1. The Mesozoic
MYA

3. Permian-Triassic Transition
Pangaea, the interior of which was desert.
Low atmospheric oxygen (~12% recovering to ~16%)
No early coal deposits; recovery took ~30 MY
Atmospheric CO2 6X pre-industrial levels
Mean global temperature 3oC higher than today
Lystrosaurus, the most common land vertebrate

4. The Triassic Period
Named by Friedrich August von Alberti in The name refers to the 3-parted geological sequence as observed in Germany
MYA
Appearance of early crocodilians, pterosaurs, dinosaurs, and mammals.
Modern coral reefs appeared; marine reptiles (Sauropterygia)
Forests recovered by the Middle Triassic (mainly conifers and some seed ferns)
Pangaea began to pull apart

5. The Triassic-Jurassic Mass Extinction
201 MYA
Loss of 76% of marine and terrestrial animals (~20% of families)
Caused by flood basalts during the break-up of Pangaea?

6. The Jurassic Period
A. Brongniart (1829) named it after the Jura Mountains
MYA
Atmospheric oxygen levels rose to an average of 26%
CO2 7X pre-industrial levels
Mean global temperature 3oC higher than today

8. End Jurassic Extinction event
Minor extinction
Loss of stegosaurids, and largest of the sauropods on land
Marine reptiles, ammonoids, and some bivalves disappeared in the oceans.
No explanation for the extinction.

9. The Cretaceous Period
140 Ma
Jean-Baptiste-Julien Omalius d’Halloy (1822) named for the extensive chalk deposits of western Europe (creta is Latin for chalk)
MYA
Atmospheric oxygen levels rose to an average of 30%
CO2 6X pre-industrial levels
Mean global temperature 4oC higher than today

11. Figure 1 from Jan de Boer, Eppinga, Wassen, and Dekker. 2012
Figure 1 from Jan de Boer, Eppinga, Wassen, and Dekker A critical transition in leaf evolution facilitated the Cretaceous angiosperm revolution. Nature Communications 3(1221): DOI: /ncomms2217

12. The End Cretaceous Mass Extinction
75% of plant and animal species became extinct
Uneven in effects: marine plankton, large animals, particularly large tetrapods, filter-feeders, and large marine predators were hit hardest
Loss of forests and immediate decline in photosynthesis caused collapse of ecosystems
Small animals, stream dwellers,and burrowing animals fared better