در دهه هفتاد میلادی، جک سپکاسکی، دیرین‌شناس امریکایی، بعد از ۱۵ سال جمع‌آوری اطلاعات فسیلهای موجودات دریایی موفق شد نقشه تنوع زیستی جانوران دریایی در طی ۵۰۰ میلیون سال گذشته را رسم کند و بر اساس آن موفق شد پنج انقراض دسته جمعی را در تاریخ حیات در کره زمین شناسایی کند. 1-Ordovician Silurian 2-End Devonian 3-End Permian (great dying) 4- End Triassic 5- K-T
در دهه هفتاد میلادی، جک سپکاسکی، دیرین‌شناس امریکایی، بعد از ۱۵ سال جمع‌آوری اطلاعات فسیلهای موجودات دریایی موفق شد نقشه تنوع زیستی جانوران دریایی در طی ۵۰۰ میلیون سال گذشته را رسم کند و بر اساس آن موفق شد پنج انقراض دسته جمعی را در تاریخ حیات در کره زمین شناسایی کند. 1-Ordovician Silurian 2-End Devonian 3-End Permian (great dying) 4- End Triassic 5- K-T
Telegram and Signal Havens for Right-Wing Extremists
Since the violent storming of Capitol Hill and subsequent ban of former U.S. President Donald Trump from Facebook and Twitter, the removal of Parler from Amazon’s servers, and the de-platforming of incendiary right-wing content, messaging services Telegram and Signal have seen a deluge of new users. In January alone, Telegram reported 90 million new accounts. Its founder, Pavel Durov, described this as “the largest digital migration in human history.” Signal reportedly doubled its user base to 40 million people and became the most downloaded app in 70 countries. The two services rely on encryption to protect the privacy of user communication, which has made them popular with protesters seeking to conceal their identities against repressive governments in places like Belarus, Hong Kong, and Iran. But the same encryption technology has also made them a favored communication tool for criminals and terrorist groups, including al Qaeda and the Islamic State.
Mr. Durov launched Telegram in late 2013 with his brother, Nikolai, just months before he was pushed out of VK, the Russian social-media platform he founded. Mr. Durov pitched his new app—funded with the proceeds from the VK sale—less as a business than as a way for people to send messages while avoiding government surveillance and censorship.
