探花直播 of Cambridge - Fossils

Bird beak evolved before dinosaur extinction

sc604 — Wed, 30 Nov 2022 15:18:58 +0000

Fossilised fragments of a skeleton, hidden within a rock the size of a grapefruit, have helped upend one of the longest-standing assumptions about the origins of modern birds.

鈥楳ysterious鈥� ancient creature was definitely an animal, research confirms

sc604 — Fri, 15 Sep 2017 11:01:21 +0000

A new study by researchers at the universities of Cambridge, Oxford, Bristol, and the British Geological Survey provides strong proof that Dickinsonia was an animal, confirming recent findings suggesting that animals evolved millions of years before the so-called Cambrian Explosion of animal life. 探花直播study is published in the journal Proceedings of the Royal Society B.

Lead author on the paper is Dr Renee Hoekzema, a PhD candidate at聽Oxford who carried out this research while completing a previous PhD in Oxford鈥檚 Department of Earth Sciences. She said: 鈥�Dickinsonia belongs to the Ediacaran biota 鈥� a collection of mostly soft-bodied organisms that lived in the global oceans between roughly 580 and 540 million years ago. They are mysterious because despite there being around 200 different species, very few of them resemble any living or extinct organism, and therefore what they were, and how they relate to modern organisms, has been a long-standing palaeontological mystery.鈥�

In 1947, Dickinsonia became one of the first described Ediacaran fossils and was initially thought to be an organism similar to a jellyfish. Since then, its strange body plan has been compared to that of a worm, a placozoan, a bilaterian and several non-animals including fungi, lichens and even entirely extinct groups.

Co-author Dr Alex Liu, from Cambridge's Department of Earth Sciences, said: 鈥楧iscriminating between these different hypotheses has been difficult, as there are so few morphological features in Dickinsonia to compare to modern organisms. In this study we took the approach of looking at populations of this organism, including assumed juvenile and adult individuals, to assess how it grew and to try to work out how to classify it from a developmental perspective.鈥�

探花直播research was carried out on the basis of a widely held assumption that growth and development are 鈥榗onserved鈥� within lineages 鈥� in other words, the way a group of organisms grows today would not have changed significantly from the way its ancestors grew millions of years ago.

Dickinsonia is composed of multiple 鈥榰nits鈥� that run down the length of its body. 探花直播researchers counted the number of these units in multiple specimens, measured their lengths and plotted these against the relative 鈥榓ge鈥� of the unit, assuming growth from a particular end of the organism. This data produced a plot with a series of curves, each of which tracked how the organism changed in the size and number of units with age, enabling the researchers to produce a computer model to replicate growth in the organism and test previous hypotheses about where and how growth occurred.

Dr Hoekzema said: 鈥榃e were able to confirm that Dickinsonia grows by both adding and inflating discrete units to its body along its central axis. But we also recognised that there is a switch in the rate of unit addition versus inflation at a certain point in its life cycle. All previous studies have assumed that it grew from the end where each 鈥渦nit鈥� is smallest, and was therefore considered to be youngest. We tested this assumption and interpreted our data with growth assumed from both ends, eventually coming to the conclusion that people have been interpreting Dickinsonia as having grown at the wrong end for the past 70 years.

鈥榃hen we combined this growth data with previously obtained information on how Dickinsonia moved, as well as some of its morphological features, we were able to reject all non-animal possibilities for its original biological affinity and show that it was an early animal, belonging to either the Placozoa or the Eumetazoa.

鈥楾his is one of the first times that a member of the Ediacaran biota has been identified as an animal on the basis of positive evidence.鈥�

Dr Liu added: 鈥楾his finding demonstrates that animals were present among the Ediacaran biota and importantly confirms a number of recent findings that suggest animals had evolved several million years before the 鈥淐ambrian Explosion鈥� that has been the focus of attention for studies into animal evolution for so long.

鈥業t also allows Dickinsonia to be considered in debates surrounding the evolution and development of key animal traits such as bilateral symmetry, segmentation and the development of body axes, which will ultimately improve our knowledge of how the earliest animals made the transition from simple forms to the diverse range of body plans we see today.鈥�

Reference:
Renee S. Hoekzema聽et al.聽鈥�Quantitative study of developmental biology confirms Dickinsonia as a metazoan鈥�. Proceedings of the Royal Society B (2017). DOI:聽10.1098/rspb.2017.1348

Adapted from a 探花直播 of Oxford press release.聽

It lived well over 550 million years ago, is known only through fossils and has variously been described as looking a bit like a jellyfish, a worm, a fungus and lichen. But was the 鈥榤ysterious鈥� Dickinsonia an animal, or was it something else?

Recent findings suggest animals had evolved several million years before the 'Cambrian Explosion' that has been the focus of attention for studies into animal evolution for so long.

Alex Liu

探花直播Ediacaran fossil Dickinsonia costata, specimen P40135 from the collections of the South Australia Museum, Adelaide

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Opinion: Six amazing dinosaur discoveries that changed the world

Anonymous — Mon, 30 Nov 2015 02:14:22 +0000

Recently, an auction of a dinosaur skeleton, discovered in Jurassic-aged rocks in the US, was held in West Sussex, England. 探花直播skeleton was that of a largely complete, immature, three-metre long carnivorous dinosaur: Allosaurus fragilis 鈥� 鈥渄elicate strange reptile鈥�. It was anticipated that the specimen would sell for somewhere in the region of 拢300,000-拢500,000. Interestingly, bidding stopped before the reserve price was reached, so the specimen is still on the open market.

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Allosaurus Scott Hartman, Author provided

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探花直播price or value of fossils has a history that is practically as long as the science of palaeontology (the study of fossils) itself. Believe it or not, the tongue-twister 鈥渟he sells seashells on the seashore鈥� has its origin in the work of one of the earliest and most celebrated fossil collectors, Mary Anning. Mary lived during the early decades of the 19th century and had the knack of finding fossils, including those of seashells 鈥� bivalves, brachiopods, belemnites and ammonites 鈥� along the shores of Dorset and in the crumbling Jurassic cliffs, which she then sold.

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Dinosaurs are fossils and do have a value, but I am only really interested in their value as scientific objects. Here are some of the discoveries that really have made a difference to science.

Megalosaurus

Pride of place must go to Megalosaurus bucklandi 鈥淏uckland鈥檚 big reptile鈥� 鈥� because it proved to be the earliest discovered and scientifically described dinosaur.

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Megalosaurus jaw Buckland Author provided

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It鈥檚 remains, though incomplete, began to be collected from quarries at the village of Stonesfield in Oxfordshire in about 1815. 探花直播bones, teeth and jaws were passed to Oxford 探花直播 Museum, where they still reside, and were studied by the greatest living anatomist of the time Georges Cuvier, who visited Oxford (and its custodian William Buckland) from Paris to see the material.

William Buckland (with Cuvier鈥檚 help) described these fossils in a scientific article published in 1824. Buckland as well as Cuvier deduced that the bones belonged to a gigantic reptile, the like of which had not been seen before. Over the next decade and half more large fossil reptile bones were recovered in England and reviewed by the British anatomist Richard Owen. In 1842 Owen decided that these fossils were so utterly different from any known reptiles that they deserved to be classified as a completely new group of giant fossil reptiles: Dinosauria 鈥� 鈥渢errible, or fearfully great, reptiles鈥�. Prior to 1842 nobody had heard of dinosaurs, the rest is, in essence, history. And Megalosaurus was the first.

Archaeopteryx

Charles Darwin profoundly disturbed the established Victorian world and galvanised scientific interest in evolution when he published his book On the Origin of Species in 1859. With masterly circumspection, his book laid out the reasons for concluding that organic life had changed or evolved over the immensity of geological time.

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Archaeopteryx restored Robert Nicholls. Sedgwick Museum, 探花直播 of Cambridge

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By an astonishing coincidence, a fossil was discovered in a quarry in southern Germany just one year after the publication of Origin. This fossil comprised the major part of the crow-sized, delicately-boned skeleton of a creature that was named by Richard Owen Archaeopteryx lithographica (鈥渁ncient wing on writing stone鈥�).

探花直播fossil was extraordinary because around the bones were seen the impressions of feathers (which of course implied that this was a bird) yet what was also seen in the skeleton were clear traces of teeth (no bird has teeth), hands with three well-developed clawed fingers (no bird has clawed fingers of that type) and its tail comprised a long string of small bones from which radiated a fan of feathers (no bird has a long string of tail bones).

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Archaeopteryx NHM Author provided

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This animal was an absolutely perfect 鈥渕issing link鈥� that connected living birds with feathers, to the group of scaly reptiles with teeth in their jaws, clawed fingers and long bony tails. Just a few years after this discovery was announced a friend and colleague of Darwin鈥檚, Thomas Henry Huxley, suggested on the basis of the structure of Archaeopteryx, that birds and dinosaurs (not just any old reptile) were close relatives.

Not many agreed with Huxley at the time, but he has been proved to have been absolutely correct. Its original remains are preserved at the Natural History Museum, London.

Diplodocus

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Diplodocus Scott Hartman

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Andrew Carnegie was a profoundly wealthy industrialist based in Pittsburgh, Pennsylvania during the latter half of the 19th century. After he had amassed his fortune, Carnegie began to spend his money philanthropically. News came to him of the discovery of impressive dinosaur skeletons in the American mid-west so he decided he wanted one for his new museum ( 探花直播Carnegie Museum) in Pittsburgh. So he financed expeditions to northern Wyoming and southern Utah to find some more dinosaurs. And find them they did, including a near complete skeleton of the biggest dinosaur discovered to date.

探花直播skeleton was named Diplodocus carnegiei 鈥撀�"Carnegie鈥檚 double-beam". 探花直播entire animal, as reconstructed (with just a few additions for completeness, such as 鈥渂orrowed鈥� front feet from another animal altogether) was over 25 metres long and dwarfed in size and completeness anything discovered up to that date.

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Diplodocus at the Natural History Museum Valdiney Pimenta/flickr, CC BY

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So proud of this dinosaur was Carnegie that he had many copies cast in plaster and sent to museums around the world. 探花直播giant dinosaur in the main hall of the Natural History Museum in London is a cast of Carnegie鈥檚 Diplodocus.

Deinonychus

In the mid 1960s a young palaeontology professor, John Ostrom from Yale 探花直播 was exploring the badlands of Montana looking for dinosaur fossils. What he found was to change our understanding of dinosaurs, their biology and behaviour in the most extraordinary way. Ostrom discovered the scattered remains of a medium-sized predatory dinosaur which he studied and then named Deinonychus antirrhopus 鈥� 鈥淭errible claw with a counterbalance鈥�.

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Deinonychus Scott Hartman, Author provided

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He realised that this animal was a fast moving, highly intelligent, keen-sighted predator (not at all the slow, lumbering and slow-witted image of the dinosaur that was current at the time). He also showed that it was remarkably bird-like in its anatomy, and suggested that the bird similarities suggested that birds and small predatory dinosaurs were so closely similar that birds probably evolved from them.

These were highly controversial views at the time, even though they echoed the early ideas of Thomas Huxley in the 1860s. They also posed serious biological questions: if birds and dinosaurs of this type are related could it be that some dinosaurs were more like birds in a biological sense? 探花直播debate raged for decades.

Scelidosaurus

I include this dinosaur, which is somewhat less heralded than the others, because it really ought to have been a dinosaur that changed the world.

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Scelidosaurus Gregory S Paul, Author provided

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In 1858 dinosaur bones were discovered in the Jurassic cliffs at Charmouth and soon a nearly complete skeleton of this dinosaur was excavated and given to Richard Owen (the person who invented the Dinosauria) at the British Museum in London.

In the 1860s, Owen named it Scelidosaurus harrisonii 鈥撀�"Harrison鈥檚 shoulder reptile", but almost inexplicably failed to grasp the importance of its anatomy, or the way in which it pointed to the divisions between differing dinosaur groups and, in fact, why dinosaurs had proved so difficult to understand at the time.

Owen had the equivalent of a Rosetta Stone before him, yet he failed to grasp its importance. 探花直播probable reason why such an insightful scientist missed such an important moment is that he was simply too busy, including setting in motion the plans to have an entirely new national museum built. Without Owen the Natural History Museum in London, where the original bones of Scelidosaurus still lie, would not have been constructed. In fact, I am studying them at this very moment 鈥� hence my undoubted bias.

Sinosauropteryx

In 1996 an astonishing discovery was made in Liaoning, China. It comprised a virtually complete skeleton of a small, predatory dinosaur (smaller than, but generally similar to, Deinonychus).

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Sinosauropteryx Author provided

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It was described briefly in 1998 and named Sinosauropteryx prima 鈥� 鈥淔irst Chinese reptile wing鈥� 鈥� but the most extraordinary feature associated with this fossil was that on the rocky slab upon which the skeleton was displayed there were traces of a wispy, dark-staining material that formed a sort of fringe following the body outline, as well as forming a dark spot in the area of the eye, and also formed a dark mass in the area of the gut/body cavity. 探花直播conditions of exceptional fossil preservation associated with these rocks in Liaoning seemed to preserve some remnant of the body tissues of the original animal.

Most intriguing was the fringe of tissue around the body: it looked like fur. 探花直播implication was that it had an epidermal covering (outer coat), perhaps an insulating layer. Given Ostrom鈥檚 earlier work on Deinonychus, the suggestion was made that this was indeed an insulated dinosaur that was able to keep its body warm (rather like a modern bird using fine down-like feathers that might have been preserved as a halo-like fringe when fossilised).

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Still with us? Danny Chapman/flickr, CC BY

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This and subsequent discoveries demonstrated the wisdom of Huxley鈥檚 intuition based largely upon Archaeopteryx and the validity of Ostrom鈥檚 work on Deinonychus. We now know that many (but not all) dinosaurs were feathered, and that some were capable of flight and some were indeed the progenitors of modern birds.

David Norman, Reader in Paleobiology, Curator of Palaeontology, Sedgwick Museum of Earth Sciences, 探花直播 of Cambridge

This article was originally published on 探花直播Conversation. Read the original article.

探花直播opinions expressed in this article are those of the individual author(s) and do not represent the views of the 探花直播 of Cambridge.

David Norman (Sedgwick Museum of Earth Sciences) discusses the fossil discoveries that really made a difference to science.

David Nicholls. Sedgwick Museum, 探花直播 of Cambridge

Deinonychus

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New CT imaging facility reveals 'internal secrets'

lw355 — Sun, 15 Feb 2015 00:00:00 +0000

探花直播Cambridge Biotomography Centre (CBC), which launched early in 2015, houses the latest high-resolution computed tomography (CT) scanner available on the market. One of only a handful in the country, the CT scanner uses X-rays to measure density differences within objects, generating a precise three-dimensional reconstruction of the internal and external architecture of almost any object or specimen.

Already being used to scan everything from ancient Egyptian leg bones and fossils hidden inside rocks, to the muscle and skeletons within dead rats, the facility has been launched with the intention of providing not just Cambridge researchers but also the wider international research community with the chance to unlock their material鈥檚 closely held secrets.

鈥淎lthough CT is frequently used in hospitals, this type of imaging has only recently become available to researchers,鈥� explained Dr Colin Shaw, one of the leaders of the facility.

His work in the Department of Archaeology and Anthropology is analysing the behaviour of our prehistoric ancestors through the analysis of their bones. 鈥淎 continuum of different behaviours that stretches from couch potato to ultramarathon runner puts stresses and strains on bones which can be measured to reconstruct what our lives were like in the past,鈥� he explained.

However, the information is hidden deep within the honeycomb-like structure of the bone itself, and the ancient remains he studies are too precious to be broken open. 鈥淔or objects like these, the ability to do this non-invasively without cutting or slicing is a real benefit,鈥� he added. 鈥淚t means we can carry on studying the object long after the measurements have been made.鈥�

探花直播CBC houses a Nikon Metrology XT H 225 ST High Resolution CT Scanner and is a multi-user research facility that supports Cambridge researchers as well as the broader national and international academic community. 探花直播Center resides in the Department of Zoology, and was funded by the School of the Biological Sciences, the Departments of Zoology and Physiology, Development and Neuroscience, and the PAVE Research Group of the Department of Archaeology and Anthropology.

A new imaging facility offers researchers in Cambridge and beyond the chance to see what lies within objects, without breaking them open.

A continuum of different behaviours that stretches from couch potato to ultramarathon runner puts stresses and strains on bones which can be measured to reconstruct what our lives were like in the past.

Colin Shaw

Ket Smithson

CT Scan

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

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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. 探花直播fish, known as Metaspriggina, shows pairs of exceptionally well-preserved arches near the front of its body. 探花直播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.聽

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 鈥� 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. 探花直播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鈥檚 Rocky Mountains, one of the richest Cambrian fossil deposits in the world. These fossils shed new light on the Cambrian 鈥榚xplosion鈥�, 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 探花直播 of Cambridge and the Royal Ontario Museum/ 探花直播 of Toronto used these fossils, along with several more specimens from the eastern United States, to reclassify Metaspriggina as one of the first vertebrates.

探花直播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.

探花直播new fossils of Metaspriggina are remarkably well-preserved. 探花直播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.

鈥� 探花直播detail in this Metaspriggina fossil is stunning,鈥� said lead author Professor Simon Conway Morris of Cambridge鈥檚 Department of Earth Sciences. 鈥淓ven the eyes are beautifully preserved and clearly evident.鈥�

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. 探花直播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. 鈥淥nce the jaws have developed, the whole world opens,鈥� said Professor Conway Morris. 鈥淗aving a hypothetical model swim into the fossil record like this is incredibly gratifying.鈥�

鈥淥bviously jawed fish came later, but this is like a starting post 鈥� everything is there and ready to go,鈥� said the paper鈥檚 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 探花直播 of Toronto. 鈥淣ot 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.鈥�

David Wilks, Member of Canadian Parliament for Kootenay-Columbia, noted, 鈥� 探花直播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.鈥�

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

Drawing by Marianne Collins. 漏 Conway Morris and Caron. Photo by Jean-Bernard Caron 漏 ROM.

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

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