File talk:Cruziana semiplicata.JPG

Age and provenance

I’ve done a little research because I wanted to know where the slab actually comes from and how old the rock that bears the traces actually is. C. semiplicata generally is characteristic for Upper Cambrian deposits. In Seileacher (2007, Trace Fossil Analysis, pl. 14, p. 41, bottom right) a sketch of a slab with C. semiplicata is figured which well may show the slab on the picture overleaf. In the corresponding text it says that it comes from the Upper Cambrian of the Sierra de la Demanda, Spain. Here at the Wayback Machine (on the left) the same slab is shown on a phototograph. The specimen on the picture overleaf appears to have been complemented by a few fragments that are missing in the sketch and picture mentioned above since the outline is somewhat different. However, the overall shape and, most important, the track patterns on the slabs indicate that the picture overleaf shows the slab from the Sierra de la Demanda. Hence, I have changed the file description accordingly. --Gretarsson (talk) 14:28, 1 August 2014 (UTC)