Fear of the Deep Sea: How Evolution Saved Us from Deep Sea Crocodiles
Many people experience thalassophobia, or fear of the oceans, and it’s not hard to understand why. The ocean is a vast, mysterious, and often hostile environment, home to some of the largest and strangest creatures on Earth. But here’s a comforting thought: evolution spared us from the existence of deep sea crocodiles.
During the middle Jurassic and early Cretaceous eras, crocodilian ancestors known as thallatosuchians roamed the oceans. These creatures, belonging to groups like teleosauridae and metriorhynchidae, had adapted to marine life with streamlined bodies and flipper-like appendages. However, they never reached the depths that dolphins and whales routinely do. Recent research using computed tomography scans of thallatosuchian skulls suggests that their snouts were not equipped to handle the pressure of deep dives.
A study published in the journal Royal Society Open Science reveals that thallatosuchians evolved smaller braincase sinuses for diving and hunting, similar to dolphins and whales. However, their snout sinuses, especially in metriorhynchids, expanded as they ventured into deeper waters.
According to lead author Mark Young, the larger snout sinuses of metriorhynchids would have caused discomfort and potential damage at greater depths due to the increasing pressure. Unlike modern cetaceans, these ancient crocodiles lacked the ability to equalize the pressure within their skulls.
While thallatosuchians could not dive as deep as cetaceans, their limitations served a purpose. These ancient marine reptiles likely used their sinuses to regulate salt levels, similar to how modern marine iguanas expel excess salt through sneezing. The intricate sinus system of metriorhynchids suggests they had evolved a unique way to handle salt in their bodies.
Mark Young speculates that if thallatosuchians had survived longer, they might have further adapted to resemble whales and dolphins. However, their extinction during the Cretaceous period sealed their fate. We can now rest assured that deep sea crocodiles are not a concern for those with thalassophobia.
