Paleonews

Il blog dedicato ai Paleontologi !!!!

2009-03-05 – Teropodi con postura da uccelli (Dinosaur imprints, birdlike arm anatomy)

Tracce di un Teropode a riposo (Giurassico inferiore, Utah – USA) rivelano una postura da uccello

Vedi approfondimento sul Blog Theropoda:

Un nuovo sito icnologico dimostra che i theropodi si accucciavano come… (Milner et al., 2009)

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Sitting dinosaur leaves karate chop handprints – March 04, 2009

45376624.jpgAncient meat-eating dinosaurs held their arms with palms facing inwards like their bird descendants, a rare set of 198-million-year-old fossilised handprints has revealed. An analysis of the prints, published this week in PLoS One, supports theories that even very early therapods [lit. ‘beast feet’] such as tyrannosaurs and velociraptors had bird-like forelimbs, and walked only on two legs, well before they evolved feathery wings.

The handprints came from a dinosaur that sat down on the edge of a lake in St George, Utah, and extended its arms far enough to leave sediment marks. Six other resting dinosaur traces have been reported before, but they all lack clear hand prints.

This means, reports the Chicago Tribune, that we must banish images of tyrannosaurs holding their forearms like monkeys, with palms facing downwards – a posture that palaeontologists apparently term the “bunny position” – as depicted in Jurassic Park. Instead, we must imagine that dinosaurs were extremely good at holding basketballs.

“What this seems to imply is that, even from fairly early in their history, dinosaurs were entirely bipedal and weren’t using their forearms to support themselves in any way,” paleontologist Tom Holtz of the University of Maryland, says. “Because of that, the hands could specialize as weapons, to grab on to a struggling animal or to fight with other dinosaurs.”

Image: Dilophosaurus wetherilli in bird-like resting pose/Heather Kyoht Luterman

source: Nature.com

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What a dinosaur handprint reveals

Los Angeles Times – ‎3-mar-2009‎
At left, dinosaur tracks with hand prints show bird-like inward-facing palms at Johnson Farm, Utah. At right, an artist’s reconstruction shows the formation
National Geographic —————————————————————————–

 

 free access article on PlosOne

Bird-Like Anatomy, Posture, and Behavior Revealed by an Early Jurassic Theropod Dinosaur Resting Trace

Andrew R. C. Milner, Jerald D. Harris, Martin G. Lockley, James I. Kirkland, Neffra A. Matthews

Abstract PDF

 

 

marzo 5, 2009 - Posted by | - R. Dinosauri, - Teropodi, - Uccelli / Birds, 2 Jurassic / Giurassico, America Northern, An. Vertebrates, Articolo sc. di riferimento, Bl - Top posts, FREE ACCESS, Mesozoic, P - Evoluzione, P - Impronte, P - morfologia funzionale, P - Paleoetologia, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , ,

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