Нови открития в палеонтологията

[Last roman]

Екип руски и шведски палеонтолози установи, че първите сухоземни животни са се появили на територията на... Сибир, естествено:

http://novokuznetsk.su/news/city/1381757206

[Last roman]

в Австралия са намерени останки на гигантска птицечовка /живяла преди 15 и 5 милиона години/.

http://www.heritagedaily.com/2013/11/fossil-of-largest-known-platypus-discovered-in-australia/99615

[lila_va]

300 млн. годишни останки на Eocasea martini илюстрират прехода от месоядни към растителноядни на сушата (независимо какво пише в най-старата книга ). Революционният преход е позволил на първите растителноядни да се възползват от обилието от хранителни ресурси, предоставяни от сухоземните растения, и буквално е насочил пътя на еволюцията.

http://www.sciencedaily.com/releases/2014/04/140416172243.htm

[Last roman]

какво ли не откриват хората по време на ергенските си партита:

Група приятели, които били тръгнали на ергенско парти, не очаквали да открият такава находка - фосилизиран череп от стегомастодон, на около 250 км от Албакърки в Ню Мексико, съобщи ЮПИ.

Младите мъже забелязали кост, която стърчи от земята. Те започнали да копаят около нея и скоро се оказало, че става въпрос за бивна.

Групата продължила да копае и намерила череп от животно, напомнящо гигантски слон.

След това тя се свързала с палеонтолога Гари Морган от Природонаучния музей на Ню Мексико. Морган пристигнал на място и установил, че младите мъже са изровили от земята череп от стегомастодон - подобен на слон праисторически бозайник, който се е срещал в Северна Америка преди около 3 милиона години.

"Този мастодонт се е скитал в долината на Рио Гранде преди 3 милиона години", поясни палеонтологът.

Младите мъже смятат, че са щастливци, тъй като известни учени не са имали късмета да попаднат на подобна находка.

"Това е уникално откритие! Ние сме големи късметлии", заяви един от участниците в нестандартното ергенско парти.

http://www.vesti.bg/tehnologii/nauka-i-tehnika/ergensko-parti-otkri-fosili-ot-cherep-na-stegomastodon-6015077

И на английски:

http://www.iflscience.com/plants-and-animals/bachelor-party-stumbles-upon-huge-fossil-skull

Редактирано Юни 19, 2014 от Last roman

[Last roman]

Гигантска костенурка, живяла преди 60 милиона години си похапвала крокодили на закуска:

http://scitechdaily.com/carbonemys-was-a-giant-turtle-from-late-paleocene/

[Last roman]

учените след 130-годишно 'взиране' най-накрая откриха полови органи при панцерни риби /демек доказателство за вътрешно оплождане/:

http://news.nationalgeographic.com/news/2014/10/141019-fossil-fish-evolution-sex-fertilization/?utm_source=Facebook&utm_medium=Social&utm_content=link_fb20141020news-fishsex&utm_campaign=Content&sf5322909=1

[Last roman]

Диметродонът преди 290 млн. години похапвал акули:

http://www.iflscience.com/plants-and-animals/permian-predator-returned-oceans-eat-shark

[Last roman]

фосил на 300 милиона години доказа наличие на цветно зрение у примитивните риби:

300-Million-Year-Old Fossil Suggests Ancient Fish Could See in Color

Fossilized rod and cone cells — the kinds that help people see — have been discovered for the first time, researchers say.

The finding reveals that such eye cells have existed for at least 300 million years, and that the ancient fish they were discovered in likely saw in color, according to the study's scientists.

Human vision depends on pigments that absorb light. These pigments lie inside cells known as rods and cones. Cones are sensitive to color and also help perceive fine detail and rapid changes. Rods are more sensitive to light than cones, but are not sensitive to color, and are responsible for peripheral and night vision. Both rods and cones are found in a layer of tissue in the back of the eye known as the retina.

Fossilized Acanthodes bridgei with eye tissues intact.

Myllokunmingia may be one of the earliest known creatures with a backbone, and this creature may have possessed a rudimentary cameralike eye, which suggests vision dates back at least 520 million years. However, much remains unknown about the evolution of vision, since the soft tissue of the eye usually decays rapidly after death.

To learn more about the evolution of vision, scientists analyzed an exceptionally well-preserved 300-million-year-old fossil specimen of a fish called Acanthodes bridgei. The fossil was excavated from Kansas and is kept at the National Museum of Nature and Science in Tokyo. The fish, which reached up to about 4 inches (10 centimeters) long, is the last known common ancestor of modern jawed fishes, including fishes with bony skeletons, such as barracudas, and cartilage skeletons, such as sharks.

http://www.nbcnews.com/science/science-news/300-million-year-old-fossil-suggests-ancient-fish-could-see-n273946

Редактирано Декември 24, 2014 от Last roman

[Last roman]

Ихтиозавър на 170 милиона години хвърля светлина върху еволюцията на тези морски влечуги през ранния Юрски период:

170-Million-Year-Old Fossil Of Previously Unknown Marine Reptile Found In Scotland

After trawling through a collection of fossil fragments gathered on the Isle of Skye, a team of paleontologists pieced together the remains of a previously unknown species of ancient marine reptile. The now extinct predatory animal, an ichthyosaur, swam the shallow waters around Scotland some 170 million years ago, during the Jurassic Period.

Alongside identifying a new species, the team also found the remains of several known species of ichthyosaur, which are believed to be the first ichthyosaurs from Scotlanddescribed so far. Not only that, but the find is helping scientists slowly fill in a frustrating gapin the fossil record during the Middle Jurassic, a 15-million-year stretch that began around 176 million years ago.

The discovery was made by researchers at the University of Edinburgh who had the laborious task of examining a collection of fragmented skulls, teeth and vertebrae unearthed by different teams of scientists and fossil hunters over the past 50 years. Several different species of ichthyosaur were discovered, which spanned the Early to Middle Jurassic, including the newly described Dearcmhara shawcrossi.

The latter part of the name is in honor of the specimen’s discoverer, Brian Shawcross, who donated the fossils to a museum after recovering them in 1959. Dearcmhara is gaelic for “marine lizard”; ichthyosaur translates to fish lizard. D. shawcrossi represents both a new species and a new genus, making the discovery particularly exciting.

The specimen, which has been described in the Scottish Journal of Geology, was around the size of an average great white shark, measuring 4.3 meters (14 ft) from snout to tail. This animal therefore sits at the smaller end of the ichthyosaur spectrum as some previously described specimens measured up to nine meters (30 ft) in length.

Ichthyosaurs were predatory marine reptiles that swam our oceans while the dinosaurs ruled the land. They lived during the Mesozoic Era, the Age of the Reptiles, first appearing during the Triassic and finally dying out during the Cretaceous. Early ichthyosaurs had long, flexible bodies and probably swam like modern day eels. However, they rapidly diversified from animals that resembled lizards with fins into a more streamlined, fish-like form that was built for speed.

Although a number of ichthyosaur fossils have been unearthed since their discovery along the Dorset coast back in 1809, skeletons from the Middle Jurassic period are rare. “It’s one of a select few specimens of that age in the world,” said paleontologist and study co-author Stephen Brusatte. Furthermore, Brusatte is excited to be able to boast that this is “the first time we’ve found a new species that was uniquely Scottish.”

[Via University of Edinburgh, Scottish Journal of Geology, BBC News and Live Science]

[Last roman]

Древнo изкопаемo може да пренапише еволюционното дърво на рибите

Рибата Janusiscus (на около 415 млн г.) е важно доказателство за добре развития външен скелет (показан в синьо) общ прародител и на костните, и на хрущялните риби.

Всички хора, както и повечето други гръбначни, принадлежат към същата група, както костните риби. Учените знаят, че тези групи са се разделили преди повече от 420 млн. години, но как е изглеждал последният общ прародител остава загадка.

Може да се изненадате, но най-важната разлика между хората и акулите не са крайниците или дори не са белите дробове в сравнение с хрилете. Нещата се свеждат до скелетите. Скелетите на акулите са от хрущял и принадлежат на група, наречена челюстни хрущялни риби.

Въпросното изкопаемо от Сибир се определя на около 415 млн. години. Досега подобни фосили се класифицираха като костни риби, принадлежащи към рода Dialipina, на базата на характеристиките на костите на главата.

За да се определи къде по-точно се вписва тази риба в еволюцията на ранните челюстни гръбначни животни, екип от учени използва микроскенер, използващ образната компютърна томография, подобен на тези, които се използват в болниците. Така може да се визуализира на структурата на костите вътре, без да се разрушава фосила. Въпреки че фосилите преди това са били класифицирани като костни риби въз основа на външните им характеристики, томографията разкри изненадваща мозайка от функции, характерни и за хрущялните, и за костните риби. Например, черепът на рибата е направен от големи, костни плочки, подобни на съвременните костни риби, но следите от нервите и кръвоносните съдове в мозъка повече напомнят за тези от хрущялните риби. В доклада си, публикуван в Nature, екипът дава име на изкопаемата риба Janusiscus schultzei на името на двуликия древноримски бог Янус.

Констатациите показват, че общият прародител на двата клона на челюстните гръбначни е имал характеристики на костна риба, които впоследствие са се загубили при по-нататъшното развитие на хрущялните риби, като костните плочки на черепа. Някои черти, за които се смята, че са уникални за костните риби, като например наличието на големи пластинчати кости, всъщност ги е имало при панцерните риби, изчезнала група челюстни риби, свързващ общ прародител както на хрущялните така и на костните риби.

Това ново изследване се подкрепя от едно друго проучване от 2014г., което показа, че изкопаема акула на 325 млн години има изненадващо много функции на костна риба, което предполага, че прародителят й също трябва да има такива функции и че акулите могат да бъдат по-специализирани, отколкото първоначално се смяташе. Тези находки като цяло може да коригират погрешната представа, че хрущялните риби са по-примитивни от костните риба, казва Сам Джайлс (Sam Giles), водещ автор на изследването.

http://offnews.bg/news/%D0%9D%D0%B0%D1%83%D0%BA%D0%B0_34/%D0%94%D1%80%D0%B5%D0%B2%D0%BDo-%D0%B8%D0%B7%D0%BA%D0%BE%D0%BF%D0%B0%D0%B5%D0%BCo-%D0%BC%D0%BE%D0%B6%D0%B5-%D0%B4%D0%B0-%D0%BF%D1%80%D0%B5%D0%BD%D0%B0%D0%BF%D0%B8%D1%88%D0%B5-%D0%B5%D0%B2%D0%BE%D0%BB%D1%8E%D1%86%D0%B8%D0%BE%D0%BD%D0%BD%D0%BE%D1%82%D0%BE-%D0%B4%D1%8A%D1%80%D0%B2%D0%BE-%D0%BD%D0%B0-%D1%80%D0%B8%D0%B1%D0%B8%D1%82%D0%B5_449019.html

[Last roman]

Нови находки на палеозмии изместиха началото на тяхната еволюция към средата на Юрския период:

Researcher Stumbles Across Oldest Snake Fossils Ever Found In Museum

Paleo reconstruction of Diablophis gilmorei (Upper Jurassic), hiding in a ceratosaur skull, from the Morrison Formation, Fruita, Colorado / Julius Csotonyi

The oldest snake fossils ever discovered represent four new species from three countries. The remarkable findings, published in Nature Communications this week, push our knowledge of the slithery reptile back by 70 million years, challenging what we long assumed about their evolution. Turns out, certain serpentine features showed up long before they even lost their legs.

An international team led by Michael Caldwell from the University of Alberta reexamined fossilized skull and jaw bones belonging to 13 snake groups stored in museum collections. They identified four new snake species from Middle Jurassic and Lower Cretaceous sediment that lived in England, Portugal, and the U.S. between 143 million and 167 million years ago. Until now, the oldest known fossil snakes date back to about 100-million-year-old Upper Cretaceous layers.

Like some of the snakes we have nowadays, these animals have sharp, backward pointing teeth. Their overall length and shape remain a mystery, since we only have vertebrae from some of them. But based on those and the presence of key snake-like features in their skull bones, the team thinks that their large, highly mobile head evolved first. The classic snake head was then followed by the evolution of the elongated, limbless body.

“The study explores the idea that evolution within the group called ‘snakes’ is much more complex than previously thought,” Caldwell says in a news release. “Importantly, there is now a significant knowledge gap to be bridged by future research, as no fossils snakes are known from between 140 to 100 million years ago.”

To the right is a reconstruction of Portugalophis lignites in a ginko tree. It was unearthed from Upper Jurassic coal swamp deposits near Guimarota, Portugal. At about a meter long, this was the largest of the snakes. The oldest one, Eophis underwoodi, was found near Kirtlington in southern England. A few fragmentary remains suggest it was a small individual, though it’s difficult to say how old it was when it was fossilized. In recognition of being the oldest known snake material, “eos” means “dawn” in Greek, and “ophis” refers to snakes.

“Based on the new evidence and through comparison to living legless lizards that are not snakes, the paper explores the novel idea that the evolution of the characteristic snake skull and its parts appeared long before snakes lost their legs,” Caldwell explains. From 167 million to 100 million years ago, snakes evolved toward the long, limb-reduced body shape that characterize the 100-million-year-old marine snakes from the West Bank, Lebanon, and Argentina—these have small but well-developed rear limbs.

These new ancient snakes hung out in different habitats across the planet. Three of them lived in swampy coastal areas on large island chains in western parts of ancient Europe. The North American species, Diablophis gilmorei (pictured at the top), was found in inland river deposits of the Morrison Formation in Fruita, Colorado. “Diablo,” or “devil” in Spanish, refers to where it was found, near Devil’s Canyon.

And finally, Parviraptor estesi was discovered in the Upper Jurassic-Lower Cretaceous Purbeck Limestone in Swanage, England. Below, it’s swimming in a freshwater lake with snails and algae:

http://www.iflscience.com/plants-and-animals/four-new-species-identified-oldest-snake-fossils-ever-discovered

Редактирано Януари 28, 2015 от Last roman

[Last roman]

анализ на скали на възраст 3,2 милиарда години показва, че животът /макар и на микробиално ниво/ е процъфтявал и тогава:

Could Life On Earth Have Thrived 3.2 Billion Years Ago?

While it isn’t known exactly how life first appeared on Earth, scientists do know a great deal about the conditions that life needs to exist, and geological records provide clues about what the atmosphere was like. A new study published in Nature provides evidence that 3.2 billion years ago, forms of life were able to pull nitrogen out of the air. Nitrogen is crucial to the formation of genetic material and would have allowed a greater number of organisms to live. This paper pushes back the earliest evidence of thriving life by over a billion years.

"People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn't until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse," co-author Roger Buick said in a press release. "Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere.”

Buick and his team analyzed rock samples that dated back 2.75-3.2 billion years. The rock's remarkable preservation is due to the fact that they came from the borders of continental shelves, not near volcanoes that would have adulterated them.

The samples were analyzed for their nitrogen isotopes in order to see if life forms were grabbing atmospheric nitrogen and converting it into a usable product. Much of the nitrogen in the atmosphere would have been triple bonded, which would have made it impossible for simple early organisms to use.

However, there are enzymes which are able to break one of those bonds, converting the nitrogen into a form that could bond with other molecules. DNA has indicated that these enzymes first appeared around 2 billion years ago, but even the samples that were 3.2 billion years old provided evidence of nitrogen isotopes that were altered in this manner.

"Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating," lead author Eva Stüeken added. "It suggests that these really complicated enzymes apparently formed really early, so maybe it's not so difficult for these enzymes to evolve.”

There are currently three primary enzymes responsible for nitrogen fixation, and the one most similar to what was seen in the rock samples is based on molybdenum. However, molybdenum was not thought to have been abundant at the time. It is possible that the molybdenum was released by simple microbial life living on rocks, though it will be hard to confirm with much certainty.

"We'll never find any direct evidence of land scum one cell thick, but this might be giving us indirect evidence that the land was inhabited," Buick concluded. "Microbes could have crawled out of the ocean and lived in a slime layer on the rocks on land, even before 3.2 billion years ago.”

The researchers will continue to analyze these ancient samples for other elements that might have affected early life on Earth.

Редактирано 18, 2015 от Last roman

[Elemag]

Аналоги современных кротов, выдр и приматов существовали уже в юрском периоде

[Last roman]

триметрово земноводно, от подразред Стереоспондили /група амфибии, характерни за триаския и юрския периоди/ е открито в Португалия:

Paleontologists Uncover “Super Salamander” Boneyard

by Brian Switek

Finding fossils takes a combination of skill on luck. You have to be looking in the right place and have some idea of how to distinguish those precious pieces of prehistoric life from all the rock surrounding it. But that’s not all. How the sun hits stone, where your eyes fall along the outcrop, and even where you stop to take a leak can make all the difference between finding something amazing and passing it by. And that’s just in the field. Museum collections hold petrified trails of bread crumbs, too, leading to forgotten places whose fossiliferous potential hasn’t been realized.

Sometime in the late 70s or early 80s, geology student Thomas Schröter was hiking through the red rocks of Algarve, Portugal when he spotted some fossil bone. They didn’t relate to the thesis he was working on, but he picked them up anyway. While not especially remarkable, the scraps nevertheless made the customary transition from field to museum collection and were later appraised as those of a metoposaur – salamander-like amphibians that could get up to 10 feet long and lived a lifestyle one of my professors once called “crocodiling before there were crocodiles.”

These enormous amphibians were, and are, anything but rare. They’re among the most common fossils found in the 237-201 million year old rock representing Late Triassic time, sometimes clustered together in dense bonebed where they died en masse. And as paleontologists Stephen Brusatte, Richard Butler, Octávio Mateus, and Sébastien Steyer found when they relocated the Algarve site in 2009 after reading a short description of the fragments plucked from the site, Schröter had discovered another such graveyard.

Paleontologists excavate the Algarve bonebed in Portugal. Photo courtesy Stephen Brusatte.

There’s more in the Algarve bonebed than has yet been excavated and prepared. So far, however, Brusatte and colleagues have uncovered multiple skulls and bones from the chests of these aquatic ambush predators. And while these remains are similar to those of other Metoposaurus found elsewhere in Europe, they’re different enough to justify establishing a new species – Metoposaurus algarvensis.

What brought so many Metoposaurus together to die isn’t clear. At this point, the researchers write, it’s unknown whether they died in the place they were entombed or their remains were washed in from elsewhere. But seasonal droughts could have played a role.

Metoposaur sites around the Triassic world. From Brusatte et al., 2015.

Algarve was much closer to the equator in the Triassic than today, scorched in dry seasons and doused by the return of the monsoons. Perhaps the unfortunate Metoposaurus were pushed together into an ever-shrinking water source, baked to death before rains returned to bury them.

Regardless of the reason for their death, though, the fossils are part of a metoposaur band that ran across the middle of Pangaea, the only outliers being a cluster in prehistoric India and Madagascar. Future finds will alter this picture to greater or lesser degrees, but it may be that metoposaurs thrived in hot, highly-seasonal environments where early dinosaurs stayed small and croc cousins ruled while different predators waited along the shores of higher-latitude habitats. The only way to find out more is to keep digging.

Reference:

Brusatte, S., Butler, R., Mateus, O., Steyer, S. 2015. A new species of Metoposaurus from the Late Triassic of Portugal and comments on the systematics and biogeography of metoposaurid temnospondyls. Journal of Vertebrate Paleontology. doi: 10.1080/2724634.2014.912988

Редактирано Март 25, 2015 от Last roman

[Last roman]

Weird fossil worm with legs and spikes finally reveals its head

It's easier to be bamboozled by a worm than you might think. This enigmatic 508-million-year-old worm-like creature has been tricking scientists since the 1970s. Reconstructions of what it would have looked like had it upside down, on its side and even back to front.

Now Martin Smith of the University of Cambridge and his colleagues think they finally have the correct description of this creature, which lived during theCambrian explosion when most major animal groups first emerge in the fossil record.

Hallucigenia was a worm-like marine animal with legs, spikes and a head that is difficult to distinguish from its tail. It is only a few centimetres long, and its body is as thin as a pin.

The late evolutionary biologist Stephen Jay Gould once recounted how Simon Conway Morris, the palaeontologist who coined the name Hallucigenia, chose it because the creature reminded him of something he'd once seen on a trip – "and I don't mean to Boston".

Wacky interpretations

"Early studies did not realise that parts of the body were buried, and parts of the fossil were not actually part of the animal – leading to the somewhat wacky early interpretations," says Smith.

Now, his team has used electron microscopy to describe the creature in unprecedented detail.

As thin as a pin and as prickly as one too (Image: Martin R. Smith)

What was once thought to be its head is in fact just a dark stain that could have been gut contents that oozed out as the animal was flattened in a submarine landslide. So they dug away the sediment around the other side of the animal to reveal its head.

There, they found a pair of simple eyes, which sat above a mouth with a ring of teeth. Its throat was also lined with needle-shaped teeth, which are thought to have worked like a ratchet, keeping food from slipping out each time it took another "suck" at its food.

The findings could help us understand the evolution of moulting animals, a diverse group that includes arthropods, velvet worms and water bears. The teeth resemble those from many other early moulting animals, suggesting that a tooth-lined throat was present in a common ancestor, the team says.

Smith thinks that we now have the final and correct view of what Hallucigeniareally looked like. "But with a creature so bizarre and full of surprises, you never know what else it might have up its sleeve."

Journal reference: Nature, DOI: 10.1038/nature14573

http://www.newscientist.com/article/dn27778-weird-fossil-worm-with-legs-and-spikes-finally-reveals-its-head.html?utm_source=NSNS&utm_medium=SOC&utm_campaign=hoot&cmpid=SOC%257CNSNS%257C2015-GLOBAL-hoot#.VYuofbbFwmM

[Малоум 2]

Имало и с нещо като перушина, казват:

http://nauka.offnews.bg/news/%D0%9D%D0%BE%D0%B2%D0%B8%D0%BD%D0%B8_1/%D0%9F%D1%8A%D1%80%D0%B2%D0%BE%D1%82%D0%BE-%D0%B1%D1%80%D0%BE%D0%BD%D0%B8%D1%80%D0%B0%D0%BD%D0%BE-%D1%81%D1%8A%D1%89%D0%B5%D1%81%D1%82%D0%B2%D0%BE-%D0%B5-%D1%81%D1%8A%D1%81-%D1%88%D0%B8%D0%BF%D0%BE%D0%B2%D0%B5-%D0%BD%D0%B0-%D0%B3%D1%8A%D1%80%D0%B1%D0%B0-%D0%B8-%D0%BD%D0%B5%D0%B6%D0%BD%D0%B8-%D0%BF%D0%B5%D1%80%D0%B0-%D0%B7%D0%B0-%D0%BA%D1%80%D0%B0%D0%B9%D0%BD%D0%B8%D1%86%D0%B8_9901.html

Eдин от първите обитатели на Земята, развили броня за защита от хищници, e малко странно създание с редици от шипове на гърба си и подобни на нежни пера предни крайници, с които е филтрирало храна от водата.

То е населявало преди повече от половин милиард години древните морета, покривали днешен Китай, където е открит този нов вид от палеонтолози от Университета Кеймбридж.

Учените обявиха в понеделник за откриването в провинция Юнан на красиви и запазени фосили на едно от най-странните животни, обитавали някога Земята. Съществото, Collinsium ciliosum, е живял през периода камбрий, време на забележителни еволюционни експерименти, когато са се появили много необичайни животни и по-късно са изчезнали.

Името му означава "космато чудовище на Колинс", заради странния му вид и косматите структури и в чест на на канадския палеонтолог Дезмънд Колинс (Desmond Collins), който за първи преди десетилетия е открил и описал подобно създание.

...

Ортега-Ернандес твърди, че Collinsium, които са живели преди около 515-518 милиона години, е далечен прародител на днешните кадифени червеи, група червеи, които обивават тропическите гори.

Collinsium са достигали до 10 cm дължина, снабдени със 72 остри шипове на гърба си, за да се предпазват от хищници и са едни от най-ранните животните, които са предпазвали меката си плът с броня.

Те имали подобно на наденица тяло със шест двойки, подобни на пера предни крайници, девет двойки задни крака с нокти и закръглена глава. Те разпервали перестите си предни крака, за да се образува нещо като кошница за улавяне на частици храна.

Collinsium е близък братовчед на друго странно същество от камбрия - Халюцигенията, Hallucigenia, с която ви запознахме скоро.

..."

...

[kall]

Изследователи са открили най-добре запазените и най-стари останки на бозайник в Испания. Откритият бозайник е представител на вида Spinolestes xenarthrosus и е с дължина 24 cm от муцуната до опашката. Удивителното в това откритие е изключително добре запазените останки, включително кожа, козина, дори вътрешни тъкани. Откритието е публикувано в Nature

http://www.nature.com/nature/journal/v526/n7573/full/nature14905.html

 

[Last roman]

Ancient ‘Fire Frog’ Among Odd New Amphibians Found in Brazil

About 278 million years ago, a diverse group of weird creatures roamed the swamps of what's now northeastern Brazil.

A rich fossil deposit in northeastern Brazil has provided paleontologists with a new look at a time when many strange amphibians—including a "fire frog"—thrived in ancient swamps.

The unusual fossil amphibians, described by Field Museum paleontologist Kenneth Angielczyk and colleagues in Nature Communications on November 5, were found in Brazil’s Paranaíba Basin and date back to the early part of the Permian period, about 278 million years ago.

Fossils have been known from this area for decades, but, Angielczyk says, it was the search for a particular kind of animal that drew him and his co-authors to take another look.

“We actually got started there with the hope of finding early therapsids"—protomammal human cousins that thrived during the Permian. (Related: "Our Prehistoric Cousins Had Demonic Skulls.")

Up until now, most of what was known about this time in Earth's history came from North America. These rocks, now in Texas and Oklahoma, were close to the Equator during the early Permian and provided only a narrow view of what life was like then.

“We are especially in the dark about what was going on in Gondwana,” or the large southern supercontinent that existed at the time, says Angielczyk, whose work was supported by the National Geographic Society's Committee for Research and Exploration.

The Paranaíba Basin seemed like a good place to look to start filling in some of the global gaps: For one, it was located in the subtropics, south of well-known territory, Angielczyk says.

And while the team has yet to uncover any therapsids, Angielczyk says, the explorations have turned up a variety of other odd fossils. (Learn more about prehistoric animals.)

“The Paranaíba Basin happens to have had a number lake and wetland environments at the time, and the fossils we’re finding show that there was a diverse community of plants, fish, sharks, and amphibians there, with reptiles present on land," Angielczyk says.

In addition to some previously known animals—such as a giant, crocodile-like amphibian named Prionosuchus plummeri—the researchers have discovered some new animals, including the salamander-like Timonya anneae and Procuhy nazariensis, whose name translates to “the fire frog from Nazaria" (a combination of the Timbira language and the name of a local town).

More Discoveries Await

“It is very exciting,” says Museum of Western Colorado paleontologist Julia McHugh.

In addition to filling a fossil gap in a previously little-known part of the world, the Paranaíba Basin has the potential to explain how some of these weird amphibians evolved and moved around the planet, says McHugh, who wasn't involved in the new study.

For example, the discovery of a type of amphibian called a dvinosaur in the Paranaíba Basin adds a new point on the map along with finds from North America and Russia, she says. “This locality bridges the biogeographical gap between disparate species of the group,” McHugh says. 

Ancient animals swim in a tropical lake in an artist's imagining. They include Timonya anneae (left foreground), the "fire frog" Procuhy nazariensis (larger animal, right), and a rhinesuchid amphibian (left, background, under a fallen branch).

 
 

And the work in Brazil isn’t yet done. Angielczyk says that efforts are continuing to dig into what might be hidden at this particular spot.

"It’s taken us a while to figure out the best places to look for fossils, and we only found our first reptiles this year,” he says.

The “fire frog," he hopes, is the just the spark for many discoveries to come.

http://news.nationalgeographic.com/2015/11/151109-ancient-amphibians-science-paleontology-fossils-mammals/?utm_source=Facebook&utm_medium=Social&utm_content=link_fb20151109news-amphibians&utm_campaign=Content&sf15100459=1

Редактирано Ноември 10, 2015 от Last roman

[Last roman]

В Норвегия откриха фосилизирана гора от Девонския период:

http://www.popsci.com/fossilized-tropical-forests-found-in-arctic?src=SOC&dom=fb

[Last roman]

бронирани и бодливи червеи населявали Земята преди половин милиард години:

Researchers working with 535 million-year-old rocks from southern China have discovered the fossils of an armored worm-like creature that’s just a few millimeters long with at least five pairs of large spikes along its body. They named it Eokinorhynchus rarus, and it’s closely related to – and possibly an ancestor of – marine invertebrates called kinorhynchs, also known as mud dragons. The findings are published in Scientific Reports this week. 

These days, there are about 240 kinorhynch species, and their bodies are divided into three sections: head, neck, and trunk. The head includes a mouth cone with circlets of teeth, and the trunk is further split up into 11 segments. Previous molecular clock estimates suggest that they diverged just before the Cambrian, but no kinorhynch fossils have been uncovered until now. The new species E. rarus – Latin for “rare” – would be the first fossil kinorhynch unearthed from the rock record. 

A team led by Huaqiao Zhang from the Chinese Academy of Sciences and Virginia Tech’sShuhai Xiao examined several microfossils collected from the early Cambrian limestone deposits of Sichuan and Shaanxi provinces. Using scanning electron microscopy, microCT scans, and phylogenetic analyses, the team uncovered several similarities between the new extinct species and today’s kinorhynchs to suggest a close evolutionary relationship.

For example, the trunk of E. rarus and modern kinorhynchs are divided into segments each consisting of small, articulated plates, and they all have hollow spines called spinose sclerites. But compared to living kinorhynchs, E. rarus has about twice as many segments, and it’s armored with larger, more distinct spines. In addition to the five pairs of large spikes arranged bilaterally around the trunk, E. rarus also has a single large spine located in the middle of its body (visible in the image labeled “b” above) and two pairs of spines located near the anus. 

Xiao thinks that the spines helped facilitate locomotion. "These tiny worms probably lived in the interstitial spaces within sandy sediments, so they likely used the spiky spines to anchor themselves when navigating among sand grains," he tells IFLScience. "They may have also functioned as defensive structures."

^{Scanning electron microscopic image of Eokinorhynchus rarus. Dinghua Yang}

Many bilaterally symmetrical animals – or bilaterians, which includes people and bugs alike – have some version of repetition or iteration of anatomical structures. Examples include the body segments and legs of both vertebrates and arthropods (the group encompassing insects, spiders, and crustaceans). Since the 19th century, scientists have been debating whether body segmentation and appendages evolved only once in the last common ancestor of bilaterians, or if they evolved multiple times independently among different animal groups.

"The current consensus is that, although the genes to pattern body segments and limb development might have been present in the last common ancestor of bilaterians, body segmentation and appendages evolved independently in different groups that recruit the same or similar genes to do the job," Xiao explains. 

But some dissenters think that the last common ancestor of kinorhynchs and arthropods had legs, which were lost later along the lineage toward mud dragons and their relatives. "These new primitive fossils tell us that early kinorhynchs diverged and evolved body segmentation more than 530 million years ago, independent of arthropods," Xiao adds, "and that they never had legs."

http://www.iflscience.com/plants-and-animals/spiky-armored-worm-lived-half-billion-years-ago

[Last roman]

В Африка е открит е най-големият прaисторически крокодил /живял преди около 150 млн. г./:

Monster-Sized Marine Crocodile Discovered

A fossil found in the African desert is the biggest of its kind.

The biggest sea-dwelling crocodile ever found has turned up in the Tunisian desert. The whopper of a prehistoric predator grew to over 30 feet long (nearly ten meters) and weighed three tons.

Paleontologists have dubbed the new species Machimosaurus rex and describe it Monday in the journal Cretaceous Research.

Although the recovered remains are fragmentary, enough remained in the 120-million-year-old rock to identify the reptile as the largest known member of a peculiar lineage of crocodiles that spent their lives almost entirely at sea.

“This is a neat new discovery from a part of the world that hasn’t been well-explored for fossils,” says University of Edinburgh paleontologist Stephen Brusatte, who was not involved with the new study.

The fossils, including a skull and a smattering of other bones, were discovered by Federico Fanti of the University of Bologna in Italy and colleagues with support from the National Geographic Society.

Big Bite

Scientists are awaiting the discovery of a more complete skeleton to figure out exactly how large Machimosaurus rex was. But assuming that the new species had similar proportions as its close relatives, Fanti estimates that Machimosaurus rex stretched about 31 feet (9.6 meters) in length.

While not as large as some of its later, distant relatives that lived in freshwater, that makes Machimosaurus rex the biggest ocean-dwelling member of the crocodile family tree

 

Giant Prehistoric Crocodile Discovered in Tunisia 

National Geographic grantee Federico Fanti and his research team discovered a giant Cretaceous crocodile skeleton in southern Tunisia dating back to 130 million years ago, with a head over five feet long.

The biggest freshwater croc ever, Sarcosuchus imperator, lived 110 million years ago, grew as long as 40 feet (12 meters), and weighed up to eight metric tons (17,500 pounds). Since the time of this and other giants such as the alligator Deinosuchus, many crocodile lineages have died out, leaving today’s saltwater crocs closely related.

The carnivore’s teeth may hint at what it fed on in the ancient ocean. “Machimosaurus rex had stocky, relatively short and rounded teeth,” Fanti says, “and a massive skull capable of a remarkable bite force.” This cluster of features leads Fanti to suggest that the croc was a generalist hunter that took a variety of prey, including large marine turtles.

“It would likely have been something of an ambush predator, hanging around in shallow water hunting turtles and fishes and maybe waiting for some land animals to come a little too close to the shore,” Brusatte adds.

Tough Survivor

For scientists, the most important aspect of Machimosaurus rex isn’t so much its size as when it lived.

Paleontologists have long debated whether or not there was a mass extinction at the end of the Jurassic period, 145 million years ago. The group that includes Machimosaurus, called the teleosaurids, is among those thought to have died out.

A reconstruction of Machimosaurus rex based on the fossil bones found (white) shows its size compared with a human.

 
ARTWORK BY MARCO AUDITORE

The discovery of Machimosaurus rex in later rocks from the Cretaceous hints that if there was a mass extinction, it didn’t kill off life planetwide. “The new find adds to growing evidence that a lot of marine reptiles made it across the boundary and through the supposed extinction,” Brusatte says.

Rather than being a rapid extermination, the extinction may have been a more drawn-out transition. “In our interpretation,” Fanti says, “the end-Jurassic event was global in its effects but was mostly likely a complex sequence of local biological crises that are still poorly documented.”

One of the outstanding mysteries is why the marine crocodiles didn’t reclaim their former glory. Even though the family of Machimosaurus rexsurvived for longer than thought, they didn’t appear to thrive as they had in the Jurassic.

While Machimosaurus rex was certainly impressive in size, Brusatte says, “it may have just been a dead croc walking.”

Machimosaurus and other ancient crocodiles will be featured in “Crocs - Ancient Predators in a Modern World,” at the National Geographic Museum in Washington, D.C., from Jan. 27 to May 8, 2016.

Read Brian Switek's blog Laelaps on NationalGeographic.com. Follow him on Twitter, Facebook, and Instagram.

 

http://news.nationalgeographic.com/2016/01/160111-ancient-crocodile-marine-largest-paleontology/?utm_source=Facebook&utm_medium=Social&utm_content=link_fbex20160111news-monstercroc&utm_campaign=Content&sf18562605=1

Редактирано Януари 11, 2016 от Last roman

[Last roman]

Шведски учени са открили микроорганизъм, който може да е преходна форма от прокариотни към еукариотни едноклетъчни организми, от които по-късно се развиват по-сложните многоклетъчни форми на живот - растения, гъби и животни.

Прокариотите, най-примитивните организми като бактерии и археи имат прост клетъчен строеж - те нямат дори ядро, но преди два милиарда години са дали началото на еукариотите. Еукариотите са вече много по-сложни клетки и изграждат всички многоклетъчни организми, включително и нас, хората.

За това, как е станал този еволюционен скок има няколко теории:

• Теорията за инвагинация (автогенната теория) предполага, че мембранните органели са произлезли чрез инвагинация (вгъване) на периферната мембрана на клетката, а автономността на пластидите и митохондриите се обяснява с превземането на генетичен материал, разсеян в клетките на прокариотите.

• Съгласно теорията на пряката филиация, всички организми на Земята са произлезли от един тип бактерии, а всички растения и животни – от един тип микроби-еукариоти. Фотосинтезиращите бактерии дали началото на водораслите, а после растенията или някои водорасли загубват своите пластиди и се превръщат в прародители на гъбите и животните.

• Според теорията за ендосимбиозата еукариотите са се появили в резултат на симбиозата на няколко разновидности на бактерии-прокариоти. Най-вероятно, митохондриите са произлезли от аеробни алфа-протобактерии, пластидите – от цианобактерии, а цитоплазмата – от някаква архея. Родоначалниците на органелите са влезли в главната клетка може би като жертва или като вътрешен паразит, след което комбинацията става взаимноизгодна за двата организма.

По някой от тези пътища (като най-голямо основание има последния) преди 2 милиарда години е станал този съдбовен преход.

Прокариотна клетка	Еукариотна клетка

Шведският биолог Тийс Етема (Thijs Ettema), изследващ археите на дъното на Атлантическия океан, смята, че е открил кандидат за "преходно звено" между прокариоти и еукариоти

Неговият екип е намерил необичайни гени в седиментни проби, събрани около подводните вулкани "Замъка на Локи" между Гренландия и Норвегия. Първоначалният анализ показвал ДНК фрагменти от неизвестен досега микроорганизъм. 

Учените пресъздали с най-голяма точност генома на създание от царството на археите,които са определение прокариоти. Те го нарекли Локи (Lokiarcheum), на името на един не много приятен скандинавски бог.

Къде се намира Локи в еволюционното дърво. Илюстрация: Nature

За своя изненада, биолозите открили гени, характерни за еукариотите - свързани с актин (протеин, изграждащ цитоскелета), гени на ензими, отговарящи за транспорта на вещества във везикулите (мехурчетата в клетките) и няколко гена на протеиновия комплекс ESCRT, които при еукариотите регулират сгъването на мембраната.

Анализът на гените на Локи показвал, че първите еукариоти са имали актинов цитоскелет и елементарна система на вътреклетъчен транспорт, но е липсвало ядро и митохондрии.

Изследването е публикувано в списание Nature, а за него съобщава Science magazine.

 

[Last roman]

515-Million-Year-Old Fossils Contain Exquisitely Preserved Nervous System

photo credit: One of the complete C. kunmingensis fossils, showing the purple-gray brain and nerve cord on the left (top), and a magnification of the nerve cord (bottom). Jie Yang and Yu Liu/Yunnan University

There have been some extraordinary examples of soft tissue preservation in fossils over the past few years, from apparent red blood cells in dinosaur bones to feathers and pigments in early birds. A new set of fossils that have come out of south China, dating to around 515 million years ago, show something else astonishing: the preservation of the creatures' nervous systems, including the brain, nerve cord, and individual nerves. Thought to be the oldest and best-preserved nervous systems ever found, they once belonged to an animal known as Chengjiangocaris kunmingensis, and are described in a paper published in PNAS. 

 

“The animal itself is an early arthropod,” explained Dr. Javier Ortega-Hernández, from theUniversity of Cambridge’s Department of Zoology, to IFLScience. “The fossils are approximately 515 million years old, so really close to the origin of animals. And we have a nerve cord, so that is a really good insight into early animal evolution.” Today, arthropods are represented by insects, crustaceans, and spiders. What made the fossils remarkable was the exquisite level of preservation of the nervous system.

“You can see this really thin strand which goes all throughout the body, and you can that it has these spots which repeat themselves a lot, and those would correspond with ganglia,” Dr. Ortega-Hernández continues. “Ganglia are masses of nervous cells, which occur in each of the segments of the arthropods.” All arthropods have segmented bodies, and each segment has its own ganglion that controls the pair of legs, not dissimilar to a "mini brain" that keeps everything in motion. Finding this in the fossil arthropods was nice to see, but expected.  

What the researchers didn’t expect, however, was the detail of the nerves preserved branching off from the ganglion. In all living arthropods, each ganglion gives rise to only a couple of long, incredibly fine nerves that serve the individual segments. The fossils, however, showed dozens of such nerves, something that's only seen today in a creature closely related to arthropods known as velvet worms. This heavy branching, suggest the researchers, shows that it is a very ancestral feature that was inherited from a velvet worm-like ancestor. Since then, there has been a loss of these neurological characteristics in modern arthropods.

But how can such fine soft tissue manage to get fossilized and preserved for over 500 million years? The answer might lie in what exactly the nervous system is made up of. “Things like the nervous system or the gut get fossilized counter-intuitively,” says Dr. Ortega-Hernández. Why this happens is believed to be “due to the chemically reactive composition of adjacent lipid-rich ganglia,” he wrote in the paper.

^{Image in text: Complete specimen of Chengjiangocaris kunmingensis, showing the individual ganglia in incredible detail. Jie Yang/Yunnan University, China}

^{http://www.iflscience.com/plants-and-animals/520-million-year-old-fossil-contains-exquisitely-preserved-nervous-system}

[Last roman]

12 гущери, съвременници на динозаврите, са намерени в кехлибар

Гущер, запазен в бирмански кехлибар от средата на Креда. Снимка: Daza et al.

Дузина гущери в кехлибар са открити в Югоизточна Азия. Те вероятно са търсели убежище в клоните на секвои, а са попаднали в капана на смолата им преди около 100 милиона години, през периода Креда.

Колекцията включва предци на съвременните гекони и хамелеони, живели по едно и също време с гигантските динозаври, съобщава NewScientist. 

Тази находка, намерена в провинция Качин, Миамар (бивша Бирма), е най-старата и вероятно най-разнообразната колекция на тропически гущери, запазени в кехлибар, според констатациите, публикувани в Science Advances тази седмица.

Има около 9900 живи видове гущери и змии, включително богатото разнообразие влечуги, обитаващи тропическите гори. Но техните вкаменелости са редки, така че малко се знае за древните тропически гущери. Намирани са най-вече раздробени кости.

Затова тази находка е изключително ценна, защото кехлибарът може да запази малки, деликатни останки, заедно с вътрешните органи и меките тъкани. Те са изследвани с помощта на рентгенова томография с висока резолюция, сканиращ електронен микроскоп и оптична микроскопия от екип, ръководен от Хуан Даза (Juan Daza) от Университета в Хюстън.

В един от кехлибарите е намерен напълно запазен гекон, при който се вижда, че още тогава тези животни са имали уникалните самозалепващи се пръсти и стъпала. В друго влечуго се вижда с изплезен език с дълъг и тесен връх, какъвто не се среща при никой от съвременните змии и гущери.

Друг малък гущер е попаднал в кехлибара заедно със скорпион и стоножка, което показва, че и древните тропически гущери са се хранели със същите животни като съвременните, обяснява Даза.

Същият гущер е особено интересен - костната му структура наподобява тази на новороден хамелеон, въпреки че хамелеоните се появяват за първи път преди около 25 милиона години. Той има слаба челюст, непригодна за хващане на плячка. Това говори за древния произход на метода за лов с помощта на стрелкащ се език, който се практикува от съвременните хамелеони. Находката също така поставя под съмнение идеята за африканския произход на тези животни.

"Новите образци са красиви и много вълнуващи," отбелязва Майкъл Колдуел (Michael Caldwell) от Университета на Алберта в Едмънтън, Канада. "Имахме малко или почти никакви фосили от родословното дърво на гущерите," добавя той.

http://nauka.offnews.bg/news/Novini_1/12-gushteri-savremennitci-na-dinozavrite-sa-namereni-v-kehlibar_39825.html

[Last roman]

Ново изследване показва, че измирането на ихтиозаврите станало на два етапа:

http://www.sciencemag.org/news/2016/03/ancient-sea-creatures-knocked-out-one-two-punch?utm_source=newsfromscience&utm_medium=facebook-text&utm_campaign=seaknock-2830