Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, India

Fossil site in Kerala, India

Fossil wood park maintained by geological survey of India at Tamilnadu

Cretaceous fossil sites india

Fossils in rack:-Cyad

Fossils in rack:-echiniderms

Fossils in rack:-Rastellum sp

Pre-historic seabed, Cretaceous period

WFS News: Reconstructing the dragonfly and damselfly family tree

November 1st, 2021 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Many people hate insects, but the iridescent colors and elegant flying style of dragonflies and damselflies have made them firm favorites worldwide. They have been around in some form for hundreds of millions of years, but the evolutionary history of these relics of prehistoric life has been poorly understood — until now.

In newly published study, researchers including a member of the University of Tsukuba have applied transcriptomics, a type of gene sequencing, to reconstruct the phylogeny of the insect order Odonata. By calibrating this sequencing using the fossil record, they have been able to determine when dragonflies and damselflies first emerged.

Transcriptomics is the study of the collection of ribonucleic acid (RNA) — known as the transcriptome — that is present in a cell at any given time. This RNA contains a wealth of information and can be used to determine relationships among different members of a species. Understanding these relationships is essential for reconstructing evolutionary histories, or phylogenies, which are essentially like a family tree in a genetic sense.

“This is the first transcriptome-based phylogenetic reconstruction of the order Odonata,” says one of the authors of the study Professor Ryuichiro Machida. “We analyzed a total of 2,980 protein-coding genes in 105 species, covering all but two of the order’s families.”

There are thousands of living (extant) species of Odonata, but few have been analyzed in a phylogenetic context, and most species have been identified or differentiated on the basis of physical characteristics, such as wing patterns or larvae appearance. Although comparing appearances can be useful for extant species, it’s not always as helpful when trying to reconstruct evolutionary histories — that’s where transcriptomics and fossil calibration are useful.

“A robust and reliable phylogenetic reconstruction is essential for dependable estimates of species divergence times,” explains Machida. “Different fossil calibration schemes can be applied, but these can greatly impact the range of estimated dates. We used a comprehensive fossil dataset combining newly assessed fossils with data from the literature to produce a well-resolved and robustly time-calibrated phylogeny for Odonata.”

This reconstruction provides the most comprehensive divergence time estimates for Odonata to date, meaning the researchers were able to determine when dragonflies and damselflies first appeared (around 200 million years ago). They were even able to estimate the time at which certain evolutionary characteristics developed, such as ovipositors (tube-shaped organs for laying eggs). Species that once flourished but have since died out were also identified. Given that these species can now only be identified in the fossil record, transcriptomics and phylogenetic reconstructions provide a unique opportunity to better understand the connections between extant and extinct species. Studies of a similar nature could shed light on equally obscured genetic histories for other species.

  1. Manpreet Kohli, Harald Letsch, Carola Greve, Olivier Béthoux, Isabelle Deregnaucourt, Shanlin Liu, Xin Zhou, Alexander Donath, Christoph Mayer, Lars Podsiadlowski, Simon Gunkel, Ryuichiro Machida, Oliver Niehuis, Jes Rust, Torsten Wappler, Xin Yu, Bernhard Misof, Jessica Ware. Evolutionary history and divergence times of Odonata (dragonflies and damselflies) revealed through transcriptomics. iScience, 2021; 103324 DOI: 10.1016/j.isci.2021.103324
University of Tsukuba. “Linking the past and present: Reconstructing the dragonfly and damselfly family tree.” ScienceDaily. ScienceDaily, 29 October 2021. <www.sciencedaily.com/releases/2021/10/211029114012.htm>.
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WFS News: A New Genus and Species of Grass, Eograminis balticus (Poaceae: Arundinoideae), in Baltic Amber

October 19th, 2021 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Amber research by the Oregon State University College of Science has produced the first definite identification of grass in fossilized tree resin from the Baltic region, home to the world’s most well-known amber deposits.

Side one view of Eograminis balticus gen. et sp. nov. in Baltic amber. The arrow indicates callus hairs. Scale bar = 1.0 mm. The inset shows details of the callus hairs (arrowhead). Scale bar = 0.3 mm.

Side one view of Eograminis balticus gen. et sp. nov. in Baltic amber. The arrow indicates callus hairs. Scale bar = 1.0 mm. The inset shows details of the callus hairs (arrowhead). Scale bar = 0.3 mm.

The specimen studied by George Poinar Jr., named Eograminis balticus, also represents the first fossil member of Arundinoideae, a subfamily of the widespread Poaceae family that includes cereal grasses, bamboos and many species found in lawns and natural grasslands.

Findings, now in preprint, will be published in the International Journal of Plant Sciences.

Blown or shoved against a resin-producing tree, the fossil grass lost one of its spikelets some 40 or 50 million years ago, along with an accompanying insect that had been feeding on it.

Detail of silica bodies (arrows) in the tip of a lemma of Eograminis balticus gen. et sp. nov. in Baltic amber. Scale bar = 13 μm

A spikelet is one unit of inflorescence, or flower arrangement, and consists of two glumes and one or more florets. A glume is a leaflike structure below the flower cluster, and a floret is one of the small flowers in the cluster.

The fossil spikelet is the first definite evidence that grasses were among the various plants in the Baltic amber forest.

“The discovery not only adds a new plant group to the extensive flora that have been described from Baltic amber but provides new insights into the forest habitat the amber came from, a controversial topic in this field of study,” said Poinar, an international expert in using plant and animal life forms preserved in amber to learn more about the biology and ecology of the distant past.

Poinar says some scientists have proposed that fossiliferous amber from the Baltic region was formed in tropical and subtropical woods, and others say it came from a humid, marshy, warm-temperate forest.

“Our new grass suggests that for at least a time the habitat was warm-temperate, like you see today in mixed deciduous and conifer forests,” said Poinar, who collaborated on the study with Roberg Soreng of the Smithsonian Institution. “Present on the spikelet is an immature grasshopper-like insect and a leaf-spot fungal spore that provide information on the microhabitat of the fossil grass. The spikelet has structural and developmental features that existed in early Cenozoic grasses and establishes an important calibration point for future studies on the origin and splitting of genera in its subtribe.”

Because of the excellent preservation of the spikelet, observations could be made under direct light with both stereoscopic and compound microscopes, Poinar said.

“The spikelet has some features of members of the extant wetland genus Molinia in the tribe Molinieae, subtribe Moliniinae,” Poinar said. “Molinia species are concentrated around the Baltic Sea, but some of those species’ characteristics are different from what we see in this fossil.”

Informally known as moor grass, Molinia is a wetland genus. In addition to the Baltic region, Molinia is found in sand in habitats ranging from coastal to subalpine, and in fens and sphagnum bogs in forests. A fen is a peat-accumulating wetland that is fed by surface or ground water rich in minerals.

The Eograminis balticus spikelet specimen originated from the Samland Peninsula in the Kalinin District of the Russian Federation, Poinar said.

The name of the genus derives from the Latin words for age (aeon) and grass (graminis).

Journal Reference:

  1. George Poinar, Robert J. Soreng. A New Genus and Species of Grass, Eograminis balticus (Poaceae: Arundinoideae), in Baltic Amber. International Journal of Plant Sciences, 2021; 000 DOI: 10.1086/716781
Oregon State University. “Grass found in Baltic amber.” ScienceDaily. ScienceDaily, 4 October 2021. <www.sciencedaily.com/releases/2021/10/211004104246.htm>
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WFS News:The Horseshoe Crab of the Genus Limulus: Living Fossil or Stabilomorph?

October 16th, 2021 Riffin

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The Horseshoe Crab of the Genus Limulus: Living Fossil or Stabilomorph?

Citation: Kin A, Błażejowski B (2014) The Horseshoe Crab of the Genus Limulus: Living Fossil or Stabilomorph? PLoS ONE 9(10): e108036. https://doi.org/10.1371/journal.pone.0108036

Editor: Alistair Robert Evans, Monash University, Australia

A new horseshoe crab species, Limulus darwini, is described from the uppermost Jurassic (ca. 148 Ma) near-shore sediments of the Kcynia Formation, central Poland. The only extant species Limulus polyphemus (Linnaeus) inhabits brackish-marine, shallow water environments of the east coast of the United States. Here it is shown that there are no important morphological differences between the Kcynia Formation specimens and extant juvenile representatives of the genus Limulus. The palaeoecological setting inhabited by the new species and the trophic relationships of extant horseshoe crabs are discussed in an attempt to determine the potential range of food items ingested by these Mesozoic xiphosurans. In this paper we propose the adoption of a new term stabilomorphism, this being: an effect of a specific formula of adaptative strategy among organisms whose taxonomic status does not exceed genus-level. A high effectiveness of adaptation significantly reduces the need for differentiated phenotypic variants in response to environmental changes and provides for long-term evolutionary success.

Comparison of modern Limulus polyphemus (left) and oldest known member of the genus Limulus darwini (right) from Corbulomima horizon of unit III from Late Jurassic (upper Tithonian = Middle Volgian) sedimentary sequence at Owadów-Brzezinki Quarry (central Poland). (X), (Y) and (Z) - details emphasized, are most substantial morphological difference between both these forms. (cl) - cardiac lobe; (opr) – opisthosomal rim; (pa) – posterial area. Morphological elements of L. darwini exoskeleton not known from the fossil record (i.e. movable spines and telson) emphasized in grey.

Comparison of modern Limulus polyphemus (left) and oldest known member of the genus Limulus darwini (right) from Corbulomima horizon of unit III from Late Jurassic (upper Tithonian = Middle Volgian) sedimentary sequence at Owadów-Brzezinki Quarry (central Poland).(X), (Y) and (Z) – details emphasized, are most substantial morphological difference between both these forms. (cl) – cardiac lobe; (opr) – opisthosomal rim; (pa) – posterial area. Morphological elements of L. darwini exoskeleton not known from the fossil record (i.e. movable spines and telson) emphasized in grey.

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WFS News: Taytalura alcoberi, Fossil of Tuatara-Like Reptile

August 31st, 2021 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Taytalura alcoberi lived in what is now Argentina during the Late Triassic epoch, approximately 231 million years ago.

The ancient reptile was a member of Lepidosauromorpha, a large group that includes squamates (lizards and snakes) and sphenodontians (tuataras).

“Lepidosauromorphs and archosauromorphs represent the two main branches of the reptile tree of life that have survived to the present,” said Dr. Ricardo Martínez from the Instituto y Museo de Ciencias Naturales at the Universidad Nacional de San Juan and his colleagues.

“Today, the former mostly comprise squamates (about 11,000 species of lizards, snakes and amphisbaenians) and the latter are mostly represented by birds (about 10,800 species).”

“However, unlike for archosauromorphs, the early evolution of lepidosauromorphs remains one of the largest knowledge gaps in reptile evolution.”

Holotype of Taytalura alcoberi. Image credit: Martínez et al., doi: 10.1038/s41586-021-03834-3.

Holotype of Taytalura alcoberi. Image credit: Martínez et al., doi: 10.1038/s41586-021-03834-3.

Taytalura alcoberi predates the split between squamates and sphenodontians, and is close to the origin of lepidosauromorphs.

The species is about 11 million years younger than the oldest known lepidosauromorphs from Europe, and approximately the same age as the oldest known South American lepidosauromorphs.

The skull of Taytalura alcoberi shares features with modern tuataras, suggesting that several anatomical features, presumed exclusive to sphenodontians, must have originated early in lepidosauromorph evolution.

“Taytalura alcoberi suggests that the strongly evolutionarily conserved skull architecture of sphenodontians represents the plesiomorphic condition for all lepidosaurs, that stem and crown lepidosaurs were contemporaries for at least 10 million years during the Triassic period, and that early lepidosauromorphs had a much broader geographical distribution than has previously been thought,” the paleontologists said.

Their paper was published in the journal Nature.

Source: http://www.sci-news.com/

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WFS News: Sustained high rates of morphological evolution during the rise of tetrapods

August 29th, 2021 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

One of the biggest questions in evolution is when and how major groups of animals first evolved. The rise of tetrapods (all limbed vertebrates) from their fish relatives marks one of the most important evolutionary events in the history of life. This “fish-to-tetrapod” transition took place somewhere between the Middle and Late Devonian (~400-360 million years ago) and represents the onset of a major environmental shift, when vertebrates first walked onto land. Yet, some of the most fundamental questions regarding the dynamics of this transition have remained unresolved for decades.

In a study published August 23 in Nature Ecology and Evolution Harvard researchers establish the origin date of the earliest tetrapods and discover they acquired several of the major new adaptive traits that enabled vertebrate life on land at accelerated evolutionary rates.

The study led by Dr. Tiago R. Simões, postdoctoral researcher, and senior author Professor Stephanie E. Pierce, both from the Department of Organismic and Evolutionary Biology, Harvard University, applied recently developed statistical methods (Bayesian evolutionary analysis) to precisely estimate the time and rates of anatomical evolution during the rise of tetrapods. The Bayesian method was adapted from methods originally developed in epidemiology to study how viruses like COVID-19 evolve and only recently became a tool in paleontology for the study of species evolution.

The study also innovates by combining data from fossil footprints and body fossils to pinpoint the time of origin of the tetrapods. “Normally footprint data shows up after body fossils of their track makers. In this case, we have tetrapod footprints much older than the first body fossils by several million years, which is extremely unusual. By combining both footprint and body fossils, we could search for a more precise age for the rise of tetrapods,” said Pierce.

“We were able to provide a very precise age for the origin of tetrapods at approximately 390 million years ago, 15 million years older than the oldest tetrapod body fossil,” said Simões.

The researchers also found that most of the close relatives to tetrapods had exceptionally slow rates of anatomical evolution, suggesting the fish relatives to tetrapods were quite well adapted to their aquatic lifestyle.

“On the other hand, we discovered the evolutionary lineages leading to the first tetrapods broke away from that stable pattern, acquiring several of the major new adaptive traits at incredibly fast rates that were sustained for approximately 30 million years,” said Simões.

Simões and Pierce also extended molecular approaches to study how fast different parts of the early tetrapod body plan evolved — such as the skull, jaws, and limbs — and the strength of natural selection acting on each of them. They found that all parts of the tetrapod skeleton were under strong directional selection to evolve new adaptive features, but that the skull and jaws were evolving faster than the rest of the body, including the limbs.

“This suggest that changes in the skull had a stronger role in the initial stages of the fish-to-tetrapod transition than changes in the rest of the skeleton. The evolution of limbs to life on land was important, but mostly at a later stage in tetrapod evolution, when they became more terrestrial,” said Pierce.

“We see several anatomical innovations in their skull related to feeding and food procurement, enabling a transition from a fish-like suction-based mode of prey capture to tetrapod-like biting, and an increase in orbit size and location” said Simões. “These changes prepared tetrapods to look for food on land and to explore new food resources not available to their fish relatives.”

The researchers also found that the fast rates of anatomical evolution in the tetrapod lineage were not associated with fast rates of species diversification. In fact, there were very few species around, so few they had a very low probability of being preserved in the fossil record.

This finding helps to answer an ongoing debate in evolution of whether new major animal groups originated under fast rates of anatomical change and species diversification (the classical hypothesis). Or, if there were high rates of anatomical evolution first, with increased rates of species diversification occurring only several million years later (a new hypothesis).

“What we’ve been finding in the last couple of years is that you have lots of anatomical changes during the construction of new animal body plans at short periods of geological time, generating high rates of anatomical evolution, like we’re seeing with the first tetrapods. But in terms of number of species, they remained constrained and at really low numbers for a really long time, and only after tens of millions of years do they actually diversify and become higher in number of species. There’s definitely a decoupling there,” said Simões.

Pierce agreed, “It takes time to get a foothold in a new niche in order to take full advantage of it.”

“Our study starts at the very beginning of this evolutionary story. There are many, many more chapters to come,” said Pierce. “We want to next dig further in terms of what happened after the origin of tetrapods, when they started to colonize land and diversify into new niches. How does that impact their anatomical rates of evolution compared to their species diversification across the planet? This is just the very beginning. It’s the introductory chapter to the book.”

  1. Tiago R. Simões, Stephanie E. Pierce. Sustained high rates of morphological evolution during the rise of tetrapods. Nature Ecology & Evolution, 2021; DOI: 10.1038/s41559-021-01532-x
Harvard University, Department of Organismic and Evolutionary Biology. “Sustained fast rates of evolution explain how tetrapods evolved from fish.” ScienceDaily. ScienceDaily, 23 August 2021. <www.sciencedaily.com/releases/2021/08/210823125839.htm>.
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WFS News: Phiomicetus anubis, A 4-Legged Whale With A Raptor-Like Eating Style

August 28th, 2021 Riffin

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A group of scientists have discovered a fossil of a now-extinct whale with four legs. This visual reconstruction shows Phiomicetus anubis preying on a sawfish. Robert W. Boessenecker

A group of scientists have discovered a fossil of a now-extinct whale with four legs. This visual reconstruction shows Phiomicetus anubis preying on a sawfish. Robert W. Boessenecker

A semiaquatic whale that lived 43 million years ago was so fearsome, paleontologists have named it after Anubis, the ancient Egyptian god of death.

The newly discovered 10-foot-long (3 meters) species, dubbed Phiomicetus anubis, was a beast; When it was alive more than 43 million years ago, it both walked on land and swam in the water and had powerful jaw muscles that would have allowed it to easily chomp down on prey, such as crocodiles and small mammals, including the calves of other whale species.

What’s more, the whale’s skull bears a resemblance to the skull of the jackal-headed Anubis, giving it another link to the death deity, the researchers observed. “It was a successful, active predator,” study lead author Abdullah Gohar, a graduate student of vertebrate paleontology at Mansoura University in Egypt, told Live Science. “I think it was the god of death for most animals that lived alongside it.”

Although today’s whales live in the water, their ancestors started out on land and gradually evolved into sea creatures. The earliest known whale, the wolf-size Pakicetus attocki, lived about 50 million years ago in what is now Pakistan. The new discovery of P. anubis sheds more light on whale evolution, said Jonathan Geisler, an associate professor of anatomy at the New York Institute of Technology who was not involved with the study.

“This fossil really starts to give us a sense of when whales moved out of the Indo-Pakistan ocean region and started dispersing across the world,” Geisler told Live Science.

Paleontologists discovered the fossil remains of P. anubis in 2008, during an expedition in Egypt’s Fayum Depression — an area famous for sea life fossils, including those of sea cows and whales, dating to the Eocene epoch (56 million to 33.9 million years ago). The expedition was led by study co-researcher Mohamed Sameh Antar, a vertebrate paleontologist with the Egyptian Environmental Affairs Agency, making this the first time that an Arab team has discovered, scientifically described and named a new species of fossil whale, Gohar said.

By analyzing the whale’s partial remains — pieces of its skull, jaws, teeth, vertebrae and ribs — the team discovered that the 1,300-pound (600 kilogram) P. anubis is the earliest (or most “primitive”) whale in Africa from a group of semiaquatic whales known as the protocetids.

P. anubis‘s remains revealed that the protocetid whales had evolved a few new anatomical features and feeding strategies. For instance, P. anubis had long third incisors next to its canines, “which suggests that incisors and canines were used to catch, debilitate and retain faster and more elusive prey items (e.g. fish) before they were moved to the cheek teeth to be chewed into smaller pieces and swallowed,” the researchers wrote in the study.

Moreover, big muscles on its head would have given it a powerful bite force, allowing it to capture large prey through snapping and biting. “We discovered how [its] fierce, deadly and powerful jaws were capable of tearing a wide range of prey,” Gohar said.

P. anubis wasn’t the only fossil whale from the middle Eocene of Egypt. Its fossils came from the same area as a previously discovered Rayanistes afer, an early aquatic whale. This finding suggests that the two early whales lived in the same time and place, but likely occupied different niches. It’s even possible that P. anubis hunted R. afer calves, making its “Anubis” name all the more appropriate, Gohar said.

Granted, to some animals, P. anubis was prey. The ribs of the newly described whale have bite marks that “suggest it was once bitten severely by sharks,” Gohar said. However the marks indicate that the sharks were small, and likely not large enough to kill the whale; rather, these sharks were likely scavenging its carcass.

Gohar and colleagues analyzed the fossils in the lab of Hesham Sallam, founder of the Mansoura University Vertebrate Paleontology Center and the study’s senior author. The study was published online Wednesday (Aug. 25) in the journal Proceedings of the Royal Society B: Biological Sciences.

Source: Originally published on Live Science.

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WFS News: Carbon concentration increases with depth of melting in Earth’s upper mantle

August 21st, 2021 Riffin

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Carbon concentration increases with depth of melting in Earth’s upper mantle

Aiuppa, A., Casetta, F., Coltorti, M. et al.  Nat. Geosci. (2021). https://doi.org/10.1038/s41561-021-00797-y

Carbon in the upper mantle controls incipient melting of carbonated peridotite and so acts as a critical driver of plate tectonics. The carbon-rich melts that form control the rate of volatile outflux from the Earth’s interior, contributing to climate evolution over geological times. However, attempts to constrain the carbon concentrations of the mantle source beneath oceanic islands and continental rifts is complicated by pre-eruptive volatile loss from magmas. Here, we compile literature data on magmatic gases, as a surface expression of the pre-eruptive volatile loss, from 12 oceanic island and continental rift volcanoes. We find that the levels of carbon enrichment in magmatic gases correlate with the trace element signatures of the corresponding volcanic rocks, implying a mantle source control. We use this global association to estimate that the mean carbon concentration in the upper mantle, down to 200 km depth, is approximately 350 ppm (range 117–669 ppm). We interpret carbon mantle heterogeneities to reflect variable extents of mantle metasomatism from carbonated silicate melts. Finally, we find that the extent of carbon enrichment in the upper mantle positively correlates with the depth at which melting starts. Our results imply a major role of carbon in driving melt formation in the upper mantle.

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WFS News: A billion years missing from geologic record: Where it may have gone.

August 20th, 2021 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

The geologic record is exactly that: a record. The strata of rock tell scientists about past environments, much like pages in an encyclopedia. Except this reference book has more pages missing than it has remaining. So geologists are tasked not only with understanding what is there, but also with figuring out what’s not, and where it went.

One omission in particular has puzzled scientists for well over a century. First noticed by John Wesley Powell in 1869 in the layers of the Grand Canyon, the Great Unconformity, as it’s known, accounts for more than one billion years of missing rock in certain places.

Scientists have developed several hypotheses to explain how, and when, this staggering amount of material may have been eroded. Now, UC Santa Barbara geologist Francis Macdonald and his colleagues at the University of Colorado, Boulder and at Colorado College believe they may have ruled out one of the more popular of these. Their study appears in the Proceedings of the National Academy of Sciences.

“There are unconformities all through the rock record,” explained Macdonald, a professor in the Department of Earth Science. “Unconformities are just gaps in time within the rock record. This one’s called the Great Unconformity because it was thought to be a particularly large gap, maybe a global gap.”

Hypothesized exhumation histories below the Great Unconformity. Orange bars depict geological constraints from Colorado. Hypothesis 1 (H1) depicts major erosion of the continents associated with assembly of the supercontinent Rodinia and mantle upwelling below it (14, 17). Hypothesis 2 (H2) depicts major erosion associated with the early breakup of Rodinia (10⇓⇓–13, 15, 16). Hypothesis 3 (H3) depicts an association with the Cryogenian Snowball Earth glaciations (18⇓⇓⇓–22). Hypothesis 4 (H4) depicts major erosion associated with the Cambrian transgressive buzzsaw and subsequent burial (4, 5), later rifting of Laurentian margins (23, 24), or the Pan-African orogeny and Transantarctic orogenies and construction of the supercontinent Pannotia (25, 26). An alternative hypothesis is that there are multiple Great Unconformities representing diachronous regional phenomena, and these features developed predominantly on Laurentia and its conjugate rifted margins.

Hypothesized exhumation histories below the Great Unconformity. Orange bars depict geological constraints from Colorado. Hypothesis 1 (H1) depicts major erosion of the continents associated with assembly of the supercontinent Rodinia and mantle upwelling below it (14, 17). Hypothesis 2 (H2) depicts major erosion associated with the early breakup of Rodinia (10⇓⇓–13, 15, 16). Hypothesis 3 (H3) depicts an association with the Cryogenian Snowball Earth glaciations (18⇓⇓⇓–22). Hypothesis 4 (H4) depicts major erosion associated with the Cambrian transgressive buzzsaw and subsequent burial (4, 5), later rifting of Laurentian margins (23, 24), or the Pan-African orogeny and Transantarctic orogenies and construction of the supercontinent Pannotia (25, 26). An alternative hypothesis is that there are multiple Great Unconformities representing diachronous regional phenomena, and these features developed predominantly on Laurentia and its conjugate rifted margins.

A leading thought is that glaciers scoured away kilometers of rock around 720 to 635 million years ago, during a time known as Snowball Earth, when the planet was completely covered by ice. This hypothesis even has the benefit of helping to explain the rapid emergence of complex organisms shortly thereafter, in the Cambrian explosion, since all this eroded material could have seeded the oceans with tremendous amounts of nutrients.

Macdonald was skeptical of this reasoning. Although analogues of the Great Unconformity appear throughout the world — with similar amounts of rock missing from similar stretches of time — they don’t line up perfectly. This casts doubt as to whether they were truly eroded by a global event like Snowball Earth.

Part of the challenge of investigating the Great Unconformity is that it happened so long ago, and the Earth is a messy system. “These rocks have been buried and eroded multiple times through their history,” Macdonald said.

Fortunately, the team was able to test this hypothesis using a technique called thermochronology. A few kilometers below the Earth’s surface, the temperature begins to rise as you get closer to the planet’s hot mantle. This creates a temperature gradient of roughly 50 degrees Celsius for every kilometer of depth. And this temperature regime can become imprinted in certain minerals.

As certain radioactive elements in rocks break down, Helium-4 is produced. In fact helium is constantly being generated, but the fraction retained in different minerals is a function of temperature. As a result, scientists can use the ratio of helium to thorium and uranium in certain minerals as a paleo-thermometer. This phenomenon enabled Macdonald and his coauthors to track how rock moved in the crust as it was buried and eroded through the ages.

“These unconformities are forming again and again through tectonic processes,” Macdonald said. “What’s really new is we can now access this much older history.”

The team took samples from granite just below the boundary of the Great Unconformity at Pikes Peak in Colorado. They extracted grains of a particularly resilient mineral, zircon, from the stone and analyzed the radio nucleotides of helium contained inside. The technique revealed that several kilometers of rock had been eroded from above this granite between 1,000 and 720 million years ago.

Importantly, this stretch of time definitively came before the Snowball Earth episodes. In fact, it lines up much better with the periods in which the supercontinent Rodinia was forming and breaking apart. This offers a clue to the processes that may have stricken these years from the geologic record.

“The basic hypothesis is that this large-scale erosion was driven by the formation and separation of supercontinents,” Macdonald said.

The Earth’s cycle of supercontinent formation and separation uplifts and erodes incredible extents of rock over long periods of time. And because supercontinent processes, by definition, involve a lot of land, their effects can appear fairly synchronous across the geologic record.

However, these processes don’t happen simultaneously, as they would in a global event like Snowball Earth. “It’s a messy process,” Macdonald said. “There are differences, and now we have the ability to perhaps resolve those differences and pull that record out.”

While Macdonald’s results are consistent with a tectonic origin for these great unconformities, they don’t end the debate. Geologists will need to complement this work with similar studies in other regions of the world in order to better constrain these events.

The mystery of the Great Unconformity is inherently tied to two of geology’s other great enigmas: the rise and fall of Snowball Earth and the sudden emergence of complex life in the Ediacaran and Cambrian. Progress in any one could help researchers finally crack the lot.

“The Cambrian explosion was Darwin’s dilemma,” Macdonald remarked. “This is a 200-year old question. If we can solve that, we would definitely be rock stars.”

 

Journal Reference:

  1. Rebecca M. Flowers, Francis A. Macdonald, Christine S. Siddoway, Rachel Havranek. Diachronous development of Great Unconformities before Neoproterozoic Snowball Earth. Proceedings of the National Academy of Sciences, 2020; 201913131 DOI: 10.1073/pnas.1913131117
University of California – Santa Barbara. “A billion years missing from geologic record: Where it may have gone.” ScienceDaily. ScienceDaily, 7 May 2020. <www.sciencedaily.com/releases/2020/05/200507130704.htm>.
@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

WFS News: Prehistoric Bat Fossil Discovered

July 18th, 2021 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

A new paper appearing in Biology Letters describes the oldest-known fragmentary bat fossils from Asia, pushing back the evolutionary record for bats on that continent to the dawn of the Eocene and boosting the possibility that the bat family’s “mysterious” origins someday might be traced to Asia.

A team based at the University of Kansas and China performed the fieldwork in the Junggar Basin — a very remote sedimentary basin in northwest China — to discover two fossil teeth belonging to two separate specimens of the bat, dubbed Altaynycteris aurora.

Upper molars of Altaynycteris aurora. IVPP V27157, holotype right M1, in buccal (a), occlusal (b) and lingual view (c); IVPP V27158, right M3, in buccal (d), occlusal (e) and lingual view (f). Metaconule indicated with (M) and postparaconule crista indicated with (P). Scale bar is 0.5 mm.

The new fossil specimens help scientists better understand bat evolution and geographic distribution and better grasp how mammals developed in general.

“Bats show up in the fossil record out of the blue about 55-ish million years ago — and they’re already scattered on different parts of the globe,” said lead author Matthew Jones, a doctoral student at the KU Biodiversity Institute and Department of Ecology & Evolutionary Biology. “Before this, the earliest bats are known from a couple of places in Europe — Portugal and southern France — and Australia. So, when they show up early in the fossil record as these fragmentary fossils they’re already effectively worldwide. By the time we get their earliest known full skeletons, they look modern — they can fly, and most of them are able to echolocate. But we don’t really know anything about this transitional period from non-bats to bats. We don’t even really know what their closest living relatives are among mammals. It’s a really big evolutionary mystery where bats came from and how they evolved and became so specialized.”

Jones’ co-authors were K. Christopher Beard, senior curator at the KU Biodiversity Institute and Foundation Distinguished Professor of Ecology & Evolutionary Biology at KU; and Qiang Li and Xijun Ni of the Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences and the Center for Excellence in Life and Paleoenvironment at the Chinese Academy of Sciences.

The ancient bat teeth were discovered through painstaking fieldwork in the Junggar Basin, where the KU researchers worked at an isolated field site established by their Chinese colleagues, one of two sites in the region the team hope will continue yielding interesting fossils.

“This was concerted effort over a long period of time by our Chinese colleagues,” Jones said.

“They suspected that there were fossiliferous deposits from the Paleocene and Eocene, and they spent several years going out there, identifying where to find fossils. Chris was a part of several seasons of fieldwork there. I was a part of one season of fieldwork there. What we did was collect a bunch of sediment to screen wash, which is sort of like panning for gold. You pour a bunch of sediment into a sievelike apparatus and let all the dirt and everything fall out, and you’re only left with particles of a certain size, but also fossils.”

Beard said the fieldwork was an outgrowth of long-standing relationships between the KU team and its Chinese counterparts.

“We’ve been fortunate enough to be able to host our Chinese colleagues here in Lawrence for extended research visits, and they’ve more than reciprocated by hosting us for research and fieldwork in China. This work in the Junggar Basin is really trailblazing work because the fossil record in this part of China is only just barely beginning to emerge, and this area is very removed and isolated. It’s just a giant empty place. There are some camels, some snakes and lizards, but you don’t see many people there. That remoteness makes the logistics to do fieldwork there quite difficult and expensive because you’ve got to bring in all your food and water from far outside — all of that hindered research in this area previously.”

Following the challenging fieldwork, the residue left behind from the screen washing at the site was sorted at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.

“In 2017, after we got back from the field, Xijun said. ‘Hey, one of the technicians picking through this sediment thinks they found a bat,'” Jones said. “Knowing I was interested in bats, they showed it to me. The next year, the other tooth was found — so there’s two teeth.”

Through meticulous morphological analysis of the teeth, along with biostratigraphy — or analyzing the position of layers of fossil remains in the deposits — the authors were able to date the specimens to the advent of the Eocene, the earliest period when bat fossils have been found anywhere on Earth. Indeed, the presence of these ancient bat fossils in Asia bolsters a theory that bats could have emerged from there in the first place, then distributed themselves worldwide when they later developed flight.

More fieldwork in the area is ongoing, and Jones and Beard said they were hopeful to find even older specimens, perhaps even dating to the Paleocene, the epoch before the Eocene, when researchers believe bats probably originated. Yet the particulars of Altaynycteris aurora remain hazy — for instance, it’s impossible to say from teeth fragments if the animal could fly or echolocate.

“These teeth look intermediate, in between what we would expect a bat ancestor to look like — and in fact, what a lot of early Cenozoic insectivorous mammals to do look like — and what true bat looks like,” Jones said. “So, they have some features that are characteristic of bats that we can point to and say, ‘These are bats.’ But then they have some features that we can call for simplicity’s sake ‘primitive.'”

The researchers said the new fossils help fill in a gap to understanding the evolution of bats, which remains a puzzle to experts — and could teach us more about mammals in general.

“I can think of two mammal groups that are alive today that are really weird,” Beard said. “One of them is bats, because they fly — and that’s just ridiculous. The other one is whales, because they’re completely adapted to life in the ocean, they can swim, obviously, and they do a little bit of sonar echolocation themselves. We know a lot about transitional fossils for whales. There are fossils from places like Pakistan that were quadrupedal mammals that looked vaguely doglike. We have a whole sequence of fossils linking these things that were clearly terrestrial animals walking around on land, through almost every kind of transitional phase you can imagine, to a modern whale. This isn’t true for bats. For bats, literally you’ve got a normal mammal and then you’ve got bats — and anytime you’ve got a fossil record that’s a giant vacuum, we need work that can fill partly that. This paper is at least a step along that path.”

Matthew F. Jones, Qiang Li, Xijun Ni, K. Christopher Beard. The earliest Asian bats (Mammalia: Chiroptera) address major gaps in bat evolution. Biology Letters, 2021; 17 (6): 20210185 DOI: 10.1098/rsbl.2021.0185

Citation :University of Kansas. “Researchers detail the most ancient bat fossil ever discovered in Asia.” ScienceDaily. ScienceDaily, 7 July 2021. <www.sciencedaily.com/releases/2021/07/210707112556.htm>.

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

WFS News: Evidence of preserved collagen in an Early Jurassic sauropodomorph dinosaur revealed by synchrotron FTIR microspectroscopy

July 17th, 2021 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Evidence of preserved collagen in an Early Jurassic sauropodomorph dinosaur revealed by synchrotron FTIR microspectroscopy

Lee, YC., Chiang, CC., Huang, PY. et al.

 Nat Commun 8, 14220 (2017). https://doi.org/10.1038/ncomms14220

New research from scientists at the University of Toronto and researchers in China and Taiwan provides the first evidence that proteins have been preserved within the 195-million-year-old rib of the sauropodomorph dinosaur Lufengosaurus. The study appears in the Jan. 31 issue of the journal Nature Communications.

“These dinosaur proteins are more than 100 million years older than anything previously discovered,” says Professor Robert Reisz, a specialist in vertebrate paleontology in the department of biology at U of T Mississauga. “These proteins are the building blocks of animal soft tissues, and it’s exciting to understand how they have been preserved.”

The Canada-Taiwan research team, led by Reisz, used the synchrotron at the Taiwanese National Synchrotron Radiation Research Centre to find the substance in place, known as collagen type I, preserved within the tiny vascular canals of the rib where blood vessels and blood would be in the living dinosaur.

(a) Rib before sectioning, (b) transverse section of the rib, small black circles are the central vascular canals in the osteons, (c) longitudinal section of the rib showing distribution of infilled vascular canals, (d–h) close ups of preserved collagen-infilling materials within the vascular canals of the rib; flat transparent preserved protein fragments that were washed out from the cut canals, as explained in the main text, are indicated by red arrows, f,h are the dark-field images of e,g, respectively, (i) SR-TXM image of microcrystals of haematite within the vascular canal, indicated by red squares, (j) microcrystal of haematite inside the vascular canal, (k) tomographic images of haematite crystal in different views, (l) lacuna within the bone matrix and (m) tomographic images of lacunae in different views.

(a) Rib before sectioning, (b) transverse section of the rib, small black circles are the central vascular canals in the osteons, (c) longitudinal section of the rib showing distribution of infilled vascular canals, (d–h) close ups of preserved collagen-infilling materials within the vascular canals of the rib; flat transparent preserved protein fragments that were washed out from the cut canals, as explained in the main text, are indicated by red arrows, f,h are the dark-field images of e,g, respectively, (i) SR-TXM image of microcrystals of haematite within the vascular canal, indicated by red squares, (j) microcrystal of haematite inside the vascular canal, (k) tomographic images of haematite crystal in different views, (l) lacuna within the bone matrix and (m) tomographic images of lacunae in different views.

The collagen was found together with lots of small, spherical hematite particles. Hematite is a mineral that can be formed from the iron in hemoglobin, the oxygen-transport protein in red blood cells. The chemical bond between iron and oxygen is what gives blood cells their red colour.

Reisz and his colleagues believe that these hematite particles were derived from the original blood of the dinosaur, and that they acted as the catalyst for preserving the protein in the vascular canals of the bone. These collagen pieces are probably remnants of the blood vessels that supplied blood to the bone cells in the living dinosaur.

Baseline-corrected and normalized characteristic infrared band assignment for preserved collagen within the central vascular canals shown in red, and the peaks were assigned for methyl group (sCH3 and as CH3) and methylene (sCH2 and as CH2) in the spectral range of 3,000–2,800 cm−1 as shown in the blue inset, collagen type I from extant calf skin dispersed in 0.1% acetic acid solution in green, preserved protein remains in flat fragments found in and near the central canals of the fossil bone in blue, bone matrix in brown, extant bacteria biofilm in black and epoxy resin in pink. It is evident that the spectra of preserved collagen and extant collagen type I are closely matched. The extant bacterial biofilm showed significant differences from fossil or extant collagen in the range of 3,100–3,600 cm−1 region (sOH).

Baseline-corrected and normalized characteristic infrared band assignment for preserved collagen within the central vascular canals shown in red, and the peaks were assigned for methyl group (sCH3 and as CH3) and methylene (sCH2 and as CH2) in the spectral range of 3,000–2,800 cm−1 as shown in the blue inset, collagen type I from extant calf skin dispersed in 0.1% acetic acid solution in green, preserved protein remains in flat fragments found in and near the central canals of the fossil bone in blue, bone matrix in brown, extant bacteria biofilm in black and epoxy resin in pink. It is evident that the spectra of preserved collagen and extant collagen type I are closely matched. The extant bacterial biofilm showed significant differences from fossil or extant collagen in the range of 3,100–3,600 cm−1 region (sOH).

“Interestingly, there was no evidence of preservation of organic remains in the main mass of the bone, only in the small vascular canals that ran along the length of the rib, where hematite was also present” says Reisz.

“Our localized search, in areas of the bone that are likely to preserve remnants of the original soft tissues, is more likely to succeed than previously used methods. This approach has great future potential, because localized searches will yield important results even when the amount of organic remains is miniscule.”

Previous evidence of preserved collagen date back to the Late Cretaceous Period — more than 100 million years younger than this discovery — but those studies extracted the organic remains by dissolving away all other parts of the fossil, without a clear understanding of the precise origins of the collagen.

This research allowed the scientists to find the collagen in place without dissolving the rest of the fossil, and it has helped them understand how the organic remains were preserved. Reisz believes that future explorations for even older proteins will be possible if this technique is used.

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

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