[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Definitive Evidence Found Of A Swimming Dinosaur
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 Rubn Ezquerra, Fundacin Patrimonio Paleontolgico 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 Plantologie et
Godynamique de Nantes, Universit 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.