̽��ֱ�� of Cambridge - Simon Conway-Morris

World first as Bell Burnell pulsar chart goes on display

sjr81 — Fri, 08 Mar 2019 09:52:27 +0000

Iconic object exhibited for the first time, alongside works by Isaac Newton and Stephen Hawking at Cambridge ̽��ֱ�� Library.

Big, shape-shifting animals from the dawn of time

sc604 — Mon, 10 Jul 2017 14:48:33 +0000

Why did life on Earth change from small to large when it did? Researchers from the ̽��ֱ�� of Cambridge and the Tokyo Institute of Technology have determined how some of the first large organisms, known as rangeomorphs, were able to grow up to two metres in height, by changing their body size and shape as they extracted nutrients from their surrounding environment.

̽��ֱ��results, reported in the journal Nature Ecology and Evolution, could also help explain how life on Earth, which once consisted only of microscopic organisms, changed so that huge organisms like dinosaurs and blue whales could ultimately evolve.

Rangeomorphs were some of the earliest large organisms on Earth, existing during a time when most other forms of life were microscopic in size. Some rangeomorphs were only a few centimetres in height, while others were up to two metres tall.

These organisms were ocean dwellers that lived during the Ediacaran period, between 635 and 541 million years ago. Their soft bodies were made up of branches, each with many smaller side branches, forming a geometric shape known as a fractal, which can be seen today in things like lungs, ferns and snowflakes.

Since rangeomorphs don’t resemble any modern organism, it’s difficult to understand how they fed, grew or reproduced, let alone how they might link with any modern group. However, although they look somewhat like plants, scientists believe that they may have been some of the earliest animals to live on Earth.

“What we wanted to know is why these large organisms appeared at this particular point in Earth’s history,” said Dr Jennifer Hoyal Cuthill of Cambridge’s Department of Earth Sciences and Tokyo Tech’s Earth-Life Science Institute, the paper’s first author. “They show up in the fossil record with a bang, at very large size. We wondered, was this simply a coincidence or a direct result of changes in ocean chemistry?”

̽��ֱ��researchers used micro-CT scanning, photographic measurements and mathematical and computer models to examine rangeomorph fossils from south-eastern Newfoundland, Canada, the UK and Australia.

Their analysis shows the earliest evidence for nutrient-dependent growth in the fossil record. All organisms need nutrients to survive and grow, but nutrients can also dictate body size and shape. This is known as ‘ecophenotypic plasticity.’ Hoyal Cuthill and her co-author Professor Simon Conway Morris suggest that rangeomorphs not only show a strong degree of ecophenotypic plasticity, but that this provided a crucial advantage in a dramatically changing world. For example, rangeomorphs could rapidly “shape-shift”, growing into a long, tapered shape if the seawater above them happened to have elevated levels of oxygen.

“During the Ediacaran, there seem to have been major changes in the Earth’s oceans, which may have triggered growth, so that life on Earth suddenly starts getting much bigger,” said Hoyal Cuthill. “It’s probably too early to conclude exactly which geochemical changes in the Ediacaran oceans were responsible for the shift to large body sizes, but there are strong contenders, especially increased oxygen, which animals need for respiration.”

This change in ocean chemistry followed a large-scale ice age known as the Gaskiers glaciation. When nutrient levels in the ocean were low, they appear to have kept body sizes small. But with a geologically sudden increase in oxygen or other nutrients, much larger body sizes become possible, even in organisms with the same genetic makeup. This means that the sudden appearance of rangeomorphs at large size could have been a direct result of major changes in climate and ocean chemistry.

However, while rangeomorphs were highly suited to their Ediacaran environment, conditions in the oceans continued to change and from about 541 million years ago the ‘Cambrian Explosion’ began – a period of rapid evolutionary development when most major animal groups first appeared in the fossil record. When the conditions changed, the rangeomorphs were doomed and nothing quite like them has been seen since.

Reference
Jennifer F. Hoyal Cuthill and Simon Conway Morris. ‘Nutrient-dependent growth underpinned the Ediacaran transition to large body size.’ Nature Ecology and Evolution (2017). DOI: 10.1038/s41559-017-0222-7.

Major changes in the chemical composition of the world’s oceans enabled the first large organisms – possibly some of the earliest animals – to exist and thrive more than half a billion years ago, marking the point when conditions on Earth changed and animals began to take over the world.

We wanted to know why these large organisms appeared at this particular point in Earth’s history.

Jennifer Hoyal Cuthill

Artist's impression of rangeomorphs

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Bag-like sea creature was humans’ oldest known ancestor

tdk25 — Mon, 30 Jan 2017 08:57:51 +0000

Researchers have identified traces of what they believe is the earliest known prehistoric ancestor of humans – a microscopic, bag-like sea creature, which lived about 540 million years ago.

Named Saccorhytus, after the sack-like features created by its elliptical body and large mouth, the species is new to science and was identified from microfossils found in China. It is thought to be the most primitive example of a so-called 'deuterostome' – a broad biological category that encompasses a number of sub-groups, including the vertebrates.

If the conclusions of the study, published in the journal Nature, are correct, then Saccorhytus was the common ancestor of a huge range of species, and the earliest step yet discovered on the evolutionary path that eventually led to humans, hundreds of millions of years later.

Modern humans are, however, unlikely to perceive much by way of a family resemblance. Saccorhytus was about one millimetre in size, and probably lived between grains of sand on the seabed. Its features were spectacularly preserved in the fossil record – and intriguingly, the researchers were unable to find any evidence that the animal had an anus.

̽��ֱ��study was carried out by an international team of academics, including researchers from Cambridge in the UK and Northwest ̽��ֱ�� in Xi’an China, with support from other colleagues at institutions in China and Germany.

Simon Conway Morris, Professor of Evolutionary Palaeobiology and a Fellow of St John’s College, ̽��ֱ�� of Cambridge, said: “We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves. To the naked eye, the fossils we studied look like tiny black grains, but under the microscope the level of detail is jaw-dropping. All deuterostomes had a common ancestor, and we think that is what we are looking at here.”

Degan Shu, from Northwest ̽��ֱ��, added: “Our team has notched up some important discoveries in the past, including the earliest fish and a remarkable variety of other early deuterostomes. Saccorhytus now gives us remarkable insights into the very first stages of the evolution of a group that led to the fish, and ultimately, to us.”

Most other early deuterostome groups are from about 510 to 520 million years ago, when they had already begun to diversify into not just the vertebrates, but the sea squirts, echinoderms (animals such as starfish and sea urchins) and hemichordates (a group including things like acorn worms). This level of diversity has made it extremely difficult to work out what an earlier, common ancestor might have looked like.

̽��ֱ��Saccorhytus microfossils were found in Shaanxi Province, in central China, and pre-date all other known deuterostomes. By isolating the fossils from the surrounding rock, and then studying them both under an electron microscope and using a CT scan, the team were able to build up a picture of how Saccorhytus might have looked and lived. This revealed features and characteristics consistent with current assumptions about primitive deuterostomes.

Dr Jian Han, of Northwest ̽��ֱ��, said: “We had to process enormous volumes of limestone – about three tonnes – to get to the fossils, but a steady stream of new finds allowed us to tackle some key questions: was this a very early echinoderm, or something even more primitive? ̽��ֱ��latter now seems to be the correct answer.”

In the early Cambrian period, the region would have been a shallow sea. Saccorhytus was so small that it probably lived in between individual grains of sediment on the sea bed.

̽��ֱ��study suggests that its body was bilaterally symmetrical – a characteristic inherited by many of its descendants, including humans – and was covered with a thin, relatively flexible skin. This in turn suggests that it had some sort of musculature, leading the researchers to conclude that it could have made contractile movements, and got around by wriggling.

Perhaps its most striking feature, however, was its rather primitive means of eating food and then dispensing with the resulting waste. Saccorhytus had a large mouth, relative to the rest of its body, and probably ate by engulfing food particles, or even other creatures.

A crucial observation are small conical structures on its body. These may have allowed the water that it swallowed to escape and so were perhaps the evolutionary precursor of the gills we now see in fish. But the researchers were unable to find any evidence that the creature had an anus. “If that was the case, then any waste material would simply have been taken out back through the mouth, which from our perspective sounds rather unappealing,” Conway Morris said.

̽��ֱ��findings also provide evidence in support of a theory explaining the long-standing mismatch between fossil evidence of prehistoric life, and the record provided by biomolecular data, known as the 'molecular clock'.

Technically, it is possible to estimate roughly when species diverged by looking at differences in their genetic information. In principle, the longer two groups have evolved separately, the greater the biomolecular difference between them should be, and there are reasons to think this process is more or less clock-like.

Unfortunately, before a point corresponding roughly to the time at which Saccorhytus was wriggling in the mud, there are scarcely any fossils available to match the molecular clock’s predictions. Some researchers have theorised that this is because before a certain point, many of the creatures they are searching for were simply too small to leave much of a fossil record. ̽��ֱ��microscopic scale of Saccorhytus, combined with the fact that it is probably the most primitive deuterostome yet discovered, appears to back this up.

̽��ֱ��findings are published in Nature. Reference: Jian Han, Simon Conway Morris, Qiang Ou, Degan Shu and Hai Huang. Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China). DOI: 10.1038/nature21072.

Inset image: Photographs of the fossils show the spectacularly detailed levels of preservation which allowed researchers to identify and study the creature. Credit: Jian Han.

A tiny sea creature identified from fossils found in China may be the earliest known step on an evolutionary path that eventually led to the emergence of humans

We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves

Simon Conway Morris

Jian Han

Artist’s reconstruction of Saccorhytus coronarius, based on the original fossil finds. ̽��ֱ��actual creature was probably no more than a millimetre in size

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Evolution website sets out to tackle great scientific unknowns

tdk25 — Wed, 18 Nov 2015 11:28:54 +0000

Are there actually Martians out there? Could life survive in boiling water? And more importantly, what is your dog really thinking?

If these are the sort of questions that keep you awake at night, then help is finally at hand, in the form of a new website created by a team of scientists at Cambridge and featuring contributions from a host of leading academics.

Named Forty Two (after Douglas Adams’ famously cryptic solution to the meaning of life), the site is an online resource dedicated to the subject of evolution, and includes video interviews in which researchers including Sir David Attenborough, Simon Conway Morris, Eugene Koonin, and Carenza Lewis offer their views on topics ranging from the nature of evolution itself, to the future of life as we know it.

Aimed at general readers and, in particular, young people who are just starting to get into science, its aim is to provide an innovative and authoritative source of information about evolution on the web.

Its creators also hope to demonstrate that evolution is a subject that is, in itself, evolving. To prove this, the site uses the study of evolution to attempt to answer a host of knotty problems drawn from the fringes of current scientific understanding – questions such as “Can you have blue blood?”, “Do insects copulate with flowers?” and “Can you see heat?”

̽��ֱ��site was created by a team led by Simon Conway Morris, Professor of Evolutionary Palaeobiology and a Fellow of St John’s College at the ̽��ֱ�� of Cambridge. “Evolution is true, and if it didn’t happen, we wouldn’t be here,” he said. “Like all the sciences, evolution is constantly, well, evolving. New insights and unexpected discoveries combine with seeing old things in a completely new light. It is active, dynamic, changing and unpredictable. We wanted to create a website that captures the excitement and thrill of that exploration.”

̽��ֱ��site features a unique video archive that collects the thoughts of leading scientists around the world. ̽��ֱ��most familiar, Sir David Attenborough, is, for example, captured reflecting with troubling pessimism about the future of the planet, in response to the question: “Are you optimistic about the human species?” “ ̽��ֱ��truthful answer is that I am not,” he replies. “It seems to me almost inevitable that things are going to get worse before they get better… and the only way that we can stop that is by reducing carbon emissions very, very quickly indeed.”

Around that archive, the website’s designers have constructed a living database of information about evolutionary studies that illustrates the scope and scale of the scientific discussion that Darwin brought to the fore of public debate more than 150 years ago.

Dr Victoria Ling, from the ̽��ֱ��’s Department of Earth Sciences, said: “When you type ‘evolution’ into Google you get a lot of information, not all of which is very reliable, but even the sources that are reliable can inadvertently give the impression that evolution was ‘solved’ with Darwin. In fact, evolution remains a vibrant area of research and there’s an awful lot left to learn. We wanted to produce a site which showcases that ongoing discussion, one which has plenty of serious content, but also a strong sense of fun.”

̽��ֱ��core material is divided into three main subject areas: “Here And Now”, for topics on which the scientific community has reached a rough consensus; “Near Horizons”, for nagging questions that are hotly debated; and “Far Horizons”, for really big issues that sit at the edge of current knowledge.

Users can also play a careers game that takes a light-hearted look at some of the real tasks real scientists can end up doing in the course of their work. This is personalised to the user’s interests based upon their answers to the questions “What am I into?” “How does my mind work?” and “Where is my focus?”. Historians can meanwhile delve into a selection of potted biographies of scientific pioneers, ranging from familiar figures such as Darwin himself, to lesser-sung heroes and heroines, such as the 19th-century fossil collector Mary Anning, and the American cytogeneticist Barbara McClintock.

Perhaps, however, the site’s most revelatory feature is its selection of Q&A topics so bizarre that they periodically sound more like something out of science fiction, as Douglas Adams himself might have hoped.

Who knew, for example, that rattlesnakes really can “see” heat, in a manner of speaking, thanks to evolved pits close to the front of their faces that relay information about thermal contrasts to the same part of the brain that registers information from the eyes? Or that dogs, which have evolved alertness to human gestures but appear to lack self-awareness may simply be part of a greater consciousness that we ourselves have yet to fathom?

As for the Martians, the answer remains similarly unclear, but Conway-Morris suggests that we might be looking at the wrong planet for alien life. One theory has it that Venus could technically be inhabited by aerial microbes – something equivalent to the extremophiles found on Earth – ekeing out their existence amid the sulphuric clouds shrouding the planet.

“Even today maybe Venusian aerial life wafts its way across the 25 million miles or so of space that separate us,” Conway Morris writes. “Unlikely? Most certainly. Impossible? Perhaps not.”

For more, visit: http://www.42evolution.org/

Additional images taken from www.42evolution.org.

Ever wondered if a fly can ride a bicycle, or whether you could survive only on water? A new website on evolution, created by Cambridge scientists and featuring contributions from luminaries including Sir David Attenborough, has some intriguing answers.

Like all the sciences, evolution is constantly, well, evolving. New insights and unexpected discoveries combine with seeing old things in a completely new light. It is active, dynamic, changing and unpredictable. We wanted to create a website that captures the excitement and thrill of that exploration.

Simon Conway-Morris

FortyTwo – Your evolution resource

www.42evolution.org

http://www.42evolution.org/ is a new website created by a team of scientists at Cambridge and featuring contributions from a host of leading academics.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

“Map Of Life” predicts ET. (So where is he?)

tdk25 — Wed, 01 Jul 2015 23:01:07 +0000

Extra-terrestrials that resemble humans should have evolved on other, Earth-like planets, making it increasingly paradoxical that we still appear to be alone in the universe, the author of a new study on convergent evolution has claimed.

̽��ֱ��argument is one of several that emerge from ̽��ֱ��Runes Of Evolution, a new book in which the leading evolutionary biologist, Professor Simon Conway Morris, makes the case for a ubiquitous “map of life” that governs the way in which all living things develop.

It builds on the established principle of convergent evolution, a widely-supported theory – although one still disputed by some biologists – that different species will independently evolve similar features.

Conway Morris argues that convergence is not just common, but everywhere, and that it has governed every aspect of life’s development on Earth. Proteins, eyes, limbs, intelligence, tool-making – even our capacity to experience orgasms – are, he argues, inevitable once life emerges.

̽��ֱ��book claims that evolution is therefore far from random, but a predictable process that operates according to a fairly rigid set of rules.

If that is the case, then it follows that life similar to that on Earth would also develop in the right conditions on other, equivalent planets. Given the growing number of Earth-like planets of which astronomers are now aware, it is increasingly extraordinary that aliens that look and behave something like us have not been found, he suggests.

“Convergence is one of the best arguments for Darwinian adaptation, but its sheer ubiquity has not been appreciated,” Professor Conway Morris, who is a Fellow at St John’s College, ̽��ֱ�� of Cambridge, said.

“Often, research into convergence is accompanied by exclamations of surprise, describing it as uncanny, remarkable and astonishing. In fact it is everywhere, and that is a remarkable indication that evolution is far from a random process. And if the outcomes of evolution are at least broadly predictable, then what applies on Earth will apply across the Milky Way, and beyond.”

Professor Conway Morris has previously raised the prospect that alien life, if out there, would resemble earthlings – with limbs, heads, and bodies – notably at a Royal Society Conference in London in 2010. His new book goes even further, however, adding that any Earth-like planet should also evolve thunniform predators (like sharks), pitcher plants, mangroves, and mushrooms, among many other things.

Limbs, brains and intelligence would, similarly, be “almost guaranteed”. ̽��ֱ��traits of human-like intelligence have evolved in other species – the octopus and some birds, for example, both exhibit social playfulness – and this, the book suggests, indicates that intelligence is an inevitable consequence of evolution that would characterise extraterrestrials as well.

Underpinning this is Conway Morris’ claim that convergence is demonstrable at every major stepping stone in evolutionary history, from early cells, through to the emergence of tissues, sensory systems, limbs, and the ability to make and use tools.

̽��ֱ��theory, in essence, is that different species will evolve similar solutions to problems via different paths. A commonly-cited example is the octopus, which has evolved a camera eye that is closely similar to that of humans, although distinctive in important ways that reflect its own history. Although octopi and humans have a common ancestor, possibly a slug-like creature, this lived 550 million years ago and lacked numerous complex features that the two now share. ̽��ֱ��camera eye of each must therefore have evolved independently.

Conway Morris argues that this process provides an underlying evolutionary framework that defines all life, and leads to innumerable surprises in the natural world. ̽��ֱ��book cites examples such as collagen, the protein found in connective tissue, which has emerged independently in both fungi and bacteria; or the fact that fruit flies seem to get drunk in the same manner as humans. So too the capacity for disgust in humans – a hard-wired instinct helping us avoid infection and disease – is also exhibited by leaf-cutter ants.

̽��ֱ��study also identifies many less obvious evolutionary “analogues”, where species have evolved certain properties and characteristics that do not appear to be alike, but are actually very similar. For example, “woodpeckerlike habits” are seen in lemurs and extinct marsupials, while the mechanics of an octopus’ tentacles are far closer to those of a human arm than we might expect, and even their suckers can operate rather like hands.

Conway Morris contends that all life navigates across this evolutionary map, the basis of what he describes as a “predictive biology”. “Biology travels through history,” he writes, “but ends up at much the same destination”.

This, however, raises fascinating and problematic questions about the possibility of life occurring on other planets. “ ̽��ֱ��number of Earth-like planets seems to be far greater than was thought possible even a few years ago,” Conway Morris said. “That doesn’t necessarily mean that they have life, because we don’t necessarily understand how life originates. ̽��ֱ��consensus offered by convergence, however, is that life is going to evolve wherever it can.”

“I would argue that in any habitable zone that doesn’t boil or freeze, intelligent life is going to emerge, because intelligence is convergent. One can say with reasonable confidence that the likelihood of something analogous to a human evolving is really pretty high. And given the number of potential planets that we now have good reason to think exist, even if the dice only come up the right way every one in 100 throws, that still leads to a very large number of intelligences scattered around, that are likely to be similar to us.”

If this is so, as the book suggests in its introduction, then it makes Enrico Fermi’s famous paradox – why, if aliens exist, we have not yet been contacted – even more perplexing. “ ̽��ֱ��almost-certainty of ET being out there means that something does not add up, and badly,” Conway Morris said. “We should not be alone, but we are.”

̽��ֱ��Runes Of Evolution was six years in the making and draws on thousands of academic sources, and throws up numerous other, surprising findings as well. Sabre-teeth, for example, turn out to be convergent, and Conway Morris explains why it is that the clouded leopard of Asia, Neofelis nebulosa, has developed features that could, as it evolves “presage the emergence of a new sabre-tooth”, although sadly it looks set to become extinct before this happens. Elsewhere, the study suggests that certain prehistoric creatures other than bats and birds may have attempted to evolve flight.

“It makes people slightly uneasy that evolution can end up reaching the same solutions to questions about how to catch something, how to digest something, and how to work,” Conway Morris added. “But while the number of possibilities in evolution in principle is more than astronomical, the number that actually work is an infinitesimally smaller fraction.”

̽��ֱ��Runes Of Evolution, by Simon Conway Morris, is published by Templeton Press

Inset images:
Top: Shark by Jeff Kubina; Pitcher Plant by NH53; Mangrove by Roberto Verzo; Mushroom by Aleksey Gnilenkov
Middle: Disgust by Stuart Hamilton; Leaf Cutter Ants by Steve Corey
Bottom: Saber-tooth Cat by Chuck Peterson

̽��ֱ��author of a new study of evolutionary convergence argues that the development of life on Earth is predictable, meaning that similar organisms should therefore have appeared on other, Earth-like planets by now.

̽��ֱ��almost-certainty of ET being out there means that something does not add up, and badly. We should not be alone, but we are.

Simon Conway Morris

Albert Kok, via Flickr. Homepage image: Eye of the Octopus by Klaus Stiefel

̽��ֱ��camera eye of an octopus is structurally similar to that of a human, but has evolved independently, making it a classic example of convergent evolution.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Licence type:

Attribution-ShareAlike

How some of the first animals lived - and died

sc604 — Mon, 11 Aug 2014 19:00:00 +0000

A bizarre group of uniquely-shaped organisms known as rangeomorphs may have been some of the earliest animals to appear on Earth, uniquely suited to ocean conditions 575 million years ago.

A new model devised by researchers at the ̽��ֱ�� of Cambridge has resolved many of the mysteries around the structure, evolution and extinction of these ‘proto animals’. ̽��ֱ��findings are reported today (11 August) in the journal Proceedings of the National Academy of Sciences of the United States of America.

Rangeomorphs were some of the earliest large organisms on Earth, existing during a time when most other forms of life were microscopic in size. Most rangeomorphs were about 10 centimetres high, although some were up to two metres in height.

These creatures were ocean dwellers which lived during the Ediacaran period, between 635 and 541 million years ago. Their bodies were made up of soft branches, each with many smaller side branches, forming a geometric shape known as a fractal, which can be seen in many familiar branching shapes such as fern leaves and even river networks.

Rangeomorphs were unlike any modern organism, which has made it difficult to determine how they fed, grew or reproduced, and therefore difficult to link them to any particular modern group. However, despite the fact that they looked like plants, evidence points to the fact that rangeomorphs were actually some of the earliest animals.

“We know that rangeomorphs lived too deep in the ocean for them to get their energy through photosynthesis as plants do,” said Dr Jennifer Hoyal Cuthill of Cambridge’s Department of Earth Sciences, who led the research. “It’s more likely that they absorbed nutrients directly from the sea water through the surface of their body. It would be difficult in the modern world for such large animals to survive only on dissolved nutrients.”

“ ̽��ֱ��oceans during the Ediacaran period were more like a weak soup – full of nutrients such as organic carbon, whereas today suspended food particles are swiftly harvested by a myriad of animals,” said co-author Professor Simon Conway Morris.

Starting 541 million years ago, the conditions in the oceans changed quickly with the start of the Cambrian Explosion – a period of rapid evolution when most major animal groups first emerge in the fossil record and competition for nutrients increased dramatically.

Rangeomorphs have often been considered a ‘failed experiment’ of evolution as they died out so quickly once the Cambrian Explosion began in earnest, but this new analysis shows just how successful they once were.

Rangeomorphs almost completely filled the space surrounding them, with a massive total surface area. This made them very efficient feeders that were able to extract the maximum amount of nutrients from the ocean water.

“These creatures were remarkably well-adapted to their environment, as the oceans at the time were high in nutrients and low in competition,” said Dr Hoyal Cuthill. “Mathematically speaking, they filled their space in a nearly perfect way.”

Dr Hoyal Cuthill examined rangeomorph fossils from a number of locations worldwide, and used them to make the first computer reconstructions of the development and three-dimensional structure of these organisms, showing just how well-suited they were to their Ediacaran environment.

As the Cambrian Explosion began however, the rangeomorphs became ‘sitting ducks’, as they had no known means of defence from predators which were starting to evolve, and the changing chemical composition of the ocean meant that they could no longer get the nutrients they required to feed.

“As the Cambrian began, these Ediacaran specialists could no longer survive, and nothing quite like them has been seen again,” said Dr Hoyal Cuthill.

New three-dimensional reconstructions show how some of the earliest animals on Earth developed, and provide some answers as to why they went extinct.

As the Cambrian began, these specialists could no longer survive, and nothing quite like them has been seen again

Jennifer Hoyal Cuthill

Palaeontological reconstruction of rangeomorph fronds from the Ediacaran Period (635-541 million years ago) built using computer models of rangeomorph growth and development.

̽��ֱ��text in this work is licensed under a Creative Commons Licence. If you use this content on your site please link back to this page. For image rights, please see the credits associated with each individual image.

Yes

New fossil find pinpoints the origin of jaws in vertebrates

sc604 — Wed, 11 Jun 2014 17:00:00 +0000

A key piece in the puzzle of the evolution of vertebrates has been identified, after the discovery of fossilised fish specimens, dating from the Cambrian period (around 505 million years old), in the Canadian Rockies. ̽��ֱ��fish, known as Metaspriggina, shows pairs of exceptionally well-preserved arches near the front of its body. ̽��ֱ��first of these pairs, closest to the head, eventually led to the evolution of jaws in vertebrates, the first time this feature has been seen so early in the fossil record.

Fish fossils from the Cambrian period are very rare and usually poorly preserved. This new discovery shows in unprecedented detail how some of the earliest vertebrates developed – the starting point of a story which led to animals such as later fish species, but also dinosaurs and mammals such as horses and even ourselves. ̽��ֱ��findings are published in the 11 June edition of the journal Nature.

Fossils of Metaspriggina were recovered from several locations including the Burgess Shale site in Canada’s Rocky Mountains, one of the richest Cambrian fossil deposits in the world. These fossils shed new light on the Cambrian ‘explosion’, a period of rapid evolution starting around 540 million years ago, when most major animal phyla originated.

Previously, only two incomplete specimens of Metaspriggina had been identified. During expeditions conducted by the Royal Ontario Museum in 2012, 44 new Burgess Shale fossils were collected near Marble Canyon in Kootenay National Park in British Columbia, which provide the basis for this study. Researchers from the ̽��ֱ�� of Cambridge and the Royal Ontario Museum/ ̽��ֱ�� of Toronto used these fossils, along with several more specimens from the eastern United States, to reclassify Metaspriggina as one of the first vertebrates.

̽��ֱ��fossils, which date from 505 million years ago, also show clearly for the first time how a series of rod-like structures, known as the gill or branchial arches, were arranged in the earliest vertebrates. These arches have long been known to have played a key role in the evolution of vertebrates, including the origin of jaws, and some of the tiny bones in the ear which transmit sound in mammals. Until now, however, a lack of quality fossils has meant that the arrangement of these arches in the first vertebrates had been hypothetical.

Vertebrates first appear in the fossil record slightly earlier than these finds, but pinpointing exactly how they developed is difficult. This is because fossils of such animals are rare, incomplete and open to varying interpretations, as they show soft tissues which are difficult to identify with complete certainty.

̽��ֱ��new fossils of Metaspriggina are remarkably well-preserved. ̽��ֱ��arrangement of the muscles shows these fish were active swimmers, not unlike a trout, and the animals saw the world through a pair of large eyes and sensed their surrounding environment with nasal structures.

“ ̽��ֱ��detail in this Metaspriggina fossil is stunning,” said lead author Professor Simon Conway Morris of Cambridge’s Department of Earth Sciences. “Even the eyes are beautifully preserved and clearly evident.”

But it is the branchial arches which makes this discovery so important. Previously, they were thought to exist as a series of single arches, but Metaspriggina now shows that they in fact existed in pairs. ̽��ֱ��anteriormost pair of arches is also slightly thicker than the remainder, and this subtle distinction may be the very first step in an evolutionary transformation that in due course led to the appearance of the jaw. “Once the jaws have developed, the whole world opens,” said Professor Conway Morris. “Having a hypothetical model swim into the fossil record like this is incredibly gratifying.”

“Obviously jawed fish came later, but this is like a starting post – everything is there and ready to go,” said the paper’s co-author Dr Jean-Bernard Caron, Curator of Invertebrate Palaeontology at the Royal Ontario Museum and and associate professor in the Departments of Earth Sciences and Ecology & Evolutionary Biology at the ̽��ֱ�� of Toronto. “Not only is this a major new discovery, one that will play a key role in understanding our own origins, but Marble Canyon, the new Burgess Shale locality itself has fantastic potential for revealing key insights into the early evolution of many other animal groups during this crucial time in the history of life.”

David Wilks, Member of Canadian Parliament for Kootenay-Columbia, noted, “ ̽��ֱ��Government of Canada is excited about this incredible fossil find. As an international leader in conservation and steward of the Burgess Shale, Parks Canada is pleased to provide its research partners with access to the fossils. Their remarkable discoveries inform the work we do to share this rich natural history through our popular guided hikes, and to protect this important Canadian heritage in a national park and UNESCO World Heritage Site.”

A major fossil discovery in Canada sheds new light on the development of the earliest vertebrates, including the origin of jaws, the first time this feature has been seen so early in the fossil record

Having a hypothetical model swim into the fossil record like this is incredibly gratifying

Simon Conway Morris

Left: Illustration of Metaspriggina swimming. Right: Fossil of Metaspriggina from Marble Canyon – head to the left with two eyes, and branchial arches at the top.

Yes

Human's oldest ancestor found

gm349 — Tue, 06 Mar 2012 08:33:49 +0000

Researchers from the ̽��ֱ�� of Cambridge, ̽��ֱ�� of Toronto and the Royal Ontario Museum (ROM) have confirmed that a 505 million-year-old creature, found only in the Burgess Shale fossil beds in Canada’s Yoho National Park, is the most primitive known vertebrate and therefore the ancestor of all descendant vertebrates, including humans.

̽��ֱ��research team’s analysis proves the extinct Pikaia gracilens is the most primitive member of the chordate family, the group of animals that today includes fish, amphibians, birds, reptiles and mammals. ̽��ֱ��study is based on the analysis of 114 specimens and was published yesterday, 05 March, in the British scientific journal Biological Reviews.

Pikaia was first described, on the basis of only a few specimens, by American palaeontologist Charles Doolittle Walcott in 1911 as a possible annelid worm, a group that includes today’s leeches and earthworms. However, scientists have long speculated that Pikaia was a chordate because it appeared to have a very primitive notochord – a flexible rod found in the embryos of all chordates – which goes on to make up part of the backbone in vertebrates.

“ ̽��ֱ��discovery of myomeres is the smoking gun that we have long been seeking,” said the study’s lead author, Professor Simon Conway Morris of the ̽��ֱ�� of Cambridge. “Now with myomeres, a nerve chord, a notochord and a vascular system all identified, this study clearly places Pikaia as the planet’s most primitive chordate. So, next time we put the family photograph on the mantle-piece, there in the background will be Pikaia.”

“Our analysis provides evidence that Pikaia indeed had a notochord,” said co-author, Jean-Bernard Caron, an assistant professor of ecology and evolutionary biology at the ̽��ֱ�� of Toronto and curator of invertebrate palaeontology at the ROM. A nerve cord and vascular system were also identified in the study. “But the real excitement was finding extensive myomeres, the blocks of skeletal muscle tissue that are characteristic of chordates.”

Averaging about five centimetres in length, Pikaia was a sideways-flattened, somewhat eel-like animal. ̽��ֱ��flattened body is divided into a series of segmented muscle blocks seen as S-shaped lines that lie on either side of the notochord which runs along most, if not all of the body length. It likely swam above the sea floor by moving its body in a series of side-to-side curves.

̽��ֱ��Burgess Shale is famous for its weird and wonderful fossils of marine organisms. ̽��ֱ��site provides vital information about evolution during the Cambrian explosion, a period over half a billion years ago that was characterized by the appearance of a vast diversity of animals over a short period of time.

̽��ֱ��study examined 114 Pikaia fossils using a range of imagery techniques, including scanning electron microscopy, to reveal fine details. ̽��ֱ��bulk of the specimens are held in trust for Parks Canada at the ROM while nearly all the remainder are housed in the National Museum of Natural History, part of the Smithsonian Institution in Washington, DC.

“It’s very humbling to know that swans, snakes, bears, zebras and, incredibly, humans all share a deep history with this tiny creature no longer than my thumb,” said Caron.

“Fossils of primitive chordates are incredibly rare. With no backbones or other mineralized elements, Pikaia would stand no chance of preservation in normal conditions outside exceptional sites like the Burgess Shale. We hope that, with continuing explorations and field work studies there, other species will be discovered allowing us to refine our understanding of the early history of our own group.”

̽��ֱ��confirmation of Pikaia as a chordate is the latest in a recent string of Burgess Shale discoveries. In November 2011, evidence of fossilized tracks of a large predator known as Tegopelte were published, and in January 2012 a bizarre tulip-shaped creature named Siphusauctum was described for the very first time.

Most primitive known vertebrate and therefore the ancestor of all descendant vertebrates, including humans, discovered.

̽��ֱ��discovery of myomeres is the smoking gun that we have long been seeking.

Professor Simon Conway Morris of the ̽��ֱ�� of Cambridge's Department of Earth Sciences

Image credit J.B. Caron

Pikaia gracilens

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Inset images: Top: Shark by Jeff Kubina; Pitcher Plant by NH53; Mangrove by Roberto Verzo; Mushroom by Aleksey Gnilenkov Middle: Disgust by Stuart Hamilton; Leaf Cutter Ants by Steve Corey Bottom: Saber-tooth Cat by Chuck Peterson

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Inset images:
Top: Shark by Jeff Kubina; Pitcher Plant by NH53; Mangrove by Roberto Verzo; Mushroom by Aleksey Gnilenkov
Middle: Disgust by Stuart Hamilton; Leaf Cutter Ants by Steve Corey
Bottom: Saber-tooth Cat by Chuck Peterson