A very strange fossil stingray from Italy

[Halichoeres]

Meet Lessianibatis aenigmatica, a newly described stingray from the Eocene of Italy. Its vertebrae are fused all the way to the pelvic girdle, and it has a tiny goofy little tail.

Here's the fossil:


And a comparison drawing showing how weird its morphology is to other rays:

(g is Lessianibatis; h, i, and k are other fossil taxa; the rest are extant rays)

Open access in Nature Scientific Reports: https://www.nature.com/articles/s41598-019-50544-y

[Faelrin]

Huh that is pretty weird. I wonder how it got around without much of a tail.

Edit: I've seen stingray's called sea pancakes before, and this one certainly lives up to that name from the looks of it.

[Ravonium]

Huh that is pretty weird. I wonder how it got around without much of a tail.

Stingrays move using their pectoral fins, so I doubt its movement would have been particularly unique.


What I'm curious to know about are the evolutionary pressures that would've led to this shape to develop in the first place.

[Halichoeres]

The synarcuals (fused vertebrae) probably make it more rigid and stable during swimming. It's true that they don't use the tail much in swimming, but a rigid trunk could reduce pitch during undulating swimming.

As for the tail, I am really not sure. It could be as simple as energy savings. Or it could be as complicated as selection in the presence of a predator that hunts using electric current. A shorter tail reduces your dipole, so a shock has a smaller chance of stunning or killing you. (This is 100% wild speculation, of course.)

[stargatedalek]

The synarcuals (fused vertebrae) probably make it more rigid and stable during swimming. It's true that they don't use the tail much in swimming, but a rigid trunk could reduce pitch during undulating swimming.

As for the tail, I am really not sure. It could be as simple as energy savings. Or it could be as complicated as selection in the presence of a predator that hunts using electric current. A shorter tail reduces your dipole, so a shock has a smaller chance of stunning or killing you. (This is 100% wild speculation, of course.)

There is a pod of orca that hunt rays by grabbing their tails. Perhaps a predator was doing something similar.

[Halichoeres]

The synarcuals (fused vertebrae) probably make it more rigid and stable during swimming. It's true that they don't use the tail much in swimming, but a rigid trunk could reduce pitch during undulating swimming.

As for the tail, I am really not sure. It could be as simple as energy savings. Or it could be as complicated as selection in the presence of a predator that hunts using electric current. A shorter tail reduces your dipole, so a shock has a smaller chance of stunning or killing you. (This is 100% wild speculation, of course.)

There is a pod of orca that hunt rays by grabbing their tails. Perhaps a predator was doing something similar.

Absolutely a possibility! I'd love to know who was trying to eat these guys.

[brontosauruschuck]

Predators would assume they were a flying saucer that crashed into the sea and not mess with them for fear that little green men would come out.

[Halichoeres]

Predators would assume they were a flying saucer that crashed into the sea and not mess with them for fear that little green men would come out.

Solid strategy.