Friday mystery object #321

This week I thought I’d give you a break from the bones and offer up a fuzzball for some Friday fun:mystery321

Any idea what this (slightly dusty looking) critter from the collections might be?

It’s probably a bit too easy for some of you, so cryptic clues and subtly veiled hints would be appreciated in the comments section please. Have fun!

Friday mystery object #320 answer

Happy New Year everyone!

Last week I gave you this skull to identify from the collections of the Dead Zoo in Dublin :

King Vulture Sarcoramphus papa (Linnaeus, 1758)

I also included the label, since it offers an interesting taxonomic twist.20171228_163420.jpg

If there’s one principle that I hope I’ve managed to convey over the last eight and half years of doing the Friday mystery object, is that you should never fully trust the label.

For starters, the number NMINH:2006.12.1698 could be misleading, as it reflects the year the specimen was catalogued rather than the year it was acquired. To explain, the NMI uses a very sensible numbering system that starts with the collection (NMINH = National Museum of Ireland Natural History) the year of registration (usually the year of acquisition) which allows you to know which register to look in, followed by the lot number (a sequential number reflecting how many acquisitions have come in that year), followed by the individual object number (the sequential number of that individual item in a particular lot). This system can have additional numbers added if necessary, such as if a piece of an individual object is removed for sampling.

However, some older objects were not registered when they entered the collection and as such they get a number that reflects the year they were documented rather than the year they were acquired. In this case the specimen was registered in 2006, but purchased from an auction of the collections of van Lidth de Jeude who died in 1863, as Nigel (the Dead Zoo Keeper) helpfully pointed out in the comments.

If the specimen had been accessioned and numbered on entering the collection back in the 1860’s then issues with the name would be expected since taxonomy constantly changes and old names are often wrong, but because of the new label and the 2006 date, you’d generally expect the name to be more up-to-date. However, it appears that the information on an old label was directly transcribed without being updated.

This is relevant because the name Orogyps auricularis is what we call a junior synonym, which means it has been used to describe a species that already has an older valid name. When this happens the older name takes precedence. In this case, Orogyps auricularis is a name applied in 1867 by Degland and Gerbe to a species that had already been named Vultur tracheliotos  by J.R. Forster in 1796 and which is now placed in a different genus, giving the name Torgos tracheliotos (Forster, 1796) – where the parentheses around the author name indicate that the scientific name has changed from the original version that was published by Forster.

These taxonomic and documentation twists are however rendered redundant as soon as you realise that this specimen is from a totally different species. In fact it’s not really anything like Torgos tracheliotos the Lappet-faced Vulture:

lappet-faced_vulture.jpg

Lappet-faced vulture

In fact, the only real similarity lies in the tip of the beak, which is a functional feature for tearing meat and which is convergent between the Old World Vultures and the New World Vultures. The Lappet-faced Vulture is an African species, while the mystery object has the distinctive deflection of the bill in the nasal region that indicates it’s a species from the Americas. This discrepancy in region was noted by palfreyman1414 and Gerard van den Brink.

Once you focus on the New World Vultures it becomes quite easy to make an identification, since there are only seven species and at 121mm this specimen is the third largest species after the condors – something easy to check on Skullsite. So well done to everyone who recognised the skull as belonging to the King Vulture Sarcoramphus papa (Linnaeus, 1758), especially palfreyman1414 who got there first.

514px-sarcoramphus_papa_-national_zoo_-washington_-usa-8a

King Vulture by Eric Kilby, 2008

As you can see, not only was the taxonomy very out of date for this specimen, it was also completely wrong, because it was misidentified 150 years ago. This is why you should never fully trust labels – they will often be wrong and if you base research on misidentified specimens, that will be wrong too.

Another mystery specimen next week!

Friday mystery object #320

I hope everyone had a lovely Christmas break!

This week I have another specimen from the Dead Zoo to identify – this one has an identification already, but the taxonomy is rather archaic and I think that once you’ve investigated the modern version of the name, you’ll realise that it’s wrong.

20171228_131937-01-01.jpg20171228_132026-01.jpg

20171228_132058-01.jpg

Skull length = 121mm

20171228_163420.jpg

So, any idea what this name should actually be and, more importantly, what the identification actually is?

As always, you can put your thoughts, questions and suggestions in the comments box below – have fun!

Friday mystery object #319 answer

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

20171214_175153-01.jpeg

It seems that everyone recognised this as the skull of a gull straightaway – the scars from the salt-glands on the top of the head and the shape of the bill combined to make it a bit of a give-away.

However, working out which species of gull is a bit more tricky, since many are remarkably similar in morphology, making size an important factor for consideration (I’ve talked about this before).

Now size is always a somewhat tricky thing to use for identification, for a variety of reasons. One is that there may be an overlap in size between species, another is that there will often be sexual dimorphism within a species that means you can’t just compare the length against another specimen of a species without considering sex. Then of course there’s age – if it’s not fully grown, it’s going to be smaller. Of course you also have to consider whether the bill sheath is present or absent, as this will add a few millimetres.

On top of all these issues, there’s the problem of how you actually measure the length in the first place. This is something I’ve researched in the past (link to pdf) and it’s a more significant problem than you might think. For example, when looking at the image I originally provided for the mystery object, it looks like the skull measures around 125mm, but if I chop the scale bar from the image, reduce the transparency to 50% and lay it directly over the centreline of the image of the specimen, it turns out to be around 128mm.

mystery319

Length is apparently 128mm

Add to this the fact that in the original image you can see a shadow under the scale bar, it becomes clear that the scale is somewhat elevated. This is because I raise the scale to be near the vertical midline of the specimen, to help keep everything in focus and limit the effect of parallax error. Normally this is good, because it allows a more accurate estimation of the length of a 3D specimen with a longest axis near the vertical midline, but in this case the longest part of the specimen is actually at the lowest part of the skull, so the elevated scale will make it look slightly shorter than it really is (due to the parallax error I was hoping to avoid…). This means that the specimen is probably closer to 129mm or 130mm in length.

With this in mind, the discussion about the lengths of various gull skulls between Wouter van Gestle (of Skullsite fame), Ric, Tim Dixon, Richard Lawrence, Gerard van den Brink and jennifermacaire needs to be reconsidered.

Richard Lawrence reported skull lengths for a variety of gulls as follows:

6x GBBG: 129 to 141 mm
2x LBBG: 117 mm
6x HG: 111 to 117mm
9x YLG: 111 to 126 mm ( larger with beak sheath though so would be smaller without).

So factoring in a length of 129-130mm for the mystery object it seems to fit well into the range for the Great Black-backed Gull Larus marinus Linnaeus, 1758. So well done to everyone who went for GBBG – this does seem most likely to be a skull from the largest gull species.

Great Black-backed Gull by Andreas Trepte, 2010

Great Black-backed Gull by Andreas Trepte, 2010

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).

20171207_180748.jpg

Hope you enjoyed the challenge!