Sharks survived asteroid attack that obliterated dinosaurs from Earth: Study

In a major discovery, a study conducted by researchers at Sweden's Uppal University proved that sharks survived an asteroid attack that wiped off dinosaurs from the face of the earth. The observation was made after a tooth morphology was carried out on a shark fossil from the Cretaceous Period. According to the study, sharks are "iconic marine predators" that have survived innumerable mass extinctions over geologic time.

Sharks survived several mass extinctions

The study by Mohammed Bazzi, which is published in PLOS Biology explored the contentions via a comprehensive assessment of shark dental morphology across the end-Cretaceous mass extinction. The researchers analyzed over 1200 fossil shark teeth from nine different selachimorph clades spanning over a period of 27 million years i.e from the Campanian to the Maastrichitian ages and the early Paleocene era. This geological period covered is called the  Cretaceous–Paleogene (K-Pg) boundary that ended the age of the dinosaurs.

The studies suggested that apex marine predators displayed disproportionate depletion before the massive asteroid attack, however, the clan quickly recovered due to their ability to repair DNA damage. "Our principal discovery of overall static disparity indicates that selachimorphs experienced no demonstrable pre extinction decline or eco-morphological turnover as postulated for other vertebrate groups," the study reported. The survivors of the explosion were mainly sharks with triangular-blade-like teeth. Presumably, these apex predators survived due to the selected elimination of their predators, the researchers suspected.

The asteroid explosion resulted in 'selective extinction' of dinosaurs

Sharks are also called "living fossils" due to their existence on the earth for over a 400million years, the study mentioned. As the study discovered, the shark population survived the massive explosion by the asteroid that obliterated the species of the Mesozoic era. The explosion resulted in the "selective extinction" of dominant Cretaceous anacoracids.

The selective extinction also enabled the thriving of other marine and vertebrate species. "From a post extinction perspective, while anacoracids disappeared, other lamniform and carcharhiniform groups ecologically proliferated during the Paleocene. Most notably, this affected odontaspidids, triakids, and scyliorhinids, which are characterized by apicobasally tall, laterally cusped teeth," Henning Blom, a co-author of the study mentioned in the report.

What happened during the asteroid explosion?

The asteroid hit being discussed occurred some 65 million years in today's Mexico. The period was dominated by humongous pre-historic creatures like reptiles, dinosaurs, and mammoths. The 10-km wide asteroid explosion annihilated about 75 per cent of life on earth, including non-avian dinosaurs and gigantic marine reptiles.

With inputs from @PlosBiology

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