Where: Morocco (32.8° N, 3.6° W: paleocoordinates 22.3° N, 2.6° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Calcaires à slumps de Taghit Formation, Late/Upper Campanian (83.5 - 70.6 Ma)

• Complete absence of index fossils (microfossils, ammonoids, rudists, etc.) makes it difficult to define a biostratigraphic age. However, studies on the stratigraphy and general geology from nearby areas (Enßlin, 1993; Charroud, 2002; Haddoumi et al., 2008) indicate an Upper Cretaceous sedimentary sequence for the regional lithostratigraphic units. With the aim to resolve the chronological uncertainty of the strata where the fossil crustaceans were found, we obtained 87Sr/86Sr isotopic analyses on carapace fragments of Ophthalmoplax minimus new species. We obtained a value of 87Sr/86Sr = 0.707595 ± 0.000028 (one standard deviation) for a run of 58 measurements. By comparison with the 87Sr/86Sr seawater curve for the Late Cretaceous–Paleogene (McArthur and Howarth, 2004), the obtained isotopic ratio corresponds to an age of late Campanian (approximately 76 Ma; Figure 5).

• group of beds-level stratigraphic resolution

Environment/lithology: lithified, yellow marl

Size class: macrofossils

Collection methods: Repository: Museo Geológico del Seminario de Barcelona (MGSB), Museo Civico di Storia Naturale di Milano (MSNM).

Primary reference: À Ossó-Morales, P. Artal, and F. J. Vega. 2010. New crabs (Crustacea, Decapoda) from the Upper Cretaceous (Campanian) of the Moyenne Moulouya, northeast Morocco. Revista Mexicana de Ciencias Geológicas 27(2):213-224 [C. Schweitzer/E. Johnson/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 133907: authorized by Carrie Schweitzer, entered by Evaline Johnson on 30.09.2012

Creative Commons license: CC BY (attribution)