Tuyet chung hang loat trog qua khu:

_Theo 1 danh gia ve so loai da ton tai tren Trai Dat thi co 99,9% so loai da bi tuyet chung.So loai hien nay la 0,1%.Co 5 thoi ki tuyet chung hang loat trog qua khu:

+Ky Ordovic cuoi(440tr nam trc):Khoang 50% so ho dong vat va 85% loai da bi tieu diet.Chu yeu la cac loai o bien

+Ky Devon muon(365tr nam trc):30% so ho cac loai DV bi tuyet chug,chu yeu la sih vat bien.Nguyen nhan do lanh toan cau va oxy trog nuoc giam

+Ky Pemi cuoi(251tr nam trc):50% cac ho dog vat bi tuyet chug va 96% loai sih vat bien.Nguyen nhan do bien dog muc nuoc bien va thay doi khi hau.

+Ky Trias cuoi(205tr nam trc):Co 35% ho cac loai dog vat va 76% loai fan lon la o bien bi tuyet chug.

+Ky Creta cuoi(65tr nam trc):Khoang 60% loai dog vat tuyet chug.Day la thoi ki cac giog dog vat bien mat tren dien rong,su bien mat cua khug long.Cac loai linh trg tien hoa phat trien manh va loai nguoi xuat hien.Nguyen nhan do thien thach lam thay doi khi hau.

Trog wa trih tien hoa,sau moi dot tuyet chug la thoi ki fuc hoi cua cac nhom loai SV.Thoi jan fuc hoi cho cac su kien tuyet chug trog qua khu cug rat dai.

Tuyet chung hang loat ngay nay:

_Xay ra vao ky Pleistocen tu hon 1 tr nam trc .Day la thoi ki co nhug bien dog lon ve khi hautoan cau,muc nuoc bien thay doi,loai nguoi mo rong fan bo.Dac tinh wan trog nhat la lien wan den su fan bo of loai nguoi.Co vai diem khac voi trog qua khu:

+Xay ra vs toc do rat nhanh.Cac chuyen ja du doan neu tiep tuc xu huong hien nay thi 100 nam toi se mat di 1/2 loai SV

+So luong loai co nguy co tuyet chung hien nay lon hon nhieu so voi trc day:Vi hien nay so lg loai cung nhieu hon trc

+Nhan to gay ra chu yeu la con nguoi.Cu 100 loai bi tuyet chung thi 99 loai la do con nguoi

+Su tuyet chung ngay nay k kem theo hih thanh loai moi