Palaeontology News - Page 2

Lt. Killer M · 28-05-2007, 18:19

4) Definitive Evidence Found of a Swimming Dinosaur

http://www.geosociety.org/news/pr/07-22.htmPress release linky
http://dx.doi.org/10.1130/G23452A.1Article Abstract linky

Boulder, Colorado, USA – An extraordinary underwater trackway with 12 consecutive prints provides the most compelling evidence to-date that some dinosaurs were swimmers. The 15-meter-long trackway, located in La Virgen del Campo track site in Spain's Cameros Basin, contains the first long and continuous record of swimming by a non-avian therapod dinosaur.

A team led by Rubén Ezquerra, Fundación Patrimonio Paleontológico de La Rioja, La Rioja, Spain, discovered the prints in an area long known for its abundance of terrestrial dinosaur trackways dating from the early Cretaceous 125 million years ago. The team's findings are reported in the June issue of GEOLOGY, published by the Geological Society of America.

The trackway consists of 6 asymmetrical pairs of 2-3 scratch marks each. Each set of scratch marks, preserved in a layer of sandstone, averages approximately 50 centimeters in length and 15 centimeters wide. The spacing between them suggests an underwater stride of 243-271 centimeters.

According to co-author Loic Costeur, Laboratoire de Planétologie et Géodynamique de Nantes, Université de Nantes, France, the S-shaped prints paint a picture of a large floating animal clawing the sediment as it swam in approximately 3.2 meters of water. Ripple marks on the surface of the site indicate the dinosaur was swimming against a current, struggling to maintain a straight path.

"The dinosaur swam with alternating movements of the two hind limbs, a pelvic paddle swimming motion," said Costeur. "It is a swimming style of amplified walking with movements similar to those used by modern bipeds, including aquatic birds."

The question of whether dinosaurs could swim has been researched for years. Until now, however, very little hard evidence existed documenting the behavior. Several earlier discoveries were later found to have been produced on dry ground or categorized as ghost traces, possible undertracks preserved in lower layers of sediment.

"The trackway at La Virgen del Campo opens the door to several new areas of research," said Costeur. "New biomechanical modeling will increase our understanding of dinosaur physiology and physical capabilities, as well as our view of the ecological niches in which they lived."

Ezquerra, R., Doublet, S., Costeur, L., Galton, P.M., Pérez-Lorente, F. (2007): Were non-avian theropod dinosaurs able to swim? Supportive evidence from an Early Cretaceous trackway, Cameros Basin (La Rioja, Spain) - Geology 35(6), 507-510

and here is a pic of the scratches they think were made by the swimming theropod:

Tubby Rower · 29-05-2007, 12:11

Just a question... but the title of the post say definitive proof but then the last sentence says they think. If it's definitive, then shouldn't that be a they know? One other question (probably stupid) how do they know that the prints are from a dinosaur? why couldn't it have been from another type of animal?

Melifluous · 29-05-2007, 13:22

Quote:

quote:Originally posted by Tubby Rower

Just a question... but the title of the post say definitive proof but then the last sentence says they think. If it's definitive, then shouldn't that be a they know?

Maybe you confuse Definitive with definite?

Code:

definitive

adjective
1. 	clearly defined or formulated; "the plain and unequivocal language of the laws"- R.B.Taney 
2. 	of recognized authority or excellence; "the definitive work on Greece"; "classical methods of navigation"
        [syn: authoritative] 
3. 	supplying or being a final or conclusive settlement; "a definitive verdict"; "a determinate answer to the problem"

Lt. Killer M · 29-05-2007, 14:55

Quote:

quote:Originally posted by Tubby Rower

Just a question... but the title of the post say definitive proof but then the last sentence says they think. If it's definitive, then shouldn't that be a they know? One other question (probably stupid) how do they know that the prints are from a dinosaur? why couldn't it have been from another type of animal?

a) see meli's reply

b) the last sentence was added by me, so it is not part fo the official press release. I am extremely cautious with the word 'proof', and I used 'they think' because theoretically, an as yet totally unknown animal extremely similar to a theropod might have made them. Unlikely, though.

Now, why is this so improbable?

- the animal must be large
- msut have the right number and position of claws
- must have the correct limb proportions and position
- must have the correct claw form
- must have sufficient power to show this behaviour.

The fauna is rather well known, and of the known animals only a theropod can have made them, all others would leave different-looking marks. So barring a totally new group of animals, it was a theropod.

28-05-2007, 18:19	#11
Lt. Killer M Emperor Join Date: Mar 2003 Location: HAWK!. Posts: 4,365	4) Definitive Evidence Found of a Swimming Dinosaur http://www.geosociety.org/news/pr/07-22.htmPress release linky http://dx.doi.org/10.1130/G23452A.1Article Abstract linky Boulder, Colorado, USA – An extraordinary underwater trackway with 12 consecutive prints provides the most compelling evidence to-date that some dinosaurs were swimmers. The 15-meter-long trackway, located in La Virgen del Campo track site in Spain's Cameros Basin, contains the first long and continuous record of swimming by a non-avian therapod dinosaur. A team led by Rubén Ezquerra, Fundación Patrimonio Paleontológico de La Rioja, La Rioja, Spain, discovered the prints in an area long known for its abundance of terrestrial dinosaur trackways dating from the early Cretaceous 125 million years ago. The team's findings are reported in the June issue of GEOLOGY, published by the Geological Society of America. The trackway consists of 6 asymmetrical pairs of 2-3 scratch marks each. Each set of scratch marks, preserved in a layer of sandstone, averages approximately 50 centimeters in length and 15 centimeters wide. The spacing between them suggests an underwater stride of 243-271 centimeters. According to co-author Loic Costeur, Laboratoire de Planétologie et Géodynamique de Nantes, Université de Nantes, France, the S-shaped prints paint a picture of a large floating animal clawing the sediment as it swam in approximately 3.2 meters of water. Ripple marks on the surface of the site indicate the dinosaur was swimming against a current, struggling to maintain a straight path. "The dinosaur swam with alternating movements of the two hind limbs, a pelvic paddle swimming motion," said Costeur. "It is a swimming style of amplified walking with movements similar to those used by modern bipeds, including aquatic birds." The question of whether dinosaurs could swim has been researched for years. Until now, however, very little hard evidence existed documenting the behavior. Several earlier discoveries were later found to have been produced on dry ground or categorized as ghost traces, possible undertracks preserved in lower layers of sediment. "The trackway at La Virgen del Campo opens the door to several new areas of research," said Costeur. "New biomechanical modeling will increase our understanding of dinosaur physiology and physical capabilities, as well as our view of the ecological niches in which they lived." Ezquerra, R., Doublet, S., Costeur, L., Galton, P.M., Pérez-Lorente, F. (2007): Were non-avian theropod dinosaurs able to swim? Supportive evidence from an Early Cretaceous trackway, Cameros Basin (La Rioja, Spain) - Geology 35(6), 507-510 and here is a pic of the scratches they think were made by the swimming theropod: __________________ One more turn..... just one more turn... one MORE!

29-05-2007, 12:11	#12
Tubby Rower Moderator Join Date: Aug 2005 Location: Middle of VA. Posts: 3,896	Just a question... but the title of the post say definitive proof but then the last sentence says they think. If it's definitive, then shouldn't that be a they know? One other question (probably stupid) how do they know that the prints are from a dinosaur? why couldn't it have been from another type of animal? __________________ 3/2006 : Now, surely that must be because some fists might have caused internal damage to certain delicate parts?