QuickCheck: Are sharks older than the North Star?

POLARIS has long helped mariners find their way through our planet's seas and oceans by pointing the way north. You would think that something as majestic as an actual star would be particularly ancient. While by human standards the North Star is old, is it true that one of Earth's most feared predators, the shark, is actually older? Verdict: TRUE Sharks have been swimming in Earth's oceans for more than hundreds of million years, making them one of the oldest species on the planet.

The first shark-like fossils found are dermal denticles (skin scales), discovered in the Harding Sandstone of Colorado and in the Carmichael Sandstone of the Stokes Formation in Australia. These scales were dated to the Ordovician period, making them about 450 million years old. It is not until the Age of Fishes in the Devonian (starting 419 million years ago) that fossil shark teeth and complete shark fossils appear.



The world's oldest intact shark fossil is of a specimen called Doliodus problematicus found in the Campbellton Formation in New Brunswick, Canada. Polaris, the North Star, on the other hand is a relatively young star in the constellation of Ursa Minor. It is a yellow supergiant star with a diameter that is roughly 46 times that of our Sun and is relatively young in cosmic terms.

It became the North Star due to the precession (wobble) of the Earth's axis, which is a gradual shift that alters where the planet's North Pole points to. The star is estimated to be around 70 million years old which makes it roughly 300 million years younger than the first sharks. Scientists determine the age of stars by studying their properties, including spin, brightness changes, and by analyzing star clusters using models of stellar evolution, and by studying the vibrations on the surface of stars.

References: 1. https://www.nhm.

ac.uk/discover/shark-evolution-a-450-million-year-timeline.html 2.

https://www.fossilguy.com/gallery/vert/fish-shark/shark_evolution/shark_evolution.

htm 3. https://www.britannica.

com/topic/The-North-Star-American-newspaper.