Category Archive : Nature

Squids Can Edit Their RNA in an Unprecedented Way, Scientists Discover

When it comes to squids, you just can’t keep them down.

Not just because they’re slippery, but also because they have an incredible genetic editing ability – it lets them tweak their own RNA long after it’s left the nucleus.

 

Here’s what that means. Genes, in humans at least, mostly stay unchanging until they’re recombined and passed onto the next generation.

This is the same for our messenger RNA (mRNA). Helpful molecules read our DNA, create short little RNA messages, and send them outside the nucleus to tell the rest of the cell which proteins need to be built.

Once that mRNA has exited the nucleus, it’s thought the genetic information it carries can’t be messed with much – but new research has shown that in squid nerves, this isn’t the case.

“We are showing that squid can modify the RNAs out in the periphery of the cell,” says Marine Biological Laboratory (MBL), Woods Hole geneticist Joshua Rosenthal.

“It works by this massive tweaking of its nervous system,” Rosenthal told Wired. “Which is a really novel way of going through life.”

The team took nerves from specimens of adult male longfin inshore squid (Doryteuthis pealeii), and analysed the protein expression, as well as the squids’ transcriptome, which is similar to a genome, but for mRNA.

 

They found that in squid nerves (or neurons), the mRNA was being edited outside of the nucleus, in a part of the cell called the axon.

This mRNA editing allows the squids to finely tune the proteins they produce at local sites (see diagram below). With this finding, squids have become the only creatures we know of that can do this.

Squid RNA Editing Graphical Abstract ver. 3(Vallecillo-Viejo et al., Nucleic Acids Research, 2020)

This isn’t the first time squids have shown off their genetic editing prowess, though. Back in 2015, a similar team at MBL discovered that squids edit their mRNA inside their nucleus to an incredibly large degree – orders of magnitude more than what happens in humans.

“We thought all the RNA editing happened in the nucleus, and then the modified messenger RNAs are exported out to the cell,” Rosenthal explains.

But the team showed that although editing is happening in both, it occurs significantly more outside the nucleus in the axon, rather than inside the nucleus.

So, why do squids bother? Why do they need to change their mRNA so much? Well, we don’t yet know, but the research team has some ideas.

 

Octopus, cuttlefish and squids all use mRNA editing to diversify the proteins produced in the nervous system. This could be one of the reasons why these creatures are so much smarter than other invertebrates.

“The idea that genetic information can be differentially edited within a cell is novel and extends our ideas about how a single blueprint of genetic information can give rise to spatial complexity,” the team writes in their new paper.

“Such a process could fine-tune protein function to help meet the specific physiological demands of different cellular regions.”

Although right now this is just an interesting genetics study into squids, the researchers think that eventually, this type of system might be able to help treat neurological disorders that include axon dysfunction.

CRISPR has completely changed the game when it comes to editing the DNA inside our cells, and RNA is significantly less permanent and therefore editing it could be less dangerous.

“RNA editing is a hell of a lot safer than DNA editing,” Rosenthal told Wired.

“If you make a mistake, the RNA just turns over and goes away.”

The research has been published in Nucleic Acids Research.

 

This Newly Identified Raptor Hunted With The Terrifying Agility of a Cheetah

A long, long time ago, in what is now the southern United States, several giant dinosaurs, including a relative of the T. rex, were once on the hunt for prey.

In their shadow, almost 70 million years later, palaeontologists have now shed light upon a much smaller competitor running underfoot. Standing only one metre tall (three feet) and roughly two metres long, this feathered carnivore may have been short, but you wouldn’t want to underestimate it.

 

Initially discovered in New Mexico in 2008, the species has only recently been identified as a dromaeosaurid – a family of dinosaurs more popularly known as ‘raptors’ – and, judging from the 20 fragmented fossils uncovered, it probably hunted with great speed and the agility of a cheetah, at times tackling prey several times its size.

Screen Shot 2020 03 25 at 1.15.34 pm(Jasinski et al., Scientific Reports, 2020)

Now, the fearsome creature has officially been named Dineobellator notohesperus, which means ‘Navajo warrior from the Southwest’ – and oh, what a fighter it was!

While this small-bodied predator is generally the same size as its relative, the velociraptor (which, contrary to the Jurassic Park films, is about the size of a large dog), the new species appears stronger and more agile.

“Features of the hand and foot claws, namely places for muscle and tendon attachments, show that Dineobellator would have had a relatively stronger grasp and grip ability then other dromaeosaurids,” palaeontologist Steven Jasinski told ScienceAlert.

Skeletons of small dinosaurs in the Late Cretaceous are very rare, as these creatures were probably not that common, and their light bones were no match for the wear of time. A find like this is remarkable in more ways than one, and this particular species has several more unique features that set it apart.

 

On the other end of the body, its stiff tail also stands out. While raptors also have long rigid appendages like this, allowing them to maintain balance while running at high speeds, this particular species appears to have had more mobility at the hips.

“Think of a cheetah hunting and pursuing a gazelle in the savannah today,” says Jasinski.

“They are very fast and their tail tends to be stiff and straight. However, when the gazelle changes directions and the cheetah must quickly do the same, the tail is whipped around to act as a counter-balance and rudder to help with that change in direction.”

In short, not only was this species fast, but also remarkably agile, which means it could have easily pursued smaller animals that quickly change direction.

Still, that doesn’t mean this raptor wasn’t thinking big. Jasinski says the strength in its upper body and feet suggests a pack could have taken down prey several times their size.

010 Image two(Steven Jasinski)

While this realisation was indeed surprising, the injuries found on the skeleton are perhaps even more so.

On the ribs, researchers found healed wounds, and on the claws, they identified gouge and puncture marks, which suggest a fight between two raptors, perhaps in competition over resources or mates. Such behavioural insights are invaluable, and they’re just part of what makes this new find so astonishing.

 

In the bigger picture, this new species can also tell us something of dinosaur evolution and migration. Dineobellator, for example, belongs to a smaller group of dinosaurs called velociraptorines, which have several other members across the ocean.

“This suggests that members from Asia migrated to North America during the Late Cretaceous, near the end of the time of the dinosaurs, and diversified into new species afterward,” Jasinski told ScienceAlert.

Then, somehow, some way, these 20 bones survived, bequeathing us with the first significant dromaeosaurid skeleton in this part of the world. 

The study was published in Scientific Reports.

 

Coronaviruses Similar to The COVID-19 One Have Just Been Found in Pangolins

A search for the ‘missing link’ in the chain of the emergence of SARS-CoV-2 has uncovered two close cousins of the new coronavirus in shipments of pangolins being smuggled into China.

 

It’s important to note that the discovery by researchers from across Hong Kong and China falls well short of identifying these precious mammals as the source of the current pandemic. However, the similarity of the strains does suggest the nation’s pangolin market is a time bomb that needs to be defused.

Ever since the nexus for the outbreak of COVID-19 was traced back to a wet market in Hubei province, the search has been on to determine the virus’s heritage. Initial studies of SARS-CoV-2’s genome suggest it’s highly possible that the virus emerged in a colony of horseshoe bats in Yunnan, a province that borders the south-east Asian country of Myanmar.

But if that is the case, it’s hard to imagine how a bat became a source of infection in a densely populated city more than 1,000 kilometres to the north of its colony.

Granted, stalls in these Chinese wet markets sell a wide variety of live animals for food and traditional medicine, many of them sourced from Asia’s tropics. Whether bats of any kind might have been present isn’t clear, since the market was cleared long before the first indications of an outbreak were known.

 

Unlike horseshoe bats, though, the pangolin is almost guaranteed to have been on sale there.

The illicit sale of the endangered mammal – prized as a delicacy and a health tonic – is an ‘open secret‘ throughout much of the nation, and a good place to start hunting for an intermediate host of the zoonotic virus currently wreaking havoc across the globe.

Frozen tissues from 18 Malayan pangolins (Manis javanica) were obtained from anti-smuggling operations carried out by Guangxi Customs during 2017 and early 2018.

Coronavirus RNA was found in six of the 43 organ samples, linking the virus with five individual animals. Techniques for reading and filling in missing sequences soon provided the team with half a dozen detailed genomes of the pangolin’s strains of the virus.

None were dead ringers for SARS-CoV-2, but there were a number of overlapping sequences that suggest these viruses were fairly closely related.

A second hunt through another batch of pangolin tissues taken from an operation later in 2018 followed, based on the newly acquired genomes. This analysis revealed a further three positive results out of 12 animals.

 

In addition to these specimens from the Guangxi operation, the team analysed pangolin scales, skin swabs, and unspecified tissues from a separate customs centre in Guangzhou, picked up in early 2019.

Taken together, the mix of newly sequenced coronavirus genomes are all 85.5 to 92.4 percent similar to SARS-CoV-2, and represent two lines of related virus. One of those lines even has a ‘haircut’ that resembles that of the COVID-19 virus, with remarkably similar receptor-binding spikes jutting from their surfaces.

The results might not be the smoking gun we’re hoping for, as the search for the connection between the coronavirus’s reservoir and the first humans to be infected continues.

Still, it’s a wake-up call we desperately need. All those animals seized by customs were destined for live animal markets somewhere in China.

As impossible as it is to predict whether those particular lines of coronavirus could have made a leap into the human population, the current pandemic emerged from just such a branch of that family tree.

The sale of pangolins in China is already far from legal, but without the political will to provide the resources necessary to enforce the law, their sale will almost certainly continue to flourish, in spite of recent widespread bans of the sale and distribution of wild meats.

A global pandemic is a tragic incentive to act. But with mounting evidence that pangolins play a strong role in the ecology of such a potential threat, perhaps it’s the push China needs to finally get a handle on its illegal animal trade. 

This research was published in Nature.

 

This Twitch Livestream of Tardigrades Is So Incredibly Soothing

Keep on Swimming

Canadian artist Julie Laurin recently started a livestream of tardigrades — microscopic, eight-legged micro-animals also known as “water bears” — wriggling around on Twitch. And it’s exactly the kind of thing we need right now.

You can watch a full, narrated hour of tardigrade action on Laurin’s Twitch channel.

The stream, first spotted by Boing Boing, is part of a project called “A Tiny World” that explores microscopic life that surrounds us.

All Around

“By sharing this journey with you, my hope is that maybe you’ll be inspired to get your own microscope, or to look closer at the little objects and creatures all around you!” Laurin’s description of the project reads on an official website.

So where is Laurin finding all of these critters? In dirt found on her balcony. “There are hundreds and hundreds of #Tardigrades that live on my balcony and I think they thrive in this brownish-greenish film and dirt that has formed over the years due to improper draining,” Laurin wrote in a tweet.

Little Water Bears

First discovered by biologists in the late 1700s, tardigrades are tiny micro-animals that can be found in a huge variety of environments, from oceans to sand dunes.

They’re also immensely resilient creatures: they can survive the vacuum of space, adapt to severe dehydration, and can even block intense blasts of radiation. But they might have an Achilles heel after all, according to recent research: global warming.

READ MORE: It’s fun to watch tardigrades squirm around on Twitch, adorably [Boing Boing]

More on tardigrades: Scientists: Global Warming Could Kill Tardigrades

New Find Contradicts The Theory Earth Mysteriously Lost Oxygen 2 Billion Years Ago

Earth didn’t always have this much oxygen. Roughly 2.4 billion years ago, the rise of cyanobacteria and the shifting of tectonic plates breathed new life into our planet, tipping off a Great Oxidation Event (GOE).

 

The surge of oxygen-hungry life that followed didn’t last for long. Today, many scientists think the evolution of life ‘overshot’ the amount of oxygen actually available in the atmosphere. Evidence found last year suggests this triggered an abrupt and catastrophic mass extinction of microorganisms around two billion years ago that was even more dire than the dinosaur die-off.

Still, while the oxygen overshoot theory has become ever more popular in recent years, new research suggests it might actually be wrong.

In Russia, analysis of ancient sedimentary rock indicates that for millions of years after the GOE, conditions on Earth were more than suitable for the continued evolution of complex life.

“What we found contradicts the prevailing view – essentially we have clear evidence that atmospheric oxygen levels rose even further after the carbon isotope anomaly ended,” says palaeogeographer Kaarel Mänd from the University of Alberta.

“This will force the Earth science community to rethink what drove the carbon and oxygen cycles on the early Earth.” 

The evidence comes from fresh drill cores in the Lake Onega area in the northwest corner of European Russia. Here, researchers have uncovered ancient shungite, a black lustrous mineral, from 2 billion years ago.

 

Composed almost solely of carbon, this shiny shale is one of the best archives we have to figure out environmental conditions from long, long ago.

At the moment, it’s generally understood that a rise in oxygen more than 2 billion years ago led to a shift in carbon isotopes within sedimentary rocks, known as the Lomagundi–Jatuli Event (LJE). This suggests that massive amounts of organic matter were being buried in ocean sediments, leading to the release of excess oxygen; but following this, levels of oxygen dropped.

But within these shungite rock cores, deposited just after the end of the LJE, researchers found strikingly high traces of molybdenum, uranium, and rhenium, and these are metals commonly associated with abundant oxygen. 

In fact, the concentrations, they discovered, were unrivalled by any other known point in early Earth’s history, roughly comparable to the most “organic-rich modern marine sediments”, or the most uranium-enriched “Precambrian shale measurement that has been reported to date.”

If the shungite was deposited, then there simply must have been enough oxygen around.

The authors argue this conclusion undoubtedly forces a “re-evaluation of our basic view of this turbulent interval of Earth’s history.”

 

Other recent discoveries have also found large eukaryotic fossils as old as 2.1 billion years old, during this supposed plummet in available oxygen, although the results remain highly contentious.

Of course, even if the findings of the new research are true, this doesn’t mean oxygen levels never went down. Instead, it implies our planet’s oceans remained well-oxygenated for much longer than we thought after the GOE. Who’s to say if oxygen levels plummeted after that.

The authors of the research argue that the strongly positive [uranium] isotopes found in the shungite samples are “most readily explained” by “globally well-oxygenated oceans and markedly elevated rates of local primary productivity.” 

This means that the end of the increased deposits of organic carbon during the LJE may not be the result of diminishing oxygen, but rather of something else. What that exactly is remains unclear, but that possibility means we might need to explore different explanations other than the ones we’ve got.

The study was published in Nature Geoscience.

 

Ce raptor nouvellement identifié chassé avec l'agilité terrifiante d'un guépard

 

Il y a très, très longtemps, dans ce qui est maintenant le sud des États-Unis, plusieurs dinosaures géants, dont un parent du T. rex , étaient autrefois à la recherche de proies.

Dans leur ombre, près de 70 millions d’années plus tard, les paléontologues ont maintenant mis en lumière un concurrent beaucoup plus petit qui courait sous les pieds. Ne mesurant qu’un mètre de haut (trois pieds) et environ deux mètres de long, ce carnivore à plumes était peut-être petit, mais vous ne voudriez pas le sous-estimer.

 

Initialement découverte au Nouveau-Mexique en 2008, l’espèce n’a été identifiée que récemment comme un dromaeosaurid – une famille de dinosaures plus populairement connue sous le nom de «rapaces» – et, à en juger par les 20 fossiles fragmentés découverts, il chassait probablement avec une grande vitesse et l’agilité d’un guépard, s’attaquant parfois à des proies plusieurs fois sa taille.

Screen Shot 2020 03 25 at 1.15.34 pm (Jasinski et al., Rapports scientifiques, 2020)

Maintenant, la redoutable créature a officiellement été nommée Dineobellator notohesperus, qui signifie «guerrier navajo du sud-ouest» – et oh, quel combattant c’était!

Bien que ce petit prédateur corpulent soit généralement de la même taille que son parent, le velociraptor ( qui, contrairement aux films de Jurassic Park , est de la taille d’un gros chien ), la nouvelle espèce apparaît plus forte et plus agile.

“Les caractéristiques des griffes de la main et du pied, à savoir les emplacements pour les attaches musculaires et tendineuses, montrent que Dineobellator aurait eu une capacité de préhension et d’adhérence relativement plus forte que celle des autres dromaeosaurids”, paléontologue Steven Jasinski a déclaré ScienceAlert.

Les squelettes de petits dinosaures du Crétacé supérieur sont très rares , car ces créatures n’étaient probablement pas si communes et leurs os clairs n’étaient pas à la hauteur du temps. Une découverte comme celle-ci est remarquable à plus d’un titre, et cette espèce particulière a plusieurs caractéristiques uniques qui la distinguent.

De l’autre côté du corps, sa queue raide se détache également. Alors que les rapaces ont également de longs appendices rigides comme celui-ci, leur permettant de maintenir l’équilibre tout en courant à des vitesses élevées, cette espèce particulière semble avoir eu plus de mobilité au niveau des hanches.

“Imaginez un guépard chassant et poursuivant une gazelle dans la savane aujourd’hui”, explique Jasinski.

“Ils sont très rapides et leur queue a tendance à être raide et droite. Cependant, lorsque la gazelle change de direction et que le guépard doit rapidement faire de même, la queue est fouettée pour agir comme contrepoids et gouvernail pour aider à ce changement de direction. ”

En bref, non seulement cette espèce était rapide, mais aussi remarquablement agile, ce qui signifie qu’elle aurait pu facilement poursuivre des animaux plus petits qui changeaient rapidement de direction.

Pourtant, cela ne signifie pas que ce rapace ne voyait pas grand. Jasinski dit que la force de la partie supérieure de son corps et de ses pieds suggère qu’un pack aurait pu abattre des proies plusieurs fois plus grandes.

010 Image two (Steven Jasinski)

Bien que cette réalisation soit en effet surprenante, les blessures trouvées sur le squelette le sont peut-être encore plus.

Sur les côtes, les chercheurs ont trouvé des plaies cicatrisées et sur les griffes, ils ont identifié des marques de gouge et de perforation, ce qui suggère un combat entre deux rapaces, peut-être en compétition pour des ressources ou des partenaires. De telles informations comportementales sont inestimables, et elles ne font que partie de ce qui rend cette nouvelle découverte si étonnante.

Dans l’ensemble, cette nouvelle espèce peut aussi nous dire quelque chose sur l’évolution et la migration des dinosaures. Dineobellator, par exemple, appartient à un plus petit groupe de dinosaures appelés velociraptorines, qui ont plusieurs autres membres à travers l’océan.

“Cela suggère que des membres d’Asie ont migré en Amérique du Nord au cours du Crétacé supérieur, vers la fin de l’époque des dinosaures, et se sont diversifiés par la suite vers de nouvelles espèces”, a déclaré Jasinski à ScienceAlert.

Puis, d’une manière ou d’une autre, ces 20 os ont survécu, nous léguant le premier squelette de dromaeosaurid significatif dans cette partie du monde.

L’étude a été publiée dans Rapports scientifiques .

Des coronavirus similaires au COVID-19 viennent d'être découverts à Pangolins

 

Une recherche du «maillon manquant» dans la chaîne de l’émergence du SRAS-CoV-2 a découvert deux cousins ​​proches du nouveau coronavirus dans des envois de pangolins introduits en contrebande en Chine.

 

Il est important de noter que la découverte par des chercheurs de partout à Hong Kong et en Chine est bien loin d’identifier ces précieux mammifères comme la source de la pandémie actuelle. Cependant, la similitude des souches suggère que le marché national du pangolin est une bombe à retardement qui doit être désamorcée.

Depuis que le lien avec l’épidémie de COVID-19 a été retracé sur un marché humide dans la province du Hubei, la recherche a été en cours pour déterminer l’héritage du virus. Les premières études sur le génome du SRAS-CoV-2 suggèrent qu’il est fort possible que le virus ait émergé dans une colonie de chauves-souris en fer à cheval dans le Yunnan, une province qui borde le pays du sud-est asiatique du Myanmar.

Mais si tel est le cas, il est difficile d’imaginer comment une chauve-souris est devenue une source d’infection dans une ville densément peuplée à plus de 1 000 kilomètres au nord de sa colonie.

Certes, les étals de ces marchés chinois humides vendent une grande variété d’animaux vivants pour l’alimentation et la médecine traditionnelle, dont beaucoup proviennent des tropiques d’Asie. La présence éventuelle de chauves-souris, quelle qu’en soit la nature, n’est pas claire, car le marché a été liquidé bien avant que les premières indications d’une épidémie ne soient connues.

Contrairement aux chauves-souris en fer à cheval, le pangolin est presque garanti d’avoir été en vente là-bas.

La vente illicite du mammifère menacé d’extinction – considéré comme un mets délicat et un tonique pour la santé – est un « secret ouvert » dans une grande partie de la nation, et un bien endroit pour commencer à chasser un hôte intermédiaire du virus zoonotique qui fait actuellement des ravages à travers le monde .

Les tissus congelés de 18 pangolins malais ( Manis javanica ) ont été obtenus grâce à des opérations anti-contrebande menées par les douanes du Guangxi en 2017 et au début de 2018.

L’ARN du coronavirus a été trouvé dans six des 43 échantillons d’organes, reliant le virus à cinq animaux individuels. Les techniques de lecture et de remplissage des séquences manquantes ont rapidement fourni à l’équipe une demi-douzaine de génomes détaillés des souches du virus du pangolin.

Aucun n’était des sonneries mortes pour le SRAS-CoV-2, mais il y avait un certain nombre de séquences qui se chevauchent qui suggèrent que ces virus étaient assez étroitement liés.

Une deuxième chasse à travers un autre lot de tissus de pangolins prélevés dans une opération plus tard en 2018 a suivi, sur la base des génomes nouvellement acquis. Cette analyse a révélé trois autres résultats positifs sur 12 animaux.

En plus de ces spécimens provenant de l’opération Guangxi, l’équipe a analysé des écailles de pangolin, des écouvillons cutanés et des tissus non spécifiés d’un centre douanier distinct à Guangzhou, ramassés au début de 2019. [19459004 ]

Pris ensemble, le mélange de génomes de coronavirus nouvellement séquencés est tous de 85,5 à 92,4 pour cent similaire au SRAS-CoV-2 et représente deux lignées de virus apparentés. L’une de ces lignées a même une coupe de cheveux qui ressemble à celle du virus COVID-19, avec des pointes de liaison aux récepteurs remarquablement similaires faisant saillie de leurs surfaces.

Les résultats ne sont peut-être pas le pistolet fumant que nous espérons, car la recherche de la connexion entre le réservoir du coronavirus et les premiers humains infectés se poursuit.

Pourtant, c’est un réveil dont nous avons désespérément besoin. Tous ces animaux saisis par les douanes étaient destinés aux marchés d’animaux vivants quelque part en Chine.

Aussi impossible qu’il soit de prédire si ces lignées particulières de coronavirus auraient pu faire un saut dans la population humaine, la pandémie actuelle est sortie d’une telle branche de cet arbre généalogique.

La vente de pangolins en Chine est déjà loin d’être légale , mais sans la volonté politique de fournir les ressources nécessaires pour faire appliquer la loi, leur vente continuera certainement de prospérer, malgré de récentes interdictions généralisées de la vente et de la distribution de viandes sauvages.

Une pandémie mondiale est une incitation tragique à agir. Mais avec des preuves de plus en plus nombreuses que les pangolins jouent un rôle important dans l’écologie d’une telle menace potentielle, c’est peut-être la poussée dont la Chine a besoin pour enfin maîtriser son commerce illégal d’animaux.

Cette recherche a été publiée dans Nature .

Le premier ancêtre de nombreux animaux modernes pourrait avoir été trouvé en Australie

 

L’ancêtre le plus ancien connu des formes de vie animale les plus connues de la planète aujourd’hui semble avoir été identifié dans l’outback australien, révélant un étrange organisme ressemblant à un ver qui mérite notre respect et notre gratitude.

 

Ikaria wariootia , une goutte paresseuse de la taille d’un grain de riz, pourrait ne pas ressembler à grand-chose, mais les scientifiques pensent que ce pourrait être le plus ancien exemple jamais découvert de bilatéraux: les animaux à corps symétrique bilatéral (côtés gauche et droit en miroir) et côté avant et côté arrière, arborant généralement une bouche et un anus. Comme vous, en d’autres termes.

“C’est ce que les biologistes évolutionnistes ont prédit”, dit la géologue Mary Droser de UC Riverside. “C’est vraiment excitant que ce que nous avons trouvé s’accorde si bien avec leur prédiction.”

007 ikaria 4 Vue d’artiste d’Ikaria wariootia. (Sohail Wasif / UCR)

Ces dernières années, les scientifiques ont beaucoup appris sur les organismes multicellulaires spongieux et visqueux qui composent ce que l’on appelle le biote d’Ediacaran – un mystérieux groupe de formes de vie anciennes qui existaient avant l’explosion cambrienne .

L’une de ces créatures en particulier, appelée Dickinsonia , a attiré beaucoup d’attention parmi les chercheurs, étant identifiée il y a quelques années comme le monde premier animal connu dans les archives fossiles.

Cependant, tout ce qui a émergé au cours de cette période n’est pas directement lié aux humains, ni à tous les autres animaux à physiologie bilatérale.

Dickinsonia et d’autres grandes choses étaient probablement des impasses évolutives”, Droser explique .

D’où venons-nous, ainsi que les autres bilatéraux, alors? Pendant de nombreuses années, un ensemble de marques de fouilles fossilisées imprimées dans des dépôts de pierre à Nilpena, Australie du Sud , ont intrigué les chercheurs.

Ces traces fossiles, appelées Helminthoidichnites , datent de la période Ediacaran (spécifiquement il y a environ 551 à 560 millions d’années), et étaient supposées être l’héritage d’une ancienne forme de vie bilatérale. Grâce à de nouvelles recherches, rendues possibles par le balayage laser des dépôts de pierre, cette spéculation semble se confirmer.

007 ikaria 4 Impressions Ikaria wariootia dans la pierre. (Droser Lab / UCR)

“Nous pensions que ces animaux auraient dû exister pendant cet intervalle, mais nous avons toujours compris qu’ils seraient difficiles à reconnaître”, dit le paléontologue Scott Evans, maintenant avec le Musée national d’histoire naturelle de la Smithsonian Institution.

“Une fois que nous avons eu les scans 3D, nous savions que nous avions fait une découverte importante.”

Les scans révèlent des impressions faites par plus d’une centaine d’animaux anciens, variant entre 2 à 7 millimètres de long et environ 1 à 2,5 millimètres de large. . lieu »et« warioota »étant nommé pour Warioota Creek, qui court dans la région.

Selon l’équipe, les traces de fossiles de I. wariootia se trouvent plus bas que les autres enregistrements du biote d’Ediacaran sur le site d’Ediacara, suggérant cette créature simple, semblable à un ver, avec un corps cylindrique et des extrémités distinctes de la tête et de la queue, antérieures à d’autres animaux de la région, sans parler de quoi que ce soit avec ce genre de complexité bilatérale, comme la symétrie et la limace Kimberella , dont des traces ont été trouvés plus élevés.

007 ikaria 4 Numérisation laser 3D d’une empreinte Ikaria wariootia. (Droser Lab / UCR)

“Nous proposons qu’Ikaria soit le fabricant de traces de Helminthoidichnites et potentiellement le plus ancien, bilatéral définitif, au moins tel que représenté dans le fossile record de l’Australie du Sud “, écrivent les chercheurs dans leur article.

La morphologie d’Ikaria implique une construction corporelle potentiellement modulaire, qui aurait aidé à l’organisation musculaire requise pour le péristaltisme [contractions du système digestif]. Le déplacement et le piégeage des sédiments révèlent que Ikaria avait probablement un cœlome, une bouche, un anus et un intestin, bien qu’il soit peu probable qu’ils soient reproduits dans les archives fossiles. ”

Bien sûr, étant donné que nous avons affaire à des traces de fossiles – des impressions de quelque chose que nous ne pouvons pas réellement voir, et qui pourraient ne pas avoir existé pendant des centaines de millions d’années – il est difficile de soyez tout à fait sûr de I. wariootia pour l’instant.

Mais si les découvertes ultérieures d’autres réserves d’Ediacaran peuvent également révéler des preuves de ces vers anciens, la découverte de cette ancienne créature semblable à un ver pourrait être une étape importante dans notre compréhension de l’ascendance animale sur Terre, y compris où – en quelque sorte – nous venons nous-mêmes.

“La principale découverte du document est qu’il s’agit probablement du plus ancien bilatéral jamais reconnu dans les archives fossiles”, a expliqué Evans The Guardian .

“Parce que les humains sont des bilatéraux, nous pouvons dire que ce fut un parent très précoce et peut-être l’un des premiers sur l’arbre de vie bilatéral divers.”

Les résultats sont rapportés dans PNAS .

The First Stegosaur Tracks in Scotland Were Just Discovered on This Windy Island

Stand on the wind-swept crags lining Scotland’s western coast today, and you’d be lucky to spot a puffin or two. But the closer we look, the more evidence we find it was once home to an incredibly diverse array of ancient beasts.

 

The discovery of new sets of fossilised tracks has expanded the list of potential dinosaur populations that roamed what is now the Isle of Skye. Among them are tracks left by an animal that would have belonged to one of the most famous plate-backed herbivore suborders, Stegosauria.

Scottish and Brazilian researchers have spent the past couple of years analysing two recently found tracksites at a spot on the island’s north-eastern coast called Rubha nam Brathairean, or Brothers’ Point.

“These new tracksites give us a much clearer picture of the dinosaurs that lived in Scotland 170 million years ago,” says University of Edinburgh palaeontologist Stephen Brusatte.

Back then, the lands making up the British Isles were nothing like they are today. Jurassic Scotland sat far closer to the equator, roughly in alignment with where Greece is today. Warm seas and a sub-tropical climate established ecosystems that were bustling with life.

Still, just because it was a virtual paradise doesn’t mean it’s been perfect for preserving the remains of ancient life. The Jurassic isn’t exactly fossil friendly as it is, but Scotland has always seemed especially thin on dinosaur tracks and bones.

 

In spite of a rich history of fossil hunting throughout much of the United Kingdom, the first clear traces of dinosaur wildlife in Scotland were finally uncovered in the early 1980s when palaeontologists John Hudson and Julian Andrews found the “unmistakable print from a large dinosaur” in a fallen limestone block at Brothers’ Point.

Since then, a plethora of tracks belonging to a wide range of long-necked sauropods and fleet-footed theropods have been identified, turning the Isle of Skye into a landmark site for Jurassic researchers.

The most recent additions include teapot-sized holes that haven’t been found elsewhere on the island – impressions that are described in palaeontological terms as belonging to a category called Deltapodus.

stegosaur footprints skyeDeltapod tracks on Isle of Skye (dePolo et al., PLOS One, 2020)

“These discoveries are making Skye one of the best places in the world for understanding dinosaur evolution in the Middle Jurassic,” says Brusatte.

Without a means of narrowing down the exact species of dinosaur responsible, the researchers are careful about jumping to any conclusions.

But it’s fair to say that this group includes a type of cow-sized dinosaur famed for its lines of geometric plates adorning its spine, and a wicked clump of ‘thagomising‘ spines on its tail.

 

The team also uncovered another potentially new addition to the list, in the form of large imprints of something with three stubby toes possibly belonging to a group of heavyweight herbivores called ornithopods.

“We knew there were giant long-necked sauropods and jeep-sized carnivores, but we can now add plate-backed stegosaurs to that roster, and maybe even primitive cousins of the duck-billed dinosaurs too,” says Brusatte.

Not only do the tracks provide tantalising evidence that stegosaurs once trod along the muddy Scottish coastline, the age of the tracks provides some of the earliest evidence of this particular dinosaur’s existence.

Only last year, a species of stegosaur was dug up in the Middle Atlas Mountains of Morocco. At an estimated age of around 168 million years old, the fossilised remains of Adratiklit boulahfa are officially the oldest of its kind.

These tracks at Brother’s Point are closer to 170 million years old. While there’s no way to confirm what kind of stegosaur might have left them behind, it does help establish timelines and distributions describing their evolution.

“In particular, Deltapodus tracks give good evidence that stegosaurs lived on Skye at this time,” says the study’s lead author, Paige dePolo from the University of Edinburgh.

With such a rich assortment of tracks being found across the island, this part of Scotland is representative of an important period in evolutionary history, where the late Jurassic’s zoo of classic creatures was just beginning to develop their famous characteristics and spread out around the globe.

This research was published in PLOS One.

 

Incredibly Rare Footage Shows a Dwarf Sperm Whale Spray Ink as It Flees an Attack

In the crystal-clear shallows of Cape Town, South Africa, a dwarf sperm whale (Kogia sima) was recently filmed attempting to flee an aggressive seal by releasing a ‘smoke bomb’ of dark, ink-like fluid.

 

As the whale rushes away from its oncoming predator and towards the shore, its wake suddenly becomes clouded with a reddish-brown material straight from its intestine.

“This ‘inking’ behaviour has been documented before,” cetacean acoustician Karlina Merkens told ScienceAlert, “but it has been observed very rarely, and probably never seen and recorded in shallow water like this before.”

Dwarf sperm whales are shy creatures that usually inhabit the deep sea. They spend very little time at the water’s surface and they almost never approach vessels. 

As a result, very little data has been gathered on them; but we do know that unlike other whales, these dolphin-sized creatures are known to use a ‘squid-like tactic’ when escaping from predators.

If dwarf sperm whales feel threatened, they can actually release more than 11 litres (3 gallons) of a dark, reddish-brown liquid from a sac in their intestine. And this can buy them time in their flight.

Unfortunately, the recent event in South Africa did not shake out in the whale’s favour. Local news reports claim the sperm whale was extensively injured and weak when officials arrived, and a decision was made to euthanise it.

 

Some have since theorised that the whale became distressed and disoriented because the shallow water stopped its echolocation from working. But Merkens, who works for the United States National Oceanic and Atmospheric Administration (NOAA) told ScienceAlert she thought this was very unlikely. 

Instead, she argues, the echoes coming off of objects in the harbour were probably confusing for the animal because it had likely never encountered any substantial solid surface before.

“Add that ‘noisy’ environment to being attacked by an aggressive animal of approximately the same size and also the possibility of an illness that caused it to be in shallow water to begin with, and it is very reasonable to assume that this animal was so highly stressed and disoriented that it was simply unable to navigate safely in such circumstances,” Merkens says.

The poor thing was in dangerous waters to begin with.