On Friday I gave you this specimen to identify:
Unsurprisingly you all recognised it as a tortoise carapace. The species was a bit more difficult though as tortoises can display quite a lot of variation in their colour and shell structure within a species.
There were various good suggestions, but in the comments only Barbara Powell made reference to what Colin McCarthy and myself thought this was from, although Maggie J Watson also identified it in a tweet.
When we saw the specimen we thought that it was probably a Yellow-footed Tortoise Chelonoidis denticulata (Linnaeus, 1766) based on the lack of a nuchal scute (the one that normally covers the neck) and the overall scute configuration with the flat sides, the dark scutes with lighter inner part and the serrated appearance of the scutes on the margins (which inspired the scientific name of the species).
The serrated margins are mainly seen in younger specimens and get lost in the adults and the heavy concentric growth rings on each scute of this specimen suggested that it was a fairly young individual when it died, as did the size. The adults of this species can reach nearly a metre long, making them one of the largest tortoise species alive. Unfortunately they seldom get to reach that size due to pressure from the pet trade and their use as food in their native South America.
However, on closer examination it seems that Barbara Powell (and microecos) may have been on the right track with the suggestion of the Texas Tortoise Gopherus berlandieri Agassiz, 1857.
It turns out that the denticulated pattern that gives the Yellow-footed Tortoise its name is not as a result of serrated overlap of the scutes, but little serrations on the individual scutes of the margin (unfortunately I can’t find a photo that has sharing rights, but here’s a link to one).
Given the flaring pattern of the scutes over the hind legs and the various other similarities, I think I may have to look at the specimen again with a different identification in mind. Thanks Barbara and microecos!
I finally got one right! I didn’t comment, as others had reached the same conclusion, but I was able to deduce that answer without looking at the clues for a change. : )