Things to Make and Do, part 3c (out of order): Wallaby skull update

July 2, 2010

It’s been a while since we last caught up with my wallaby, which I am suddenly going to decide to call Logan.  When we saw him last, I was concentrating on his feet, although the initial post does also include a photo of the partially prepped skull in right lateral view.

Back in the day — and this was eight months ago, remember — I wrote “I think that [the skull] would benefit from a third simmer-and-pick session before I put [it] out somewhere for invertebrates to deal with.”  That’s what I did, but the results were not encouraging.  I put the skull (and first three cervical vertebrae, which I’d prepared with it) into a plastic box with air-holes and left it in the woodshed — an approach that’s worked well for Darren Naish many times, and has also served me well regarding that baby rabbit that I keep meaning to show you.  But when I went to retrieve Logan’s skull a few days ago, I found that it had gone mouldy!

There should be a picture of Mouldy Logan here, but I stupidly forgot to take one.  So instead here is the fifth cervical vertebra of the Erketu ellisoni holotype IGM 100/1803, with its bizarrely sigmoid centrum, from Ksepka and Norell (2006: fig. 5).

Well, anyway — ouch!  I didn’t even know bone could go mouldy.  And what I didn’t appreciate at that point is that the mould had also made the bone fragile, brittle — crumbly, even.  Not good at all.  To get rid of the mould, I simmered the skull and vertebrae gently for an hour or so, then cleaned it up with a toothbrush and some washing-up liquid (or “dish soap”, as you wacky colonials apparently call it).  It was at this point that the crumbliness became apparent, of course: the respiratory turbinates were completely gone, and the nasals, having come away from the rest of the skull, broke into three pieces each.  Also, the dorsal margins of the maxillae and premaxillae, where they abut the nasals, started to crumble.  Finally, the bone directly above the foramen magnum whose name I can never remember came away, and a small chunk came away from the bone that that abuts it to the left.  It wasn’t pretty.

Anyway, I cleaned the bones as carefully as I could, then let them soak overnight in dilute hydrogen peroxide before carefully rinsing them and leaving them to dry.  The result still looks good, but it’s disturbingly fragile.  Here it is:

Subadult male Bennett's Wallaby, "Logan": mandible, cranium and fragmented nasals in dorsal view; cervical vertebra 3, axis, odontoid and atlas (top to bottom).

I also prepared a red-cyan anaglyph of these bones, from an aspect slightly anterodorsal of dorsal.  Those of you who have not yet obtained red-cyan glasses for viewing these, get your arses in gear — they are really informative.

Finally, here is a close-up of the crumbling nasal region, and the remaining pieces of the nasal bones.  You can see that the bone has lost integrity.

(Those two fragments at the bottom of the picture are, I think, from the dorsal border of the right maxilla.)

And now, gentle reader, I come to you for advice.  What can I do to strengthen poor Logan’s skull?  I guess there must be some kind of commercially available compound that I can soak it in or paint on to it to consolidate the friable bone?  Help me out, please.  I don’t want to lose Logan.

And by the way …

I realise that SV-POW! has been heavy on these extant-animal-skeleton posts recently, and correspondingly light on actual, you know, sauropod vertebrae.  I hope no-one feels too short-changed: I’ve been assuming that among that constituency that appreciates sauropod vertebrae, there’s a corresponding liking for ostrich and wallaby skulls.  Do let me know if it ain’t so (or indeed if it is).

11 Responses to “Things to Make and Do, part 3c (out of order): Wallaby skull update”

  1. BJN Says:

    A thin solution of cynaoacrylate would be my first thought to use as a consolidant. It leaves less surface coating than other consolidants I use. You can glue broken fragments with cyanoacrylate gel.

    A Vinac (PVA in acetone) solution would be my second thought, but it usually leaves more of a surface film if you want to avoid the “varnished” look. If you apply Vinac only to the more porous and weak areas and avoid smooth bone surfaces you can avoid adding a sheen to your specimen.

    There’s also PEG (polyethylene glycol. It’s used to stabilize weakened wood and I’d suppose that it would also work with porous bone. I don’t have any experience with PEG saturation. We use it as a temporary water soluble wax support for thin fossilized structures.

  2. Mike Taylor Says:

    Cyanoacrylate … that’s superglue, right? But I can’t imagine how I’d make ip[ a thin solution of it without it setting all over the container, the mixer, and of course the brush that I’d use to apply it. Is there a special technique? I’m a total novice here.

  3. Your wallaby went overcooked. The same happened to a nice tamandua skeleton I was preparing once. Turbinals got lost and many postcranials suffered too much as well. I guess the main cause is bone collagen denaturation because of overcooking.

    If you have access to Paraloyd B-72 it will work very well, first (and very thin, at low concentration in acetone or ethanol) as a consolidant of every piece, and then (in higher concentrations, more viscous) as a glue for different pieces. you can even use paraloid beams to strenghten some structures (e. g. mandibular symphysis).

  4. Mike Taylor Says:

    Thanks Jorge, I’ll look into that. I don’t think it was the cooking itself that caused the problems, though — that was only in water and maybe a little detergent, and I’ve cooked plenty of other skulls and bones in a similar way without seeing mould.

    By the way, I went to your blog earlier today (because the WordPress dashboard showed me that you’d linked here) and I read Google’s Spanish->English translations. Great stuff — that’s an amazing collection you have there. What are the middle two skulls on the bottom row of your cabinet? Some kind of fish and a bit carnivoran?

  5. Oh yes! I´m glad you liked the stuff in my blog. The skulls you ask are a Jaguar (Panthera onca) and a Crucifix catfish (Arius sp.). This one took a long time of reassembling… I think fish skulls are a real challenge for the skull colector.

  6. Mike Taylor Says:

    How on earth did you manage to get hold of a panther?! Awesome! I thought it was a big cat when I saw it, but couldn’t make myself believe you’d scored one.

  7. I got it in a field trip in the Putumayo and Caquetá rivers, it was just among the litter in the backyard of some cattle rancher.

  8. Bruce J. Mohn Says:

    Hi Mike:

    The Paleobond folks make a consolidant that should do the trick.

    I’ve also used very dilute white glue or dilute lacquer.


  9. Nathan Myers Says:

    I feel compelled to add that that E. ellisoni must be the most beautiful vertebra I have seen featured on this site since its inception. My flying car will look exactly like that when it’s done.

  10. […] from waaay back in late 2009. Here’s how I butchered him, and some detail on his feet, and how his skull  turned out. Back then I prepped out a forelimb and a hindlimb, the skull and first few cervicals, and the tail […]

  11. […] the sheep skull ten days ago, here is Logan the wallaby in all his […]

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