Use 'coeval' to emphasize that events or objects originated or occurred at the exact same period. Gothic architecture is coeval with the high and late medieval period.
Pro Tip 2/3
Historical Context
'Coeval' is well-suited for discussions about history or scientifically dated events. Dinosaurs were not coeval with human beings.
Pro Tip 3/3
Avoid Present
It's less common to use 'coeval' about the present; instead, it's mostly used in historical or academic contexts. Steam engines were coeval with the Industrial Revolution.