Before trees even existed, sharks were already patrolling the oceans
They have survived five mass extinctions and outlasted the rise of land plants. While we often call them 'living fossils,' the true history of sharks is a 450-million-year saga of radical evolution, shifting shapes, and much-debated ancestral origins.
The shark lineage is staggeringly ancient, with fossil evidence of shark-like scales dating back 450 million years to the Late Ordovician Period. However, the identity of these earliest organisms remains a subject of scientific debate. Curator Emma Bernard notes that because no teeth have been found with these specific scales, scientists are still questioning whether they represent true sharks or merely shark-like animals that may have been toothless.
The evolutionary trajectory of cartilaginous fishes—a group including sharks, rays, skates, and chimaeras—is marked by significant divergence. Molecular and DNA evidence suggests that chimaeras may have split from the shark lineage approximately 420 million years ago, a period that coincided with the first plants invading terrestrial environments. While modern chimaeras are often found in the deep ocean, their ancestors shared a common evolutionary starting point with sharks.
Finding the 'first' recognizable shark is equally complex. Around 410 million years ago, during the Early Devonian, the fish Doliodus problematicus possessed shark-like teeth, though it emerged from the acanthodian group, characterized by diamond-shaped scales and spines. By 380 million years ago, genera like Antarctilamna and Cladoselache appeared. Cladoselache possessed the torpedo-shaped bodies and dorsal fins we associate with modern predators, yet some researchers suggest it might actually belong to the chimaera branch.
The true era of shark dominance arrived during the Carboniferous Period, starting 359 million years ago. Following a Devonian extinction event that wiped out at least 75% of all Earth's species, the vacuum left in the oceans allowed sharks to diversify into a vast array of forms, cementing their role as the ocean's enduring apex predators.
Source: How old are sharks? | A closer look at shark history
