Although turtles belong to the reptiles, their skulls differs markedly from those of other members of this group. Credit: I. Werneburg
The origin of turtles is among the most debated topics in evolutionary biology. In a recently published study in the journal Nature Scientific Reports, Senckenberg scientist Ingmar Werneburg, in cooperation with an international research team, refutes existing hypotheses and sheds a new light on the evolution of the skull architecture. The results indicate a close link between skull evolution and the highly flexible neck of these armored reptiles.
In addition to their shell, turtles are characterized by their flexible necks and small heads. “Although turtles belong to the reptiles, their skulls differs markedly from those of other members of this group, which—together with their unique armored skeleton—makes it difficult to assess their phylogenetic origin,” explains PD Dr. Ingmar Werneburg of the “Senckenberg Centre for Human Evolution and Palaeoenvironment (SHEP) an der Universität Tübingen.”
Fossils suggest that several modifications during turtle evolution drove the initially mobile skull to transform to a rigid structure. In this process, the temporal openings behind the eyes closed as well, forming a so-called anapsid skull, which is not found in any other living reptile.
At the same time, the animals developed a unique arrangement of their jaw muscles, comparable to a pulley system. “Until now, it was assumed that these modifications led to an increased bite force in turtles, and that this development constituted a functional adaptation to a modified feeding behavior,” adds Werneburg.
This hypothesis was now tested for the first time under biomechanical aspects by an international research team led by Werneburg. The scientist from Tübingen comments as follows: “To our surprise, the results do not show any support for an increased bite force—neither due to the skull’s rigidity nor caused by the rearranged jaw musculature.” However, the analyses reveal that the evolutionary innovations led to an optimized skull structure, which can withstand higher stress loads while requiring less bone material.
“We combined our new findings with the previous paleontological and anatomical knowledge, allowing us to develop a new scenario,” explains Werneburg. The key feature in this scenario is the close link between the evolution of the skull and the highly flexible neck. “We assume that the skull of modern turtles is the result of a complex process that has been taking place since the emergence of the shell.” On the one hand, the neck movement facilitates a general increase in the animal’s mobility, which counteracts its otherwise rigid body. On the other hand, the option of retracting the neck serves as an additional protective mechanism in dangerous situations.
Moreover, the modifications in the turtles’ skull may not only have led to an improved stress distribution but may also have paved the way for the evolution of new species. “The evolutionary potential for a novel skull architecture and longer, more flexible necks enabled the development of a larger diversity among turtles during and after the Jurassic period,” adds Werneburg in closing.
Reference:
Gabriel S. Ferreira et al. Feeding biomechanics suggests progressive correlation of skull architecture and neck evolution in turtles, Scientific Reports (2020). DOI: 10.1038/s41598-020-62179-5
Evolutionary history of ecological interactions between terrestrial arthropods and vascular plants
The interactions between the terrestrial arthropods and vascular plants comprise one of more complex and intriguing terrestrial ecosystems that have persisted from Early Devonian times until today. These interactions are diverse, with multiple species of arthropods, mainly insects, and host-plants interacting over a range of trophic levels through predation (i.e. herbivory), parasitism, and pollination. The features, intensity and diversity of these interactions are mainly influenced by climatic and environmental conditions. Galling represents the most biologically complex of all major arthropod–plant interactions, consisting of parasitic relationships, which are characterized by the endophytic insect-induced plant tissue damage that can occur on all major plant organs. The insect-induced galling damage consists of atypically enlarged plant structures, three-dimensional, conspicuous, generally of bilateral or radial symmetry and externally hardened, that offers to the encapsulated insect larvae a microclimate, nutrition, and protection from natural enemies. The insect galls affect usually the plants only locally, but in some instances can cause systemic effects.
The insect galls have a long evolutionary history and earliest fossil records are known from the Pennsylvanian strata. These earliest insect galls occurred on stems of arborescent ferns and calamitalean sphenopsids. Although insect galls have been well-documented in a wide range of host-plant species, about 80% of extant galls occur on leaves. The Pennsylvanian-age galls are very poorly known because they are rarely found and only occasionally reported in the fossil record.
Host ancient “horsetail” shows insect gall preserved in situ
The horsetails are plants with a very old historical lineage, with fossil record from the Late Devonian to the present day, existing in abundance in Portugal today. The new species hosted Annularia paisii shows an insect gall induced by parasitoid insects (popularly known as galling insects), which is an ichnospecies until now unknown for science that received a name of Paleogallus carpannularites. This shows the existence of complex insect-plant relationships 303 million years ago and reiterates the importance of the fossil record of the Portuguese Carboniferous. The patterns of herbivory of insects and other arthropods on horsetails are little known. In our paper, recently published in the International Journal of Plant Sciences, we addresses this subject, in which they document 315 million years of sphenophyte herbivory relationships by arthropod.
Ecological adaptation of Annularia paisii
The arrangement of the leaves of Annularia paisii appears anomalous for a species of Annularia. Its leaves are arranged in cup-shaped whorls, a typical characteristic of other calamitalean sphenopsid like fossil genus Asterophyllites. Several explanations can account for this condition. The leaves of Annularia paisii perhaps were retracted into a cup shape during their burial. Alternatively, the cup shape could have been an induced feature resulting from their sensitivity to sunlight or an external tactile stimulus similar to the modern sensitive plant, Mimosa pudica. Another possibility is a physiological reaction from an herbivorous insect, such as a gall antagonism. Annularia paisii is named in honor of the Portuguese paleobotanist João Pais (1949–2016) from Nova University in Lisbon (Portugal).
Reference:
Pedro Correia, Arden R. Bashforth, Zbynĕk Šimůnek, Christopher J. Cleal, Artur A. Sá, and Conrad C. Labandeira, “The History of Herbivory on Sphenophytes: A New Calamitalean with an Insect Gall from the Upper Pennsylvanian of Portugal and a Review of Arthropod Herbivory on an Ancient Lineage,” International Journal of Plant Sciences. DOI: 10.1086/707105
Flake of clear yellow amber from Anglesea, Victoria containing a new, beautifully preserved biting midge ca. 41 million years old. Credit: Enrique Peñalver.
The oldest known animals and plants preserved in amber from Southern Gondwana are reported in Scientific Reports this week. Gondwana, the supercontinent made up of South America, Africa, Madagascar, India, Antarctica and Australia, broke away from the Pangea supercontinent around 200 million years ago. The findings further our understanding of ecology in Australia and New Zealand during the Late Triassic to mid-Paleogene periods (230-40 million years ago).
Jeffrey Stilwell and colleagues studied more than 5,800 amber pieces from the Macquarie Harbour Formation in Western Tasmania, dating back to the early Eocene Epoch (~54-52 million years ago) and Anglesea Coal Measures in Victoria, Australia, from the late middle Eocene (42-40 million years ago). The authors report a rare “frozen behaviour” of two mating long-legged flies (Dolichopodidae). The specimens also include the oldest known fossil ants from Southern Gondwana and the first Australian fossils of ‘slender springtails’, a tiny, wingless hexapod. Other organisms preserved in the amber include a cluster of juvenile spiders, biting midges (Ceratopogonidae), two liverwort and two moss species.
The authors also studied deposits found at locations in southeastern Australia, Tasmania and New Zealand. These include the oldest reported amber from Southern Pangea dating back to 230 million years ago, 96-92 million year old deposits from forests near the South Pole and an intact fossil of an insect called a felt scale (Eriococcidae) from 54-52 million years ago.
The findings provide new insights into the ecology and evolution of Southern Gondwana and indicate that there may be a vast potential for future, similar finds in Australia and New Zealand.
Reference:
Amber from the Triassic to Paleogene of Australia and New Zealand as exceptional preservation of poorly known terrestrial ecosystems, Scientific Reports (2020). DOI: 10.1038/s41598-020-62252-z
Charlotte Pearson’s eyes scanned a palm-sized chunk of ancient tree. They settled on a ring that looked “unusually light,” and she made a note without giving it a second thought. Three years later, and armed with new methodology and technology, she discovered that the light ring might mark the year that the Thera volcano on the Greek island of Santorini erupted over the ancient Minoan civilization. The date of the eruption, which is one of the largest humanity has ever witnessed, has been debated for decades.
Pearson, a University of Arizona assistant professor of dendrochronology and anthropology, is lead author of a paper, published in the Proceedings of the National Academy of Sciences, in which she and her colleagues have used a new hybrid approach to assign calendar dates to a sequence of tree rings, which spans the period during which Thera erupted, to within one year of a calendar date. This allows them to present new evidence that could support an eruption date around 1560 B.C.
Filling the Gaps
“In every tree ring, you have this time capsule that you can unpack,” Pearson said.
Trees grow in accordance with the conditions of their local environment. Each year, trees produce a new layer of concentric growth, called a tree ring, which can record information about rainfall, temperature, wildfires, soil conditions and more. Trees can even record solar activity as it waxes and wanes.
When a sequence of rings from trees of various ages are overlapped and added together, they can span hundreds or thousands of years, providing insight about past climate conditions and context for concurrent civilizations.
“The longest chronology in the world stretches back 12,000 years. But in the Mediterranean, the problem is that we don’t have a full, continuous record going back to the time of Thera,” Pearson said. “We have recorded the last 2,000 years very well, but then there’s a gap. We have tree rings from earlier periods, but we don’t know exactly which dates the rings correspond to. This is what’s called a ‘floating chronology.'”
Filling this gap could help pin down the Thera eruption date and paint a climatic backdrop for the various civilizations that rose and fell during the Bronze and Iron ages, which together spanned between 5,000 and 2,500 years ago.
“Until you can put an exact year on events on a scale that makes sense to people—one year—it’s not quite as powerful,” Pearson said. “This study is really about taking (my co-author and tree ring lab research professor) Peter Kuniholm’s chronology that he’s put together over 45 years of work and dating it in a way not possible before. Most importantly, it is fixed in time, just as if we had filled our tree ring gap.”
A Hybrid Approach
Since the inception of the UArizona Laboratory of Tree-Ring Research in 1937, an assortment of tree ring samples from all over the world accumulated in less-than-ideal conditions beneath Arizona Stadium. But since the completion of the university’s upgraded Bryant Bannister Tree Ring Building in 2013, the curation team, led by Peter Brewer, has been relocating, organizing and preserving samples for future research.
“This is the collection that founded the field of tree ring research, and it’s by far the world’s largest,” Brewer said. “Researchers come from all over to use our collection.”
“It’s just crammed full of the remains of ancient forests and archaeological sites, which no longer exist, and it contains wood samples that were fundamental in the growth of the discipline of dendrochronology,” Pearson said.
The collection includes timbers from the Midas Mound Tumulus at Gordion in Turkey—a giant tomb of a man that was likely Midas’ father or grandfather. From timbers like these, Kuniholm has been building a tree ring chronology from the Mediterranean for nearly a half century. Together, Kuniholm’s record from the B.C. period spans over 2,000 years, including trees growing downwind of the Thera eruption, making it key to the team’s research.
Despite the length of this chronology, it remained undated. To pin it down, the team decided to try something new.
When cosmic rays from space enter the Earth’s atmosphere, neutrons collide with nitrogen atoms to create a radioactive version of carbon, called carbon-14, which spreads around the planet. All other life on Earth, including tree rings, pick up the carbon-14, and because tree-rings lock away a measurement of carbon-14 for each year that they grow, they hold patterns showing how it changed over time. These patterns of carbon-14 in tree rings around the world should match.
Pearson and her team used the patterns of carbon-14 captured in the Gordion tree rings to anchor the floating chronology to similar patterns from other calendar dated tree ring sequences.
“It’s a new way to anchor floating tree ring chronologies that makes use of the annual precision of tree rings,” Pearson said.
To validate their findings, the team turned to the calendar-dated rings of high-elevation bristlecone pines from western North America that lived at the same time as the Gordion.
“When there are large volcanic eruptions, it often scars bristlecone by freezing during the growing season, creating a frost ring,” said second author Matthew Salzer, research scientist at the tree ring laboratory. “Then we compared the dates of the frost rings with what was going on in the Mediterranean trees, which respond to volcanoes by growing wider rings. And it worked. It showed that the wide rings in the Mediterranean chronology occurred in the same years as the frost rings in the bristlecone. We took that to be confirmation that the dating was probably correct.”
The team then thought to use a new piece of technology in the lab called the X-ray fluorescence machine to scan the wood for chemical changes.
“We scanned the entire period across when Thera is known to have happened,” Pearson said, “and we detected a very slight depletion in calcium, right where I saw this lighter ring years ago.”
While it’s a slight fluctuation, it is significant and only occurs at one point in the years around 1560 B.C.
“We put that in the paper and tentatively suggest it’s a possible date for Thera,” Pearson said.
Something changed the chemistry of the environment in which the tree grew; acid deposition from a volcano is one possibility, wildfire is another, but because the date happens to coincide with other tree ring markers for a major eruption, Pearson she says it’s worthy of further exploration.
“I think to do good science you have to investigate everything and keep an open mind until sufficient data comes together,” Pearson said. “This is another little piece of the puzzle.”
Reference:
Charlotte Pearson el al., “Securing timelines in the ancient Mediterranean using multiproxy annual tree-ring data,” PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.1917445117
A seismogram of 2011 Tōhoku earthquake and tsunami recorded at Weston Observatory in Massachusetts, USA. Credit: Image from Wikimedia Commons.
The world’s most powerful earthquakes strike at subduction zones, areas where enormous amounts of stress build up as one tectonic plate dives beneath another. When suddenly released, this stress can cause devastating “megaquakes” like the 2011 Mw 9.0 Tohoku event, which killed nearly 16,000 people and crippled Japan’s Fukushima Dai-ichi Nuclear Power Plant. Now a study published in Geology suggests that sediments atop the downgoing slab can play a key role in determining the magnitude and location of these catastrophic events.
In this newly published study, a team led by Gou Fujie, a senior scientist at the Japan Agency for Marine-Earth Science and Technology, used a trio of geophysical methods to image the subducting sediments in the northeastern Japan arc, where the Tohoku event occurred. The findings suggest that variations caused by volcanic rocks intruded into these sediments can substantially influence the nature of subduction zone earthquakes.
“Our imaging shows that the enormous amount of slip that occurred during the 2011 Tohoku earthquake stopped in an area of thin sediments that are just starting to subduct,” says Fujie. “These results indicate that by disturbing local sediment layers, volcanic activity that occurred prior to subduction can affect the size and the distribution of interplate earthquakes after the layers have been subducted.”
Researchers first began to suspect that variations in subducting sediments could influence megaquakes after the 2011 Tohoku event, when international drilling in the northeastern Japan arc showed that giant amounts of slip during the earthquake occurred in a slippery, clay-rich layer located within the subducting sediments. To better understand the nature of the downgoing slab in this region, Fujie’s team combined several imaging techniques to paint a clearer picture of the subseafloor structure.
The researchers discovered there are what Fujie calls “remarkable regional variations” in the sediments atop the downgoing plate, even where the seafloor topography seems to be flat. There are places, he says, where the sediment layer appears to be extremely thin due to the presence of an ancient lava flow or other volcanic rocks. These volcanic intrusions have heavily disturbed, and in places thermally metamorphosed, the clay layer in which much of the seismic slip occurred.
Because the type of volcanism that caused sediment thinning in the northeastern Japan arc has also been found in many areas, says Fujie, the research suggests such thinning is ubiquitous—and that this type of volcanic activity has also affected other seismic events. “Regional variations in sediments atop descending oceanic plates appear to strongly influence devastating subduction zone earthquakes,” he concludes.
Reference:
Gou Fujie et al. Spatial variations of incoming sediments at the northeastern Japan arc and their implications for megathrust earthquakes, Geology (2020). DOI: 10.1130/G46757.1
The team’s experiments compared carbon’s compatibility with the silicates that comprise the Earth’s mantle (outer circle) to its compatibility with the iron that comprises the planet’s core (inner circle) while under conditions mimicking the Earth’s interior during its formative period. They found that more carbon would have stayed in the mantle than previously thought. Credit: Rebecca Fischer, Elizabeth Cottrell and Marion Le Voyer, Kanani Lee, and the late Erik Hauri.
Carbon is essential for life as we know it and plays a vital role in many of our planet’s geologic processes — not to mention the impact that carbon released by human activity has on the planet’s atmosphere and oceans. Despite this, the total amount of carbon on Earth remains a mystery, because much of it remains inaccessible in the planet’s depths.
New work published this week in Proceedings of the National Academy of Sciences reveals how carbon behaved during Earth’s violent formative period. The findings can help scientists understand how much carbon likely exists in the planet’s core and the contributions it could make to the chemical and dynamic activity occurring there — including to the convective motion powering the magnetic field that protects Earth from cosmic radiation.
Earth’s core is comprised mostly of iron and nickel, but its density indicates the presence of other lighter elements, such as carbon, silicon, oxygen, sulfur, or hydrogen. It’s been long suspected that there’s a tremendous reservoir of carbon hiding down there. But to attempt to quantify it, the research team used laboratory mimicry to understand how it got into the core in the first place.
The group was comprised of Harvard University’s Rebecca Fischer, the Smithsonian Institution’s Elizabeth Cottrell and Marion Le Voyer, both former Carnegie postdoctoral fellows, Yale University’s Kanani Lee, and Carnegie’s late Erik Hauri, the memory of whom the authors acknowledge.
“To understand present day Earth’s carbon content, we went back to our planet’s babyhood, when it accreted from material surrounding the young Sun and eventually separated into chemically distinct layers — core, mantle, and crust,” said Fischer. “We set out to determine how much carbon entered the core during these processes.”
This was accomplished by lab experiments that compared carbon’s compatibility with the silicates that comprise the mantle to its compatibility with the iron that comprises the core while under the extreme pressures and temperatures found deep inside the Earth during its formative period.
“We found that more carbon would have stayed in the mantle than we previously suspected,” explained Cottrell. “This means the core must contain significant amounts of other lighter elements, such as silicon or oxygen, both of which become more attracted to iron at high temperatures.”
Despite this surprising discovery, the majority of Earth’s total carbon inventory does likely exist down in the core. But it still makes up only a negligible component of the core’s overall composition.
“Overall, this important work improves our understanding of how Earth’s carbon was accumulated during the planetary formation process and sequestered into the mantle and core as they chemically differentiated,” concluded Richard Carlson, Director of Carnegie’s Earth and Planets Laboratory, where Hauri worked. “I only wish Erik was still with us to see the results published this week.”
This work was supported by a National Science Foundation postdoctoral fellowship.
Reference:
Rebecca A. Fischer, Elizabeth Cottrell, Erik Hauri, Kanani K. M. Lee, Marion Le Voyer. The carbon content of Earth and its core. Proceedings of the National Academy of Sciences, 2020; 201919930 DOI: 10.1073/pnas.1919930117
Formation pressure governs the generation, expulsion, migration, accumulation and preservation of petroleum. Fluid-rock interactions during diagenesis and mineralization are also affected by the formation pressure. Thus, investigating the formation paleo-pressure in sedimentary basins is an important aspect of research into the mechanisms and processes related to hydrocarbon accumulation, and it plays an increasingly important role in hydrocarbon exploration and prospective prediction.
Formation pressure occurs during the long-term evolution of basins, and is regulated by tectonism, deposition, diagenesis, fluid flow, geothermal field, and magmatic activity. Oil and gas exploration is increasingly directed at deep, ultra-deep and ancient strata which, however, have generally experienced multiple stages of tectonic movements. Reconstruction of formation paleo-pressure in these strata is not easy.
Various methods have been established for paleo-pressure reconstruction in sedimentary basins, including approaches based on basin modelling, fluid inclusion analysis, differential stress of rocks, transformation of clay minerals, acoustic transit time of mudstones, and seismic wave velocity. Each of these methods has advantages and limitations, but most can only determine the formation pressure in a certain geological period, rather than the whole pressure evolution process. Furthermore, some of these methods were established based on simple porosity evolution models, which are not applicable to reservoirs with complex fluid flows, intense tectonic activities, and abnormal porosity evolution paths.
Origins of abnormal pressures typically change during geological history. In this study, a new method is proposed for reconstructing the paleo-pressures in strata by integrating various paleo-pressure calculation methods according to the identification of the formation mechanism and the main factors responsible for controlling abnormal pressures. According to the geological background, quantitative analyses of the factors that might control overpressure were first conducted to clarify the contributions of each mechanism during different geological periods. Pressure evolution was reconstructed by fluid-compaction modelling with constraints imposed by paleo-pressures obtained from fluid inclusions or differential stress methods. Determining the mechanisms responsible for overpressures during geological history is the basic prerequisite for paleo-pressure research. Thus, quantitative studies were conducted of the contributions of disequilibrium compaction, gas charging, oil cracking, temperature reduction, and tectonic uplift and subsidence to overpressures.
Three case studies of paleo-pressure reconstruction were performed for the Sinian strata in the Sichuan Basin, Ordovician strata in the north uplift in the Tarim Basin and the Permian strata in the Sulige Gas Field in the Ordos Basin, where these three study sites are normally pressured, weakly over-pressured and abnormally low pressured at present, respectively.
The Sinian formation in the central Sichuan Basin is mainly normally pressured at present. Under the constraint of the trapping pressures due to fluid inclusions in three periods, which were calculated using PVTsim software, the evolution of pressure in the Dengying Formation was obtained by basin modelling with a fluid-compaction coupling model. Pressure in the Sinian Dengying Formation is due to a combination of hydrocarbon accumulation, oil cracking to form gas, and temperature reductions caused by tectonic uplift, where these different factors played dominant roles during diverse periods.
The Sulige Gas Field in the Ordos Basin is a typical gas field with an abnormally low pressure. A great temperature reduction from 165°C to 105°C occurred in the last 100 Ma. Regardless of gas dissipation, pressure would be decreased by 17.7-22% when temperature declined by 50-60°C. On the other hand, gases were dissipated 17-24 vol%, resulting in 23-32% decreases in the formation pressure. Based on fluid inclusion analysis and numerical modelling, weak overpressures occurred twice throughout the geological history, where the first overpressure was generated at 195 Ma, which was suspended by the uplift at 160 Ma before, overpressure was generated again after 140 Ma, where it was maximized in 98 Ma at a greatest depth of 4425.6 m and with a pressure coefficient value of 1.1. Subsequently, both the formation pressure and pressure coefficient decreased gradually due to uplift and denudation, and changed to an abnormally low pressure with a coefficient of 0.85 at present.
The fluid pressure during the critical period of tectonic compression can be quantitatively calculated using the differential stress method with calcite twins as a paleo-barometer. The paleo- pressure in the Ordovician Yinshan carbonate strata in the Shunnan Area of the Tarim Basin was reconstructed as a case study. The Shunnan Area was in a tectonic compression environment from the middle and late Caledonian to the Hercynian period, and the orientation of the principal stress changed from SW-NE to SE-NW. The paleo-stress ranged from 66.15 to 89.17 MPa, with an average of 82.06 MPa in the Caledonian, and ranged from 56.97 to 79.29 MPa, with an average value of 66.80 MPa in the Hercynian. The excess fluid pressure in the carbonate strata during tectonic compression deformation was calculated by the difference between realistic effective vertical stress and theoretical vertical stress. Combined with modelling results, a weak overpressure was developed in the Ordovician strata during the middle to late Caledonian period by the strong compression related to the Paleo-Kunlun Ocean subduction. The formation pressure gradually deceased to normal pressure because of strata uplift and stress field conversion. Another two phases of overpressure were formed at the end of the Permian and Neogene periods, originated from southeast-trending compression and gas filling, respectively.
Pressure analysis is the basis of fluid dynamic system analysis, which is significant for hydrocarbon migration and reservoir diagenesis. The development of effective paleo-pressure recovery methods for carbonate strata may be essential for addressing various problems in deep and ultra-deep layer pressure research.
Reference:
Nansheng Qiu et al, Quantitative reconstruction of formation paleo-pressure in sedimentary basins and case studies, Science China Earth Sciences (2020). DOI: 10.1007/s11430-019-9556-8
Photomicrographs showing anorthosites with ‘correct’ and ‘wrong’ proportions of chromite from the Bushveld Complex, South Africa. Credit: Wits University
Researchers at Wits University in Johannesburg, South Africa, have found the answer to an enigma that has had geologists scratching their heads for years.
The question is that of how certain magmatic rocks that are formed through crystallisation in magmatic chambers in the Earth’s crust, defy the norm, and contain minerals in random proportions.
Normally, magmatic rocks consist of some fixed proportions of various minerals. Geologists know, for instance, that a certain rock will have 90% of one mineral and 10% of another mineral.
However, there are some magmatic rocks that defy this norm and do not adhere to this general rule of thumb. These rocks, called non-cotectic rocks, contain minerals in completely random proportions.
One example is chromite-bearing anorthosite from the famous Bushveld Complex in South Africa. These rocks contain up to 15% to 20% of chromite, instead of only 1%, as would normally be expected.
“Traditionally, these rocks with a ‘wrong’ composition were attributed to either mechanical sorting of minerals that crystallised from a single magma or mechanical mixing of minerals formed from two or more different magmas,” says Professor Rais Latypov from the Wits School of Geosciences.
Seeing serious problems with both these approaches, Latypov and his colleague Dr. Sofya Chistyakova, also from the Wits School of Geosciences, found that there is actually a simple explanation to this question—and it has nothing to do with the mechanical sorting or mixing of minerals to produce these rocks.
Their research, published in the journal Geology, shows that an excess amount of some minerals contained in these rocks may originate in the feeder conduits along which the magmas are travelling from the deep-seated staging chambers towards Earth’s surface.
“While travelling up through the feeder channels, the magma gets into contact with cold sidewalls and starts crystallising, thereby producing more of the mineral(s) than what should be expected,” says Chistyakova.
The general principle of this approach can be extended to any magmatic rocks with ‘wrong’ proportions of minerals in both plutonic and volcanic environments of the Earth.
“It is possible that a clue to some other petrological problems of magmatic complexes should be searched for in the feeder conduits rather than in magma chambers themselves. This appealing approach holds great promise for igneous petrologists working with basaltic magma complexes,” says Latypov.
Reference:
R.M. Latypov et al, Origin of non-cotectic cumulates: A novel approach, Geology (2020). DOI: 10.1130/G47082.1
Photograph of the fossil sandgrouse Linxiavis inaquosus (left) with a fabricated-color image (right) of the bird’s skeleton based on CT scanning data Credit: IVPP
Researchers from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences have found a new species of sandgrouse in six to nine million-year-old rocks in Gansu Province in western China. The newly discovered species points to dry, arid habitats near the edge of the Tibetan Plateau as it rose to its current extreme altitude.
According to their study published in Frontiers in Ecology and Evolution on Mar. 31, the new species, named Linxiavis inaquosus, fills a nearly 20 million-year gap in the sandgrouse fossil record.
The fossil of the partial skeleton includes much of the body, such as the shoulder girdles, wishbone, bones from both wings, vertebrae, and part of a leg. Unfortunately, the head is missing.
“As the oldest fossil of a sandgrouse in Asia and the most complete fossil known from the group, the new skeleton provides a key link in expanding our understanding of the evolution of the sandgrouse living in China today, as well as the ecosystem associated with the Tibetan Plateau and the species that live only there,” said Dr. Li Zhiheng, first author of the study.
Sandgrouse are a group of 16 species of birds related to doves and pigeons that live in some of the most arid areas across Europe, Asia, and Africa. The association between sandgrouse and dry environments has helped scientists determine that the area next to the Tibetan Plateau was equally arid when Linxiavis inaquosus lived during the period known as the late Miocene.
“Most people would probably think of the Tibetan Plateau, with its high elevation, low oxygen levels, and harsh sun as one of the last places to be invaded by a group of animals. But in this case, our fossil suggests that sandgrouse might have quickly adapted to the dry, mountainous plateau millions of years ago,” said the coauthor Dr. Thomas A. Stidham.
Importantly, this fossil is from the time period known as the late Miocene when the Tibetan Plateau was continuing to rise rapidly in altitude and changing the climate of central Asia with an increase in aridity, along with a strong monsoon season.
This fossil was found at over 2,000 meters above sea level and within sight of Tibetan Plateau peaks that exceed 4,000 meters. That elevation is far greater than where all species of sandgrouse, except for the specialized Tibetan Sandgrouse, live today.
Despite the elevation and arid conditions, other fossils from the area show that the ecosystem was quite diverse. Dr. Stidham explains, “If you were on the edge of the Tibetan Plateau where our fossil is from six or seven million years ago, it would have looked quite like a nature documentary about the savannas in Africa, with the horizon filled with extinct relatives of hyenas, elephants, rhinos, pigs, antelopes, horses, ostriches, vultures, falcons, and of course now, sandgrouse.”
“We are discovering many fossil birds in this area by the Tibetan Plateau that help us to understand the relationships between the plateau, climate change, and biodiversity. We’re likely to keep uncovering more unusual and amazing bird fossils like this sandgrouse and the pheasant with a windpipe longer than its body that we reported a couple of years ago,” said Dr. Li.
Reference:
Zhiheng Li et al, Evidence of Late Miocene Peri-Tibetan Aridification From the Oldest Asian Species of Sandgrouse (Aves: Pteroclidae), Frontiers in Ecology and Evolution (2020). DOI: 10.3389/fevo.2020.00059
Image shows artwork of the Afrotapejara zouhrii. Credit: Megan Jacobs, Baylor University, Texas
You wait ages for a pterosaur and then four come along at once.
Hot on the heels of a recent paper discovering three new species of pterosaur, University of Portsmouth palaeobiologists have identified another new species—the first of its kind to be found on African soil.
Pterosaurs are the less well-known cousins of dinosaurs. They had adept flying ability—some as large as a fighter jet and others as small as a model aeroplane.
The new species belongs to a group of pterosaurs called tapejarids from the Cretaceous period. Tapejarids were small to medium-sized pterosaurs with wingspans perhaps as wide as four metres, most of which had large, broad crests sweeping up from the front of the skull.
They are well known in Brazil and China, and specimens have also been discovered in Europe, but this is the first time the flying reptile has been found in Africa.
It differs from the three recent species discovered as this one had no teeth—it was ‘edentulous’.
Professor David Martill, from the University’s School of the Environment, Geography and Geosciences, led the study. He said: “The study of Moroccan material shows that we are still far from having found all the paleontological treasures of North Africa. Even fragmentary fossils, like the jaw piece of the new pterosaur, can give us important information about the biodiversity of the past.”
Ph.D. student Roy Smith, one of the co-authors, said: “I feel very privileged to be part of such an exciting discovery. Working in the Sahara was a life-changing experience, and discovering a new species of pterosaur is the icing on the cake.”
The new pterosaur has been named Afrotapejara zouhrii to honour the Moroccan palaeontologist Professor Samir Zouhri. Originally a mammal specialist, Zouhri also contributed to several discoveries of prehistoric reptiles in Morocco, including dinosaurs and pterosaurs.
Professor Martill said: “The opportunity to illuminate the diversity of pterosaurs in Africa while honouring a colleague does not happen every day.”
The research team included Dr. David Unwin from the University of Leicester and Dr. Nizar Ibrahim from the University of Detroit Mercy.
Palaeontologist Dr. Ibrahim, said: “Samir Zouhri has played an important role in the development of Moroccan palaeontology, not only through his publications, but also because he organised scientific conferences in Morocco and edited an entire volume for the Geological Society of France on the subject of vertebrate palaeontology in Morocco.”
The fossil material is part of the collections of the Faculty of Sciences Aïn Chock, Casablanca Hassan II University and the paper was published in Cretaceous Research.
Reference:
David M. Martill et al, A new tapejarid (Pterosauria, Azhdarchoidea) from the mid-Cretaceous Kem Kem beds of Takmout, southern Morocco, Cretaceous Research (2020). DOI: 10.1016/j.cretres.2020.104424
A new feathered dinosaur that lived in New Mexico 67 million years ago is one of the last known surviving raptor species, according to a new publication in the journal Scientific Reports. Dineobellator notohesperus adds to scientists’ understanding of the paleo-biodiversity of the American Southwest, offering a clearer picture of what life was like in this region near the end of the reign of the dinosaurs. Credit: Sergey Krasovskiy
A new feathered dinosaur that lived in New Mexico 67 million years ago is one of the last known surviving raptor species, according to a new publication in the journal Scientific Reports.
Dineobellator notohesperus adds to scientists’ understanding of the paleo-biodiversity of the American Southwest, offering a clearer picture of what life was like in this region near the end of the reign of the dinosaurs.
Steven Jasinski, who recently completed his Ph.D. in Penn’s Department of Earth and Environmental Sciences in the School of Arts and Sciences, led the work to describe the new species, collaborating with doctoral advisor Peter Dodson of the School of Veterinary Medicine and Penn Arts and Sciences and as well as Robert Sullivan of the New Mexico Museum of Natural History and Science in Albuquerque.
In 2008, Sullivan found fossils of the new species in Cretaceous rocks of the San Juan Basin, New Mexico. He, along with his field team of Jasinski and James Nikas, collected the specimen on U.S. federal land under a permit issued by the Bureau of Land Management. The entire specimen was recovered over four field seasons. Jasinski and his coauthors gave the species its official name, Dineobellator notohesperus, which means “Navajo warrior from the Southwest,” in honor of the people who today live in the same region where this dinosaur once dwelled.
Dineobellator, as well as its Asian cousin Velociraptor, belong to a group of dinosaurs known as the dromaeosaurids. Members of this group are commonly referred to as “raptor” dinosaurs, thanks to movies such as “Jurassic Park” and “Jurassic World.” But unlike the terrifying beasts depicted in film, Dineobellator stood only about 3.5 feet (about 1 meter) at the hip and was 6 to 7 feet (about 2 meters) long — much smaller than its Hollywood counterparts.
Raptor dinosaurs are generally small, lightly built predators. Consequently, their remains are rare, particularly from the southwestern United States and Mexico. “While dromaeosaurids are better known from places like the northern United States, Canada, and Asia, little is known of the group farther south in North America,” says Jasinski.
While not all of the bones of this dinosaur were recovered, bones from the forearm have quill nobs — small bumps on the surface where feathers would be anchored by ligaments — an indication that Dineobellator bore feathers in life, similar to those inferred for Velociraptor.
Features of the animal’s forelimbs, including enlarged areas of the claws, suggest this dinosaur could strongly flex its arms and hands. This ability may have been useful for holding on to prey — using its hands for smaller animals such as birds and lizards, or perhaps its arms and feet for larger species such as other dinosaurs.
Its tail also possessed unique characteristics. While most raptors’ tails were straight and stiffened with rod-like structures, Dineobellator’s tail was rather flexible at its base, allowing the rest of the tail to remain stiff and act like a rudder.
“Think of what happens with a cat’s tail as it is running,” says Jasinski. “While the tail itself remains straight, it is also whipping around constantly as the animal is changing direction. A stiff tail that is highly mobile at its base allows for increased agility and changes in direction, and potentially aided Dineobellator in pursuing prey, especially in more open habitats.”
This new dinosaur provides a clearer picture of the biology of North American dromaeosaurid dinosaurs, especially concerning the distribution of feathers among its members.
“As we find evidence of more members possessing feathers, we believe it is likely that all the dromaeosaurids had feathers,” says Jasinski. The discovery also hints at some of the predatory habits of a group of iconic meat-eating dinosaurs that lived just before the extinction event that killed off all the dinosaurs that weren’t birds.
Jasinski plans to continue his field research in New Mexico with the hope of finding more fossils.
“It was with a lot of searching and a bit of luck that this dinosaur was found weathering out of a small hillside,” he says. “We do so much hiking and it is easy to overlook something or simply walk on the wrong side of a hill and miss something. We hope that the more we search, the better chance we have of finding more of Dineobellator or the other dinosaurs it lived alongside.”
Reference:
Steven E. Jasinski, Robert M. Sullivan, Peter Dodson. New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous. Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-61480-7
Texas and New Mexico each have a good range of mineral specimens to be found from fluorite, quartz, opals, barite, agates, chalcedony and more. In particular, Texas has a great range of fossil specimens that you can find, too. Some states offer many pay-to-dig incentives.
What minerals can be found in Texas?
In the Central Texas region of Llano is where topaz, quartz crystals, agate, onyx, pyrite, feldspar crystals, mica, garnet, Llanonite (only present in Llano, TX), gold, fluorite, hematite, blue quartz, smoky quartz, platinum, tourmaline, opal species and many more can be present in the Llano basin.
What minerals can be found in New Mexico?
New Mexico is a popular state for searching for a range of rocks, minerals, and gems. There is an array of numerous styles that can be mined here, some of which are pretty good.
Few of the most highly desired minerals that you can find in the state of New Mexico. Turquoise, Opal, Amethyst, Jasper, Red Beryl, Peridot & Azurite
Public Gem Mines in Texas
Mineral Wells Fossil Park
Mineral Wells Fossil Park provides the fossil enthusiast, paleontologist, and student an excellent opportunity to see and collect well preserved “Pennsylvanian Period” fossils with ease and abundance. These fossils have been dated to be just over 300 million years old. Yes, you read correctly, you may collect and take fossils out of the park – for personal use only. See the park rules for more information.
The park as it exists today is a result of 20 years of erosion of the old City of Mineral Wells landfill’s borrow pit, which was closed in the early 1990s. The erosion of the borrow pit has revealed fossils documenting ancient sea species of crinoids (sea lilies), echinoids (urchins), brachiopods, pelecypods (clams and oysters), bryozoans, corals, trilobites (arthropods), plants and even primitive sharks.
In recent years, the borrow pit has become a mecca for the avid fossil hunter, the amateur and professional paleontologist, and various fossil, paleontological, gem and mineral groups and societies in Texas and the surrounding states.
What Can I Find in Mineral Wells Fossil Park?
The most common fossil found at Mineral Wells Fossil Park are the stalks of crinoids (sea lilies). While crinoids may look like weird plants, they are actually animals. There are likely dozens of species found here, each with their own design and ornamentation. Some even have spikes.
Seaquist Family Ranch
In 1887, Rev. Thomas A. Broad began constructing a handsome, two-story sandstone house north of Mason’s courthouse square on Comanche Creek. The house was later purchased in 1891 by Edward M. Reynolds, a banker from New York, who hired the German architect Richard Grosse to remodel and enlarge the house. In 1919, the property was sold to Swedish immigrant Oscar Seaquist, after which the family made several improvements to the house. Oscar Seaquist died in 1933, leaving his widow, Ada, to care for the mansion until her death in 1972.
The Seaquists’ son and daughter-in-law, Garner and Clara Seaquist, began the first major refurbishment of the house in 1972. Work was completed in the summer of 1973 and for the first time the mansion was opened to the public for tours. It received a Texas state historical marker in 1974 and is listed on the National Register of Historic Places. The Seaquist House Foundation purchased the house in January of 2015 and continues to restore the property.
In Texas the Seaquist Family Ranch is topaz Hunting’s most famous spot. Like the other privately owned places that do not permit public collecting, Seaquist Family Ranch is available to anyone, so you can dig up so gather as many jewels as you may like. Topaz is the most precious gem found here but exquisite quartz as well as chalcedony, jasper and agate can also be found here. The spring rain will rush the work, wiping the top dirt away and unveiling fresh gems.
Bar M Ranch Services
At Bar M Ranch, guests are invited to search Honey Creek and its tributaries for topaz. Blue Topaz is the state gem of Texas—naturally occurring topaz of this variety is quite rare. Mason County, located in the heart of Texas, is the best place in the state for hunters to find the colorless and light blue varieties. As there is no commercial mining of topaz in our area, Bar M Ranch offers everyone the opportunity to search for (and keep, of course!) the gem.
Teri Smith Rock Hunts
To beginner rockhounds who are interested in hiring a guide to help them discover the isolated mineral and fossil hunting areas of Texas, this is a rare opportunity. Some of his favorite locations include trips for agate and other collectible rocks to some of the Texas ‘ famous rockhounds.
Such supervised excursions encourage novices and seasoned rockhounds alike to find a wide range of minerals. One of the best aspects about the Teri Smith Rock Hunts is the access provided to certain unique Texas ranches which some have not yet looked for. The chances of discovering mineral quality specimens are very good.
Public Gem Mines in New Mexico
Desert Rose Mine
This mine is located on Highway 380 approximately three miles west of Bingham, next to the Blanchard Rock Shop in Bingham, New Mexico. When you want to find minerals of high quality than this is one of the finest pay-to-dig mines you can visit.
Good tabular barite crystals and cubic fluorite specimens can be found, as well as galena crystals and other wonderful minerals. When you wish your loved ones to collect ready gemstones as presents then you can buy them in the adjacent Blanchard Rock Store.
Rockhound State Park
Rockhound State Park is a state park of New Mexico, United States, located 7 miles (11 km) southeast of Deming. It is named for the abundance of minerals in the area, and visitors can search for quartz crystals, geodes, jasper, perlite, and many other minerals. The park is located in the Little Florida Mountains, a range of low mountains that have become sky islands due to the arid desert between the peaks.
It is a free collection place, where you can visit in the Little Florida Mountains. What makes this place so unique is that it’s one of the few state parks in the nation that has been expressly built for rock collectors. Several kinds of collectable gemstones can be found from quartz, agates, chalcedony, and opals. Rockhounds can carry up to 15 pounds of rocks a day, and it’s not costing you money.
Kelly Mine
Kelly Mine is a disused metalliferous mine located on Dartmoor’s eastern slope near Lustleigh village in Devon, England. This was active intermittently from the 1790s until 1951. It is one of some ten mines and two or three trials within the triangle created by the towns of Bovey Tracey and Moretonhampstead and the village of Hennock, which worked micaceous haematite deposits, known as “shiny rock.’ The mine is the focus of a volunteer restoration effort since 1984.
A mining lease dating back to the 1790s marks the first mining record on this site, and some activity may have lasted until the early 1870s. The mine reopened in 1879 and produced 324 tons of haematite from then until 1891—a comparatively small amount. From 1892 until 1900 the mine was closed when it restarted under the Scottish Silvoid Company which operated it until 1917 when it was taken over by Ferrubron, who also operated the nearby Great Rock Mine. Ferrubron worked the mine until 1946, when work on the property ceased. The Pepperdon Mining company opened a level for the extraction of ore near Kelly Mining for a year or two from 1950, and the washing plant at Kelly was used for the initial treatment of this ore.
The mine never employed a large number of people; in the fifty years to 1938 it had an average of six workers, and rarely more than ten.
A 3D laser scan of an Ikaria wariootia impression. (Droser Lab/UCR)
A team led by UC Riverside geologists has discovered the first ancestor on the family tree that contains most familiar animals today, including humans.
The tiny, wormlike creature, named Ikaria wariootia, is the earliest bilaterian, or organism with a front and back, two symmetrical sides, and openings at either end connected by a gut. The paper is published today in Proceedings of the National Academy of Sciences.
The earliest multicellular organisms, such as sponges and algal mats, had variable shapes. Collectively known as the Ediacaran Biota, this group contains the oldest fossils of complex, multicellular organisms. However, most of these are not directly related to animals around today, including lily pad-shaped creatures known as Dickinsonia that lack basic features of most animals, such as a mouth or gut.
The development of bilateral symmetry was a critical step in the evolution of animal life, giving organisms the ability to move purposefully and a common, yet successful way to organize their bodies. A multitude of animals, from worms to insects to dinosaurs to humans, are organized around this same basic bilaterian body plan.
Evolutionary biologists studying the genetics of modern animals predicted the oldest ancestor of all bilaterians would have been simple and small, with rudimentary sensory organs. Preserving and identifying the fossilized remains of such an animal was thought to be difficult, if not impossible.
For 15 years, scientists agreed that fossilized burrows found in 555 million-year-old Ediacaran Period deposits in Nilpena, South Australia, were made by bilaterians. But there was no sign of the creature that made the burrows, leaving scientists with nothing but speculation.
Scott Evans, a recent doctoral graduate from UC Riverside; and Mary Droser, a professor of geology, noticed miniscule, oval impressions near some of these burrows. With funding from a NASA exobiology grant, they used a three-dimensional laser scanner that revealed the regular, consistent shape of a cylindrical body with a distinct head and tail and faintly grooved musculature. The animal ranged between 2-7 millimeters long and about 1-2.5 millimeters wide, with the largest the size and shape of a grain of rice — just the right size to have made the burrows.
“We thought these animals should have existed during this interval, but always understood they would be difficult to recognize,” Evans said. “Once we had the 3D scans, we knew that we had made an important discovery.”
The researchers, who include Ian Hughes of UC San Diego and James Gehling of the South Australia Museum, describe Ikaria wariootia, named to acknowledge the original custodians of the land. The genus name comes from Ikara, which means “meeting place” in the Adnyamathanha language. It’s the Adnyamathanha name for a grouping of mountains known in English as Wilpena Pound. The species name comes from Warioota Creek, which runs from the Flinders Ranges to Nilpena Station.
“Burrows of Ikaria occur lower than anything else. It’s the oldest fossil we get with this type of complexity,” Droser said. “Dickinsonia and other big things were probably evolutionary dead ends. We knew that we also had lots of little things and thought these might have been the early bilaterians that we were looking for.”
In spite of its relatively simple shape, Ikaria was complex compared to other fossils from this period. It burrowed in thin layers of well-oxygenated sand on the ocean floor in search of organic matter, indicating rudimentary sensory abilities. The depth and curvature of Ikaria represent clearly distinct front and rear ends, supporting the directed movement found in the burrows.
The burrows also preserve crosswise, “V”-shaped ridges, suggesting Ikaria moved by contracting muscles across its body like a worm, known as peristaltic locomotion. Evidence of sediment displacement in the burrows and signs the organism fed on buried organic matter reveal Ikaria probably had a mouth, anus, and gut.
“This is what evolutionary biologists predicted,” Droser said. “It’s really exciting that what we have found lines up so neatly with their prediction.”
Reference:
Scott D. Evans, Ian V. Hughes, James G. Gehling, and Mary L. Droser. Discovery of the oldest bilaterian from the Ediacaran of South Australia. PNAS, March 23, 2020 DOI: 10.1073/pnas.2001045117
Example coprolites from Rancho La Brea (A) prior to asphalt removal with surrounding sediments, (B) showing intact pellets with plant material, (C) isolated, cleaned pellets. Figure 2, from: Mychajliw et al. 2020. Exceptionally preserved asphaltic coprolites expand the spatiotemporal range of a North American paleoecological proxy. Credit: Carrie Howard
While Rancho La Brea, commonly known as the La Brea Tar Pits, is famous for its thousands of bones of large extinct mammals, big insights are coming from small fossils, thanks to new excavation and chemical techniques.
Today, a team of researchers from La Brea Tar Pits, the University of Oklahoma and the University of California Irvine report the first coprolites — or fossil feces — ever discovered in an asphaltic — or tar pit — context. These hundreds of fossilized rodent pellets were found during the excavation of a parking garage for the Los Angeles County Museum of Art in Hancock Park in 2016, which had also yielded the more traditional La Brea fossils, such as extinct mammoths, dire wolves and saber-toothed cats.
Alexis Mychajliw, a postdoctoral research associate at OU, is the lead author of the study. The details of the research team’s findings were published today in Scientific Reports.
“It’s incredible that after more than a century of excavation and study, we are still unearthing new types of fossils from La Brea’s treasure trove of deposits,” said Emily Lindsey, assistant curator at La Brea Tar Pits. “These tiny finds may lead to big discoveries about the climate and ecosystems of Ice Age Los Angeles.”
Researchers were skeptical at first, given the abundance of urban rats in the area.
“We noted the occasional rodent fecal pellet in the processed matrix before, but it was easy to explain it away as modern contamination,” said Laura Tewksbury, senior preparator at La Brea Tar Pits.
But, with more and more pellets appearing encased in asphalt, Tewksbury recalled, “We stared at the sheer number of pellets in silence for a minute, before looking at each other and stating, ‘There’s just no way that much is contamination.'”
Indeed, radiocarbon dates generated at UC Irvine would confirm the pellets were ~50,000 years old.
Rancho La Brea has been associated with the image of big animals getting stuck in “tar pits,” or shallow, sticky asphalt pools, with carnivores attracted en masse by struggling herbivore prey. But these coprolites tell a new story of how fossils can be preserved at Rancho La Brea.
“The intact nature and density of the fossils require a taphonomic explanation other than entrapment. The preservation is more likely the result of an asphalt seep overtaking an existing rodent nest,” noted Karin Rice, preparator at La Brea Tar Pits.
Using a suite of cutting-edge tools, including stable isotope analysis and scanning electron microscopy, the researchers demonstrated that the fecal pellets were associated with beautifully preserved twigs, leaves, and seeds, apparently as part of an intact nest made by a woodrat. Woodrats — also known as packrats — are well-known in the paleontological community for their hoarding behavior that produces massive nests that can be preserved for thousands of years. Slices of plant material from these nests, in turn, represent snapshots of vegetation and climate conditions of the past.
“This nest provides an unparalleled view of what was beneath the feet of Rancho La Brea’s famous megafauna,” Mychajliw said. “And to me, it emphasizes the importance of studying small mammals, too. Woodrats survived the Ice Age and still build nests in local urban green spaces like Griffith Park! By studying these nests, we have a direct line from the past to the present through which to trace human impacts on Los Angeles’ nature over time.”
Reference:
Alexis M. Mychajliw, Karin A. Rice, Laura R. Tewksbury, John R. Southon, Emily L. Lindsey. Exceptionally preserved asphaltic coprolites expand the spatiotemporal range of a North American paleoecological proxy. Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-61996-y
Dr Daniel Field holding a replica version of the ‘Wonderchicken’ skull
The oldest fossil of a modern bird yet found, dating from the age of dinosaurs, has been identified by an international team of palaeontologists.
The spectacular fossil, affectionately nicknamed the ‘Wonderchicken’, includes a nearly complete skull, hidden inside nondescript pieces of rock, and dates from less than one million years before the asteroid impact which eliminated all large dinosaurs.
Writing in the journal Nature, the team, led by the University of Cambridge, believe the new fossil helps clarify why birds survived the mass extinction event at the end of the Cretaceous period, while the giant dinosaurs did not.
Detailed analysis of the skull shows that it combines many features common to modern chicken- and duck-like birds, suggesting that the ‘Wonderchicken’ is close to the last common ancestor of modern chickens and ducks. The fossil was found in a limestone quarry near the Belgian-Dutch border, making it the first modern bird from the age of dinosaurs found in the northern hemisphere.
The fossil doesn’t look like much on first glance, with only a few small leg bone fragments poking out from a piece of rock the size of a deck of cards. Even those small bones attracted the researchers’ interest, since bird fossils from this point in Earth’s history are so rare.
Using high-resolution X-ray CT scans, the researchers peered through the rock to see what was lying beneath the surface. What they saw, just one millimetre beneath the rock, was the find of a lifetime: a nearly complete 66.7-million-year-old bird skull.
“The moment I first saw what was beneath the rock was the most exciting moment of my scientific career,” said Dr Daniel Field from Cambridge’s Department of Earth Sciences, who led the research. “This is one of the best-preserved fossil bird skulls of any age, from anywhere in the world. We almost had to pinch ourselves when we saw it, knowing that it was from such an important time in Earth’s history.
“The ability to CT scan fossils, like we can at the Cambridge Biotomography Centre, has completely transformed how we study palaeontology in the 21st century.”
“Finding the skull blew my mind,” said co-author Juan Benito, also from Cambridge, who was CT scanning the fossils with Field when the skull was discovered. “Without these cutting-edge scans, we never would have known that we were holding the oldest modern bird skull in the world.”
The skull, despite its age, is clearly recognisable as a modern bird. It combines many features common to the group that includes living chickens and ducks — a group called Galloanserae. Field describes the skull as a kind of ‘mash-up’ of a chicken and a duck.
“The origins of living bird diversity are shrouded in mystery — other than knowing that modern birds arose at some point towards the end of the age of dinosaurs, we have very little fossil evidence of them until after the asteroid hit,” said co-author Albert Chen, a PhD student based at Cambridge. “This fossil provides our earliest direct glimpse of what modern birds were like during the initial stages of their evolutionary history.”
While the fossil is colloquially known as the Wonderchicken, the researchers have given it the slightly more elegant name of Asteriornis, in reference to Asteria, the Greek Titan goddess of falling stars.
“We thought it was an appropriate name for a creature that lived just before the end-Cretaceous asteroid impact,” said co-author Dr Daniel Ksepka from the Bruce Museum in Greenwich, Connecticut. “In Greek mythology, Asteria transforms herself into a quail, and we believe Asteriornis was close to the common ancestor that today includes quails, as well as chickens and ducks.”
The fact that Asteriornis was found in Europe is another thing which makes it so extraordinary. “The late Cretaceous fossil record of birds from Europe is extremely sparse,” said co-author Dr John Jagt from the Natuurhistorische Museum Maastricht in the Netherlands. “The discovery of Asteriornis provides some of the first evidence that Europe was a key area in the early evolutionary history of modern birds.”
“This fossil tells us that early on, at least some modern birds were fairly small-bodied, ground-dwelling birds that lived near the seashore,” said Field. “Asteriornis now gives us a search image for future fossil discoveries — hopefully it ushers in a new era of fossil finds that help clarify how, when and where modern birds first evolved.”
The announcement of the Wonderchicken find coincides with a new exhibit at Cambridge’s Sedgwick Museum of Earth Sciences, where visitors can learn more about Asteriornis and see the fossil up close. “Dawn of the Wonderchicken” runs from 19 March to 15 June. Admission is free.
Dr Daniel Field is funded by a UKRI Future Leaders Fellowship. He is a University Lecturer in the Department of Earth Sciences at the University of Cambridge, and a Fellow of Christ’s College Cambridge.
Reference:
Daniel J. Field, Juan Benito, Albert Chen, John W. M. Jagt, Daniel T. Ksepka. Late Cretaceous neornithine from Europe illuminates the origins of crown birds. Nature, 2020; 579 (7799): 397 DOI: 10.1038/s41586-020-2096-0
Note: The above post is reprinted from materials provided by University of Cambridge. Original written by Sarah Collins. The original story is licensed under a Creative Commons License.
Researchers dated ash deposits from this hill, called a koppie in South Africa. The lower part of koppie Loskop exposes strata from before the end-Permian extinction (Palingkloof Member of the Balfour Formation), while the upper part contains layers deposited after the extinction (Katberg Formation). Credit: John Geissman
The mass extinction at the end of the Permian Period 252 million years ago—one of the great turnovers of life on Earth—appears to have played out differently and at different times on land and in the sea, according to newly redated fossils beds from South Africa and Australia.
New ages for fossilized vertebrates that lived just after the demise of the fauna that dominated the late Permian show that the ecosystem changes began hundreds of thousands of years earlier on land than in the sea, eventually resulting in the demise of up to 70% of terrestrial vertebrate species. The later marine extinction, in which nearly 95% of ocean species disappeared, may have occurred over the time span of tens of thousands of years.
Though most scientists believe that a series of volcanic eruptions, occurring in large pulses over a period of a million years in what is now Siberia, were the primary cause of the end-Permian extinction, the lag between the land extinction in the Southern Hemisphere and the marine extinction in the Northern Hemisphere suggests different immediate causes.
“Most people thought that the terrestrial collapse started at the same time as the marine collapse, and that it happened at the same time in the Southern Hemisphere and in the Northern Hemisphere,” said paleobotanist Cindy Looy, University of California, Berkeley, associate professor of integrative biology. “The fact that the big changes were not synchronous in the Northern and Southern hemispheres has a big effect on hypotheses for what caused the extinction. An extinction in the ocean does not, per se, have to have the same cause or mechanism as an extinction that happened on land.”
Did loss of ozone layer contribute to extinction?
Members of Looy’s lab have conducted experiments on living plants to determine whether a collapse of Earth’s protective ozone layer may have irradiated and wiped out plant species. Other global changes—a warming climate, a rise in carbon dioxide in the atmosphere and an increase in ocean acidification—also occurred around the end of the Permian period and the beginning of the Triassic and likely contributed.
On land, the end-Permian extinction of vertebrates is best documented in Gondwana, the southern half of the supercontinent known as Pangea that eventually separated into the continents we know today as Antarctica, Africa, South America and Australia. There, in the South African Karoo Basin, populations of large herbivores, or plant eaters, shifted from the Daptocephalus assemblage to the Lystrosaurus assemblage. These groups are now extinct.
In the ocean, the extinction is best documented in the Northern Hemisphere, in particular by Chinese fossils. The end-Permian extinction is perhaps best associated with the demise of trilobites.
To improve on previous dates for the land extinction, an international team of scientists, including Looy, conducted uranium-lead dating of zircon crystals in a well-preserved volcanic ash deposit from the Karoo Basin. Looy, who is also a curator of paleobotany at the campus’s Museum of Paleontology and curator of gymnosperms at the University and Jepson Herbaria, confirmed that sediments from several meters above the dated layer were devoid of Glossopteris pollen, evidence that these seed ferns, which used to dominate late Permian Gondwanan floras, became extinct around that time.
At 252.24 million years old, the zircons—microscopic silicate crystals that form in rising magma inside volcanoes and are spewed into the atmosphere during eruptions—are 300,000 years older than dates obtained for the confirmed Permian-Triassic (P-T) boundary in China. This means that the sediment layer assumed to contain the P-T boundary in South Africa was actually at least 300,000 years too old.
Dates for an ash deposit in Australia, just above the layers that document the initial plant extinction, similarly came in almost 400,000 years older than thought. That work was published in January by Christopher Fielding and colleagues at the University of Nebraska in Lincoln.
“The Karoo Basin is the poster child for the end-Permian vertebrate turnover, but until recently, it was not well-dated,” Looy said. “Our new zircon date shows that the base of the Lystrosaurus zone predates the marine extinction with several hundred thousand years, similar to the pattern in Australia. This means that both the floral and faunal turnover in Gondwana is out of sync with the Northern Hemisphere marine biotic crisis.
“For some years now, we have known that—in contrast to the marine mass extinction—the pulses of disturbance of life on land continued deep into the Triassic Period. But that the start of the terrestrial turnover happened so long before the marine extinction was a surprise.”
In their paper, Looy and an international team of colleagues concluded “that greater consideration should be given to a more gradual, complex, and nuanced transition of terrestrial ecosystems during the Changhsingian (the last part of the Permian) and, possibly, the early Triassic.”
Looy and colleagues published their findings March 19 in the open access journal Nature Communications.
Reference:
Robert A. Gastaldo et al. The base of the Lystrosaurus Assemblage Zone, Karoo Basin, predates the end-Permian marine extinction, Nature Communications (2020). DOI: 10.1038/s41467-020-15243-7
The world’s largest piece of rough tanzanite has been found at a mine in northern Tanzania in 2005, well over six pounds.
The discovery was made about 885 feet underground at Bravo Shaft of TanzaniteOne Ltd., the southernmost shaft of the world’s leading tanzanite miner and marketer. Weighing in at cts 16.839. (Well over six pounds) and measuring 8.6 inchesx 3.15 inchesx 2.8 inches, the rugged tanzanite piece is remarkable in size and shape and is the world’s largest single piece of tanzanite ever mined, said the company.
The company named the piece “The Mawenzi” after Kilimanjaro’s second highest peak. “We were reluctant to name it Uhuru, after Kilimanjaro’s highest peak, on the off chance that a larger piece is ever found,” said Ian Harebottle, TanzaniteOne’s president and COO
No value was put on stone. TanzaniteOne said it plans to examine and evaluate the piece before any final decision on the potential cutting and polishing from this crystal of individual tanzanite gems is made. The business is considering before cutting and polishing putting The Mawenzi on display.
Ami Mpungwe, TanzaniteOne’s deputy chairman said the find is comparable to what the Cullinan Diamond is to the diamond industry and that the stone will be cut and polished in Tanzania.
“It is only fitting that The Mawenzi is cut and polished here in Tanzania,” Mpungwe said. “We expect to produce some truly exquisite gems from it, some of which we will put on display at Tanzania’s National Museum.”
What is Tanzanite?
Tanzanite is the mineral zoisite (a calcium aluminum hydroxyl sorosilicate) blue and violet type caused by small amounts of vanadium belonging to the group of epidotes. Tanzanite is found only in Tanzania, in a very small mining area (about 7 km (4.3 mi) long and 2 km (1.2 mi) wide) close to the Mirerani Hills.
Tanzanite is known for its remarkably strong trichroism, appearing in turn blue, violet and burgundy depending on the orientation of the crystal. When viewed under different lighting conditions tanzanite can also appear differently. When exposed to fluorescent light the blues become more visible, and when viewed under incandescent lighting, the violet hues can be readily seen. A reddish brown to clear is colored in its rough state tanzanite, and it needs heat treatment to dissolve the brownish “veil” to bring out the stone’s blue violet.
The gemstone was given the name ‘tanzanite’ by Tiffany & Co. after Tanzania, the country in which it was discovered. The scientific name of “blue-violet zoisite” was not thought to be consumer friendly enough by Tiffany’s marketing department, who introduced it to the market in 1968. In 2002, the American Gem Trade Association chose tanzanite as a December birthstone, the first change to their birthstone list since 1912.
This mural was originally made for a recent Royal Ontario Museum exhibit about a fossil ankylosaur named Zuul crurivastator. That fossil is found within a couple of meters stratigraphically/temporally of the site described in this paper. The last author on the study, David Evans, is the dinosaur curator at the Royal Ontario Museum and was also involved in the description of Zuul and design of that exhibit. Credit: Danielle Dufault, Royal Ontario Museum.
A topic of considerable interest to paleontologists is how dinosaur-dominated ecosystems were structured, how dinosaurs and co-occurring animals were distributed across the landscape, how they interacted with one another, and how these systems compared to ecosystems today. In the Late Cretaceous (~100-66 million years ago), North America was bisected into western and eastern landmasses by a shallow inland sea. The western landmass (Laramidia) contained a relatively thin stretch of land running north-south, which was bordered by that inland sea to the east and the rising Rocky Mountains to the west. Along this ancient landscape of warm and wet coastal plains comes an extremely rich fossil record of dinosaurs and other extinct animals.
Yet, from this record, an unexpected pattern has been identified: Most individual basins preserve an abundant and diverse assemblage of dinosaur species, often with multiple groups of co-occurring large (moose- to elephant-sized) herbivorous species, yet few individual species occur across multiple putatively contemporaneous geological formations (despite them often being less than a few hundred kilometers apart). This is in fairly stark contrast to the pattern seen in modern terrestrial mammal communities, where large-bodied species often have very extensive, often continent-spanning ranges. It has therefore been suggested that dinosaurs (and specifically large herbivorous dinosaurs) were particularly sensitive to environmental differences over relatively small geographic distances (particularly with respect to distance from sea level), and may have even segregated their use of the landscape between more coastal and inland sub-habitats within their local ranges.
In their new study published in Geology, Thomas Cullen and colleagues sought to test some of these hypotheses as part of their broader research reconstructing the paleoecology of Late Cretaceous systems.
One of the methods they’re using to do that is stable isotope analysis. This process measures differences in the compositions of non-decaying (hence, “stable”) isotopes of various common elements, as the degree of difference in these compositions in animal tissues and in the environment have known relationships to various factors such as diet, habitat use, water source, and temperature. So the team applied these methods to fossilized teeth and scales from a range of animals, including dinosaurs, crocodilians, mammals, bony fish, and rays, all preserved together from a relatively small region over a geologically short period of time in sites called vertebrate microfossil bonebeds.
By analyzing the stable carbon and oxygen isotope compositions of these fossils they were able to reconstruct their isotopic distributions in this ecosystem — a proxy for their diets and habitat use. They found evidence of expected predator-prey dietary relationships among the carnivorous and herbivorous dinosaurs and among aquatic reptiles like crocodilians and co-occurring fish species.
Critically, says Cullen, “What we didn’t see was evidence for large herbivorous dinosaurs segregating their habitats, as the hadrosaurs, ceratopsians, and ankylosaurs we sample all had strongly overlapping stable carbon and oxygen ranges. If some of those groups were making near-exclusive use of certain parts of the broader landscape, such as ceratopsians sticking to coastal environments and hadrosaurs sticking to more inland areas, then we should see them grouping distinctly from each other. Since we didn’t see that, that suggests they weren’t segregating their resource use in this manner. It’s possible they were doing so in different ways though, such as by feeding height segregation, or shifting where in the landscape they go seasonally, and our ongoing research is investigating some of these possibilities.”
Another important part of their study was comparing the fossil results to an environmentally similar modern environment in order to examine how similar they are ecologically. For a modern comparison, they examined the animal communities of the Atchafalaya River Basin of Louisiana, the largest contiguous wetland area in the continental U.S. The landscape of this area is very similar to their Cretaceous system, as are many elements of the plant and animal communities (not including the non-avian dinosaurs, of course).
From their comparisons, the team found that the Cretaceous system was similar to the Louisiana one in having a very large amount of resource interchange between the aquatic and terrestrial components of the ecosystem, suggesting that fairly diverse/mixed diets were common, and food being obtained from both terrestrial and aquatic sources was the norm. They also found that habitat use differences among the herbivorous mammals in the Louisiana system was more distinct than among those large herbivorous dinosaurs in the Cretaceous system, lending further evidence to their results about their lack of strict habitat use preferences.
Lastly, the team used modified oxygen stable isotope temperature equations to estimate mean annual temperature ranges for both systems (with the Louisiana one being a test of the accuracy of the method, as they could compare their results to directly measured water and air temperatures). The team found that in their Late Cretaceous ecosystem in Alberta, mean annual temperature was about 16-20 degrees C, a bit cooler than modern day Louisiana, but much warmer than Alberta today, reflecting the hotter greenhouse climate that existed globally about 76 million years ago.
Characterizing how these ecosystems were structured during this time, and how these systems changed across time and space, particularly with respect to how they responded to changes in environmental conditions, may be of great importance for understanding and predicting future ecosystem responses under global climate change. The team’s research continues and should reveal much more about the food webs and ecology of the dinosaurs and other organisms that inhabited these ancient landscapes.
Reference:
D.C. Evans, M.J. Ryan, M.B. Goodwin, F. Fanti, L. Huang, U.G. Wortmann, F.J. Longstaffe, T.M. Cullen. Large-scale stable isotope characterization of a Late Cretaceous dinosaur-dominated ecosystem. Geology, 2020; DOI: 10.1130/G47399.1
Numerous specimens of Kateretidae in a piece of amber from the Institute of Geology and Palaeontology in Nanjing (China). Included are also pollen grains from primitive water lilies. Credit: Georg Oleschinski/Uni Bonn
Like a snapshot, amber preserves bygone worlds. An international team of paleontologists from the University of Bonn has now described four new beetle species in fossilized tree resin from Myanmar, which belong to the Kateretidae family. They still exist today, with only a few species. As well as the about 99 million years old insects, the amber also includes pollen. It seems that the beetles helped the flowering plants to victory, because they contributed to their propagation. In turn, the beetles benefited from the new food source. The results have now been published in the journal iScience.
The researchers have described the new beetle species using specimens in four amber pieces from Myanmar (previously known as Burma). The pieces are estimated to be 99 million years old and date from the Cretaceous period, when dinosaurs were a rich and diverse group. Two of the pieces are in the Museum of Natural Sciences of Barcelona (Spain), while the other two specimens are kept in the Institute of Geology and Palaeontology in Nanjing (China).
“Although Myanmar surprises us time and again with finds of great scientific importance, amber pieces containing numerous organisms are not often found there,” says project leader Dr. David Peris, who comes from Spain and is a postdoc at the Institute for Geosciences at the University of Bonn with an Alexander von Humboldt Foundation fellowship. He carried out the project with scientists from the USA, Spain, Germany, China and the Czech Republic.
Three of the examined amber pieces contained numerous beetles, while the fourth piece contained only one specimen of this family. Many pollen grains of different groups of seed plants, some of them long extinct, have been preserved with the beetles in the tree resin. Peris: “This close association suggests that the grains were distributed in the viscous lump of resin by the movement of the beetles.”
The beetle family still exists today
The Kateretidae are a small family of beetles with less than 100 described modern species that today live in South America and other temperate and subtropical regions. The species of this family feed on pollen and flower parts. Due to their dietary habits, they are nowadays regarded as pollinators of flowering plants (angiosperms). But in the middle Cretaceous period their rapid development had just begun. Previously, the Earth was colonized by gymnosperms, literally meaning “naked seeds”, which also includes our conifers. “The most important aspect of this study is that the pollen grains in three of the amber pieces do not belong to flowering plants,” says Peris. The pollen grains on the beetle of the fourth piece of amber, however, come from a water lily, a group of very primitive angiosperms that emerged at an early stage.
Living together for mutual benefit
There are other pollinating insects in amber, but almost all of them concern gymnosperms. When flowering plants (angiosperms) began their early development, they represented a new resource that was used by the Kateretidae. The beetles adapted quickly and formed a mutually beneficial symbiosis: The flowering plants served the beetles as a food source and these animals contributed to the propagation of the new angiosperms by pollination.
In earlier studies it was speculated that the beetles might belong to the insect groups that pollinated the earliest flowers. Some of these animals had developed the ability to pollinate gymnosperms well before the appearance of angiosperms. “Our study supports this hypothesis of significant host plant relocation, as there are no Kateretidae associated with gymnosperms today,” says Peris. Adapting to the new resource has proven to be an evolutionary advantage.
Reference:
David Peris et al, Generalist Pollen-Feeding Beetles During the Mid-Cretaceous, SSRN Electronic Journal (2019). DOI: 10.2139/ssrn.3492117
Geologists studying rock samples from Baffin Island find lost fragment of continent. Credit: istock
Sifting through diamond exploration samples from Baffin Island, Canadian scientists have identified a new remnant of the North Atlantic craton—an ancient part of Earth’s continental crust.
A chance discovery by geologists poring over diamond exploration samples has led to a major scientific payoff.
Kimberlite rock samples are a mainstay of diamond exploration. Formed millions of years ago at depths of 150 to 400 kilometers, kimberlites are brought to the surface by geological and chemical forces. Sometimes, the igneous rocks carry diamonds embedded within them.
“For researchers, kimberlites are subterranean rockets that pick up passengers on their way to the surface,” explains University of British Columbia geologist Maya Kopylova. “The passengers are solid chunks of wall rocks that carry a wealth of details on conditions far beneath the surface of our planet over time.”
But when Kopylova and colleagues began analyzing samples from a De Beers Chidliak Kimberlite Province property in southern Baffin Island, it became clear the wall rocks were very special. They bore a mineral signature that matched other portions of the North Atlantic craton—an ancient part of Earth’s continental crust that stretches from Scotland to Labrador.
“The mineral composition of other portions of the North Atlantic craton is so unique there was no mistaking it,” says Kopylova, lead author of a new paper in the Journal of Petrology that outlines the findings. “It was easy to tie the pieces together. Adjacent ancient cratons in Northern Canada—in Northern Quebec, Northern Ontario and in Nunavut—have completely different mineralogies.”
Cratons are billion-year old, stable fragments of continental crust—continental nuclei that anchor and gather other continental blocks around them. Some of these nuclei are still present at the center of existing continental plates like the North American plate, but other ancient continents have split into smaller fragments and been re-arranged by a long history of plate movements.
“Finding these ‘lost’ pieces is like finding a missing piece of a puzzle,” says Kopylova. “The scientific puzzle of the ancient Earth can’t be complete without all of the pieces.”
The continental plate of the North Atlantic craton rifted into fragments 150 million years ago, and currently stretches from northern Scotland, through the southern part of Greenland and continues southwest into Labrador.
The newly identified fragment covers the diamond bearing Chidliak kimberlite province in southern Baffin Island. It adds roughly 10 percent to the known expanse of the North Atlantic craton.
This is the first time geologists have been able to piece parts of the puzzle together at such depth—so called mantle correlation. Previous reconstructions of the size and location of Earth’s plates have been based on relatively shallow rock samples in the crust, formed at depths of one to 10 kilometers.
“With these samples we’re able to reconstruct the shapes of ancient continents based on deeper, mantle rocks,” says Kopylova. “We can now understand and map not only the uppermost skinny layer of Earth that makes up one percent of the planet’s volume, but our knowledge is literally and symbolically deeper. We can put together 200-kilometer deep fragments and contrast them based on the details of the deep mineralogy.”
The samples from the Chidliak Kimberlite Province in southern Baffin Island were initially provided by Peregrine Diamonds, a junior exploration company. Peregrine was acquired by the international diamond exploration company and retailer De Beers in 2018. The drill cores sample themselves are very valuable, and expensive to retrieve.
“Our partner companies demonstrate a lot of goodwill by providing research samples to UBC, which enables fundamental research and the training of many grad students,” says Kopylova. “In turn, UBC research provides the company with information about the deep diamondiferous mantle that is central to mapping the part of the craton with the higher changes to support a successful diamond mine.”
Reference:
M G Kopylova et al. The metasomatized mantle beneath the North Atlantic Craton: Insights from peridotite xenoliths of the Chidliak kimberlite province (NE Canada), Journal of Petrology (2019). DOI: 10.1093/petrology/egz061
