Posted on 05/25/2007 8:11:25 AM PDT by Redcitizen
PARIS (AFP) - Twelve footprints found in the bed of an ancient lake in northern Spain have thrown up the first compelling evidence that some land dinosaurs could swim, researchers reported Thursday.
The 15-metre (48.75-feet) -long track in sandstone "strongly suggests a floating animal clawing the sediment" as it swam against a current, they say.
The swimmer is believed to have been a therapod -- the vast family of carnivorous dinos that included the mighty Tyrannosaurus rex -- which lived in the Early Cretaceous, some 125 million years ago.
The trackway in the former lakebed consists of six asymmetrical pairs of two or three S-shaped scratch marks. Each set measures some 50 centimetres (20 inches) in length and 15 cms (six inches) wide.
The prints paint a beguiling picture of a large, buoyant dinosaur whose clawed feet raked the sediment as it swam in a depth of some 3.2 metres (10.4 feet) of water, according to the paper, which appears in the June issue of the US journal Geology.
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 co-author Loic Costeur of the Laboratory for Planetology and Geodynamics at the University of Nantes, western France.
"It is a swimming style of amplified walking, with movements similar to those used by modern bipeds, including aquatic birds."
The question as to whether dinosaurs could swim has been debated for years.
Until now, no firm evidence had come to light, just mysterious "ghost traces" at various sites.
Asked by AFP to speculate as to which dinosaur may have made the tracks, Costeur cautiously pointed to the allosaurus -- a bipedal carnivorous dinosaur with a large skull balanced by a long, heavy tail. Some allosauruses could reach more than 10 metres (32 feet) in length.
The discovery opens up new avenues in dinosaur research, said Costeur.
Computer modelling will be able to reveal more about anatomy and biomechanics, "as well as our view of the ecological niches in which they lived."
The Virgen del Campo track is located at the Cameros Basin in La Rioja, at the site of a delta to a former lake. The basin is already known as a treasure trove of footprints of walking theropods.
Lead author is Ruben Ezquerra of the Foundation for Palaeontological Patrimony in La Rioja.
“a bipedal carnivorous dinosaur with a large skull balanced by a long, heavy tail.”
Teddy K.?
"Watson, we are looking a red-headed man, about six foot four. He is employed as a mason, but last Saturday he earned a few shillings as a bootblack. He was born in Blackpool but now resides near Charring Cross."
"My God Holmes! How do you know all this?"
"Elementary my dear Watson. He left a half-smoked cigar in that ashtray. That tells me everything I need to know about him."
Assumptions...assumptions...does not make it so!
Definitely describes Clintoon & Pelosi.
As the creature became more adapted to water, it became increasingly ungainly on land...
I always thought that many of the Dinosaurs would have lived much of their lives in water to help support their weight.
Given the size of many of the examples one would think that the atmospheric pressure was much higher then or they were more at home in the water.
If the feet are touching the bottom, it was wading, not swimming. Probably just trying to get to shore at the time of the flood.
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