Friday mystery object #268 answer


Happy New Year! I hope everyone had a lovely festive period.

I gave you this distinctive specimen from the Grant Museum of Zoology to try your hand at identifying:

mystery268

Despite being distinctive, it raised some discussion about the identification, because there are few resources available for comparison.

Phil Cox was the first to get the right Family (at least in the comments – @MelanieGbones got it on Twitter) – the Chrysochloridae or Golden Moles. Then the discussion got a bit more involved as species were discussed and the possibility of the convergent Marsupial Moles was considered.

There are 21 species of Golden Mole, all of which occur in southern Africa, which could have made this a very difficult identification to species, if it wasn’t for the large size of the skull and the very characteristic large and vertically-posteriorly flaring zygomatic arch that continues round to near the back of the skullThis narrows it down to one of two species in the genus Crysospalax

The extent of this feature in this specimen, plus the shape of the palate, suggest to me that this particular specimen is from the Giant Golden Mole Chrysospalax trevelyani (Günther, 1875).

The Giant Golden Mole spends more time foraging above ground than the other Golden Moles. The reason for the weirdly enlarged zygomatic arch is not currently understood, but I wonder if it might play a role in improving transmission of sound, given the relationship with the bones around the ear.

This would make a degree of sense, since the Golden Moles have incredibly poor eyesight and lack external auditory pinna (earlobes), so the Giant Golden Mole may have utilised an osteological adaptation to improve their ability to listen out for predators and prey when foraging on the surface. Pure speculation, but perhaps worth looking in to?

Have a wonderful 2016 – may there be many more mystery objects to keep you occupied throughout the year!

5 thoughts on “Friday mystery object #268 answer

  1. 21 different species! Well that explains why I couldn’t find a single picture online of a golden mole skull that looked like this one.

    Thirding the thanks for your FMOs. They are always very entertaining, even if I can’t identify them.

    I hope 2016 will be a good year for you.

  2. Paolo, thank you for the answer… and for all the good things you have shown us through the year! And best wishes for 2016!

    Interesting speculation about the function of the “flange” on the zygomatic arch: from the photo, it certainly looks as if it has fairly good bone connection to the bulla. So maybe it is for underground hearing what the pinna is for aerial? A large surface on the side of the head that can receive vibrations from the soil, and then transmit them to the middle ear? In the course of trying to find out what the animal was, I found out that Golden Moles have the largest ear ossicles (relative to overall size) of any mammal, and one photo showed what certainly seemed like an anomalously large, bulbous, ossicle. Which certainly suggests that the Chrysochlorids are adapted for “hearing” vibrations in the soil rather than sound waves in air.

    Fascinating animal. (Though, when it comes to mammalian burrowers from the southern hemisphere, I find almost more fascinating the suggestion that the Australianone might not be a marsupial but rather a surviving Spalacotheriid related to Necrolestes!)

  3. Pingback: Friday mystery object #310 answer | Zygoma

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