• Fossiliferous level "...consists predominantly of clays affected by a wide variety of pedogenic processes and contains fragments of eggshell throughout its length. Three types of facies can be recognized at this level. Those of type I, with a reddish matrix and a great presence of gray and yellowish spots. Carbonate nodules and striated surfaces abound, while rhizolites are narrow and very few. They are interpreted as well-drained paleosols. Type II facies are gray clays that turn purple. They are more carbonated than those of type I and present fenestral porosity and evidence of successive dissolution-dolomitization processes. Carbonate nodules and thicker rhizoliths abound than in type I facies. This level is the one that has produced the large accumulations of eggshells and complete eggs (fig. 6). Finally, type III facies are similar to type I but with a markedly coarser grain, and although no rhizoliths or nodules are observed, fractures abound. Facies II and III have been interpreted as poorly drained paleosols."