Monday, July 15, 2013

What do you get when you cross a turtle, a seahorse, and a beaked whale?

Turns out, you would get the newly-described turtle dubbed Ocepechelon bouyai. Hailing from the latest Cretaceous of Morocco, this turtle was far from out of place: at the time, North Africa was covered in a shallow sea that hosted a variety of strange marine reptiles, including sea snakes and mosasaurs, as well as other species of turtle. But nothing could even come close to the weirdness of Ocepechelon.

Dorsal (left) and ventral views of the holotype skull of Ocepechelon bouyai. From Bardet et. al, 2013.

All we know of the turtle thus far is its skull, but skulls are often the most revealing fossils, especially when they're as outlandish as that of Ocepechelon. Measuring 70cm long, it is clear that this turtle was a giant, definitely one of the largest to ever live. But what makes the skull particularly unique is its shape and, thus, its function: although it is very long, it tapers into a very slender and narrow mouth, the opening of which measures only 6cm in diameter.

Lateral view of the holotype skull of Ocepechelon. From Bardet et. al, 2013.

This pipe-like tube of a mouth is reminiscent of animals which aren't even slightly related to turtles, namely beaked whales*, pipefish and seahorses. All of these animals have tiny mouths when compared to the size of their heads, and all feed on tiny prey using suction as their primary hunting method. It would appear that, without any adaptations to pin down, grasp, or pierce prey items, Ocepechelon was also a suction-feeder, spending its time close to the surface of the open Cretaceous seas, sucking in jellies and cephalopods which lingered nearby.

*Also strangely similar to whales is the position of Ocepechelon's nostrils: they are located far back on the skull, as far as turtles go. This also suggests it spent more time at the surface of the water.

Ocepechelon bouyai, in the flesh. I... Uh, I don't really know... What to say. It's just a weird, weird creature.
We often think of turtles as relicts of a bygone era, unchanged by the ages, deserving of that oft-misunderstood title of "living fossils." However, over the course of their 250-million-year-old history, it is more than clear that turtles have evolved into an incredibly diverse group. Surely Ocepechelon is the tube-mouthed figurehead of turtle diversity.

References
Bardet, Nathalie, Nour-Eddine Jalil, France de Lapparent de Broin, Damien Germain, Olivier Lambert, and Mbarek Amaghzaz. 2013. “A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a Suction Feeding Apparatus Unique Among Tetrapods.” PLoS ONE 8 (7) (July 11): e63586. doi:10.1371/journal.pone.0063586.

For more on giant, weird turtles, see...

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