Extended Data Fig. 1: δ18O belemnite values from the Western Tethys.
From: Jurassic greenhouse ice-sheet fluctuations sensitive to atmospheric CO2 dynamics
Note general congruence of data prior to the T-CIE, and greater scattering during and after. Study areas in the northern Tethys (Bulgaria72; Yorkshire, UK, plus symbol73; Yorkshire, UK, gray square74; Yorkshire, UK, orange circle75; S. France76; Belgium77; Germany78; and S. France77) were likely influenced by freshwater lowering δ18O values during the T-CIE, where because of anoxia, belemnites may have migrated to warmer surface habitats further lowering isotopic values50. Scattered δ18O values after the T-CIE are attributed to the evolution of new belemnite species adapted to different habitats in the water column50. Data from Portugal and Spain (N. Spain, gray circle23; N. Spain, blue circle22; N. Spain, red circle24; Portugal, green circles19) were influenced less by freshwater and anoxia, and used for the sea level computations.
