Friday mystery object #295

For many of you, last week’s mystery object answer was a little disappointing, since I was unable to pin down what the specimen was. Normally with birds it’s not so difficult, because of useful resources like skullsite.com, but the fact is that some bird groups are still quite poorly represented in collections and finding comparative material is difficult, especially online.

The most frustrating thing about last week’s object is that it did once have a label, but at some point in the past it was lost, so the only information with the specimen now is this:

mystery295_label

However, this label does offer a glimmer of hope, since it identifies the specimen as being from a particular collection and that can often mean there will be more information somewhere.

As it turns out, this specimen is one of several that were purchased in 1867 from an auction of the collections of Dutch anatomist Theodoor Gerard van Lidth de Jeude. This is helpful because auction catalogues can contain information like the species names of the specimens being sold. It is particularly helpful when you have the original catalogue with annotations about the specimens bought by your institution.

Fortunately, at the Dead Zoo we have the auction catalogues. Unfortunately we bought quite a lot of stuff, so working out which of the specimens our mystery object represents is still quite a lot of work.

However, if other specimens from the auction have their names and numbers, it should be easier to narrow down the ones that lost their labels. It also can also help to have an identification of the specimen to track back to the catalogue, which is why I was keen to get your thoughts last time and why this week’s mystery object is from the same collection.

So can you help me work out what species this skull belonged to?

mystery295

No need for cryptic clues, but if you want to show off your taxonomic prowess you could always offer the 1860’s scientific name or the name of what you think it is in Dutch.

I hope you have fun with this one!

Friday mystery object #293 answer

Last Friday I gave you this unidentified specimen from Dublin’s Dead Zoo and asked you to help me work out what it was:

mystery293

The response was incredibly helpful and it was great to see that most of you were drawn by the morphology to make a similar identification to me.

The fact that it’s from the family Anatidae (the ducks, geese and swans) was immediately noticed, and from there the likely genus was quickly narrowed down to Branta, based on the morphology. This is the genus containing the ‘burnt’ geese (that’s what ‘branta’, derived from the Old Norse, means), which includes: the Brant Goose; Barnacle Goose; Canada Goose; Cackling Goose; Red-breasted Goose, and Hawaiian Goose.

However, the nominate examples of all these species (that means the ones derived from the type on which the species name is based) are either the wrong shape or a bit too large to have this skull, which you can see by checking them on the excellent Skullsite by Wouter van Gestel.

The closest species in terms of morphology are the Cackling Goose (B. hutchinsii), Canada Goose (B. canadensis) and Barnacle Goose (B. leucopsis), but it turns out that there are various subspecies of each and one (that was previously recognised as a subspecies of Canada Goose, but which is now considered a subspecies of Cackling Goose) is rather small, as flagged by the subspecies name minima.

This smallest subspecies seems to fit both the morphology and the size very well, so I’m quite confident to identify the mystery specimen as the Small Cackling Goose Branta hutchinsii minima (Ridgway, 1885).

640px-small_cackling_goose_brood

A family of Small Cackling Geese, by Tim Bowman, USFWS, 2003

So thanks to you all for helping me to narrow down where in the Anatidae to start looking! More mysteries from the Dead Zoo next week.

Friday mystery object #293

This week I have the first of what I hope will be many mystery objects from my new job as zoology curator at the National Museum of Ireland:

mystery293.jpg

I haven’t quite got myself a proper photographic set up yet, but I hope this photo of an unidentified skull in the collection will be good enough for you to be able to help me work out what species it belongs to.

As usual you can leave your thoughts, questions and suggestions in the comments section below. Have fun!

Friday mystery object #291 answer

Last week I gave you this skull from the Grant Museum of Zoology to identify:

mystery291

I thought this would be a fairly easy one and so I wasn’t surprised when Chris was straight in with a correct identification, in a suitably cryptic manner of course.

The huge open sinuses inside the orbit and openings around the auditory bullae (as spotted by palfreyman1414) immediately suggest that this is an animal that dives deep underwater, as the large openings help prevent pressure from building up inside the skull. The shape of the teeth are another giveaway that this is a fish-catching mammal in the Order Carnivora. It is of course a seal.

But what kind of seal? There are 33 species of pinniped, so there are a few options, although the large and distinctive species like Walruses can be ruled out for obvious reasons. In this size range and with multicusped teeth like these we’re looking at one of the true seals (the Phocidae) at the medium to small end of the size range.

When you start looking at the skulls of seals in this range, you need to look  closely. It lacks the flat top of the head and steeply sloping profiles following the nares of a Grey Seal, plus the interorbital distance (the distance between the eyes) is much smaller.

It lacks the inflated nasal region of the cold water Bearded Seal, Ribbon Seal, Ringed Seal and Harp Seal, which need well developed nasal turbinates to help warm the air they breathe in. It also lacks the deflection of the zygomatic below the orbit that is seen in the smaller species like the Caspian and Baikal Seals.

Overall the morphology is most similar to either the Spotted Seal or Harbour Seal, but picking between the two is tricky, especially since the Harbour Seal has around five subspecies that vary somewhat in size and shape of things like the auditory bullae. There is a list of characters that can be used to distinguish between the skulls of the two species by John J. Burns in the Encyclopedia of Marine Mammals. Using that as a guide I think this is a Harbour Seal Phoca vitulina Linnaeus, 1758.

Thanks to everyone who had a go at identifying this – I hope you had fun with it!

Friday mystery object #291

Today’s mystery object is a fairly straightforward one from the Grant Museum, although I’m hoping that we’ll get a species identification for the specimen. Any idea what this is?

mystery291

As usual, a nice cryptic clue would be appreciated so that we can have some fun and not give away what it is too soon for those who are developing their identification skills. Enjoy!

Friday mystery object #284 answer

Last week I gave you this part of a skull to have a go at identifying:

mystery284

It’s quite a distinctive structure and very particular to one particular group of mammals. It is of course an external auditory meatus (or ear hole as it’s more commonly known), but instead of opening directly into the auditory bulla (the inflated bony bulb that holds the ear bones) it has a long and robust tube.

Lee Post, Daniel Calleri & Dan Jones and Allen Hazen recognised this characteristic feature as belonging to a Beaver and Richard Lawrence went one better and narrowed it down to Castor canadensis Kuhl, 1820 – an identification that I agree with having seen the whole skull:

beaver_skull

I’m not sure if there’s any real functional reason for the ear tube, but it looks to me like it might be a “spandrel” a feature that’s an artefact of another adaptive feature – in this case the articulation of the mandible.

beaver_jaw

Gnawing through a tree trunk is no easy task, so it’s not surprising that the Beaver has some serious adaptations to deal with the work involved. Unlike carnivores, which have a fixed lateral mandibular articulation powered mainly by the temporalis muscles, rodents have a dorso-ventral articulation usually powered by the masseter muscles, which allows the jaw to move backward and forward. In the Beaver the sagittal crest suggests that the temporal muscles are more involved than usual which, with the orientation of the articulation, may necessitate the ear tubes as lateral braces against which the mandible can secondarily articulate. That’s my guess…

Great work on identifying this specimen using very limited information!