Navigation Links
Oldest evidence of dinosaurs found in Polish footprints
Date:10/5/2010

The oldest evidence of the dinosaur lineagefossilized tracksis described this week in Proceedings of the Royal Society B. Just one or two million years after the massive Permian-Triassic extinction, an animal smaller than a house cat walked across fine mud in what is now Poland. This fossilized trackway places the very closest relatives of dinosaurs on Earth about 250 million years ago5 to 9 million years earlier than previously described fossilized skeletal material has indicated. The paper also described the 246-million-year-old Sphingopus footprints, the oldest evidence of a bipedal and large-bodied dinosaur.

"We see the closest dinosaur cousins immediately after the worst mass extinction," says Stephen Brusatte, a graduate student affiliated with the Division of Paleontology at the American Museum of Natural History. "The biggest crisis in the history of life also created one of the greatest opportunities in the history of life by emptying the landscape and making it possible for dinosaurs to evolve."

The new paper analyzes three sets of footprints from three different sites in the Holy Cross Mountains of central Poland. The sites, all quarries within a 25-mile radius of each other, are windows into three ecosystems because they represent different times periods. The Stryczowice trackway is the oldest at 250 million years. The Baranw trackway is the most recent at 246 million years of age while the Wiry trackway is sandwiched in time between the others.

Because footprints are only an imprint of a small part of the skeleton, identification of trackmakers is often tricky. Luckily, dinosaurs have a very distinctive gait, especially when compared to their diapsid relatives (the evolutionary group that includes birds, reptiles, and extinct lineages) like crocodiles and lizards. While lizards and crocodiles have a splayed walking style, dinosaurs place their two feet closer together. The footprints at all three Polish sites show this feature as well as indisputable dinosaur-like features, including three prominent central toes and reduced outer two toes, a parallel alignment of these three digits (a bunched foot), and a straight back edge of footprints, additional evidence of a dinosaur-like simple hinged ankle.

Because all of these features are seen in footprints at the oldest site, Brusatte and colleagues conclude that the Stryczowice printswhich are only a few centimeters in lengthare the oldest evidence of the dinosaur lineage. These dinosaurs, though, are considered "stem dinosaurs," or the immediate relatives of dinosaurs not part of the slightly more derived clade that technically defines dinosaurs. Also, this animal did walk on all four limbs, an abnormal posture for early dinosaurs and their close relatives, although it appears that its forelimbs were already being reduced to more dinosaur-like proportions since the footprints overstep handprints.

The Baranw and Wiry trackways show changes early in the evolutionary history of dinosaurs. Wiry at 248� million years ago shows slight diversification in the types of tracks, but all tracks remain quadrupedal. Footprints from Baranw at 246 million years ago, however, may be the earliest evidence of moderately large-bodied and bipedal true dinosaurs. These tracks, which are called Sphingopus, are 15 centimeters long.

"Poland is a new frontier for understanding the earliest evolution of dinosaurs," says Grzegorz Niedźwiedzki of the University of Warsaw and the Polish Academy of Sciences, who led the project and has been excavating footprints from the three sites for nearly a decade. "It used to be that most of the important fossils were from Argentina or the southwestern U.S., but in Poland we have several sites that yield footprints and bones from the oldest dinosaurs and their closest cousins, stretching throughout the entire Triassic Period."

Finally, although the dinosaur group emerged soon after the Permian extinction, dinosaur-like tracks are rare in the footprint assemblages, representing only 2𔃁 percent of the prints discovered as opposed to 40󈞞 percent for crocodile-like archosaurs. Dinosaurs became more abundant tens of millions of years later.

"For the first 20󈞞 million years of dinosaur history, dinosaurs and their closest relatives were living in the shadow of their much more diverse, successful, and abundant crocodile-like cousins," says Brusatte. "The oldest dinosaurs were small and rare."


'/>"/>

Contact: Kristin Elise Phillips
kphillips@amnh.org
212-496-3419
American Museum of Natural History
Source:Eurekalert  

Related biology news :

1. Researchers uncover worlds oldest fossil impression of a flying insect
2. 4,000-year-old coral beds among worlds oldest living things, prof says
3. Kent State University Professor C. Owen Lovejoy helps unveil oldest hominid skeleton
4. Ardi displaces Lucy as oldest hominid skeleton
5. Dinosaur-chewing mammals leave behind oldest known tooth marks
6. Oldest Earth mantle reservoir discovered
7. Scientists discover oldest evidence of human stone tool use and meat-eating
8. UNH researcher helps identify key reproductive hormone in oldest vertebrate
9. Genetic evidence for avian influenza movement from Asia to North America via wild birds
10. Mounting evidence shows health benefits of grape polyphenols
11. New evidence that people make aspirins active principle -- salicylic acid
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Oldest evidence of dinosaurs found in Polish footprints
(Date:4/19/2016)... -- The new GEZE SecuLogic access control ... system solution for all door components. It can be ... interface with integration authorization management system, and thus fulfills ... dimensions of the access control and the optimum integration ... considerable freedom of design with regard to the doors. ...
(Date:4/15/2016)... 15, 2016 Research and ... Biometrics Market 2016-2020,"  report to their offering.  , ... , ,The global gait biometrics market is expected ... the period 2016-2020. Gait analysis generates ... be used to compute factors that are not ...
(Date:4/13/2016)... CHICAGO , April 13, 2016  IMPOWER physicians ... are setting a new clinical standard in telehealth ... By leveraging the higi platform, IMPOWER patients can ... weight, pulse and body mass index, and, when they ... quick and convenient visit to a local retail location ...
Breaking Biology News(10 mins):
(Date:5/19/2016)... There is no saying when ... relentless pressures in pricing and lack in consumer confidence. ... though - numerous opportunities are up for grabs but ... presents four names in this sector: Portola Pharmaceuticals Inc. ... VTAE ), Anthera Pharmaceuticals Inc. (NASDAQ: ...
(Date:5/19/2016)... 2016 - I dati saranno ... il 52 ° Congresso della ... - Le conclusioni dello studio indicano un tasso ... di cui il 90% presenta una d urata della ... Il settantadue per cento dei pazienti ha riscontrato un beneficio ...
(Date:5/18/2016)... The Biotech industry continues to face ... there are no opportunities ahead. Today, ActiveWallSt.com has on its ... THLD ), Seattle Genetics Inc. (NASDAQ: SGEN ), ... (NASDAQ: OPHT ). Sign up now to receive ... http://www.activewallst.com/ Threshold Pharmaceuticals Inc.,s shares gained 0.68%, ...
(Date:5/18/2016)... ... 18, 2016 , ... The Academy of Model Aeronautics has been helping graduating ... a total of $1 million in awarded scholarships. , The AMA is happy to ... across the nation has helped bring the total of AMA scholarships that have been ...
Breaking Biology Technology: