Paleonews

Il blog dedicato ai Paleontologi !!!!

2009-06-19 – Mongolia: Nuovo Psittacosauro (new Psittacosaur)

Parrot-like dinosaur found in Mongolia

A new dinosaur resembling a giant parrot has been discovered in Mongolia.

 By Chris Irvine
Published: 7:00AM BST 17 Jun 2009
New dinosaur, Psittacosaurus gobiensis: Parrot-like dinosaur found in Mongolia
A new dinosaur, named Psittacosaurus gobiensis, meaning ‘parrot dinosaur’ has been discovered in Mongolia

The creature, Psittacosaurus gobiensis whose name means “parrot lizard”, is thought to have lived about 110 million years ago.

Psittacosaurs are noted for being the most species-rich dinosaur genus with at least nine different species, including the latest found in the Gobi Desert, a famous dinosaur graveyard.

Features of the dinosaur included a near perfect skull, strong jaw muscles and a powerful biting and crushing bill – showing that it evolved structures like those in today’s parrots.

The three feet long psittacosaurs may also have had a diet dominated by nuts and seeds, owing to the presence of many large stomach stones, according to the findings published in Proceedings of the Royal Society B: Biological Sciences.

Prof Paul Sereno, a Biologist from the University of Chicago, said analysis of its skull showed it chewed its food in a similar way to modern parrots.

“These and other features, along with the presence of numerous large stomach stones, suggest that psittacosaurs may have had a high-fibre, nut eating diet,” he said.

Its short snout just a third of the skull length was different to most dinosaurs, giving the skull its parrot-esque profile.

They ate nothing but plants and walked normally on two legs but could reach the ground with their three-fingered hands.

They were good runners and were extremely successful in Asia about 100 million years ago, during the Cretaceous Period.

“Psittacosaurs are all relatively small in body size, ranging from one to two metres in body length. Their geographic range is limited to central Asia, and their temporal range may be as narrow as 10-20 million years in the mid Cretaceous,” said Prof Sereno.

It is a member of the Ceratopsia group of herbivorous, beaked dinosaurs, which also include the more famous Triceratops.

source: telegraph.co.uk

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Other links: click here

giugno 19, 2009 Posted by | 1 Cretaceo, Articolo sc. di riferimento, Asia, Mesozoic, P - Preservazione eccezionale, P - Ritrovamenti fossili | , , , , | Lascia un commento

2009-05-10 – Utah, USA: ritrovata una tartaruga fossile incinta (fossil pregnant turtle)

Rare prehistoric pregnant turtle found in Utah

At least three eggs are visible from the outside of the fossil, and Montana State University researchers this week have been studying images taken from a CT scan in search of others inside.

Montana State graduate student Michael Knell says the turtle was probably about a week from laying her eggs when she died and became entombed for millions of years in sandstone.

The fossil was found in 2006 in a remote part of Grand Staircase-Escalante National Monument. The eggs weren’t discovered until after it sat in storage for two years and was being re-examined by a volunteer.

This image provided Montana State University shows CT technician, Tanya Spence preparing to run a 75 million-year-old turtle fossil through a CT scanner at Deaconess Hospital in Bozeman, Mont. (AP Photo/Montana State University, Kelly Gorham)

This image provided Montana State University shows CT technician, Tanya Spence preparing to run a 75 million-year-old turtle fossil through a CT scanner at Deaconess Hospital in Bozeman, Mont. (AP Photo/Montana State University, Kelly Gorham)

maggio 10, 2009 Posted by | - Rettili, 1 Cretaceo, America Northern, An. Vertebrates, Articolo sc. di riferimento, Mesozoic, P - Preservazione eccezionale, P - Ritrovamenti fossili, Paleontology / Paleontologia, X - Nature | , , , , , , , , , | Lascia un commento

2009-05-02 – Estratte proteine da un dinosauro di 80 milioni di anni (Brachylophosaurus, Dinosaur, Proteins, soft tissue)

Proteins, soft tissue from 80-million-year-old dino support theory that molecules preserve over time

A North Carolina State University paleontologist has more evidence that soft tissues and original proteins can be preserved over time – even in fossilized remains – in the form of new protein sequence data from an 80 million-year-old hadrosaur, or duck-billed dinosaur.

Dr. Mary Schweitzer, associate professor of marine, earth and atmospheric sciences at NC State with a joint appointment at the N.C. Museum of Natural History, along with colleague Dr. John Asara from the Beth Israel Deaconess Medical Center (BIDMC) and Harvard Medical School, Dr. Chris Organ from Harvard University, and a team of researchers from Montana State University, the Dana Farber Cancer Institute, and Matrix Science Ltd. analyzed the hadrosaur samples.

The researchers’ findings appear in the May 1 edition of Science.

Schweitzer and Asara had previously used multiple methods to analyze soft tissue recovered from a 68 million-year-old Tyrannosaurus Rex. Mass spectrometry conducted on extracts of T. rex bone supported their theory that the materials were original proteins from the dinosaur.

These papers were controversial, and the team wanted to demonstrate that molecular preservation of this sort in dinosaurs was not an isolated event. Based upon other studies, they made predictions of the type of environment most likely to favor this preservation, so Schweitzer and students, working with Jack Horner’s Museum of the Rockies field crews, went looking for a dinosaur preserved under a lot of sandstone. Using specially designed field methodology, with the aim of avoiding environmental exposure until the fossil was inside the lab, they set aside the femur from a Brachylophosaurus canadensis – a hadrosaurid dinosaur–buried deeply in sandstone in the Judith River formation.

“This particular sample was chosen for study because it met our criteria for burial conditions of rapid burial in deep sandstones,” Schweitzer says. “We know the moment the fossil is removed from chemical equilibrium, any organic remains immediately become susceptible to degradation. The more quickly we can get it from the ground to a test tube, the better chance we have of recovering original tissues and molecules.”

Preliminary results seemed to confirm their methodology, as Schweitzer found evidence of the same fibrous matrix, transparent, flexible vessels and preserved microstructures she had seen in the T. rex sample in the much older hadrosaur bone. Because of the rapidity of analyses after the bones were removed, the preservation of these dinosaurian components was even better. The samples were examined microscopically via both transmitted light and electron microscopes to confirm that they were consistent in appearance with collagen. They were also tested against antibodies that are known to react with collagen and other proteins.

Next, Schweitzer sent the samples to Asara’s lab to be analyzed by a new mass spectrometer, capable of producing sequences with much greater resolution than the one used previously. Mass spectrometry identifies molecules by measuring the mass of the protein fragments, or peptides, that result from breaking apart molecules with specific enzymes. The masses are measured with very high mass accuracy, and then compared with existing databases of proteins to achieve a best fit. In this way, Asara was able to identify eight collagen peptides from the hadrosaur, then confirm the identity of the sequences by comparing them both to synthesized fragments and to modern proteins analyzed under the same conditions. Once sequence data were validated, they were evaluated by Organ who determined that, like T.rex, this dinosaur’s protein family tree is closer to that of modern birds than that of alligators.

All results were independently verified by researchers at BIDMC, Montana State University, Harvard University, the Dana Farber Cancer Institute, and Matrix Science of London.

The data were consistent with that of the earlier T. rex analysis, confirming that molecular preservation in fossilized remains is not an isolated event. “We used improved methodology with better instrumentation, did more experiments and had the results verified by other independent labs,” Schweitzer says. “These data not only build upon what we got from the T. rex, they take the research even further.”

Schweitzer hopes that this finding will lead to more work by other scientists on these ancient molecules.

“I’m hoping in the future we can use this work as a jumping off point to look for other proteins that are more species-specific than collagen. It will give us much clearer insight into all sorts of evolutionary questions.”

Contact: Tracey Peake – tracey_peake@ncsu.edu – 919-515-6142 – North Carolina State University###

 source: eurekalert

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An abstract of the paper follows.

“Biomolecular Characterization and Protein Sequences of the Campanian Hadrosaur Brachylophosaurus canadensis
Authors: Mary H. Schweitzer, North Carolina State University and the N.C. Museum of Natural Sciences; John M. Asara, Beth Israel Deaconess Medical Center and Harvard Medical School, et al.
Published: May 1, 2009 in Science

Abstract: Molecular preservation in non-avian dinosaurs is controversial. We present multiple lines of evidence that endogenous proteinaceous material is preserved in bone fragments and soft tissues from an 80 million year old Campanian hadrosaur, Brachylophosaurus canadensis (MOR 2598). Microstructural and immunological data are consistent with preservation of multiple bone matrix and vessel proteins, and phylogenetic analyses of Brachylophosaur collagen sequenced by mass spectrometry robustly support the bird-dinosaur clade, consistent with an endogenous source for these collagen peptides. These data complement earlier results from Tyrannosaurus rex (MOR 1125) and confirm that molecular preservation in Cretaceous dinosaurs is not a unique event.

maggio 2, 2009 Posted by | - Ornitopodi, - R. Dinosauri, 1 Cretaceo, America Northern, An. Vertebrates, Articolo sc. di riferimento, Bl - Top posts, Mesozoic, P - Preservazione eccezionale, Paleontology / Paleontologia, X - Science | , , , , , | Lascia un commento

2009-03-19 – Tianyulong confuciusi: un nuovo dinosauro con le piume (feathered Ornithopd Dinosaur)

Un nuovo dinosauro con le piume

Scoperto in Cina un fossile risalente a più di 100 milioni di anni fa

 Il ritrovamento in Cina di un nuovo fossile di dinosauro dotato di piumaggio riapre il dibattito sulla diffusione di questi rettili preistorici. Questa volta gli scienziati hanno portato alla luce un piccolo esemplare che viveva nelle regioni nord-orientali del continente asiatico più di cento milioni di anni fa. L’animale aveva il corpo coperto da lunghi filamenti simili a piume, era piccolo, agile e scattante. Camminava su due zampe, aveva una lunga coda e si cibava probabilmente di piante, insetti e piccoli vertebrati.

PENNUTI PREISTORICI - È stato chiamato Tianyulong confuciusi, dalla somma del nome del museo dove è conservato e di quello del filosofo Confucio. Diversamente dai dinosauri «piumati» ritrovati fino ad oggi e appartenenti al sottordine dei teropodi (di cui fa parte anche il T-rex), questo pennuto preistorico è un eterodontosauride vissuto nel Cretaceo inferiore, circa 144 milioni di anni fa. Secondo gli scienziati le sue piume sono diverse sia da quelle degli uccelli che da quelle dei cugini teropodi: si tratta infatti di strutture meno flessibili e più compatte, e comunque non adatte al volo. Ma nonostante le differenze, sicuramente tutte le tipologie di proto-piume conosciute sono correlate tra loro.

  L’ETÀ DELLE PIUME - Secondo alcuni paleontologi quindi le piume primitive sono una caratteristica ereditata dai due gruppi di dinosauri da un antenato comune e risalgono presumibilmente a 200 milioni di anni fa. Grazie alle particolari condizioni geologiche della provincia cinese del Liaoning, è sempre più frequente il ritrovamento di fossili di dinosauri provvisti di piume, e ciò fa pensare che fossero molto più diffusi di quanto si pensasse fino a pochi anni fa. Resta comunque ancora oscura la funzione (probabilmente ornamentale) di queste appendici che, come le piume degli uccelli attuali, erano molto colorate ma sicuramente alle origini non erano nate per volare

Valentina Tubino
19 marzo 2009

fonte: corriere.it

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Reconstruction of Tianyulong confuciusi, a feathered heterodontosaurid ornithischian dinosaur (Illustration: Li-Da Xing)
Reconstruction of Tianyulong confuciusi, a feathered heterodontosaurid ornithischian dinosaur (Illustration: Li-Da Xing)

Approfondimento sui Blog

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 An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures

Xiao-Ting Zheng, Hai-Lu You, Xing Xu & Zhi-Ming Dong

Nature 458, 333-336 (19 March 2009) | doi:10.1038/nature07856

Ornithischia is one of the two major groups of dinosaurs, with heterodontosauridae as one of its major clades. Heterodontosauridae is characterized by small, gracile bodies and a problematic phylogenetic position1, 2. Recent phylogenetic work indicates that it represents the most basal group of all well-known ornithischians3. Previous heterodontosaurid records are mainly from the Early Jurassic period (205–190 million years ago) of Africa1, 3. Here we report a new heterodontosaurid, Tianyulong confuciusi gen. et sp. nov., from the Early Cretaceous period (144–99 million years ago) of western Liaoning Province, China. Tianyulong extends the geographical distribution of heterodontosaurids to Asia and confirms the clade’s previously questionable temporal range extension into the Early Cretaceous period. More surprisingly, Tianyulong bears long, singular and unbranched filamentous integumentary (outer skin) structures. This represents the first confirmed report, to our knowledge, of filamentous integumentary structures in an ornithischian dinosaur.

Correspondence to: Hai-Lu You: Email: youhailu@gmail.com).

·         abstract and links

·         Figures and tables

·         Supplementary info

marzo 19, 2009 Posted by | - Ornitopodi, - R. Dinosauri, 1 Cretaceo, America Northern, An. Vertebrates, Articolo sc. di riferimento, Bl - Top posts, Blogs, Lang. - Italiano, Mesozoic, P - Evoluzione, P - morfologia funzionale, P - Paleoetologia, P - Preservazione eccezionale, Paleontology / Paleontologia, SVPOW, Theropoda, X - Nature | , , , | Lascia un commento

2009-03-17 – Trappola mortale per i piccoli dinosauri (Sinornithomimus herd)

Sulla rivista “Acta Palaeontologica Polonica”

Trappola mortale per i piccoli dinosauri

I resti suggeriscono che gli individui ancora immaturi venissero lasciati badare a loro stessi mentre gli adulti erano occupati nella costruzione del nido o nella cova delle uova

Un branco di giovani dinosauri simili a uccelli hanno trovato la morte nei fangosi margini di un lago circa 90 milioni di anni fa, secondo quanto annunciato da un gruppo di paleontologi cinesi e statunitensi che hanno scavato in un sito del Deserto del Gobi, nella parte occidentale della Mongolia interna.

L’improvvisa morte degli animali in una trappola di fango fornisce una rara istantanea del loro comportamento sociale. Composto soltanto da esemplari giovani di una singola specie di dinosauri ornitomimidi (Sinornithomimus dongi), il branco suggerisce che gli individui ancora immaturi venissero lasciati badare a loro stessi mentre gli adulti erano occupati nella costruzione de nido o nella cova delle uova.

“Non c’erano adulti intorno, questi cuccioli scorrazzavano da soli”, ha spiegato Paul Sereno, professore dell’Università di Chicago ed esploratore del National Geographic e coautore dell’articolo apparso sulla rivista “Acta Palaeontologica Polonica”.

Le prime ossa vennero scoperte da un geologo cinese nel 1978 alla base di una piccola collina in una desola regione del Deserto del Gobi e circa 20 anni fa un gruppo sino-giapponese estrasse i primi scheletri, battezzando il dinosauro Sinornithomimus (“che somiglia a un uccello cinese”).

Sereno e colleghi hanno seguito lo scavo di uno scheletro dopo l’altro fino a penetrare in profondità nella base della collina. Complessivamente, sono stati estratti 25 individui di età compresa tra uno e sette anni, come determinato dagli anelli di crescita annuale delle loro ossa.

Il gruppo ha poi registrato in meticolosamente la posizione di tutte le ossa e i dettagli degli strati di roccia per cercare di comprendere in che modo cosi tanti individui di una stessa specie siano periti nello stesso luogo. Gli scheletri mostrano un ottimo stato di conservazione e il fatto che siano tutti nella stessa direzione fa supporre che siano morti anche entro un arco temporale molto breve.

I dettagli forniscono le prove di una piccola tragedia. “Gli animali hanno subito una morte lenta in una trappola di fango, e la loro agitazione è servita solo ad attrarre predatori o animali che si nutrivano di carogne”, ha concluso Sereno. Di solito gli eventi atmosferici, l’azione di altri animali o il trasporto di ossa cancellano qualunque prova diretta delle cause di morte. Perciò questo sito è unico per ricchezza di dettagli sugli animali e sulla loro morte.” (fc)

fonte: lescienze

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Photo: “Teen” Dinosaurs Roamed in Herds, Mass Grave Suggests

Young Sinornithomimus dinosaurs may have wandered in packs (illustrated at top), fending for themselves while adults were busy nesting, according to a recent report.
Two juvenile Sinornithomimus skeletons (photo at bottom) died when they were a little over one year old. In their rib cages are stomach stones and the carbonized remains of the last plants they consumed.

Illustration by Todd Marshall, courtesy Project Exploration; photograph by Mike Hettwer, courtesy Project Exploration

Illustration by Todd Marshall, courtesy Project Exploration; photograph by Mike Hettwer, courtesy Project Exploration

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MSU paleontologist authors paper on social behavior among adolescent dinosaurs

March 16, 2009 — By Michael Becker, MSU News Service

BOZEMAN — A Montana State University researcher is the lead author of a recently published paper that sheds new light on the behaviors of dinosaur families and gives a rare glimpse into the social life — and death — of a herd of dinosaurs.
David Varricchio, an assistant professor and paleontologist in the Department of Earth Sciences, and colleagues from the University of Chicago and China wrote the paper after a 2001 expedition to the Gobi Desert. It was published in December in the journal Acta Palaeontologica Polonica.
The paper describes the team’s work at a 90-million-year-old dry lake bed in western Mongolia. Over the past decade, paleontologists have recovered more than two dozen fossilized skeletons of the dinosaur Sinornithomimus.
All of the skeletons belonged to animals between one and seven years old and were well-preserved. Most of skeletons were facing the same direction, suggesting that they died together in a short period of time, Varricchio said.
“Normally there are a lot of post-mortem effects that transpire between when a dinosaur died and when it was buried,” he said. “This site really provides, in my mind, better evidence than any other dinosaur locality of how the dinosaurs perished, and that’s pretty rare for any fossil vertebrate.”

Varricchio believes that the dinosaurs probably became mired in the mud around a partially dry lakebed during the Cretaceous Period. During times of drought, as were common in the region at the time, these oases likely attracted many animals, he said.

Many of those animals were probably weak from starvation and dehydration, which could explain why so many of them became trapped in the mud. It’s a phenomenon that’s still seen around dry desert lakes today, he said.

The fact that so many young dinosaurs of the same species died at roughly the same time and in the same place tells paleontologists something about the social behavior of the animals, Varricchio said. It may be that young dinosaurs — too old for the nest but not yet old enough to fend for themselves — roamed together in social herds, he said.

“We get a snapshot-like view of what a herd of these animals looked like back in the Cretaceous Period,” Varricchio said. “That snapshot gives us a glimpse into their biology and their behavior.”

Past studies have theorized that dinosaurs had strong and complicated parenting relationships with their young, Varricchio said. Female — and even male — dinosaurs were tied to a nesting spot for the breeding portions of the year while they took care of their eggs, he said.

The fact that the parent dinosaurs were busy with the eggs could explain why a group of adolescent dinosaurs was roaming together without adult supervision, Varricchio said. These and most dinosaurs would take several years, at least, to fully mature. Groups of juveniles would consist of those individuals too old to be cared for by parents, but too young to breed, he said.

“This site argues that this might be a general trend among dinosaurs,” and is further evidence of the theory that dinosaurs were dedicated parents, he said.

Varricchio’s collaborators include Paul Sereno from the University of Chicago, Tan Lin from he Department of Land and Resources of Inner Mongolia and Zhao Xijin from the Chinese Academy of Sciences. Also on the team were Jeffrey Wilson from the University of Michigan and Gabrielle Lyon from Project Exploration.

The work was funded by the National Geographic Society and the David and Lucile Packard Foundation.

 

 

 

 

Contact: David Varricchio at 406-994-6907 or djv@montana.edu.
 
 Hi-Resolution Image or PDF Available:
[View or Download] 1. MSU’s David Varricchio examines fossils in his laboratory in the basement of Traphagen Hall. (MSU photo by Kelly Gorham)

source: http://www.montana.edu/cpa/news/nwview.php?article=6951

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Teen dinosaurs hung out, got into trouble

MSNBC – ‎17 ore fa‎
Like teenagers today, some juvenile dinosaurs used to hang out together, according to research announced today. Also like teens, the dinos sometimes hung
Boston Globe

 

Frozen in time: Dinosaur herd’s mass grave unearthed

ABC Online – ‎5 ore fa‎
In the rocky desert of Inner Mongolia, an international team of palaeontologists has unearthed a mass grave of young dinosaurs. The 25 birdlike dinosaurs
Montana State University

marzo 17, 2009 Posted by | - R. Dinosauri, - Teropodi, 1 Cretaceo, An. Vertebrates, Asia, Bl - Top posts, Mesozoic, P - Paleoetologia, P - Preservazione eccezionale, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , , | Lascia un commento

2009-02-08 – L’origine delle chele (Schinderhannes bartelsi, Bundenbach) (Origin of claws)

Scoperto negli scisti devoniani di Bundenbach, Germania (Hunsrück Slate) un nuovo artropode chiamato Schinderhannes bartelsi. I ricercatori ritengono che le sue espansioni frontali rappresentano le “strutture progenitrici” delle omologhe chele di scorpioni e limuli attuali

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Origin of claws seen in 390-million-year-old fossil

February 5th, 2009 in General Science / Archaeology & Fossils

A missing link in the evolution of the front claw of living scorpions and horseshoe crabs was identified with the discovery of a 390 million-year-old fossil by researchers at Yale and the University of Bonn, Germany.

The specimen, named Schinderhannes bartelsi, was found fossilized in slate from a quarry near Bundenbach in Germany, a site that yields spectacularly durable pyrite-preserved fossils — findings collectively known as the Hunsrück Slate. The Hunsrück Slate has previously produced some of the most valuable clues to understanding the evolution of arthropods – including early shrimp-like forms, a scorpion and sea spiders as well as the ancient arthropods trilobites.

“With a head like the giant Cambrian aquatic predator Anomalocaris and a body like a modern arthropod, the specimen is the only known example of this unusual creature,” said Derek Briggs, director of Yale’s Peabody Museum of Natural History and an author of the paper appearing in the journal Science.

Scientists have puzzled over the origins of the paired grasping appendages found on the heads of scorpions and horseshoe crabs. The researchers suggest that Schinderhannes gives a hint. Their appendages may be an equivalent to those found in the ancient predatory ancestor, Anomalocaris — even though creatures with those head structures were thought to have become extinct by the middle of the Cambrian Period, 100 million years before Schinderhannes lived.

The fossil’s head section has large bulbous eyes, a circular mouth opening and a pair of segmented, opposable appendages with spines projecting inward along their length. The trunk section is made up of 12 segments, each with small appendages, and a long tail spine. Between the head and trunk, there is a pair of large triangular wing-like limbs — that likely propelled the creature like a swimming penguin, according to Briggs. Unlike its ancestors from the Cambrian period, which reached three feet in length, Schinderhannes is only about 4 inches long.

This finding caps almost 20 years of study by Briggs on the Hunsrück Slate. “Sadly, the quarry from which this fabulous material comes has closed for economic reasons, so the only additional specimens that are going to appear now are items that are already in collectors’ hands and that may not have been fully prepared or realized for what they are,” said Briggs.

Source: Yale University

source: http://www.physorg.com/news153065999.html

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Science 6 February 2009: Vol. 323. no. 5915, pp. 771 – 773 – DOI: 10.1126/science.1166586

A Great-Appendage Arthropod with a Radial Mouth from the Lower Devonian Hunsrück Slate, Germany

Gabriele Kühl, Derek E. G. Briggs, Jes Rust

Great-appendage arthropods, characterized by a highly modified anterior limb, were previously unknown after the Middle Cambrian. One fossil from the Lower Devonian Hunsrück Slate, Germany, extends the stratigraphic range of these arthropods by about 100 million years. Schinderhannes bartelsi shows an unusual combination of anomalocaridid and euarthropod characters, including a highly specialized swimming appendage. A cladistic analysis indicates that the new taxon is basal to crown-group euarthropods and that the great-appendage arthropods are paraphyletic. This new fossil shows that features of the anomalocaridids, including the multisegmented raptorial appendage and circular plated mouth, persisted long after the initial radiation of the euarthropods.

 Abstract »   Full Text »   PDF »   Supporting Online Material »  (Supporting Online Material: free access with photos)

febbraio 8, 2009 Posted by | - Artropodi, An. Invertebrates, Articolo sc. di riferimento, Bl - Top posts, Europa, Italiano (riassunto), P - Evoluzione, P - Fossili viventi, P - Preservazione eccezionale, P - Ritrovamenti fossili, Paleontology / Paleontologia, Paleozoico, X - Science | , , , , , , , , , , , , | 1 commento

2009-02-07 – Tra i fossili più antichi: Spugne (precambrian fossil sponges)

Antichissime impronte rinvenute nel precambriano dell’arabia Saudita sono state riconosciute come impronte di spugne. La scoperta ha ovviamente importantissime implicazioni di carattere ia tassonomico che soprattutto paleobiologico ed evoluzionistico

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Ancient sponges leave their mark

By Jonathan Amos
Science reporter, BBC News

Rocks in Oman
The rocks date to a time of dramatic gaciation on Earth

Traces of animal life have been found in rocks dating back 635 million years.

The evidence takes the form of chemical markers that are highly distinctive of sponges when they die and their bodies break down in rock-forming sediments.

The discovery in Oman pushes back the earliest accepted date for animal life on Earth by tens of millions of years.

Scientists tell Nature magazine that the creatures’ existence will help them understand better what the planet looked like all that time ago.

“The fact that we can detect these signals shows that sponges were ecologically important on the seafloor at that time,” said lead author Gordon Love, from the University of California, Riverside.

“We’re not saying we captured the first animal; we’re saying they’re an early animal phylum and we’re capturing them when their biomass was significant.”

Tiny creatures

Researchers can usually determine the presence of ancient life in rock strata by looking for the fossilised remains of skeletons or the hardened record of the creatures’ movements, such as their footprints or crawl marks.

Sponges
Sponges are among the simplest multi-celled organisms

But for organisms deep in geological history that were extremely small and soft bodied, scientists have had to develop novel techniques to uncover their existence.

One of these newer methods involves detecting breakdown products from the lipid molecules which act as important structural components in the cell membranes of animals.

Over time, these will transform to leave a molecule known as cholestrane; and for sponges, this exclusively takes the form known as 24-isopropylcholestane.

Dr Love’s team found high concentrations of this biomarker in rocks located at the south-eastern edge of the Arabian peninsula.

They were laid down in what would have been a shallow marine environment at least 635 million years ago.

“Even though there must have been sufficient oxygen in the water to maintain the metabolism of these primitive animals, I think their size would have been restricted by oxygen being nowhere near modern values,” the UC Riverside researcher said.

“We’re probably talking about small colonies of sponges with body dimensions of a few millimetres at most. They’d have been filtering organic detritus in the water column.”

Icy planet

The discovery is fascinating because it pre-dates the end of the Marinoan glaciation, a deep freeze in Earth history that some argue shrouded the entire planet in ice.

Scientists often refer to the term “snowball Earth” to describe conditions at this time.

So to find animal life apparently thriving during this glaciation seems remarkable, commented Jochen Brochs, from the Australian National University, Canberra.

“If there really was a snowball Earth, how did those sponges survive? The full snowball Earth hypothesis would predict that the oceans were frozen over by 2km, even at the equator,” he told BBC News.

“Only at hot springs could any organism survive but it is questionable that you would have sponges in a hot spring. I haven’t made my mind up about snowball Earth but perhaps these sponges are telling us something about this glaciation.”

Dr Love’s view is that the presence of these animals puts limits on the scale of the ice coverage.

“I believe there were areas of what we might call refugia – areas of open ocean where biology could go on. And in this case, it could be evidence that we had some sort of evolutionary stimulation of new grades of organisms as well.”

Jonathan.Amos-INTERNET@bbc.co.uk

 

http://news.bbc.co.uk/2/hi/science/nature/7871099.stm

febbraio 7, 2009 Posted by | An. Invertebrates, Articolo sc. di riferimento, Asia, Bl - Top posts, Italiano (riassunto), P - Preservazione eccezionale, P - Ritrovamenti fossili, Paleontology / Paleontologia, Precambriano, X - Nature | , , , , , , , | Lascia un commento

2009-01-13 – Beipaosaurus, le prime piume non per il volo in Teropodi non aviani (Beipaosaurus, feathers for show)

Alcuni ricercatori cinesi hanno riconosciuto nelle piume apparteneti ad un Beipaosaurus (Dinosauria, Theropoda, Therizinosauridae) un morfotipo attualmente associato a piume utilizzate per “esibizionismo” (display) e non per il volo. Questa é la prima volta che viene riscontrata questa peculiarità in Teropodi non aviani.

Beipioaosaurus feathers

Beipioaosaurus feathers

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Earliest Feathers for Show, Not Flight

Jennifer Viegas, Discovery News

Jan. 12, 2009 — The world’s first feathers probably had nothing to do with flight or staying warm but were instead for showy display purposes, according to a new study that documents the most primitive known version of feathers, which were found on a Chinese dinosaur.

The dinosaur, Beipiaosaurus, sported the likely colorful feathers on its limbs, trunk, tail, head and neck, with the neck feathers resembling a lion’s mane.

Paleontologists now believe feathers evolved very early in archosaurs, the group that included dinosaurs, pterosaurs and relatives of crocodiles, in addition to today’s modern birds, crocodiles and alligators.

“Our analysis suggests that feathers might have a much longer history than previously thought,” lead author Xing Xu told Discovery News.

“The first feathers might have appeared in the fossil record in the Middle Triassic about 235 million years ago,” said Xu, a paleontologist at the Chinese Academy of Sciences in Beijing.

Xu and colleagues Xiaoting Zheng and Hailu You studied the remains of the Chinese dinosaur, which was excavated at the Early Cretaceous Yixian Formation of Jianchang, western Liaoning. They noticed two types of feathers on the specimen: short, thread-like structures, and longer, stiff, broader ones that represent the rudimentary feathers, according to the study.

Both types are described in a paper published in this week’s Proceedings of the National Academy of Sciences.

Similar structures have been found on Psittacosaurus, or “Parrot Lizard,” as well as some pterosaurs. The researchers therefore suspect the common ancestor of these creatures — along with Beipiaosaurus, which lived 125 million years ago — had the early feathers too.

Previously documented feathers on dinosaurs were described as having multiple filaments, or many fluff-creating strands. The feathers on the recently documented Chinese dinosaur, however, are believed to represent a much more primitive stage, since the feathers consist of just a single broad filament, but have a different structure than hair.

The morphology and distribution of these early feathers rule out use for flight and helping to keep the dinosaur warm, but instead suggest they were flashed during displays, perhaps for mating, identification and competition purposes.

“Most previous studies suggest that insulation might have been the primary function for the first feathers, but our discovery supports that display represents one of the earliest functions for feathers,” Xu said, adding that “flight function appears very late in feather evolution.”

The discovery negates the prior theory that feathers and flight co-evolved. It instead indicates pterosaurs, birds and other fliers recruited already existing feathers for flight.

Xu and her colleagues aren’t certain how feathers came into being in the first place, but they suspect that at some point, an animal’s skin developed epidermal tissue that gave rise to the thin, tubular protrusions. Members of the opposite sex must have liked what they saw in displays, since the trait stuck and flourished. An average bird today has over 20,000 feathers.

Cheng-Ming Chuong and his team from the Keck School of Medicine at the University of Southern California foreshadowed the recent discovery. Their studies on chickens predicted what these first, more basic, feathers would’ve looked like.

“Just like Rome, feathers are not made in one process,” Chuong said, hinting that a long and colorful history for feathers would likely emerge as more findings, such as the new discovery on Beipiaosaurus, come to light.

He added, “While Darwin’s theory has explained the ‘why’ of evolution, much of the ‘how’ remains to be learned. Evo-Devo (evolution of development) research promises a new level of understanding.”

The remains of the flashy, primitive-feathered Chinese dinosaur are now housed at the Shandong Tianyu Museum of Nature in China.

source: Dicovery channel news

other links:


BBC News

Downy dinosaur found in China was an early bird
Times Online - 15 ore fa
A dinosaur that would have been covered with feathers has been discovered in China, adding to evidence that supports the theory that birds evolved from ancient reptiles.
Dinosaur fossil reveals creature of a different feather Science News
Paleontologists Find Dinosaur Protofeather Wired News
ShortNews.com – LiveScience.com – Discovery Channel – BBC News
e altri 10 articoli simili »

IN GERMAN: faz.net

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A new feather type in a nonavian theropod and the early evolution of feathers (PNAS link)

Xing Xu, Xiaoting Zheng and Hailu You

 Abstract

All described feathers in nonavian theropods are composite structures formed by multiple filaments. They closely resemble relatively advanced stages predicted by developmental models of the origin of feathers, but not the earliest stage. Here, we report a feather type in two specimens of the basal therizinosaur Beipiaosaurus, in which each individual feather is represented by a single broad filament. This morphotype is congruent with the stage I morphology predicted by developmental models, and all major predicted morphotypes have now been documented in the fossil record. This congruence between the full range of paleontological and developmental data strongly supports the hypothesis that feathers evolved and initially diversified in nonavian theropods before the origin of birds and the evolution of flight.

gennaio 13, 2009 Posted by | - R. Dinosauri, 1 Cretaceo, Articolo sc. di riferimento, Asia, Bl - Top posts, Italiano (riassunto), Mesozoic, P - Evoluzione, P - morfologia funzionale, P - Paleoetologia, P - Preservazione eccezionale, Paleontology / Paleontologia, X - PNAS | , , , , , , , , , , , , | Lascia un commento

2008-11-26 – Biofilm batterici implicati nel processo di fossilizzazione (Bacterial biofilms as fossil makers)

Un team internazionale di ricercatori tramite un esperimento ha mostrato come i batteri in determinate condizioni possono indurre precipitazione di carbonato di calcio in organismi viventi morenti (nel caso specifio cellule embrionali di echinodermi) favorendo quindi la formazione di un “calco”.

Tale fenomeno mostra come i batteri possono aver avuto un ruolo fondamentale nei processi di fossilizzazione.

Inoltre tra i fossili candidati come possibili esempi di tale processo sono stati indicati i famosi embrioni fossilizzati del Precambriano di Doushantuo, Cina (sebbene non è attualmente possibile avere una prova a definitiva a riguardo).

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Public release date: 24-Nov-2008

Contact: David Bricker – brickerd@indiana.edu – 812-856-9035 – Indiana University

Bacterial biofilms as fossil makers

 BLOOMINGTON, Ind. — Bacterial decay was once viewed as fossilization’s mortal enemy, but new research suggests bacterial biofilms may have actually helped preserve the fossil record’s most vulnerable stuff — animal embryos and soft tissues.

 

A team of 13 scientists led by Indiana University Bloomington biologists Rudolf and Elizabeth Raff found that the invasion of dying embryo cells by bacteria — and the subsequent formation of densely packed bacterial biofilms inside the embryo cells — can completely replace embryo cell structure, generating a faithful replica of the embryo. The scientists call this formation a “pseudomorph,” a model of the embryo made of bacteria. Their report will appear online via the Proceedings of the National Academy of Sciences “Early Edition” as early as Nov. 24.

“The bacteria consume and replace all the cytoplasm in the cells, generating a little sculpture of the embryo,” said Elizabeth Raff, the report’s lead author. “We did find, however, that certain conditions must be met if the bacteria are going to aid the preservation process.”

Among those conditions, Raff said that at the time of its death, the embryo must exist in a low-oxygen or reducing environment, such as the bottom of a deep ocean or buried in anoxic lakeside mud. If significant oxygen is available, the embryo will undergo “autolysis,” or self-destruction, as digestive enzymes get free and wreak havoc. Without oxygen, autolytic enzymes remain stuck inside their organelle prisons.

“The next step, we believe, is that bacteria able to survive in low-oxygen conditions must then infest the cells of the dying embryo,” Raff said.

The bacteria form biofilms, crowded assemblies of bacterial cells held together by sticky fibers made of proteins and sugars. As the biofilms fill the embryo cells, the tiny bacteria insinuate themselves between and among the organelles, forming a faithful representation of the cell’s innards.

Lastly, the bacteria must leave a permanent record. In the case of finely preserved fossil embryos, the bacteria likely excrete tiny crystals of calcium phosphate (CaPO4), which eventually replace the bacterial sculptures. It is these crystals, Raff says, that provide the support for embryo and soft tissue fossilization.

“That’s a crucial step,” said Rudolf Raff. “Calcium deposits can show us even minute details of structure and shape, not only of the bacteria laying down the minerals, but also of the embryo cell structures all around them. In our experiments, we observed bacteria depositing calcium carbonate (CaCO3), but not calcium phosphate. We’ll need to simulate different conditions to fully replicate this step.”

High resolution imaging of a trove of half-a-billion-year-old animal embryo fossils from Doushantuo, China, provided scientists with tantalizing evidence that bacteria may have been involved in the preservation of the delicate cells. Scanning electron microscopy shows oblong concavities on the surface of the embryo fossils, suggesting the cells had been infested with bacteria or bacterial biofilms.

The research presented in the PNAS paper reveals how bacteria-aided fossilization could happen.

The Raffs studied early-stage embryos of two Australian sea urchin species, Heliocidaris erythrogramma and Heliocidaris tuberculata. The experimental results with modern embryos were compared to the high resolution images of fossil embryos prepared by colleagues from China, England, Sweden, and Switzerland.

The scientists examined embryos in the presence of high and low oxygen, with or without inoculums of oxygen-poor marine mud, and in the presence or absence of bacteria-killing antibiotics. In the experiments that produced embryo-infesting biofilms, the scientists used DNA sequence comparisons to identify the bacterial species present.

The researchers learned low-oxygen conditions block autolysis, and that embryos prevented from autolyzing are quickly colonized by marine bacteria. Once inside, the bacteria form biofilms that fill the embryo cells. Sturdy cell membranes and the embryo’s fertilization envelope provide the exterior cast. These biofilms formed detailed replicas of the embryos they had replaced.

Species of the common marine bacterium Pseudoalteromonas provided the majority of the bacterial flora present inside the embryo cells under aerobic conditions. Under oxygen-poor conditions, a much greater diversity of bacterial species was present, not detectable under aerobic conditions.

The scientists also examined oxygen-starved embryos exposed to inoculums of oxygen-poor marine mud, and again found a high diversity of bacterial flora present in embryo replica biofilms, with species of the Bacteroidetes phylum being most common.

Although it is impossible to know whether bacteria aided the preservation of 550-million-year-old embryo fossils from Doushantuo and elsewhere, the Raffs argue the evidence they gathered strongly favors the view that bacteria are a fundamental force in fossil formation, as rapid biological processes must be available to convert highly delicate cells into a stable form and catalyse mineralization.

“This work is important because it helps us understand fossilization as a biological as well as geological process,” Elizabeth Raff said. “It gives us a window onto the evolution of the embryos of the earth’s first animals.”

###

Kaila Schollaert, David Nelson, F. Rudolf Turner, Barry Stein (Indiana University Bloomington), Philip Donoghue, Ceri-Wyn Thomas (University of Bristol), Xiping Dong (Peking University), Stefan Bengtson (Swedish Museum of Natural History), Therese Huldtgren (Swedish Museum of Natural History and Stockholm University), Marco Stampanoni (Paul Scherrer Institute and Institute for Biomedical Engineering), and Yin Chongyu (Chinese Academy of Geological Scientists) also contributed to this report. The Raffs’ research was supported largely by Indiana University.

To speak with Elizabeth or Rudolf Raff, please contact David Bricker, University Communications, at 812-856-9035 or brickerd@indiana.edu.

source: eurekalert

novembre 26, 2008 Posted by | Articolo sc. di riferimento, G - Biomineralizzazione, Geology - Geologia, Italiano (riassunto), P - Preservazione eccezionale, Paleontology / Paleontologia | , , , , , , , | Lascia un commento

2008-10-29 – La fossilizzazione delle argilliti di Burgess (Burgess Shale’s fossil diagenesis)

Nuove indiazioni sul processo di fossilizzazione che ha portato alla formazione dei fossili dei Burgess Shale’s (argilliti di Burgess, Canada – Cambriano).

Lo studio pubblicato sul numero di Novembre di Geology sostiene che i fossili si sono formati in una fase diagenetica precoce (metamorfismo di basso grado) con la migrazione di fillosilicati che si sono sostituiti al materiale originale delle diverse specie e dei diversi tessutti di esse gradualmente e in maniera differenziale a seconda del loro grado di decomposizione.

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Riddle of Burgess Shale’s fossil-rich deposits solved: Scientists

Area of B.C.’s Yoho a treasure trove for fossilized prehistoric soft tissue

Randy Boswell ,  Canwest News Service

Published: Tuesday, October 28, 2008

Researchers have unravelled how one of Canada’s greatest gifts to science – the Burgess Shale fossil site in British Columbia – survived a subterranean superheating a half-billion years ago to preserve hundreds of “exquisite” images of slithering creatures, including a primeval human ancestor, from the “dawn of animal life.”

The existence of the Burgess Shale, a UNESCO World Heritage Site found on a Rocky Mountain cliff in Yoho National Park, is “a paradox,” says a British team that has published a study in the November issue of the journal Geology.

“The fossils have been buried deep in Earth’s crust and heated to over 300 degrees C before being thrust up by tectonic forces to form a mountainous ridge in the Rocky Mountains,” said a statement announcing the study. “Usually, such extreme conditions are thought to destroy fossils. But, in the Burgess Shale, the most exquisite detail of soft tissues has been preserved.”

 'Usually, such extreme conditions are thought to destroy fossils. But, in the Burgess Shale, the most exquisite detail of soft tissues has been preserved,' an article in the November issue of Geology states.

 

‘Usually, such extreme conditions are thought to destroy fossils. But, in the Burgess Shale, the most exquisite detail of soft tissues has been preserved,’ an article in the November issue of Geology states. J.B. Caron

The team, claiming to have “solved this riddle,” concludes that the “beautiful, silvery fossils” survived because the animals’ tissues were replaced during heating in the underground crucible by minerals able to withstand the high temperatures and capture “intricate details such as gills, guts, and even eyes.”

The special geological conditions in which shale formed, helped to “accentuate fossil outlines” and contributed to their “exceptional preservation,” the scientists note in the journal article, written by University of Cambridge geologist Alex Page and three co-authors.

The latest study follows the publication of a paper earlier this year that reconstructed how the sudden burial of an entire seabed ecosystem, following a catastrophic underwater landslide, led to the formation of the Burgess Shale some 530 million years ago.

That study described how an avalanche of “mud-rich slurry” killed tens of thousands of marine animals representing hundreds of species, then sealed them instantly – and enduringly – in a deep-sea tomb.

Interest in solving the mysteries surrounding the formation of the Canadian fossil treasure is further testament to its international importance for scientists.

The site, close to the B.C.-Alberta border, is considered crucial to understanding the so-called Cambrian “explosion” of life – a time when the future Canadian land mass was drifting in tropical climes close to the Earth’s equator.

U.S. paleontologist Charles Walcott, following reports of fabulous fossil finds by railway workers laying tracks across the Rockies in the late 19th century, is said to have tripped over a block of shale that revealed the area’s remarkable supply of fossils.

Scientists have gathered tens of thousands of specimens from the site, capturing in remarkable detail the rich diversity of organisms that suddenly filled the world’s oceans a half-billion years ago.

Among the imprints of animal remains excavated from the Burgess Shale is one called pikaia, an eel-like creature that has been classified as the earliest known, identifiable ancestor of modern vertebrates – including humans.

© Canwest News Service 2008

source: http://www.canada.com/topics/news/national/story.html?id=235d4299-5943-48bb-9aaf-aaffd5305b8d

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Original article:

Geology – Volume 36, Issue 11 (November 2008) pag.855

Ubiquitous Burgess Shale–style “clay templates” in low-grade metamorphic mudrocks

Alex Page, Sarah E. Gabbott, Philip R. Wilby, and Jan A. Zalasiewicz

Abstract . Full Text . PDF (473K)

Abstract:

Despite the Burgess Shale’s (British Columbia, Canada) paleobiological importance, there is little consensus regarding its taphonomy. Its organic fossils are preserved as compressions associated with phyllosilicate films (“clay templates”). Debate focuses on whether these templates were fundamental in exceptional preservation or if they formed in metamorphism, meaning that it is important to establish the timing of their formation relative to decay. An early diagenetic origin has been proposed based on anatomy-specific variations in their composition, purportedly reflecting contrasts in decay. However, we demonstrate that these films bear a remarkable similarity to those that occur on organic fossils in graptolitic mudrocks and form as a normal product of low-grade metamorphism. Such phyllosilicates may also occur within voids created by volume loss in maturation, a process that may have aided their formation. In bedding-plane assemblages from graptolitic mudrocks, different taxa are associated with distinct phyllosilicates. This likely reflects stepwise maturation of their constituent kerogens in an evolving hydrothermal fluid, with different phyllosilicates forming as each taxon progressively underwent maturation. These observations provide an analogue for the distribution and composition of phyllosilicates on Burgess Shale fossils, which we interpret as reflecting variations in the maturation of their constituent tissues. Thus, their clay templates seem unremarkable, forming too late to account for exceptional preservation.

Received: March 25, 2008; Revised: July 9, 2008; Accepted: July 22, 2008

DOI: 10.1130/G24991A.1

 *E-mail: aap30@esc.cam.ac.uk.

ottobre 29, 2008 Posted by | America Northern, Articolo sc. di riferimento, G - Diagenesi, Italiano (riassunto), P - Preservazione eccezionale, Paleontology / Paleontologia | , , , , , , , , , , | Lascia un commento

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