LETHALLY HOT TEMPERATURES DURING THE EARLY TRIASSIC GREENHOUSE
Tetrapods are excluded from equatorial latitudes during peak temperature intervals. Amphibians, a group that normally thrives in equatorial warmth, were entirely absent from the Early Triassic tropics but instead successfully radiated at higher latitudes. Similarly marine reptiles make their appearance at high latitudes at this time time but are absent from low latitudes.
Extreme warmth exerts a strong selection pressure for small organisms and a “Lilliput effect” has long been known in diverse Early Triassic groups.
Photosynthetic algae struggle to survive as temperatures rise above 32°C whilst cyanobacterial photosynthesis continues unabated even at temperatures >40°C. Biomarker evidence indicators a switch to cyanobacterial-dominated plankton populations at the start of the Triassic.
Terrestrial plant productivity was severely curtailed in the Early Triassic and re-establishment of peat formation only began in the later Triassic at higher latitudes.