Friday mystery object #428

This week I’m delighted to have a guest mystery object for you, presented by Rohan Long, Curator of the Harry Brookes Allen Museum of Anatomy & Pathology at the University of Melbourne (who is on Twitter as @zoologyrohan) and photographed beautifully by his colleague Gavan Mitchell:

This is a skull from the Harry Brookes Allen Museum of Anatomy and Pathology at the University of Melbourne. Although the focus of our museum is on human anatomy, we have a significant comparative anatomy collection, which comprises hundreds of specimens of vertebrate animals – skeletal material, skulls, and potted specimens. Occasionally, I’ve encountered animal specimens that are very difficult to definitively ID, and this partial skull is one of them.

Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022

Our comparative anatomy collections date from the earliest 20th century and are predominantly native Australian mammals and domestic animal species. However, the academics at the University have always had international networks, and there are species represented in the collection from all over the world. Many have been prepared in a lab for class specimens, many have been collected in the field. The latter are assumed to have been associated with Frederic Wood Jones, a British anatomist with a fondness for comparative anatomy and island collecting trips who was head of our Anatomy Department from 1930 to 1937.

Do you have any ideas what this portion of skull might be from? I don’t think we need cryptic answers for this one. Rohan will be keeping a close eye on the comments, so do feel free to ask questions.

I hope you have fun with it!

21 thoughts on “Friday mystery object #428

  1. I almost give up. The general shape of the brain case remind me of shrews. But they don’t have zygomatic archs. I looked at shrews-like rodents but it doesn’t fit as rodents doesn’t have this very special zygomatic process that is extending towards the occipital, and quite high on the lateral view. I looked at marsupial like oppossum and marsupial rats but marsupials tend to have a large face. Back to marsupials, the zygomatic process is vaguely similar to macropodids although is doesn’t go up to the interparietal bone. Can’t find anything closer at the moment

  2. I’m with Palfreyman: mammal, and I’m not confident of anything more.
    Some portion of the front of the snout is missing: at a guess, the intact skull would have been maybe 7 centimeters long. (So, not a shrew, even if Remi hadn’t pointed out that shrews don’t have zygomatic arches.)
    As to zygomatic arches: the right is missing entirely, and the left is partial. Maybe the break in the left is at the site of the suture between the (back) part of the zygomatic. ar. coming from the temporal and the front part that connects more or less to the maxilla? I think the location of this suture differs somewhat from mammal to mammal, so maybe this might be useful?
    Looks as if it had fairly large eyes: probably not nocturnal or fossorial.
    Forced to guess, I’d go for a smallish Carnivoran. Or maybe some sort of marsupial: there are a lot of kinds to choose from!

  3. A lot of discussion has been playing out on Twitter. Yes, mammal; yes, probably marsupial; yes, probably juvenile. It looks like it’s got grains of sand or sediment adhering to it, which suggests it was found in the field and adds to the suggestion that it is an Australian native. Robin Beck suggests a phalangerid. Jillian Garvey suggests macropod. I’m going to do some comparisons today.

  4. I like Jennifer Macaire’s pangolin suggestion! Not sure it’s right, but I like it. Pangolins have an incomplete zygomatic arch: front part doesn’t meet the back part; there’s a gap more or less below the orbit. Which fits with one puzzling thing about Rohan Long’s specimen: what I took to be the broken stub of the left z.a. looks as if it has a smooth and rounded end: which would be strange if it were actually a broken end, but is consistent with it being the end of the rear partial z.a. of a pangolin. … Rohan, could you tell us whether the end of that stub looks like a break or a natural profile?

  5. Whilst broken, the zygomatic arch has the distinct shape of marsupials. It is very likely from a young animal, given the unfused nature of the sutures, which will explain why everything from the frontal bone forwards (and a fair amount backwards too…) is missing. As a sweeping generalisation, marsupials tend to have a rostrum that is about a third the length of the whole skull so we are looking at a skull with a total length of about 8cm plus (very about). Looking at likely candidate marsupials of the right size, and comparing the angle the Zygomatic arch makes with the rest of the skull in the ventral view, I suspect that this is most likely a Common Brushtail Possum, Trichosurus vulpecula. But I don’t have pictures or specimens to compare with the other, closely related species (or the time to look them up on the internet).

  6. What I thought was a massive zygomatic process appears to be, with a closer look, a large inflated middle ear. It is the case in bandicoots and bilbies. The larger one would be Magotis lagotis. But it was mystery object #269 and the morphology is not quite the same.

  7. I changed my mind. Let’s say it is not from Australia. It has a large middle ear area and the frontal and parietal are very straight. It might be a young specimen, still the skull is not very rounded. Something reminds me of some Xenarthra species. Might be Chaetophractus villosus, Calyptophractus retusus or a species of the Dasypus genus. All armadillos but I couldn’t find good pictures of all the species

  8. My mother brought me here, love games ! I was drawn towards the wallaby family at first as the hint for the explorer points towards Oceania… But then I stumbled upon the idea of the porcupine family. In any case, I was thinking a juvenile of any of these two species might do as much of the skull seems to be missing. Can’t wait for the answer to this !

  9. It’s too big to be A. pygmaeus (whose total head-and-body length is about what is estimated for this skull). But there are lots of other possum species.

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