Friday mystery object #318 answer


Last week I gave you this bird skull from the Dead Zoo in Dublin to have a go at identifying:

20171129_162916.jpg

It’s a fairly distinctive looking specimen with that massive bill, immediately narrowing down the possible families to two likely contenders – the Toucans (Ramphastidae) or the Hornbills (Bucerotidae).

On closer examination it lacks the serrated bill margins and remarkably long medial (in this case that means ‘towards the midline of the skull’) process of the quadrate bone (a part of the jaw in birds that I’ve blogged about before) that you see in Toucans. So, it’s a Hornbill – as everyone correctly spotted in the comments – but then we have the question of the species.

There are around 60 Hornbill species, with most of them sporting quite distinctive casques which make them quite identifiable (I’ve blogged about several before):

Ceratogymna atrata skull

Black Hornbill Ceratogymna atrata

mystery240

Great Hornbill Buceros bicornis

Bucorvus abyssinicus (Boddaert, 1783) sectioned skull

Northern Ground-hornbill Bucorvus abyssinicus

However, this specimen seems to be lacking a casque. This could be due to a few reasons. There are some casqueless species, such as the Sri Lanka Grey Hornbill, it could be a young female adult from a small casqued species with sexual dimorphism in casque development, or it could be a young juvenile from a species that has a small casque that grows as the animal matures.

Assuming it’s one of these, it’s easy to check the few casqueless species by looking at the overall bill shape, the position of the nares (nostrils) relative to the orbits (eye sockets) and checking the structure of the jugal and quadratojugal (the thin bones on the side of the skull under the orbit) – this last only if you can find a reliable skull image for comparison.

Using Skullsite and images on the internet it’s time-consuming, but straightforward to rule out a lot of possibilities, since most Hornbills have a fairly robust jugal/quadratojugal and nares located much further away from the orbit than you see in the mystery specimen. In fact the only Hornbills with a similar nares/orbit position and gracile (skinny) jugal/quadratojugal and in the right size range (that I was able to find) were in the genus Rhyticeros L. Reichenbach, 1849.

Unfortunately I’ve not found good skull images of juveniles for all of the species to make a final comparison and you can’t just compare the skull of a juvenile with an adult and expect to see the same configuration and development of features, as there’s still growth to happen (something else I’ve talked about before).

So based on the information it looks like jennifermacaire was the closest with her suggestion of Wreathed Hornbill, although I’m leaning slightly more towards the Papuan Hornbill Rhyticeros plicatus (J.R.Forster, 1781).

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Hope you enjoyed the challenge!

4 thoughts on “Friday mystery object #318 answer

  1. Thank you for this. I felt an utter idiot for thinking Hornbill as soon as I saw it, and had no chance at species identification. But am feeling well chuffed that my suspicion, adolescent/female might be correct.

    And yes, congratulations to Jennifer for being so good at this stuff. And so many other things. I hates her, I hates her forever! 😉

    • Thanks Wouter, your input is always appreciated! I noticed that skullsite has been revamped – it certainly looks nice, although I think I may have to go through all my links to your pages on my blog and correct them once you’ve finished with the upgrade. It’s a great resource!

  2. Sorry about the links, my cousin Jan made a new version of the skullsite because Google kept bitching about the outdated software on our 15 year old website which did not match very well with their searching tools. It still needs a lot of fine tuning, and we’ll also need to replace a number of pictures of the most recent photo session, which are of insufficient quality.
    A nice new feature Jan added is a blog function, which I intend to use for showing interesting details about skulls and for preparation tutorials, as soon as I’ve learned how to work with it properly (I’m in no way a computer wizzard)

    Wouter

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