While analyzing some xrays of Anolis cybotes for my thesis work, I came across a few specimens that appear to have small dark masses in their guts. The numbers are pretty low – in over 200 xrays, I can only detect these masses in a handful of individuals. My curiosity was piqued. At first glance, they look like they might be gastroliths. Gastroliths, or gizzard stones, are rocks that animals eat to aid in digestion. Basically, the rocks help manually grind the food into smaller bits in a special portion of the digestive track called the gizzard. We know that many archosaurs (crocodilians, dinosaurs [including birds], and pterosaurs) have gizzards. Dinosaur gastroliths are some of my favorite fossils because they are usually polished and quite beautiful. However, unless I’m mistaken, lepidosaurs (squamates and rhynchocephalians) don’t have gizzards and aren’t known to have gut stones. Does anyone have an idea about what this could be? It’s possible that these are just accidental ingestions of small pebbles. Anolis cybotes do often forage near or on the ground, so perhaps it’s not so far-fetched for them to pick up a little rocky debris.
Also, check out this image of a regenerated tail!