Paleonews

Il blog dedicato ai Paleontologi !!!!

2008-10-03 – Fluttuzioni del livello del mare nel Paleozoico (Paleozoic Sea-Level Changes)

A Chronology of Paleozoic Sea-Level Changes

Bilal U. Haq1* and Stephen R. Schutter2

Science 3 October 2008:
Vol. 322. no. 5898, pp. 64 – 68
DOI: 10.1126/science.1161648

Abstract »   Full Text »   PDF »   Supporting Online Material »  

In the free access Pdf of “supporting online material” there is the Chart with sea level fluctuations

Bilal U. Haq

COVER Ordovician sedimentary rocks at Presqu

Abstract – Sea levels have been determined for most of the Paleozoic Era (542 to 251 million years ago), but an integrated history of sea levels has remained unrealized. We reconstructed a history of sea-level fluctuations for the entire Paleozoic by using stratigraphic sections from pericratonic and cratonic basins. Evaluation of the timing and amplitude of individual sea-level events reveals that the magnitude of change is the most problematic to estimate accurately. The long-term sea level shows a gradual rise through the Cambrian, reaching a zenith in the Late Ordovician, then a short-lived but prominent withdrawal in response to Hirnantian glaciation. Subsequent but decreasingly substantial eustatic highs occurred in the mid-Silurian, near the Middle/Late Devonian boundary, and in the latest Carboniferous. Eustatic lows are recorded in the early Devonian, near the Mississippian/Pennsylvanian boundary, and in the Late Permian. One hundred and seventy-two eustatic events are documented for the Paleozoic, varying in magnitude from a few tens of meters to 125 meters.

1 National Science Foundation, Arlington, VA 22230, USA.
2 Murphy Oil International, Houston, TX 77094, USA.
* To whom correspondence should be addressed. E-mail: bhaq@nsf.gov

Abstract »   Full Text »   PDF »   Supporting Online Material »  

 

ottobre 3, 2008 Posted by | Articolo sc. di riferimento, Geology - Geologia, Lang. - Italiano, Paleontology / Paleontologia, Paleozoico | , , , , | Lascia un commento

I dinosauri molto più vecchi di quanto si pensava (2) (Dinosaurier-spuren, Isochirotherium, Germany)

Continuano le ricerche sulle “presunte” impronte di dinosauro ritrovate in agosto in Germania e che sposterebbero indietro di 15 milioni di anni la “nascita dei dinosauri”

Dinosaurier 15 Millionen Jahre älter als gedacht

Die Abdrücke in einem Tagebau beweisen es: Dinosaurier gab es bereits vor 243 Millionen Jahren – 15 Millionen Jahre früher als angenommen. Die bereits im Juni bei Bernburg in Sachsen-Anhalt freigelegten Spuren gelten als seltener und äußerst spektakulärer Fund.

Die Spuren beweisen, dass es bereits vor fast 245 Millionen Jahren Dinosaurier gab - 15 Millionen Jahren früher als bisher angenommen

Isochirotherium - Größe des Saurierabdrucks: Die Spuren beweisen, dass es bereits vor fast 245 Millionen Jahren Dinosaurier gab - 15 Millionen Jahren früher als bisher angenommen

Bernburg – “Das war schon eine Sensation”, schwärmte Cajus Diedrich, der Entdecker der Saurierspuren. “Uns war klar, dass das etwas Großes werden kann.” Der Forscher von der Universität Osnabrück hatte im Oktober 2007 gemeinsam mit Frank Trostheide vom Magdeburger Museum für Naturkunde in einem Kalksteinbruch bei Bernburg die Fährten von frühen Dinosauriern entdeckt.

Vom 9. Juni bis 4. Juli 2008 wurden in einem fünf Meter mächtigen Muschelkalkpaket fünf Schichten freigelegt und auf einer 50 mal 40 Meter großen Fläche die Spuren gesichert. Angesichts der großen Dichte von Fährten sprach Diedrich von einem spektakulären Fund. Inzwischen ist belegt, dass die Spuren zwischen 243,5 bis 243,9 Millionen Jahre alt sind. Bislang hatten Wissenschaftler angenommen, dass sich Dinosaurier erst im mittleren Trias vor 235 Millionen Jahren von anderen Archosauriern abgespaltet hatten.

Die Fährten könnten neue Erkenntnisse zur Evolution der ausgestorbenen Tiere liefern. “Woher die Saurier kamen, in dieser Beziehung herrschte bislang eine große Wissenslücke”, sagte Diedrich. “Aus der Mitteltrias gab es bislang weder Fährten- noch Skelettfunde von echten elefantenfüßigen Dinosauriern. Die Evolution muss also irgendwo dazwischen stattgefunden haben.” Mit den Funden von Bernburg sei nunmehr bewiesen, dass die Spezialisierung der Arten bereits in der Mitteltrias eingesetzt habe.

Die Dinos pressten die Fährten seinerzeit ins Watt eines sich vom heutigen Rhein bis nach Böhmen erstreckenden Binnenmeeres, dessen Boden sich durch Ebbe und Flut sowie unter wüstenartigen Bedingungen schnell verfestigte und die Spuren so konservierte. In seiner zwölfjährigen Forschung habe er andernorts bereits mehrere kleinere Spuren gefunden, sagte Diedrich, in Bernburg seien es jedoch ganze Spurenfolgen gewesen.

 

Als bemerkenswert bezeichnete er die 20 Meter lange Fährte eines primitiven Prosauropoden. Diedrich vermutet, dass sie von einer drei Meter langen, hochbeinigen Echse hinterlassen wurde, die einem Krokodil ähnelte. Diese Raubsaurierspur wird von einer Fährte eines elefantenfüßigen großen Dinos gekreuzt. “Ein einmaliger Fund”, meint Diedrich.

Neben den Fährten wurden unter anderem Knochen wie Rippen, Wirbelbögen und Sitzbeine gefunden. Laut Diedrich könnte die seltene Kombination von Fährten und Knochen eine neue Vorstellung von der Nahrungskette im Trias-Watt liefern.

Die ältesten bekannten Dinosaurierarten lebten vor mehr als 200 Millionen Jahren. Die meisten bewohnten Gebiete mit reicher Vegetation in der Nähe von Küsten und Binnengewässern. Sie waren an warmes, subtropisches Klima angepasst, konnten aber auch Kälteperioden überstehen.

Dinosaurier kamen in vielen verschiedenen Arten vor. Die kleinsten waren rund 30 Zentimeter, die größten 37 Meter lang. Manche ernährten sich von Pflanzen, andere von Fleisch und Aas. Die Ursachen für das Aussterben der Dinosaurier vor rund 65 Millionen Jahren sind bis heute noch nicht ganz geklärt. Wahrscheinlich ist, dass sich die hoch spezialisierten Tiere nicht an grundlegend veränderte Umweltbedingungen anpassen konnten. Die meisten Forscher gehen davon aus, dass der Einschlag eines Meteoriten, ein Vulkanausbruch oder beides die Umwelt über Jahre hinweg stark veränderten und so den Niedergang der Dinosaurier einleiteten.

 

hda/ddp/AP/dpa

link: http://www.spiegel.de/wissenschaft/natur/0,1518,581983,00.html (see also for additional photo)

DINOSAURIER: ÄLTER ALS GEDACHT

Fotostrecke starten: Klicken Sie auf ein Bild (7 Bilder)

see also previous post (link)

————————————————————————————

Other links (news, In german)

Halle: 243 Millionen Jahre alte Dinosaurier-Spuren vorgestellt
ZEIT ONLINE - 21 ore fa
Rund 243 Millionen Jahre alte Dinosaurier-Spuren sind am Donnerstag in Halle der Öffentlichkeit vorgestellt worden. Der spektakuläre Fund, darunter eine 25
245 Millionen Jahre alte Saurierspuren entdeckt
MDR - 21 ore fa
Wissenschaftler haben bei Grabungen in einem Kalkstein-Tagebau bei Bernburg fast 245 Millionen Jahre alte Spuren von Dinosauriern entdeckt.
SPUREN IN SACHSEN-ANHALT Dinosaurier 15 Millionen Jahre älter als
Spiegel Online - 21 ore fa
Die Abdrücke in einem Tagebau beweisen es: Dinosaurier gab es bereits vor 243 Millionen Jahren – 15 Millionen Jahre früher als angenommen.
Sensationsfund in Sachsen-Anhalt:
Netzeitung - 22 ore fa
Ein Kalksteinbruch in Bernburg macht Experten euphorisch: Schlappe 15 Millionen Jahre weichen die dort gefundenen Spuren vom bisher angenommenen Alter ab.
243 Millionen Jahre alte Dinosaurier-Spuren vorgestellt
Mitteldeutsche Zeitung - 22 ore fa
Halle/dpa/ddp. Bei Grabungen in einem Kalkstein-Tagebau bei Bernburg in Sachsen-Anhalt haben Wissenschaftler fast 245 Millionen Jahre alte Spuren von

ottobre 3, 2008 Posted by | - R. Dinosauri, 3 Triassico, Bl - Top posts, Lang. - German, P - Impronte, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , , , , , , , , | 1 commento

2008-10-02 – Uragano Ike scopre resti dell’era glaciale in Texas, USA (Mammoth, Ice Age – Mammuth)

Hurricane Ike yields ice-age discovery

10/2/2008

 

 

When Lamar University professor Dorothy Sisk returned to her beachfront home in Caplen, she knew there would be little left.  Instead, she was part of a discovery of something that tells a different story of Texas’ continually changing coastline.

Taking little with her when she evacuated before Hurricane Ike, she searched through what few belongings were strewn about —a bowl, a broken vase, a scrap of fabric.

“She picked up a couple things,” said LU colleague Jim Westgate, who had volunteered to drive her to the site in his pickup.  “We searched through a little scrub forest across the highway and she recognized a few things.”

All that remained of the home west of Rollover Pass were scraps of concrete and splintered pilings.

“It was while we were looking at the house, or at least what was left of the foundation, that I saw it lying there with lots of shell debris in what had been the front yard,” Westgate said.

What Westgate, a trained paleontologist and a research associate with the Vertebrate Paleontology Laboratory at the University of Texas Memorial Museum, recognized was the fossil tooth of a mammoth.

“This is the first one I’ve found in 19 years,” Westgate said. “People bring in pieces and parts from the beach for me to identify, and I haven’t seen one in this good a condition.”

The 6-pound tooth, which resembles a series of boot soles or slices of bread wedged together, is most probably that of the Columbian Mammoth (Mammuthus columbi), a species common to North America until around 10,000 years ago, Westgate said.  Ancestors of the modern elephant, mammoths and mastodons roamed the continent in large numbers.

Their fossil teeth are easily distinguished from one another by the grinding surface, Westgate said. Mastodon teeth are bumpy, and resemble a series of steep mountains and deep valleys, whereas mammoth teeth are flatter and well-suited to grinding. The diet of the mastodon is believed to have comprised leaves, bark and fruits, whereas mammoths were predominately grazers.

Like modern elephants, mammoths grew a total of six sets of teeth during their lifetime, ejecting worn teeth “like a shotgun, loading a newly formed tooth in its place,” Westgate said. The discovered tooth is unworn, so it was either newly erupted or a “tooth in waiting” when the animal died, Westgate said.

How likely is it to find fossils in the area?  “It is pretty common after we’ve had storms,” Westgate said. “McFaddin beach is a hot spot with local collectors.  After a storm, or when a blue northern has blown in and the water is pushed way off shore, they will go down the beach looking for fossils.”

What they’re likely to find are examples from the fossil record of a world much different than the seascape of today, Westgate said.  The area is well known for fossil mastodon, mammoth, ground sloth, tapir, camels and other late Pleistocene (Ice Age) mammals.

Russell Long, professor emeritus of biology at Lamar from 1951 to 1979, had an extensive collection of fossils from the area and supervised a master’s thesis by Jeffrey Russell in 1975 that detailed the megafauna of the region documenting a wide array of extinct animals including the above, as well as saber-toothed cats, early horses and more.

Westgate said the fossils likely come from ancient stream channels where the bones collected when the land that is now beachfront was 100 or more miles inland.

But don’t expect every bone you find to be a genuine fossil. “A lot of time you can’t tell if it’s a fossil or not,” Westgate said. “Bison bones look just like cow bones. If you bury a cow bone in that dark mud it stains pretty quickly. So, the ones we know for sure are at least 10,000 years old are the ones that are extinct locally, like mastodon, mammoth, ground sloth, tapir and camels.”

Also, don’t expect to find complete skeletons or easily recognizable skulls. Mammoth skulls, while massive, are fairly fragile. It is unlikely, Westgate said, that such structures would have survived intact. “Skulls look pretty solid on the outside, but really they are thin bone,” he said. “Teeth tend to survive the process.”

The fossil will join the collection of the Texas Memorial Museum in Austin and “Dorothy’s address will actually be the site locality for this specimen. Normally we don’t have house addresses for our fossil localities,” he said.

“There are stream channels sitting off shore waiting to be excavated by storm waves,” Westgate said.

While those future storms will bring their share of loss, they may also bring discovery.

http://www.lamar.edu/newsevents/news/207_6977.htm

———————————————————————————–

Other links (news) :

Giant tooth discovered in paleontologist’s home
guardian.co.uk - 3 ore fa
A giant tooth was discovered by two paleontologists in the wreckage of a Texan home destroyed by Hurricane Ike. Dorothy Sisk, a scientist at Lamar
Big fossil found in paleontologist’s yard post-Ike
The Associated Press - 11 ore fa
CAPLEN, Texas (AP) — A paleontologist whose beachfront home in Texas was destroyed during Hurricane Ike has found a football-size tooth in the debris.
6-pound fossil tooth found at Ike-damaged Caplen
Houston Chronicle - 16 ore fa
AP Texas News © 2008 AP CAPLEN, Texas — Hurricane Ike took a bite out of some Texas beaches and in one case revealed a 6-pound tooth.
Big fossil found in paleontologist’s yard post-Ike
Centre Daily Times - 11 ore fa
- AP CAPLEN, Texas — A paleontologist whose beachfront home in Texas was destroyed during Hurricane Ike has found a football-size tooth in the debris.
Hurricane Ike yields ice-age discovery
Lamar University - 18 ore fa
When Lamar University professor Dorothy Sisk returned to her beachfront home in Caplen, she knew there would be little left. Instead, she was part of a

ottobre 3, 2008 Posted by | - Ice Age, - Mammiferi, 1 Olocene b, America Northern, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , , | 1 commento

2008-10-03 – “Pliocenica 2008″

Visite gratuite al Museo ”Cortesi”

Sarà davvero una giornata di “Geologia in festa a Castellarquato”: domenica 5 ottobre, in occasione del meeting di esperti “Pliocenica 2008″, il Museo geologico “Cortesi” del borgo medievale della Valdarda rimarrà aperto per visite gratuite.

E per l’occasione, per la prima volta, sarà anche esposto lo scheletro del rinoceronte di 800mila anni ritrovato qualche mese fa nel greto dell’Arda.

“Pliocenica 2008″ è organizzata dal Museo, dalla Riserva naturale geologica del Piacenziano e dal Servizio geologico della Regione Emilia-Romagna in collaborazione con l’assessorato alla cultura del Comune di Castellarquato, l’Associazione italiana geologia e turismo, il Gruppo mineralogico paleontologico piacentino, il Gruppo paleontologico La Xenophora, la Società piacentina di scienze naturali.

“Pliocenica”, appuntamento annuale per parlare di geologia, paleontologia musei e aree protette, inizierà alle 9.30 con i saluti delle autorità e, alle 10, l’apertura lavori. Seguiranno gli interventi di Simona Guioli (Civico museo di scienze naturali, Voghera) su “Museo e carcere: la nuova guida paleontologica del Museo civico di scienze naturali di Voghera”; Stefano Dominici (Museo di storia naturale Sezione di geologia e paleontologia, Università di Firenze) su “Resoconto del recente convegno romano della società paleontologica italiana”; Francesca Campanini (Civico museo di scienze naturali, Voghera) su “Le conchiglie tra le rocce: laboratori didattici di paleontologia in museo”. Alle 12.30 ci sarà il conferimento dell'”Albo d’oro” del Museo geologico.

Nel pomeriggio, alle 14.30 toccherà invece a Ignazio Bianco (Sim Sezione Piemonte) su “Geometria delle conchiglie”; Girolamo Lo Russo (Museo geologico Cortesi, Castellarquato) su “Nuovo sistema di catalogazione informatizzata del Museo geologico di Castellarquato”.

Dal 1991, anno in cui il Museo arquatese ha trovato la propria sede definitiva nell’Ospitale Santo Spirito, l’attività della struttura museale è stata indirizzata ad una maggiore valorizzazione dei beni geologici presenti sul territorio cercando di potenziare le caratteristiche specifiche di unicità e nello stesso tempo puntando ad una riscoperta e qualificazione di buona parte della fascia pedecollinare orientale della provincia di Piacenza caratterizzata dalla presenza degli affioramenti fossiliferi. L’area geologica prossima al borgo e compresa tra Tabiano Bagni ad est e la Valvezzeno a ovest è stata definita in un recente convegno della Società paleontologica italiana «la zona più classica del Pliocene mediterraneo».

Anche l’avvio di un Centro di educazione ambientale (istituito in collaborazione con la Regione Emilia-Romagna e l’Amministrazione provinciale di Piacenza. nell’ambito dei Piano territoriale di tutela ambientale) attivato presso il Museo geologico e la collocazione della sede operativa della Riserva geologica naturale del Piacenziano nello stesso edificio che ospita il Cea rientrano in quest’ottica di valorizzazione dei beni paleontologici e delle emergenze geologiche della Valdarda con una funzione di collegamento tra museo e aree fossilifere, a disposizione di un’utenza varia che va dalle scuole elementari, medie e superiori fino all’università e agli specialisti del settore.

03/10/2008 10.10.57

http://pcturismo.liberta.it/asp/default.asp?IDG=49970&H=


ottobre 3, 2008 Posted by | - Italia, 4 Pliocene, conferenze, Lang. - Italiano, Musei, Paleontology / Paleontologia, x Terziario | , , , , , , , , , , | Lascia un commento

   

Iscriviti

Ricevi al tuo indirizzo email tutti i nuovi post del sito.