s arcade game Galaga, which inspired the genus name,” said co-author Pete Makovicky, a paleontologist and Field Museum dinosaur curator.

Each Galagadon tooth measures less than a millimetre across, helping researchers estimate the small size of the shark. (Terry Gates/North Carolina State University/Reuters)

Each Galagadon tooth measures less than a millimetre across, helping researchers estimate the small size of the shark. (Terry Gates/North Carolina State University/Reuters)

Scientists also are studying fossils of at least two other shark species from Sue’s river. Virtually all sharks live in the sea, though two freshwater species today reside permanently in rivers and lakes, and some other species venture into freshwater.

“I doubt Galagadon spent its whole life in freshwater habitats,” Makovicky said, suggesting its river may have been connected to an inland sea 160 kilometres away that at the time split North America in half.

Source: CBC News.

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WFS News: World’s oldest fossil mushroom

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CHAMPAIGN, Ill. — Roughly 115 million years ago, when the ancient supercontinent Gondwana was breaking apart, a mushroom fell into a river and began an improbable journey. Its ultimate fate as a mineralized fossil preserved in limestone in northeast Brazil makes it a scientific wonder, scientists report in the journal PLOS ONE.

The world’s oldest fossil mushroom was preserved in limestone, an extraordinarily rare event, researchers say. Photo by Jared Thomas / Drawing by Danielle Ruffatto

The world’s oldest fossil mushroom was preserved in limestone, an extraordinarily rare event, researchers say.Photo by Jared Thomas / Drawing by Danielle Ruffatto

The mushroom somehow made its way into a highly saline lagoon, sank through the stratified layers of salty water and was covered in layer upon layer of fine sediments. In time – lots of it – the mushroom was mineralized, its tissues replaced by pyrite (fool’s gold), which later transformed into the mineral goethite, the researchers report.

The mushroom lived during the Early Cretaceous, a time of dinosaurs when the ancient supercontinent Gondwana was breaking apart. Graphic by Danielle Ruffatto

The mushroom lived during the Early Cretaceous, a time of dinosaurs when the ancient supercontinent Gondwana was breaking apart.Graphic by Danielle Ruffatto

“Most mushrooms grow and are gone within a few days,” said Illinois Natural History Surveypaleontologist Sam Heads, who discovered the mushroom when digitizing a collection of fossils from the Crato Formation of Brazil. “The fact that this mushroom was preserved at all is just astonishing.

“When you think about it, the chances of this thing being here – the hurdles it had to overcome to get from where it was growing into the lagoon, be mineralized and preserved for 115 million years – have to be minuscule,” he said.

The Crato Formation mushroom fossil is the oldest ever discovered. All others have been found in amber. Graphic by Danielle Ruffatto

The Crato Formation mushroom fossil is the oldest ever discovered. All others have been found in amber.Graphic by Danielle Ruffatto

Before this discovery, the oldest fossil mushrooms found had been preserved in amber, said INHS mycologist Andrew Miller, a co-author of the new report. The next oldest mushroom fossils, found in amber in Southeast Asia, date to about 99 million years ago, he said.

“They were enveloped by a sticky tree resin and preserved as the resin fossilized, forming amber,” Heads said. “This is a much more likely scenario for the preservation of a mushroom, since resin falling from a tree directly onto the forest floor could readily preserve specimens. This certainly seems to have been the case, given the mushroom fossil record to date.”

The mushroom was about 5 centimeters (2 inches) tall. Electron microscopy revealed that it had gills under its cap, rather than pores or teeth, structures that release spores and that can aid in identifying species.

“Fungi evolved before land plants and are responsible for the transition of plants from an aquatic to a terrestrial environment,” Miller said. “Associations formed between the fungal hyphae and plant roots. The fungi shuttled water and nutrients to the plants, which enabled land plants to adapt to a dry, nutrient-poor soil, and the plants fed sugars to the fungi through photosynthesis. This association still exists today.”

The researchers place the mushroom in the Agaricales order and have named it Gondwanagaricites magnificus.

The INHS is a division of the Prairie Research Institute at the University of Illinois. The National Science Foundation is funding a project to digitize INHS fossil collections.

Citation:Heads SW, Miller AN, Crane JL, Thomas MJ, Ruffatto DM, Methven AS, et al. (2017) The oldest fossil mushroom. PLoS ONE 12(6): e0178327. https://doi.org/10.1371/journal.pone.0178327

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WFS News: Surface exposure dating with cosmogenic nuclides

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Surface exposure dating with cosmogenic nuclides

 SUSAN IVY-OCHS & FLORIAN KOBER

Eiszeitalter und Gegenwart Quaternary Science Journal,57/1–2,157–189,Hannover 2008

Abstract: In the last decades surface exposure dating using cosmogenic nuclides has emerged as a powerful
tool in Quaternary geochronology and landscape evolution studies. Cosmogenic nuclides are produced in
rocks and sediment due to reactions induced by cosmic rays. Landforms ranging in age from a few hundred
years to tens of millions of years can be dated (depending on rock or landform weathering rates) by measuring nuclide concentrations. In this paper the history and theory of surface exposure dating are reviewed
followed by an extensive outline of the fields of application of the method. Sampling strategies as well as
information on individual nuclides are discussed in detail. The power of cosmogenic nuclide methods lies in
the number of nuclides available (the radionuclides 10Be, 14C, 26Al, and 36Cl and the stable noble gases 3
He and 21Ne), which allows almost every mineral and hence almost every lithology to be analyzed. As a result
focus can shift to the geomorphic questions. It is important that obtained exposure ages are carefully scrutinized in the framework of detailed field studies, including local terrace or moraine stratigraphy and regional
morphostratigraphic relationships; as well as in light of independent age constraints.

Schematic diagram showing the various landforms that can be dated and approaches for using cosmogenic nuclides to address questions of timing and rates of landscape change (see also BIERMAN & NICHOLS 2004).

Schematic diagram showing the various landforms that can be dated and approaches for using cosmogenic nuclides to address questions of timing and rates of landscape change (see also BIERMAN & NICHOLS 2004).

Summary and outlook
The ability to use cosmogenic nuclides to determine how long minerals have been exposed at the surface of the earth provides an unrivaled tool for determining ages of landforms and rates of geomorphic processes. Depending or rock and landform weathering rates, landforms ranging in age from a few hundred years to tens of millions of years can be dated. Because of this unique capability, the variety of applications of cosmogenic nuclides will continue to grow. Concern about methodological uncertainties, such as those associated with the production rates, the site latitude and
altitude scaling factors, as well as the effect of past changes in the Earth’s magnetic field, has led to the establishment of an international consortium made up of CRONUS-Earth (www.physics.purdue.edu/cronus) and CRONUS-EU (www.cronus-eu.net).

Analysis of artificial targets and samples from natural sites with independent age control are underway to refine production rates. Scaling factors are being evaluated with neutron monitors and analysis of same age natural samples taken along altitudinal transects (for example lava flows). Numerical modeling is being used to
constrain production rates and scaling factors both now and in the past. The half-lives of radioactive nuclides must be accurately known. In the case of 10Be, two different half-lives have been published, 1.51 and 1.34 Ma (GRANGER
2006; NISHIIZUMI et al. 2007). When these factors are better constrained the errors of the final ages will be closer to the range of the AMS and noble gas mass spectrometry measurement uncertainties (of the order of 1-4 %). With improved knowledge of production rates and their scaling to the site, the precision of obtained ages will improve. But the accuracy of the ages remains a question of geological uncertainties. The degradation of both rock surfaces and the landforms with time imposes clear limitations on the time range and accuracy of dating. Similarly, the natural variability of samples depends on landform morphology and its age. Obtained exposure ages must be evaluated individually for conformity with field relationships, including local terrace or moraine stratigraphy and regional morphostratigraphic relationships; as well as with independent age constraints for the same or correlative features. For older landforms (more than a hundred thousand years) measurement of mulitple cosmogenic nuclides can reveal fundamental information, such as non-continuous exposure, which must be factored into interpretations (ALVAREZ-MARRÓN et al. 2007; KOBER et al. 2007). Cosmogenic nuclides provide a powerful and multifaceted tool whose potential has yet to be fully realized. But this power is tempered with the need for careful sampling based on detailed field mapping.

Source: https://www.researchgate.net/profile/Florian_Kober/publication/236668263_Surface_exposure_dating_with_cosmogenic_nuclides/links/0c960518cc15a63b25000000/Surface-exposure-dating-with-cosmogenic-nuclides.pdf

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WFS News: An unexpected noncarpellate epigynous flower from the Jurassic of China

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Idealized reconstruction of Nanjinganthus. 1, branches of dendroid style; 2, dendroid style; 3, sepal; 4, ovarian roof; 5, scale; 6, seed; 7, cup-form receptacle/ovary; 8, bract; 9, petal; 10, unknown organ (staminode?). https://doi.org/10.7554/eLife.38827.019

Idealized reconstruction of Nanjinganthus.
1, branches of dendroid style; 2, dendroid style; 3, sepal; 4, ovarian roof; 5, scale; 6, seed; 7, cup-form receptacle/ovary; 8, bract; 9, petal; 10, unknown organ (staminode?).
https://doi.org/10.7554/eLife.38827.019

Despite the importance of, the great interest in and intensive effort spent on investigating angiosperms, a controversy remains as to when and how this group came into existence. Since the time of Darwin, some scholars have proposed that angiosperms existed before the Cretaceous (Smith et al., 2010Clarke et al., 2011Zeng et al., 2014Buggs, 2017), although the conclusion ‘there are no reliable records of angiosperms from pre-Cretaceous rocks’ made almost 60 years (Scott et al., 1960) seemed to be recently re-confirmed (Herendeen et al., 2017). Such uncertainty makes answers to many questions about the phylogeny and systematics of angiosperms tentative. Some reports of early angiosperms (i.e., Monetianthus (Friis et al., 2001)) are based on a single specimen, which restricts further testing and confirming. Better and more specimens of early age and with features unique to angiosperms are highly sought-after to test related evolutionary hypotheses. Here, we report an unusual actinomorphic flower, Nanjinganthus gen. nov., from the Lower Jurassic based on the observations of 264 specimens of 198 individual flowers on 34 slabs preserved in various orientations and states (Supplementary file 1). The abundance of specimens allowed us to dissect some of them, thus demonstrate and recognize a cup-form receptacle, ovarian roof, and enclosed ovules/seeds in Nanjinganthus. These features are consistent with the inference that Nanjinganthus is an angiosperm. The origin of angiosperms has long been an academic ‘headache’ for many botanists, and we think that Nanjinganthus will shed a new light on this subject.

Siltstone slabs bearing Nanjinganthus. All bars are 1 cm long. (A) Six flowers (1-6) on the same slab, and an associated triangular leaflet with parallel venation. PB22227. (B) Several flowers on the same slab. 1–3 are shown in detail in Figures 2f and 6d,e. PB22226. (C) Several flowers (1-8) on the same slab and the associated Nilssonia parabrevis (top). PB22220. (D) Several flowers (1-6) on the same slab. 1–3 are shown in detail in Figures 2h and 3a–c. PB22224. (E) Many flowers on the same slab. Some of the numbered ones are shown in detail in later figures. PB22222a. (F) A slab with numerous flowers. PB22221. (G) A slab almost fully covered with flowers. PB22228.

Siltstone slabs bearing Nanjinganthus. All bars are 1 cm long. (A) Six flowers (1-6) on the same slab, and an associated triangular leaflet with parallel venation. PB22227. (B) Several flowers on the same slab. 1–3 are shown in detail in Figures 2f and 6d,e. PB22226. (C) Several flowers (1-8) on the same slab and the associated Nilssonia parabrevis (top). PB22220. (D) Several flowers (1-6) on the same slab. 1–3 are shown in detail in Figures 2h and 3a–c. PB22224. (E) Many flowers on the same slab. Some of the numbered ones are shown in detail in later figures. PB22222a. (F) A slab with numerous flowers. PB22221. (G) A slab almost fully covered with flowers. PB22228.https://doi.org/10.7554/eLife.38827.005

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WFS News: Trilobite ancestral range in the southern hemisphere reconstructed

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The first appearance of trilobites in the fossil record dates to 521 million years ago in the oceans of the Cambrian Period, when the continents were still inhospitable to most life forms. Few groups of animals adapted as successfully as trilobites, which were arthropods that lived on the seabed for 270 million years until the mass extinction at the end of the Permian approximately 252 million years ago.

The longer ago organisms lived, the more rare are their fossils and the harder it is to understand their way of life; paleontologists face a daunting task in endeavoring to establish evolutionary relationships in time and space.

Surmounting the difficulties inherent in the investigation of a group of animals that lived such a long time ago, Brazilian scientists affiliated with the Biology Department of São Paulo State University’s Bauru School of Sciences (FC-UNESP) and the Paleontology Laboratory of the University of São Paulo’s Ribeirão Preto School of Philosophy, Science and Letters (FFCLRP-USP) have succeeded for the first time in inferring paleobiogeographic patterns among trilobites.

Schematic drawing showing the major exoskeleton elements of the dorsal surface of Metacryphaeus.

Schematic drawing showing the major exoskeleton elements of the dorsal surface of Metacryphaeus.

Paleobiogeography is a branch of paleontology that focuses on the distribution of extinct plants and animals and their relations with ancient geographic features. The study was conducted by Fábio Augusto Carbonaro, a postdoctoral researcher at UNESP’s Bauru Macroinvertebrate Paleontology Laboratory (LAPALMA) headed by Professor Renato Pirani Ghilardi. Other participants included Max Cardoso Langer, a professor at FFCLRP-USP, and Silvio Shigueo Nihei, a professor at the same university’s Bioscience Institute (IB-USP).

The researchers analyzed the morphological differences and similarities of the 11 species of trilobites described so far in the genus Metacryphaeus; these trilobites lived during the Devonian between 416 million and 359 million years ago (mya) in the cold waters of the sea that covered what is now Bolivia, Peru, Brazil, the Malvinas (Falklands) and South Africa.

The Devonian Period is subdivided into seven stages. Metacryphaeus lived during the Lochkovian (419.2-410.8 mya) and Pragian (410.8- 407.6 mya) stages, which are the earliest Devonian stages.

The results of the research were published in Scientific Reportsand are part of the project “Paleobiogeography and migratory routes of paleoinvertebrates of the Devonian in Brazil,” which is supported by São Paulo Research Foundation -FAPESP and Brazil’s National Council for Scientific and Technological Development (CNPq). Ghilardi is the project’s principal investigator.

“When they became extinct in the Permian, 252 million years ago, the trilobites left no descendants. Their closest living relatives are shrimps, and, more remotely, spiders, scorpions, sea spiders and mites,” Ghilardi said.

Trilobite fossils are found abundantly all over the world, he explained — so abundantly that they are sometimes referred to as the cockroaches of the sea. The comparison is not unwarranted because anatomically, the trilobites resemble cockroaches. The difference is that they were not insects and had three longitudinal body segments or lobes (hence the name).

In the northern hemisphere, the trilobite fossil record is very rich. Paleontologists have so far described ten orders comprising over 17,000 species. The smallest were 1.5 millimeters long, while the largest were approximately 70 cm long and 40 cm wide. Perfectly preserved trilobites can be found in some regions, such as Morocco. These can be beautiful when used to create cameos or intaglio jewelry. Trilobite fossils from Brazil, Peru and Bolivia, in contrast, are often poorly preserved, consisting merely of the impressions left in benthic mud by their exoskeletons.

“Although their state of preservation is far from ideal, there are thousands of trilobite fossils in the sediments that form the Paraná basin in the South region of Brazil, and the Parnaíba basin along the North-Northeast divide,” said Ghilardi, who also chairs the Brazilian Paleontology Society.

According to Ghilardi, their poor state of preservation could be due to the geological conditions and climate prevailing in these regions during the Paleozoic Era, when the portions of dry land that would one day form South America were at the South Pole and entirely covered by ice for prolonged periods.

During the Devonian, South America and Africa were connected as part of the supercontinent Gondwana. South Africa was joined with Uruguay and Argentina in the River Plate region, and Brazil’s southern states were continuous with Namibia and Angola.

Parsimonious analysis

The research began with an analysis of 48 characteristics (size, shape and structure of organs and anatomical parts) found in some 50 fossil specimens of the 11 species of Metacryphaeus.

“In principle, these characteristics serve to establish their phylogeny — the evolutionary history of all species in the universe, analyzed in terms of lines of descent and relationships among broader groups,” Ghilardi said.

Known as a parsimonious analysis, this method is widely used to establish relationships among organisms in a given ecosystem, and in recent years, it has also begun to be used in the study of fossils.

According to Ghilardi, parsimony, in general, is the principle that the simplest explanation of the data is the preferred explanation. In the analysis of phylogeny, it means that the hypothesis regarding relationships that requires the smallest number of characteristic changes between the species analyzed (in this case, trilobites of the genus Metacryphaeus) is the one that is most likely to be correct.

The biogeographic contribution to the study was made by Professor Nihei, who works at IB-USP as a taxonomist and insect systematist. The field of systematics is concerned with evolutionary changes between ancestries, while taxonomy focuses on classifying and naming organisms.

“Biogeographic analysis typically involves living groups the ages of which are estimated by molecular phylogeny, or the so-called molecular clock, which estimates when two species probably diverged on the basis of the number of molecular differences in their DNA. In this study of trilobites, we used age in a similar manner, but it was obtained from the fossil record,” Nihei said.

“The main point of the study was to use fossils in a method that normally involves molecular biogeography. Very few studies of this type have previously involved fossils. I believe our study paves the way for a new approach based on biogeographic methods requiring a chronogram [a molecularly dated cladogram] because this chronogram can also be obtained from fossil taxa such as those studied by paleontologists, rather than molecular cladograms for living animals.”

As a vertebrate paleontologist who specializes in dinosaurs, Langer acknowledged that he knows little about trilobites but a great deal about the modern computational techniques used in parsimonious analysis, on which his participation in the study was based. “I believe the key aspect of this study, and the reason it was accepted for publication in as important a journal as Scientific Reports, is that it’s the first ever use of parsimony to understand the phylogeny of a trilobite genus in the southern hemisphere,” he said.

Gondwanan dispersal

The results of the paleobiogeographical analyses reinforce the pre-existing theory that Bolivia and Peru formed the ancestral home of Metacryphaeus.

“The models estimate a 100% probability that Bolivia and Peru formed the ancestral area of the Metacryphaeus clade and most of its internal clades,” Ghilardi said. Confirmation of the theory shows that parsimonious models have the power to suggest the presence of clades at a specific moment in the past even when there are no known physical records of that presence.

In the case of Metacryphaeus, the oldest records in Bolivia and Peru date from the early Pragian stage (410.8-407.6 mya), but the genus is believed to have evolved in the region during the Lochkovian stage (419.2-410.8 mya).

Parsimony, therefore, suggests Metacryphaeus originated in Bolivia and Peru some time before 410.8 mya but not earlier than 419.2 mya. In any event, it is believed to be far older than any known fossils.

According to Ghilardi, the results can be interpreted as showing that the adaptive radiation of Metacryphaeus to other areas of western Gondwana occurred during episodes of marine transgression in the Lochkovian-Pragian, when the sea flooded parts of Gondwana.

“The dispersal of Metacryphaeus trilobites during the Lochkovian occurred from Bolivia and Peru to Brazil — to the Paraná basin, now in the South region, and the Parnaíba basin, on the North-Northeast divide — and on toward the Malvinas/Falklands, while the Pragian dispersal occurred toward South Africa,” he said.

Fossil trilobites have been found continuously in the Paraná basin in recent decades. Trilobites collected in the late nineteenth century in the Parnaíba basin were held by Brazil’s National Museum in Rio de Janeiro, which was destroyed by fire in September 2018.

“These fossils haven’t yet been found under the rubble and it’s likely that nothing is left of them. They were mere shell impressions left in the ancient seabed. Even in petrified form, they must have dissolved in the blaze,” Ghilardi said.

Journal Reference:

  1. Fábio Augusto Carbonaro, Max Cardoso Langer, Silvio Shigueo Nihei, Gabriel de Souza Ferreira, Renato Pirani Ghilardi. Inferring ancestral range reconstruction based on trilobite records: a study-case on Metacryphaeus (Phacopida, Calmoniidae)Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-33517-5

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WFS News:The mysteries of a giant prehistoric marine reptile unlocked with the help of Medical scanner

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Descriptive anatomy of the largest known specimen of Protoichthyosaurus prostaxalis (Reptilia: Ichthyosauria) including computed tomography and digital reconstruction of a three-dimensional skull

Three-dimensional skull of BMT 1955.G35.1, Protoichthyosaurus prostaxalis. (A) Original photograph of the first skull reconstruction (left lateral view) within a couple of years of the 1955 excavation. Note that the prefrontal and postorbital are present, which we have been unable to locate in our study. (B) Skull in left lateral view, as reconstructed in 2015. (C) Skull in right lateral view, as reconstructed in 2015. Note the distinctive asymmetric maxilla with long, narrow anterior process. Teeth are not in their original positions. Scale bar represents 20 cm.

Three-dimensional skull of BMT 1955.G35.1, Protoichthyosaurus prostaxalis.
(A) Original photograph of the first skull reconstruction (left lateral view) within a couple of years of the 1955 excavation. Note that the prefrontal and postorbital are present, which we have been unable to locate in our study. (B) Skull in left lateral view, as reconstructed in 2015. (C) Skull in right lateral view, as reconstructed in 2015. Note the distinctive asymmetric maxilla with long, narrow anterior process. Teeth are not in their original positions. Scale bar represents 20 cm.

Surface models (generated from CT scan data) of the skull of BMT 1955.G35.1, Protoichthyosaurus prostaxalis. After the removal of minor damage and duplication/mirroring of asymmetrically preserved elements, and digital articulation of individual bones to produce a more accurate digital 3D reconstruction. Displacement of the lower jaw and premaxillae and nasals are the result of deformation (see text). Left lateral (A) dorsal (B) ventral (C) anterior (D) and posterior (E) views of the upper and lower jaws. Individual bones labelled using the same colours as Figs. 2–4.

Surface models (generated from CT scan data) of the skull of BMT 1955.G35.1, Protoichthyosaurus prostaxalis.
After the removal of minor damage and duplication/mirroring of asymmetrically preserved elements, and digital articulation of individual bones to produce a more accurate digital 3D reconstruction. Displacement of the lower jaw and premaxillae and nasals are the result of deformation (see text). Left lateral (A) dorsal (B) ventral (C) anterior (D) and posterior (E) views of the upper and lower jaws. Individual bones labelled using the same colours as Figs. 2–4.

Citation:Lomax DR, Porro LB, Larkin NR. 2019Descriptive anatomy of the largest known specimen of Protoichthyosaurus prostaxalis (Reptilia: Ichthyosauria) including computed tomography and digital reconstruction of a three-dimensional skullPeerJ 7:e6112https://doi.org/10.7717/peerj.6112

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WFS News: Introduction to dating glacial sediments

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Many methods of dating glacial sediments

Glacial Sediments

                                                                        Glacial Sediments

As glacial geologists, some of the biggest questions that we’d like to answer are not only how large former ice sheets were, but also how fast did the recede and how quickly did they thin? This information is vital for numerical models, and answers questions about how dynamic ice sheets are, and how responsive they are to changes in atmospheric and oceanic temperatures.

Unfortunately, glacial sediments are typically difficult to date. Most methods rely on indirect methods of dating subglacial tills, such as dating organic remains above and below glacial sediments. Many methods are only useful for a limited period of time (for radiocarbon, for example, 40,000 years is the maximum age possible). Scientists dating Quaternary glacial sediments in Antarctica most commonly use one of the methods outlined below, depending on what kind of material they want to date and how old it is.

Cosmogenic nuclide dating is useful for directly dating rocks on the Earth’s surface. It gives an Exposure Age: that is, how long the rock has been exposed to cosmic radiation. It is effective on timescales of several millions of years. It assumes that boulders have not been buried and then re-exposed at the Earth’s surface.

Radiocarbon dating dates the decay of Carbon-14 within organic matter. Organic matter needs to have been buried and preserved for this technique. It is effective for up to the last 40,000 years. It assumes that organic material is not contaminated with older radiocarbon (which, for example, is a common problem with organic material from marine sediment cores around Antarctica).

Amino Acid Racemisation dates the decay and change in proteins in organisms such as shells.

Optically Stimulated Luminescence dates the radiation accumulated in quartz or feldspar grains within sand. The radiation emanates from radioactive grains within the sediment, such as zircons. It is effective for hundreds of thousands of years, and dates how long the sediment has been buried.

Other methods of dating glacial sediments

There are so many other methods of dating Quaternary sediments and organic material that it is impractical to cover them all here in detail. Uranium-series uses the decay of uranium and thorium isotopes (238U, 235U and 232Th) in calcites in particular, such as stalactites and stalagmites in caves. Potassium-argon and argon-argon dating can be used to date the formation of volcanic rocks.

Older marine sediments can be dated using palaeo-magnetism. This is because the earth’s magnetic field varies in strength and polarity direction. This is caused by a number of factors, including variations in solar radiation, magnetic storms, and internal geophysical factors. Unconsolidated sediments contain magnetic minerals, such as those on the continental shelf and slope. These minerals are magnetised during formation. The remnant magnetism of the sediment is a reflection of the earth’s palaeomagnetic field at the time of deposition. The sediments can be compared to palaeo magnetostratigraphic data, and this can be used as a proxy age determination.

Source: Article By 

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WFS News: Tooth Loss Precedes the Origin of Baleen in Whales

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Rivaling the evolution of feathers in dinosaurs, one of the most extraordinary transformations in the history of life was the evolution of baleen — rows of flexible hair-like plates that blue whales, humpbacks and other marine mammals use to filter relatively tiny prey from gulps of ocean water. The unusual structure enables the world’s largest creatures to consume several tons of food each day, without ever chewing or biting. Now, Smithsonian scientists have discovered an important intermediary link in the evolution of this innovative feeding strategy: an ancient whale that had neither teeth nor baleen.

(A–G) Dorsal (A) and ventral (B) views of the holotype skull; lateral (C) view of the right mandible; dorsal (D), lateral (E), medial (F), and ventral (G) views of left tympanic bulla.

(A–G) Dorsal (A) and ventral (B) views of the holotype skull; lateral (C) view of the right mandible; dorsal (D), lateral (E), medial (F), and ventral (G) views of left tympanic bulla.

In the Nov. 29 issue of the journal Current Biology, scientists at the Smithsonian’s National Museum of Natural History and colleagues describe for the first time Maiabalaena nesbittae, a whale that lived about 33 million years ago. Using new methods to analyze long-ago discovered fossils housed in the Smithsonian’s national collection, the team, which includes scientists at George Mason University, Texas A&M University and the Burke Museum of Natural History and Culture in Seattle, have determined that this toothless, 15-foot whale likely had no baleen, showing a surprising intermediary step between the baleen whales that live today and their toothed ancestors.

Figure illustrates a composite phylogeny including results from this analysis (Figure S4) and recently published analyses [5, 7, 8]. (A) Time calibrated simplified phylogeny, with collapsed clade resolution for Mammalodontidae, Aetiocetidae and Eomysticetidae, and crown Mysticeti. (B–E) Colored bars indicate groups figured; gray bars indicate groups not figured. Panels (b–e) represent 3D models of select specimens in lateral view with artistic reconstructions of their feeding modes: (B) Basilosaurus isis; (C) Coronodon havensteini; (D) Maiabalaena nesbittae; and (E) Balaenoptera musculus. These panels illustrate the loss of a functional dentition, the intermediate phase with neither teeth nor baleen, and the subsequent origin of baleen. Illustrations are original artwork by Alex Boersma (www.alexboersma.com).

Figure illustrates a composite phylogeny including results from this analysis (Figure S4) and recently published analyses [5, 7, 8].
(A) Time calibrated simplified phylogeny, with collapsed clade resolution for Mammalodontidae, Aetiocetidae and Eomysticetidae, and crown Mysticeti.
(B–E) Colored bars indicate groups figured; gray bars indicate groups not figured. Panels (b–e) represent 3D models of select specimens in lateral view with artistic reconstructions of their feeding modes: (B) Basilosaurus isis; (C) Coronodon havensteini; (D) Maiabalaena nesbittae; and (E) Balaenoptera musculus. These panels illustrate the loss of a functional dentition, the intermediate phase with neither teeth nor baleen, and the subsequent origin of baleen. Illustrations are original artwork by Alex Boersma (www.alexboersma.com).

“When we talk about whale evolution, textbooks tend to focus on the early stages, when whales went from land to sea,” said National Museum of Natural History’s curator of fossil marine mammals. “Maiabalaena shows that the second phase of whale evolution is just as important for evolution over big scales. For the first time, we can now pin down the origin of filter-feeding, which is one of the major innovations in whale history.”When whales first evolved, they used teeth to chew their food, just like their land-dwelling ancestors. As time went on, many descendants of these early whales continued to chew their food, inheriting this trait from their predecessors. But as the oceans around them changed and animals evolved, entirely new feeding strategies arose, including baleen filter feeding, says National Museum of Natural History predoctoral fellow Carlos Mauricio Peredo, the lead author of the study who analyzed the Maiabalaena fossils.

Whales were the first mammals to evolve baleen, and no other mammal uses any anatomical structure even remotely similar to it to consume its prey. But frustratingly, baleen, whose chemical composition is more like that of hair or fingernails than bone, does not preserve well. It is rarely found in the fossil record, leaving paleontologists without direct evidence of its past or origins. Instead, scientists have had to rely on inferences from fossils and studies of fetal-whale development in the womb to piece together clues about how baleen evolved.

As a result, it has not been clear whether, as they evolved, early baleen whales retained the teeth of their ancestors until a filter-feeding system had been established. An early initial assumption, Peredo said, was that ocean-dwelling mammals must have needed teeth or baleen to eat — but several living whales contradict that idea. Sperm whales have teeth in their bottom jaw, but none on the top, so they cannot bite or chew. Narwhals’ only teeth are their long tusks, which they do not use for feeding. And some species of beaked whales, despite being classified as toothed whales, have no teeth at all.

Because of its age, Peredo said, paleontologists suspected Maiabalaena might hold important clues about baleen’s evolution. The fossil comes from a period of massive geological change during the second major phase of whale evolution, around the time the Eocene epoch was transitioning to the Oligocene. With continents shifting and separating, ocean currents were swirling around Antarctica for the first time, cooling the waters significantly. The fossil record indicates that whales’ feeding styles diverged rapidly during this timeframe, with one group leading to today’s filter-feeding whales and the other leading to echolocating ones.

Consequently, Maiabalaena had received plenty of scrutiny since its discovery in Oregon in the 1970s, but the rock matrix and material that the fossil was collected in still obscured many of its features. It was not until Peredo finally cleaned the fossil and then examined it with state-of-the-art CT scanning technology that its most striking features became clear. Maiabalaena‘s lack of teeth was readily apparent from the preserved bone, but the CT scans, which revealed the fossil’s internal anatomy, told the scientists something new: Maiabalaena‘s upper jaw was thin and narrow, making it an inadequate surface from which to suspend baleen.

“A living baleen whale has a big, broad roof in its mouth, and it’s also thickened to create attachment sites for the baleen,” Peredo said. “Maiabalaena does not. We can pretty conclusively tell you this fossil species didn’t have teeth, and it is more likely than not that it didn’t have baleen either.”

While Maiabalaena would not have been able to chew or to filter feed, muscle attachments on the bones of its throat indicate it likely had strong cheeks and a retractable tongue. These traits would have enabled it to suck water into its mouth, taking up fish and small squid in the process. The ability to suction feed would have rendered teeth, whose development requires a lot of energy to grow, unnecessary. The loss of teeth, then, appears to have set the evolutionary stage for the baleen, which the scientists estimate arose about 5 to 7 million years later.

Peredo and Pyenson see studying whale evolution as key to understanding their survival in today’s rapidly changing oceans. Like the emergence of baleen, tooth loss in whales is evidence of adaptability, suggesting that whales might be able to adapt to challenges posed in the ocean today. Still, Peredo cautions, evolutionary change may be slow for the largest whales, which have long life spans and take a long time to reproduce.

“Given the scale and rate of changes in the ocean today, we don’t exactly know what that will mean for all of the different species of filter-feeding whales,” he said. “We know that they’ve changed in the past. It’s just a matter of whether they can keep up with whatever the oceans are doing — and we’re changing the oceans pretty quickly right now.”

  1. Carlos Mauricio Peredo, Nicholas D. Pyenson, Christopher D. Marshall, Mark D. Uhen. Tooth Loss Precedes the Origin of Baleen in WhalesCurrent Biology, 2018; DOI: 10.1016/j.cub.2018.10.047
Source: Smithsonian. “Whales lost their teeth before evolving hair-like baleen in their mouths: Newly described fossil whale in museum collections reveals a surprising intermediate step in their evolution.” ScienceDaily. ScienceDaily, 29 November 2018. <www.sciencedaily.com/releases/2018/11/181129142423.htm>.
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