Nonstandard scale bars for photographing turtles: an international collaboration

October 10, 2020

Henry and Cheeto

This past summer, I got into a Facebook conversation with Steve Kary about turtles and tortoises. He was posting photos of Henry, his Russian tortoise (Agrionemys horsfieldii, formerly Testudo horsfieldii), and I was struck by how not-big Henry is. I am not a tortoise expert and what little direct experience I have is with desert tortoises and the big-to-giant species like Sulcatas and the Galapagos and Aldabra giant tortoises. I know the popular pet species like Greek and Russian tortoises and the small African species much less well. Offhand, Henry looked about as big as our three-toed box turtle, Easty (Terrapene carolina triunguis), so I asked Steve if he’d mind posting a photo with a scale bar. This is what Steve sent:

Clockwise from the top we have an ink pen, a 75-million-year-old caudal centrum of a crocodile, a bottle cap, a Nebulon-B frigate from Star Wars Armada, a screwdriver, a nail clipper, a small bottle of Tylenol, and a coin. Oh, and a DVD of an awesome movie.

Naturally, I felt compelled to respond in kind:

Here we have Easty with a similarly eclectic selection of small objects. Again from the top: a rat skull in a plastic bottle, a bottle cap, a d20, a small Altoids tin, an ink pen, a nail clipper, a small metal toy from China, and a nickel. Oh, and a DVD of an awesome movie. Yes, Easty is investigating the d20 as a possible food item. She tried to bite it, but since it’s bigger in diameter than her head, all she achieved was to send it shooting across the floor when her beak slammed shut on one of the vertices.

Here I’ve scaled the two photos to the same size. Henry is definitely wider than Easty, and he has a bigger head and chunkier-looking limbs. In fact, having spent most of my life around box turtles, that’s always my thought when I see a small tortoise: “How do they get so much critter into such a small shell?” It may have to do with space packing. Box turtles have to be able to pull everything in all the way so they can raise the drawbridge, as it were, and use their hinged plastron to close everything up tight (hence the name). Most tortoises lack hinged shells and use the tough scales on their legs and feet to complete the defensive perimeter between carapace and plastron. The limbs don’t have to pull all the way in, so they can be a little bigger.

Anyway, if you’d like to join in this pursuit–photographing turtles with collections of random objects–let me know in the comments. You can post your photos there, or I can add them to the body of the post.

Other turtle posts:

5 Responses to “Nonstandard scale bars for photographing turtles: an international collaboration”

  1. llewelly Says:

    pet turtles: adorable, but, you know, they usually end up needing a clause in your will, because they are likely to outlive you, even if you are in good health and not particularly old.

  2. Matt Wedel Says:

    Yep. That’s why Easty’s tank is in my son’s room, and he understands that taking care of her may be a lifelong responsibility for him, and hopefully for his children in turn.

  3. llewelly Says:

    oh, and also an interesting question – would sauropod vertebrae, especially neck vertebrae, with all their pneumatic spaces, be vulnerable to chomping by scavenging turtles?

  4. llewelly Says:

    Wise decision on passing the stewardship of the turtle to your son.

    I ought to have thought about how rude my first comment might seem before posting.

  5. Matt Wedel Says:

    Probably! Easty likes munching on rat skulls, specifically by breaking off bits of the thin bone from the edge of the braincase. I’d think a big turtle could break off chunks of a sauropod vertebra similarly. We’re unlikely to ever get direct evidence, though, first because a turtle levering off pieces that way would be unlikely to leave diagnostic traces, and also because broken sauropod vertebrae exposed on the surface were probably even less likely to be preserved than ones buried intact and with some flesh protecting them.

    But that’s okay, animals engage in all kinds of behaviors that don’t leave diagnostic fossilizable traces, and it’s not much of a stretch to infer that if modern turtles like chomping on bones, so did extinct ones. In fact, it’s far less reasonable to posit that Mesozoic turtles did not munch on sauropod vertebrae when the opportunity arose–as it frequently must have, since sauropods and turtles were both mega-abundant in most ecosystems for most of the Mesozoic.


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