User:Abyssal/Gironnette dinosaur tracksite

Picaud farm, on the outskirts of Corgnac France, is the site of a dinosaur tracksite that has been called the best in the entire country. The farm is owned by Jean and Colette Picaud. The farm had belonged to Colette's grandmother. She used to visit the farm and play there with here brother, Jean-Pierre. The two children noticed a footprint-like shape in a slab of rock in front of the farmhouse. Years later, Jean Pierre visited the Esperaza in Pyrenees and saw some dinosaur footprints there. Reminded of the shape he had seen in the farmhouse slab, he returned to the farm and re-examined the slab. Finding that the shape in the rock probably really was a dinosaur footprint, he contacted Esperaza's Dinosaur Museum. Jean Le Loeuff, director of the museum, verified the tracks at the Picaud farm.

The tracks have yet to be studied in detail by scientists, but preliminary a report in a French magazine article claimed the Picaud farm was home to three different kinds of dinosaur tracks. Two of these were left by theropods, with one kind of track being attributable to the ichnogenus Grallator. Authors Lockley and Meyer have collaborated with Le Loeuff to study the purported ornithopod trackway and instead concluded that it was left by a stegosaur or a closeley related form of early armored dinosaur. Lockley and Meyer based their identification on several features exhibited by the tracks. First, at 40 centimeters long and almost 30 centimeters wide, they are larger than those of any known ornithopod. The tracks had a stride length of about 1.23 m. The tracks were also slightly angled toward the mid-line of the trackmaker's body. Contemporary ornithopods were smaller, had different numbers of phalanges in the hindfeet, and longer heels.

However, the stegosaur interpretation of these tracks is somewhat controversial because some researchers interprets some of the footprints in the trackway as bearing faint impressions left by the first digit of the hindfoot. Since the stegosaur hindfoot has only the second, third, and fourth digits this interpretation excludes them as a trackmaker. Assuming digit I traces are present, the trackways would likely have been left by an ancestral relative of the stegosaurs instead, like a basal thyreophoran.

If these footprints really are stegosaurian, they are the oldest known stegosaur fossils, and push back the known age of the group by 30 to 40 million years.

History

A farm on the outskirts of Corgnac, France is the site of a dinosaur tracksite that has been called the best in the entire country. The farm is owned by Jean and Colette Picaud. The farm had belonged to Colette's grandmother. She used to visit the farm and play there with here brother, Jean-Pierre. The two children noticed a footprint-like shape in a slab of rock in front of the farmhouse. Years later, Jean Pierre visited the Esperaza in Pyrenees and saw some dinosaur footprints there. Reminded of the shape he had seen in the farmhouse slab, he returned to the farm and re-examined the slab. Finding that the shape in the rock probably really was a dinosaur footprint, he contacted Esperaza's Dinosaur Museum. Jean Le Loeuff, director of the museum, verified the tracks at the Picaud farm.

The tracks have yet to be studied in detail by scientists, but preliminary a report in a French magazine article claimed the Picaud farm was home to three different kinds of dinosaur tracks. Two of these were left by theropods, with one kind of track being attributable to the ichnogenus Grallator. Authors Lockley and Meyer have collaborated with Le Loeuff to study the purported ornithopod trackway and instead concluded that it was left by a stegosaur or a closeley related form of early armored dinosaur. Lockley and Meyer based their identification on several features exhibited by the tracks.

Paleofauna

The tracks have yet to be studied in detail by scientists, but preliminary a report in a French magazine article claimed the Picaud farm was home to three different kinds of dinosaur tracks. Two of these were left by theropods, with one kind of track being attributable to the ichnogenus Grallator. Authors Lockley and Meyer have collaborated with Le Loeuff to study the purported ornithopod trackway and instead concluded that it was left by a stegosaur or a closeley related form of early armored dinosaur. Lockley and Meyer based their identification on several features exhibited by the tracks. First, at 40 centimeters long and almost 30 centimeters wide, they are larger than those of any known ornithopod. The tracks had a stride length of about 1.23 m. The tracks were also slightly angled toward the mid-line of the trackmaker's body. Contemporary ornithopods were smaller, had different numbers of phalanges in the hindfeet, and longer heels.

However, the stegosaur interpretation of these tracks is somewhat controversial because some researchers interprets some of the footprints in the trackway as bearing faint impressions left by the first digit of the hindfoot. Since the stegosaur hindfoot has only the second, third, and fourth digits this interpretation excludes them as a trackmaker. Assuming digit I traces are present, the trackways would likely have been left by an ancestral relative of the stegosaurs instead, like a basal thyreophoran.

If these footprints really are stegosaurian, they are the oldest known stegosaur fossils, and push back the known age of the group by 30 to 40 million years.

See also

• Hoganas Formation

References

• Le Loeuff, Jean; Lockley, Martin; Meyer, Christian; Petit, Jean-Pierre (1999). "Discovery of a thyreophoran trackway in the Hettangian of central France". Discovery of a thyreophoran trackway in the Hettangian of central France. 328 (3): 215–219.
• Lockley, Martin G.; Meyer, C. A. (2000). Dinosaur Tracks and other fossil footprints of Europe. New York: Columbia University Press. ISBN 0-231-10710-2.