The data were generated at ESRF beamline ID22 with an incident energy at 17 keV. Watznaueria britannica were analyzed with 0.1 µm x 0.1 µm pixel size and 2 s time analysis per pixel. Both coccoliths were picked from sample CM62 from Murtinheira section at Cabo Mondego, Portugal dated to the lower Bajocian (Middle Jurassic). Sample position in the section in Suchéras-Marx et al. (2012). Data treatment is made using PyMCA. For each calcareous nannofossil, the raw data (.edf in .zip) and the pondered spectrum (.csv) are given. The fit file given (.cfg) was used for both coccoliths. Those data were acquired through the project EC811 at ESRF.