French researchers discover biggest dinosaur footprints
French researchers on Tuesday said they had uncovered the biggest dinosaur footprints in the world, left by giant sauropods that may have weighed 40 tonnes or more.
An extraordinary track of footprints was found in April this year in the Jura plateau at Plagne, near the southeastern city of Lyon, by a pair of amateur fossil-hunters, the National Centre for Scientific Research (CNRS) said in a press release.
Professional palaeontologists have since authenticated the find.
"According to the researchers' preliminary inspections, the footprints appear to be the biggest seen so far," the CNRS said.
"In addition, the tracks formed by the footprints extend over dozens, even hundreds, of metres. Further digs will be carried out in the coming years and they may reveal that the site at Plagne is one of the biggest of its kind in the world."
The footprints entail circular depressions in chalky sediment that has been dated to the Upper Jurassic period, around 150 million years ago, when the area was covered by a warm, shallow sea.
"The prints are very big, reaching 1.20 to 1.50 metres (3.9 to 4.9 feet) across, which corresponds to animals exceeding 30 or 40 tonnes in weight and measuring more than 25 metres (81 feet) in length," the CNRS said.
Big as these four-footed beasts were, they were not the largest dinosaurs that lived.
Candidates for the much-disputed title include Amphicoelias fragillimus, speculated to be between 40-60 metres (131-196 feet) long and up to 122 tonnes in weight, and Argentinosaurus, between 30-35 metres (98-110 feet) and as much as 80-100 tonnes.
The biggest dinosaurs were all sauropods, long-necked, four-footed herbivores.
Evidence mainly comes from fossilised bones, sometimes single or fragmented, and the sketchiness of such proof often sparks heated debate.