Abstract
Proarticulates have been found for the first time in Spain at the lower boundary of the Vegadeo Limestone. They show good preservation of geometry and volume. These characteristics are difficult to explain because the Proarticulates are contained within high strained limestone. Textural analysis reveal that the key to the undeformed fossil preservation are the brittle-ductile strain conditions, which increased the rheological contrast between the quartz and calcite. Hence the fossils, having been replaced by quartz while the matrix is calcitic. The system matrix/fossil presents a characteristic rheological behaviour model of a rigid solid into the plastic matrix.
