Comb jellies, jellyfish relatives after all?


This 21 August 2016 video says about itself:

Comb jellies look like creatures from another planet. Despite their name and physical appearance, these sea creatures are different from jellyfish. They’re also about as far from us on the tree of life as a species can get and still be considered an animal. But based on new research findings, we may have something very basic to our lives in common with them.

That was three years ago. Now, new research …

From the University of Bristol in England:

Half-a-billion-year-old fossil reveals the origins of comb jellies

March 21, 2019

One of the ocean’s little known carnivores has been allocated a new place in the evolutionary tree of life after scientists discovered its unmistakable resemblance with other sea-floor dwelling creatures.

Comb jellies occupy a pivotal place in the history of animal evolution with some arguing that they were among the first animals to evolve. Now an international team of palaeontologists have found fossil evidence that proves comb jellies are related to ancestors that sat on the sea floor with polyp-like tentacles.

As reported today in Current Biology, researchers from the University of Bristol, Yunnan University in China and London’s Natural History Museum, compared a 520 million-year-old fossil with fossils of a similar skeletal structure and found that all evolved from the same ancestors.

The fossil, set in a yellow and olive coloured mudstone and resembling a flower, was found in outcrops south of Kunming in the Yunnan Province, South China by Professor Hou Xianguang, co-author of the study.

Several amazingly preserved fossils have been unearthed from outcrops scattered among rice fields and farmlands in this part of tropical China in the last three decades.

It has been named Daihua after the Dai tribe in Yunnan and the Mandarin word for flower ‘Hua’, a cup-shaped organism with 18 tentacles surrounding its mouth. On the tentacles are fine feather-like branches with rows of large ciliary hairs preserved.

“When I first saw the fossil, I immediately noticed some features I had seen in comb jellies”, said Dr Jakob Vinther, a molecular palaeobiologist from the University of Bristol. “You could see these repeated dark stains along each tentacle that resembles how comb jelly combs fossilise. The fossil also preserves rows of cilia, which can be seen because they are huge. Across the Tree of Life, such large ciliary structures are only found in comb jellies.”

In today’s oceans, comb jellies are swimming carnivores. Some of them have become invasive pests. They swim using bands of iridescent, rainbow coloured comb rows along their body composed of densely packed cellular protrusions, known as cilia. Their hair-like structures are the largest seen anywhere in the tree of life.

The researchers noticed that Daihua resembled another fossil, a famous weird wonder from the Burgess Shale (508 million years old) called Dinomischus. This stalked creature also had 18 tentacles and an organic skeleton and was previously assigned to a group called entoprocts.

“We also realised that a fossil, Xianguangia, that we always thought was a sea anemone is actually part of the comb jelly branch”, said co-author Prof Cong Peiyun.

This emerging pattern led researchers to see a perfect transition from their fossils all the way up to comb jellies.

“It was probably one of the most exhilarating moments of my life,” said Dr Vinther. “We pulled out a zoology textbook and tried to wrap our head around the various differences and similarities, and then, bam! — here is another fossil that fills this gap.”

The study shows how comb jellies evolved from ancestors with an organic skeleton, which some still possessed and swam with during the Cambrian. Their combs evolved from tentacles in polyp-like ancestors that were attached to the seafloor. Their mouths then expanded into balloon-like spheres while their original body reduced in size so that the tentacles that used to surround the mouth now emerges from the back-end of the animal.

“With such body transformations, I think we have some of the answers to understand why comb jellies are so hard to figure out. It explains why they have lost so many genes and possess a morphology that we see in other animals,” added co-author Dr Luke Parry.

Until around 150 years ago, zoologists had considered comb jellies and cnidarians to be related. This theory was challenged more recently by new genetic information suggesting comb jellies could be a distant relative to all living animals below the very simple looking sponges.

The authors of this new study believe their findings make a strong case for repositioning the comb jelly back alongside corals, sea anemones and jellyfish.

Many Cambrian fossil animals discovered in China


This 21 March 2019 video is called Spectacular New Fossil Bonanza Captures Explosion Of Early Life.

One of the newly discovered animals, photo Science

From Science, 22 March 2019:

The Qingjiang biota—A Burgess Shale–type fossil Lagerstätte from the early Cambrian of South China

A treasure trove of Cambrian secrets

Animal life exploded in diversity and form during the Cambrian period about 500 million years ago. Fu et al. describe an early Cambrian fossil site in China that contains a variety of specimens, more than half of which are previously undescribed (see the Perspective by Daley). The site rivals previously described Cambrian sites, such as the Burgess Shale, and should help to elucidate biological innovation and diversification during this period.

Abstract

Burgess Shale–type fossil Lagerstätten provide the best evidence for deciphering the biotic patterns and magnitude of the Cambrian explosion. Here, we report a Lagerstätte from South China, the Qingjiang biota (~518 million years old), which is dominated by soft-bodied taxa from a distal shelf setting. The Qingjiang biota is distinguished by pristine carbonaceous preservation of labile organic features, a very high proportion of new taxa (~53%), and preliminary taxonomic diversity that suggests it could rival the Chengjiang and Burgess Shale biotas. Defining aspects of the Qingjiang biota include a high abundance of cnidarians, including both medusoid and polypoid forms; new taxa resembling extant kinorhynchs; and abundant larval or juvenile forms. This distinctive composition holds promise for providing insights into the evolution of Cambrian ecosystems across environmental gradients.

Reconstruction of seafloor life in China, 518 million years ago, by Science

So far, nearly 4500 animals of over 100 species have been found. Including small trilobites, early chordates and sponges. And the oldest kinorhynchs animals known so far.

See beautiful fossils from top Cambrian sites around the world: here.

Worms lived on Cambrian seafloor


This 2012 video from Canada says about itself:

Associate Curator Jean-Bernard Caron presents an overview of the fossil collection from the Burgess Shale, B.C., highlighting a number of specimens.

From the University of Saskatchewan in Canada:

500-million-year old worm ‘superhighway’ discovered in Canada

February 28, 2019\

Prehistoric worms populated the sea bed 500 million years ago — evidence that life was active in an environment thought uninhabitable until now, research by the University of Saskatchewan (USask) shows.

The sea bed in the deep ocean during the Cambrian period was thought to have been inhospitable to animal life because it lacked enough oxygen to sustain it.

But research published in the scientific journal Geology reveals the existence of fossilized worm tunnels dating back to the Cambrian period — 270 million years before the evolution of dinosaurs.

The discovery, by USask professor Brian Pratt, suggests that animal life in the sediment at that time was more widespread than previously thought.

The worm tunnels — borrows where worms lived and munched through the sediment — are invisible to the naked eye. But Pratt “had a hunch” and sliced the rocks and scanned them to see whether they revealed signs of ancient life.

The rocks came from an area in the remote Mackenzie Mountains of the Northwest Territories in Canada which Pratt found 35 years ago.

Pratt then digitally enhanced images of the rock surfaces so he could examine them more closely. Only then did the hidden ‘superhighway’ of burrows made by several different sizes and types of prehistoric worm emerge in the rock.

Some were barely a millimetre in size and others as large as a finger. The smaller ones were probably made by simple polychaetes — or bristle worms — but one of the large forms was a predator that attacked unsuspecting arthropods and surface-dwelling worms.

Pratt said he was “surprised” by the unexpected discovery.

“For the first time, we saw evidence of large populations of worms living in the sediment — which was thought to be barren,” he said. “There were cryptic worm tunnels — burrows — in the mud on the continental shelf 500 million years ago, and more animals reworking, or bioturbating, the sea bed than anyone ever thought.”

Pratt, a geologist and paleontologist and Fellow of the Geological Society of America, found the tunnels in sedimentary rocks that are similar to the Burgess Shale, a famous fossil-bearing deposit in the Canadian Rockies.

The discovery may prompt a rethink of the level of oxygenation in ancient oceans and continental shelves.

The Cambrian period saw an explosion of life on Earth in the oceans and the development of multi-cellular organisms including prehistoric worms, clams, snails and ancestors of crabs and lobsters. Previously the seas had been inhabited by simple, single-celled microbes and algae.

It has always been assumed that the creatures in the Burgess Shale — known for the richness of its fossils — had been preserved so immaculately because the lack of oxygen at the bottom of the sea stopped decay, and because no animals lived in the mud to eat the carcasses.

Pratt’s discovery, with co-author Julien Kimmig, now of the University of Kansas, shows there was enough oxygen to sustain various kinds of worms in the sea bed.

“Serendipity is a common aspect to my kind of research,” Pratt said. “I found these unusual rocks quite by accident all those years ago. On a hunch I prepared a bunch of samples and when I enhanced the images I was genuinely surprised by what I found,” he said.

“This has a lot of implications which will now need to be investigated, not just in Cambrian shales but in younger rocks as well. People should try the same technique to see if it reveals signs of life in their samples.”

The research was funded by the Natural Sciences and Engineering Research Council of Canada.

Ancient Cambrian worms family tree research


This June 2018 video in Portuguese is about the fossil worm Amiskwia.

From the University of Bristol in England:

Half-a-billion-year-old weird wonder worm finally gets its place in the tree of life

February 21, 2019

Summary: Paleobiologists have shed new light on a jaw-snapping species of prehistoric worm using half-a-billion-year-old fossils kept at the Smithsonian Institute in Washington, D.C.

Amiskwia was originally described by the famous palaeontologist Charles Doolittle Walcott (1850-1927) in 1911 who compared it to the modern arrow worms (chaetognaths) — a group of ocean-dwelling worms that are fierce predators, equipped with an array of spines on their head for grasping small prey.

Such organisms are found world-wide at sites like the famous Burgess Shale in the Canadian Rockies, where their soft bodies are preserved intact.

The strange anatomies exhibited by these animals led the American palaeontologist Stephen Jay Gould (1941-2002) to speculate that these organisms represented extinct body plans that are no longer seen today and that if we were to wind back the clocks to the Cambrian, more than 500-million-years-ago, and re-run the tape of life, then perhaps the animals alive today would look very different.

More than 50 years after Doolittle Walcott came up with his theory about Amiskwia, scientists investigated its affinities and rejected his interpretation as they could not find evidence of the canonical grasping spines.

Instead, they suggested it could be a ribbon worm, or its own distinct lineage only distantly related to anything that resembles it today.

When Dr Jakob Vinther from the University of Bristol’s Schools of Earth Sciences and Biological Sciences and Luke Parry, now at Yale University, studied specimens of Amiskwia, kept at the Smithsonian Institution they found something that had been missed before.

Dr Vinther said: “I coated the specimen with ammonium chloride smoke to make the relief of the fossil stand out and then I could see that in the head was a pair of robust elements.”

Interpreting these structures as a set of jaws, their resemblance led him to think of a group of animals, called gnathiferans, which include rotifers, gnathostomulids and micrognathozoans. These animals are microscopic worms, with a distinctive internal jaw apparatus.

The scientists realised that Amiskwia suddenly had a jaw of a gnathiferan, but a body of an arrow worm.

Dr Vinther said: “The bizarre combination of anatomy seemed altogether alien back in 2012.

“Some people have proposed that there could be a relationship between arrow worms and gnathiferans based on their shared possession of a jaw apparatus, both made of a substance called chitin.

“However, there was little other evidence to suggest a relationship, such as evidence from phylogenetic analyses of DNA.”

Luke Parry added: “It altogether seemed like heresy to propose that gnathiferans and arrow worms may be related back then so we held off publishing our intriguing results out of fear of criticism from our peers.

“However, new DNA studies have since emerged that found arrow worms to be more and more closely affiliated to the Gnathifera in the Tree of Life.

Worms family tree

“In particular, some researchers found that arrow worms share a duplication of the important Hox genes with a gnathiferan, the rotifers. We suddenly felt no more in a deadlock situation.”

Now the authors have published their findings in the journal Current Biology. The study follows a new phylogenetic study, which finds robust support for arrow worms forming an evolutionary group with gnathiferans.

Luke Parry said: “We were excited to see that these researchers found a relationship between arrow worms and rotifers.

“Our phylogenetic analysis, based on anatomical features, strongly suggest a relationship between these two groups of animals as well.”

The researchers find that Amiskwia is a stem lineage to arrow worms that possess the jaw apparatus seen in gnathiferan worms.

This jaw evolved into the fearsome grasping spines in living arrow worms, which now is an important link in the marine food chain. Small crustacean larvae have evolved long protective spines to protect themselves from being swallowed by arrow worms.

Cambrian animals’ eyes, new research


This video says about itself:

Colours of Life – The Evolution of Colour Vision Expressed in Musical Colours – Iris Stal

23 August 2018

A composition by Iris Stal.

This is a composition I wrote for a university assignment for a course on interdisciplinary evolution. It’s the very first composition I’ve ever written! 🙂 This piece for orchestra is supposed to express how colour vision has evolved throughout its evolutionary timeline, using musical colours.

Our eyes use cones to detect the colours in the light waves that we pick up. In the music, I attempted to explain which cones came up with which group of animals and how that affected the way they saw their environment. If important, I also tried to take important events or circumstances along in the atmosphere, such as natural selection influences or extinctions. I followed the lineage from one of the very first light-sensitive eyecups all the way up to human eyes. Lineages that branched off I didn’t include as it would be too much.

The coloured bars on the left show what cones the animals had. The cones symbolize cones for blue light, red, green and UV. I used video footage and/or illustrations that I edited to show how the species potentially perceived their environment. It’s not super accurate, but it’s hard imitating a colour the human eye can’t see. 😀 Looking at you, ultraviolet!

This project was sooo much fun to create! It was tons of work but it was absolutely worth the effort. I finished the project with a 9/10. It inspired me to continue with my passion for music. I hope you enjoy the video! 🙂

From the University of Bristol in England:

Enhancing our vision of the past

December 5, 2018

An international group of scientists led by researchers from the University of Bristol have advanced our understanding of how ancient animals saw the world by combining the study of fossils and genetics.

Ancestors of insects and crustaceans that lived more than 500 million years ago in the Cambrian period were some of the earliest active predators, but not much is known about how their eyes were adapted for hunting.

Work published in the Proceedings of the Royal Society B today suggests that when fossil and genetic data are assessed in tandem, previously inaccessible and exciting conclusions about long dead species can be made.

By examining the morphological characteristics of fossils’ eyes, alongside the genetic visual pigment clues, a cross-disciplinary team led by a collaboration between the University of Bristol’s Davide Pisani, Professor of Phylogenomics in the School of Earth Sciences and Nicholas Roberts, Professor of Sensory Ecology in the School of Biological Sciences, were able to find that ancient predators with more complex eyes are likely to have seen in colour.

Professor Pisani remarked: “Being able to combine fossil and genetic data in this way is a really exciting frontier of modern palaeontological and biological research. Vision is key to many animals’ behaviour and ecology, and understanding how extinct animals perceived their environment will help enormously to clarify how they evolved.”

By calculating the time of emergence of different visual pigments, and then comparing them to the inferred age of origin of key fossil lineages, the researchers were able to work out the number of pigments likely to have been possessed by different fossil species. They found that fossil animals with more complex eyes appeared to have more visual pigments, and that the great predators of the Cambrian period may have been able to see in colour.

Dr James Fleming, Professor Pisani and Roberts’ former PhD student, explained: “Animal genomes and therefore opsin genes (constituting the base of different visual pigments) evolve by processes of gene duplication. The opsin and the pigment that existed before the duplication is like a parent, and the two new opsins (and pigments) that emerge from the duplication process are like children on a family tree.

“We calculated the birth dates of these children and this allowed understanding of what the ancient world must have seemed like to the animals that occupied it. We found that while some of the fossils we considered had only one pigment and were monochromat, i.e. they saw the world as if looking into a black and white TV, forms with more complex eyes, like iconic trilobites, had many pigments and most likely saw their world in colours.”

The combinations of complex eyes and multiple kinds of visual pigments are what allows animals to distinguish between different objects based on colour alone — what we know as colour vision.

Professor Roberts commented: “It is remarkable to see how in only a very few million years the view those animals’ had of their world changed from greys to the colourful world we see today.”

The project involved scientists from all across the world — from the UK as well as Denmark, Italy, Korea and Japan, where Dr Fleming has now moved to work as a postdoctoral researcher. Each of them brought their own specialities to this multidisciplinary work, providing expertise in genetics, vision, taxonomy and palaeontology.

Cambrian animals caused global warming


This 2015 video says about itself:

What caused the Cambrian explosion? | The Economist

For most of the Earth’s history, life consisted of the simplest organisms; but then something happened that would give rise to staggering diversity, and, ultimately, life as complex as that which we see today. Scientists are still struggling to figure out just what that was.

From the University of Exeter in England:

World’s first animals likely caused global warming

July 2, 2018

The evolution of Earth’s first animals more than 500 million years ago caused global warming, new research shows.

Some 520-540 million years ago, animal life evolved in the ocean and began breaking down organic material on the seafloor, leading to more carbon dioxide and less oxygen in the atmosphere.

In the 100 million years that followed, conditions for these earliest animals became much harsher, as ocean oxygen levels fell and carbon dioxide caused global warming.

The research, published in Nature Communications, is from the Universities of Exeter, Leeds and Antwerp, and the Vrije Universiteit Brussel.

“Like worms in a garden, tiny creatures on the seabed disturb, mix and recycle dead organic material — a process known as bioturbation”, said Professor Tim Lenton, from the University of Exeter.

“Because the effect of animals burrowing is so big, you would expect to see big changes in the environment when the whole ocean floor changes from an undisturbed state to a bioturbated state.”

“We did indeed see a decrease in oxygen levels in the ocean around 520 million years ago”, said Professor Filip Meysman, from the University of Antwerp.

“But evidence from the rock record showed sediment was only a little disturbed.”

Professor Simon Poulton, from the University of Leeds, said: “This meant that the animals living in the seafloor at that time were not very active, and did not move very deep into the seabed.

“At first sight, these two observations did not seem to add up.”

Lead author Dr Sebastiaan van de Velde, of the Vrije Universiteit Brussel, explained: “The critical factor was to realise that the biggest changes happen at the lowest levels of animal activity.

“This meant that the first bioturbators had a massive impact.”

The researchers said this realisation was the “missing piece of the puzzle,” and allowed them to construct a mathematical model of Earth around that time to look to the changes caused by these early life forms.

Dr Benjamin Mills, also from the University of Leeds, who led this part of the research, said: “When we ran our model, we were surprised by what we saw.

“The evolution of these small animals did indeed decrease the oxygen in the ocean and atmosphere, but also increased atmospheric carbon dioxide levels to such an extent that it caused a global warming event.

“We knew that warming occurred at this point in Earth history, but did not realise it could be driven by animals.”

This process made conditions worse for these animals, which possibly contributed to a number of mass extinction events during the first 100 million years of animal evolution.

“There is an interesting parallel between the earliest animals changing their world in a way that was bad for them, and what we human animals are doing to the planet now“, said Professor Lenton, director of Exeter’s new Global Systems Institute, which aims to develop transformative solutions to the challenges facing the world today.

“We are creating a hotter world with expanding ocean anoxia (oxygen deficiency) which is bad for us and a lot of other creatures we share the planet with.”

Sponge-like Cambrian fossil discovery


Allonia nuda. Credit: Derek Siveter/Tom Harvey/Peiyun Cong

From the University of Leicester in England:

Strange sponge-like fossil creature from half a billion years ago

June 19, 2018

Summary: A discovery of a new species of sponge-like fossil from the Cambrian Period sheds light on early animal evolution.

Scientists have discovered the fossil of an unusual large-bodied sponge-like sea-creature from half a billion years ago.

The creature belongs to an obscure and mysterious group of animals known as the chancelloriids, and scientists are unclear about where they fit in the tree of life.

They represent a lineage of spiny tube-shaped animals that arose during the Cambrian evolutionary “explosion” but went extinct soon afterwards. In some ways they resemble sponges, a group of simple filter-feeding animals, but many scientists have dismissed the similarities as superficial.

The new discovery by a team of scientists from the University of Leicester, the University of Oxford and Yunnan University, China, adds new evidence that could help solve the mystery.

The researchers have published their findings in the Royal Society journal Proceedings of the Royal Society B. The Leicester authors are Tom Harvey, Mark Williams, David Siveter & Sarah Gabbott.

The new species, named Allonnia nuda, was discovered in the Chengjiang deposits of Yunnan Province, China. It was surprisingly large in life (perhaps up to 50 cm or more) but had only a few very tiny spines. Its unusual “naked” appearance suggests that further specimens may be “hiding in plain sight” in fossil collections, and shows that this group was more diverse than previously thought.

Furthermore, the new species holds clues about the pattern of body growth, with clear links to modern sponges. It is too soon to say the mystery has been solved, but the discovery highlights the central role of sponge-like fossils in the debate over earliest animal evolution.

Dr Tom Harvey, from the University of Leicester’s School of Geography, Geology and the Environment, explained: “Fossil chancelloriids were first described around 100 years ago, but have resisted attempts to place them in the tree of life. We argue that their pattern of body growth supports a link to sponges, reinvigorating an old hypothesis. We’re not suggesting that it’s “case closed” for chancelloriids, but we hope our results will inspire new research into the nature of the earliest animals.”

Dr Peiyun Cong, from the Yunnan Key Laboratory for Palaeobiology, Kunming, China, and The Natural History Museum, UK, added: “The Chengjiang deposits of Yunnan Province continue to reveal surprising new fossils we could hardly have imagined. Together, they provide a crucial snapshot of life in the oceans during the Cambrian explosion.”

Cambrian explosion and arthropod evolution


This 2015 video from the USA says about itself:

What is an Arthropod?

Dan Babbitt, manager of the Smithsonian’s Insect Zoo, shows why the name of the zoo is a little imprecise. The Insect Zoo is home to all five major groups of arthropods—insects, arachnids, crustaceans, millipedes, and centipedes—all of which Babbitt defines.

From the University of Oxford in England:

Major fossil study sheds new light on emergence of early animal life 540 million years ago

Most comprehensive analysis of Earth’s largest animal group — the euarthropods — shows they evolved gradually, challenging major theories of early animal evolution

May 21, 2018

All the major groups of animals appear in the fossil record for the first time around 540-500 million years ago — an event known as the Cambrian Explosion — but new research from the University of Oxford in collaboration with the University of Lausanne suggests that for most animals this ‘explosion’ was in fact a more gradual process.

The Cambrian Explosion produced the largest and most diverse grouping of animals the Earth has ever seen: the euarthropods. Euarthropoda contains the insects, crustaceans, spiders, trilobites, and a huge diversity of other animal forms alive and extinct. They comprise over 80 percent of all animal species on the planet and are key components of all of Earth’s ecosystems, making them the most important group since the dawn of animals over 500 million years ago.

A team based at Oxford University Museum of Natural History and the University of Lausanne carried out the most comprehensive analysis ever made of early fossil euarthropods from every different possible type of fossil preservation. In an article published today in the Proceedings of the National Academy of Sciences they show that, taken together, the total fossil record shows a gradual radiation of euarthropods during the early Cambrian, 540-500 million years ago.

The new analysis presents a challenge to the two major competing hypotheses about early animal evolution. The first of these suggests a slow, gradual evolution of euarthropods starting 650-600 million years ago, which had been consistent with earlier molecular dating estimates of their origin. The other hypothesis claims the nearly instantaneous appearance of euarthropods 540 million years ago because of highly elevated rates of evolution.

The new research suggests a middle-ground between these two hypotheses, with the origin of euarthropods no earlier than 550 million years ago, corresponding with more recent molecular dating estimates, and with the subsequent diversification taking place over the next 40 million years.

“Each of the major types of fossil evidence has its limitation and they are incomplete in different ways, but when taken together they are mutually illuminating and allow a coherent picture to emerge of the origin and radiation of the euarthropods during the lower to middle Cambrian”, explains Professor Allison Daley, who carried out the work at Oxford University Museum of Natural History and at the University of Lausanne. “This indicates that the Cambrian Explosion, rather than being a sudden event, unfolded gradually over the ~40 million years of the lower to middle Cambrian.”

The timing of the origin of Euarthropoda is very important as it affects how we view and interpret the evolution of the group. By working out which groups developed first we can trace the evolution of physical characteristics, such as limbs.

It has been argued that the absence of euarthropods from the Precambrian Period, earlier than around 540 million years ago, is the result of a lack of fossil preservation. But the new comprehensive fossil study suggests that this isn’t the case.

“The idea that arthropods are missing from the Precambrian fossil record because of biases in how fossils are preserved can now be rejected”, says Dr Greg Edgecombe FRS from the Natural History Museum, London, who was not involved in the study. “The authors make a very compelling case that the late Precambrian and Cambrian are in fact very similar in terms of how fossils preserve. There is really just one plausible explanation — arthropods hadn’t yet evolved.”

Harriet Drage, a PhD student at Oxford University Department of Zoology and one of the paper’s co-authors, says: “When it comes to understanding the early history of life the best source of evidence that we have is the fossil record, which is compelling and very complete around the early to middle Cambrian. It speaks volumes about the origin of euarthropods during an interval of time when fossil preservation was the best it has ever been.”

Brachiopod fossils, clue to Cambrian climate


This 2008 video says about itself:

Invertebrate Fossils – Lesson 16 – Part 2 of 7

Horn coral
Brachiopod shells with external spines
• Seasonal growth of coral
Cambrian fauna
• Precambrian Ediacara fauna Australia – First fossils formed with many cells

From the University of Leicester in England:

Tiny fossils unlock clues to Earth’s climate half a billion years ago

May 9, 2018

An international collaboration of scientists, led by the University of Leicester, has investigated Earth’s climate over half a billion years ago by combining climate models and chemical analyses of fossil shells about 1mm long.

The research, published in Science Advances, suggests that early animals diversified within a climate similar to that in which the dinosaurs lived.

This interval in time is known for the ‘Cambrian explosion‘, the time during which representatives of most of the major animal groups first appear in the fossil record. These include the first animals to produce shells, and it is these shelly fossils that the scientists used.

Scientists have long thought that the early Cambrian Period was probably a greenhouse interval in Earth’s climate history, a time when there were no permanent polar ice sheets.

Until now, however, scientists have only had a sense of what the Cambrian climate was like because of the types of rock that were deposited at this time — while it has long been believed that the climate was warm, specific details have largely remained a mystery.

Data from the tiny fossil shells, and data from new climate model runs, show that high latitude (~65 °S) sea temperatures were in excess of 20 °C. This seems very hot, but it is similar to more recent, better understood, greenhouse climates like that of the Late Cretaceous Period.

Thomas Hearing, a PhD student from the University of Leicester’s School of Geography, Geology and the Environment, explained: “Because scientists cannot directly measure sea temperatures from half a billion years ago, they have to use proxy data — these are measurable quantities that respond in a predictable way to changing climate variables like temperature. In this study, we used oxygen isotope ratios, which is a commonly used palaeothermometer.

“We then used acid to extract fossils about 1mm long from blocks of limestone from Shropshire, UK, dated to between 515 — 510 million years old. Careful examination of these tiny fossils revealed that some of them have exceptionally well-preserved shell chemistry which has not changed since they grew on the Cambrian sea floor.”

Dr Tom Harvey, from the School of Geography, Geology and the Environment, added: “Many marine animals incorporate chemical traces of seawater into their shells as they grow. That chemical signature is often lost over geological time, so it’s remarkable that we can identify it in such ancient fossils.”

Analyses of the oxygen isotopes of these fossils suggested very warm temperatures for high latitude seas (~65 °S), probably between 20 °C to 25 °C.

To see if these were feasible sea temperatures, the scientists then ran climate model simulations for the early Cambrian. The climate model simulations also suggest that Earth’s climate was in a ‘typical’ greenhouse state, with temperatures similar to more recent, and better understood, greenhouse intervals in Earth’s climate history, like the late Mesozoic and early Cenozoic eras.

Ultimately, these findings help to expand our knowledge of the early animals of the period and the environment in which they lived.

Thomas Hearing said: “We hope that this approach can be used by other researchers to build up a clearer picture of ancient climates where conventional climate proxy data are not available.”

The research was carried out as an international collaboration involving scientists from the University of Leicester (UK), British Geological Survey (BGS; UK), and CEREGE (France). This collaboration brought together expertise in geochemistry, palaeontology and climate modelling to tackle this longstanding problem.

The scientists have co-authored an open access (publicly available) paper in the journal Science Advances.

Land plants older than than previously thought


This 2016 video says about itself:

Right at the beginning of the Paleozoic, there was a huge explosion of more complex life. And that’s when things started to get really interesting. This is our second installment on the history of life, but you can watch in any order you like!

From the University of Bristol in England:

Plants colonized Earth 100 million years earlier than previously thought

February 19, 2018

Summary: A new study on the timescale of plant evolution has concluded that the first plants to colonize the Earth originated around 500 million years ago — 100 million years earlier than previously thought.

For the first four billion years of Earth’s history, our planet’s continents would have been devoid of all life except microbes.

All of this changed with the origin of land plants from their pond scum relatives, greening the continents and creating habitats that animals would later invade.

The timing of this episode has previously relied on the oldest fossil plants which are about 420 million years old.

New research, published today in the journal Proceedings of the National Academy of Sciences, indicates that these events actually occurred a hundred million years earlier, changing perceptions of the evolution of the Earth’s biosphere.

Plants are major contributors to the chemical weathering of continental rocks, a key process in the carbon cycle that regulates Earth’s atmosphere and climate over millions of years.

The team used ‘molecular clock’ methodology, which combined evidence on the genetic differences between living species and fossil constraints on the age of their shared ancestors, to establish an evolutionary timescale that sees through the gaps in the fossil record.

Dr Jennifer Morris, from the University of Bristol’s School of Earth Sciences and co-lead author on the study, explained: “The global spread of plants and their adaptations to life on land, led to an increase in continental weathering rates that ultimately resulted in a dramatic decrease [of] the levels of the ‘greenhouse gas’ carbon dioxide in the atmosphere and global cooling.

“Previous attempts to model these changes in the atmosphere have accepted the plant fossil record at face value — our research shows that these fossil ages underestimate the origins of land plants, and so these models need to be revised.”

Co-lead author Mark Puttick described the team’s approach to produce the timescale. He said: “The fossil record is too sparse and incomplete to be a reliable guide to date the origin of land plants. Instead of relying on the fossil record alone, we used a ‘molecular clock’ approach to compare differences in the make-up of genes of living species — these relative genetic differences were then converted into ages by using the fossil ages as a loose framework.

“Our results show the ancestor of land plants was alive in the middle Cambrian Period, which was similar to the age for the first known terrestrial animals.”

One difficulty in the study is that the relationships between the earliest land plants are not known. Therefore the team, which also includes members from Cardiff University and the Natural History Museum, London, explored if different relationships changed the estimated origin time for land plants.

Leaders of the overall study, Professor Philip Donoghue and Harald Schneider added: “We used different assumptions on the relationships between land plants and found this did not impact the age of the earliest land plants.

“Any future attempts to model atmospheric changes in deep-time must incorporate the full range of uncertainties we have used here.”

The ancestors of land plants were string-like (2D), aquatic green algae that looked very different from the three-dimensional (3D), upright stems and leaves of plants we are familiar with today. Now, researchers have revealed exciting insights into how land plants evolved these 3D forms that were crucial for their advancement onto land: here.