Circles on Sand Dollar

[Top Trilo]

I’ve had this mepygurus marmonti sand dollar from the Jurassic of Madagascar for years now and when I was looking at it I noticed these small circles on the bottom. Are these on every sand dollar, it appears to be a part of it so my guess was some sort of way for tiny legs to attach but it’s just a guess the sand dollar is 7.5 centimeters and each dot is just under 1 millimeter

[Rockwood]

Sand dollars are just flat echinoids. Its spines articulated on the bumps.

[FossilsandScience]

Agreed! I have a few fossilized sand dollars and they have the same bumps. It's just apart of the anatomy of the echinoid. You can see the same structure on modern sand dollars as well.

[grandpa]

See the following:  https://www.biologydiscussion.com/zoology/practicals/structure-of-sand-dollar-echinarachinus-with-diagram-zoology/60727

[Coco]

Please show us a complete view of the other side of the sea urchin.

 

Coco

[Top Trilo]

5 hours ago, Coco said:

 

Please show us a complete view of the other side of the sea urchin.

 

 

[caterpillar]

I could be wrong but Mepygurus is not considered as sand dollar. Rather sea urchins of the order Clypeasteroides

 

 

[jpc]

44 minutes ago, caterpillar said:

I could be wrong but Mepygurus is not considered as sand dollar. Rather sea urchins of the order Clypeasteroides

 

 

yup

[Top Trilo]

4 hours ago, caterpillar said:

I could be wrong but Mepygurus is not considered as sand dollar. Rather sea urchins of the order Clypeasteroides

 

 

Thank you for the correction