Which two eras ended with mass extinctions?
its paleozoic and mesozoic right? ?

basic principles: federalism, separation of powers, checks and balances, judicial review, representative democracy, limited government, rule of law, individual rights and responsibilities, consent of the governed, majority rule, popular sovereignty, equal protection.

islam spread slowly through much of africa through trade and preaching.

once he became head of state in 1915, venustiano (his name was not victoriano) carranza was able to implement some of his ideas, such as the drafting and the promulgation of the mexican constitution of 1917, which is still the current constitution of that country.