World’s big­gest shark was wiped out dur­ing a global ex­tinc­tion of ocean’s megafauna

Tehran Times - - SCIENCE -

The big­gest shark to have ever lived was wiped out dur­ing a pre­vi­ously un­known global ex­tinc­tion event that saw 36 per­cent of the world’s marine megafauna dis­ap­pear.

Car­charo­cles mega­lodon could reach up to 60 feet in length and had jaws mea­sur­ing 9 feet wide. It lived from 23 mil­lion years ago up un­til the end of the Pliocene Epoch, around 2.6 mil­lion years ago. What caused its ex­tinc­tion has been the mat­ter of de­bate for many years — shift­ing en­vi­ron­men­tal con­di­tions, a de­cline in prey and the emer­gence of new marine preda­tors all ap­pear to have played a role.

How­ever, in a study pub­lished in Na­ture Ecol­ogy & Evo­lu­tion, sci­en­tists found the demise of the mega­lodon was part of a larger ex­tinc­tion event that af­fected huge swaths of marine life dur­ing the Pliocene (5.3 mil­lion to 2.6 mil­lion years ago).

The end of the Pliocene saw huge changes to the world’s cli­mate. Global tem­per­a­tures and sea lev­els fell dra­mat­i­cally, lead­ing to widespread changes to Earth’s flora and fauna. In the ocean, many in­di­vid­ual species were known to have gone ex­tinct as oth­ers be­gan to emerge. But to what ex­tent this was hap­pen­ing was not known.

Sci­en­tists led by Catalina Pimiento from Switzer­land’s Univer­sity of Zurich, car­ried out a meta-anal­y­sis in which they gath­ered all of the pub­lished fos­sil records from this pe­riod.

The pre­vi­ously un­known ex­tinc­tion event in­cluded marine mam­mals, seabirds, tur­tles and sharks, with species be­ing lost at a rate of around three times higher than dur­ing the Ceno­zoic Era — the ge­o­log­i­cal pe­riod to which the Pliocene be­longs.

Newspapers in English

Newspapers from Iran

© PressReader. All rights reserved.