There’s been a lot out this week about the discovery of a proto-turtle with a plastron (front plate) but no shell. Very cool!
Turtles are extremely interesting in an evolutionary sense because it is completely not clear how their shells developed. This new discovery begins to answer one part of that question — OK, it seems the front bit of the shell began to develop, and then later on the dorsal part joined it.
But it still leaves unanswered the main question of turtle evolution, which is: how on earth did the turtle’s hips and shoulders end up inside its ribcage? Think about it for a minute. What is the interim stage there? And why would it ever have been evolutionarily successful given the wide selection of large predators back when turtles were developing?
This isn’t a criticism of the interpretation of the new fossil turtle find at all, just a general statement about the extreme mysteriousness of turtles. Who have been the same for 150+ million years now (vs. our 200,000-ish). Whatever they’ve got, it works. But we may never know how they got there.
And, you can make me wonder about turtles.