Friday mystery object #377 answer

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

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It didn’t prove too difficult to narrow it down, with everyone recognising it as a mustelid and Rémi immediately recognising it as being one of the Martens. But salliereynolds and Chris managed to get it down to the species, which is a bit of work.

There are around seven living species in the Genus Martes, although the total number varies depending on the sources you read. They have very similar skull shapes, the same dental formula and very similar tooth shape. In my experience the main feature to differentiate them lies in the auditory bullae.

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There are some decent online resources with images of Marten skulls, so it is possible to get a handle on some options. Each bulla is a 3 dimensional structure that is inflated in subtly different ways that are really hard to describe.

In a previous post I had a similar specimen (the same species as it happens) as a mystery object and I compared some bullae, but alas the image I referred to has since been removed. However, the important point is that there’s only one of the Martens that seems to have an outermost lobe that has a well-defined anterior sulcus (a fissure towards the front edge). This feature makes me think that this is a European Pine Marten Martes martes Linnaeus, 1758.

Thanks for your help in working it out!

Friday mystery object #373 answer

Last week I gave you this pretty cool skull to have a go at identifying:

 

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As everyone recognised, it’s the skull of a snake. I think that’s clear from those extremely long quadrate bones (highlighted in purple in the top view), with which the lower jaw articulates to allow a huge gape for swallowing prey whole. However, there are a lot of snakes out there – around 3,600 species, which means there are lots of possibilities for the species that this particular skull belongs to.

The side view allows us to rule out quite a few possibilities, since it’s clear from the teeth that this isn’t one of the front-fanged snakes (vipers and elapids).

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Rattlesnake skull, with its big front fangs.

The light construction of the skull suggests it’s not one of the constricting snakes, which have much more robust skulls for dealing with the forces generated by the struggles of relatively large prey.

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Python skull, with a robust construction for wrangling prey.

The teeth are quite small and although there are a couple of slightly longer ones in the tooth row, they hardly count as real fangs at a paltry 3mm long. So we’re probably dealing with one of the ‘non-venomous’ colubrid snakes (many of these are actually venomous, but lack the appropriate tools to deliver that venom through human skin).

Of course, there are still well over a thousand possible species in the Colubridae – but this is where you have to start ruling out possibilities by comparing the specimen against species that are common and widespread, to begin the process of narrowing down the options.

Since this specimen is in the Museum in Ireland, Europe is a good place to start looking for likely candidates (Ireland itself being famously devoid of native snakes). There is a rather old (published in 1913), but still very useful reference called The Snakes of Europe, by G. A. Boulenger which has a section on identifying species based on their skulls.

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Fig. 6Skull of Tropidonotus natrix. (From British Museum Catalogue of Snakes). Illustration from The Snakes of Europe, by G. A. Boulenger, 1913

If you take a look through, it quickly becomes apparent that there is one species that matches the mystery object very closely – even to the position of the slightly larger teeth. It’s a species that has an interesting defense mechanism that jennifermacaire referred to:

…The closest skull I could find is from a snake that likes to roll over and play dead…

This is a fascinating behaviour seen in several snake species, but Jennifer is correct that it is seen in the species that this skull is from – the European Grass snake Natrix sp.

Of course, the story then gets more complicated again, since a couple of subspecies of Grass snake have been elevated to species in the last few years. The Iberian subspecies Natrix natrix astreptophora was recognised as N. astreptophora in 2016 and the subspecies N. n. helvetica found west of the Rhine (including in the UK) was updated to N. helvetica in 2017.

These studies were based on genetics and I’ve yet to see any way of differentiating between these species using skeletal features, so for now the best I can say about this specimen is that it’s Natrix sp. I hope you enjoyed that little slither into the world of snakes, which seems to have opened a bit of a can of worms…

 

 

Friday mystery object #370 answer

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

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It proved a little more tricky than I thought it would, but I shouldn’t have been surprised given the poor quality of the photo and the fact that the cranium isn’t properly seated on the mandible (as pointed out by Allen Hazen).

Of course, that didn’t keep you all confused for too long. The large sinuses and relatively undifferentiated and widely-spaced teeth – except for those large canines – suggest that this is the skull of a some kind of seal.

Jeanie and salliereynolds noted the large, depressed opening over the nasal region, which is definitely one of the most distinctive features of this species. However, it also misled in the first place, with discussion of the possibility of it being from an Elephant Seal taking over for a while.

However, salliereynolds got back on the right track, while on Twitter Ray Chatterji was on the right track from the start with his suggestion:

The Hooded Seal Cystophora cristata (Erxleben, 1777) is really weird – well, the male is. He has an inflatable bladder on its head and one nostril contains a membrane that he can inflate to show off to other Hooded Seals.

I find it hard to think of this as anything other than nature’s attempt at making slightly disgusting balloon animals.

Well done to everyone who worked it out – I have a couple of fun guest mystery objects for you next week!

 

Friday mystery object #331

This week I have couple of specimens for you to have a go at identifying:

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I think these have been mislabelled and need their identifications checked to see if it’s a simple label swap or if it’s a deeper problem with the documentation. I won’t make it easier by providing the labels I’m suspect about – let’s see what you think working just from these images…

Have fun!

Friday mystery object #273 answer

Last week I gave you this mystery object to get your input on:

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It was labelled Ovis aries, which didn’t ring quite true for me, so I thought it would be good to see if you also had other ideas, since I’ve noticed that there is a tendency for ungulates of a certain size in museum collections to be assumed to be Sheep.

In other museums I’ve found female Red Deer, Gerenuk and on one occasion even a Badger skull that had been labelled “Sheep”.

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Labelled “Sheep” but actually a Gerenuk.

This is what a sheep looks like:

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You’ll probably notice the “Roman nose” that is quite distinctively sheepy, it also has no gaps between the premaxilla and maxilla and there is a small depression in front of the eye.

When you look underneath, one of the key things that jumps out is the difference in size of the auditory bullae (mystery on the left, sheep on the right):

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So I’m pretty sure that the mystery object isn’t a sheep, but what is it?

There were lots of suggestions of exotic and interesting ungulates, but after looking at the skulls of a huge number of ungulates I can to the conclusion that Latinka Hristova and Jake were on the right track with the simple suggestion of Goat Capra hircus (Linnaeus, 1758).

Taking a look at Goat specimens on the incredibly useful Mammalian Crania Photographic Archive has convinced me that this is what the mystery object actually is. Not a million miles from Sheep I suppose, but they are different and it’s helpful finding some small differences that help distinguish between them.

Thanks for your input!

Friday mystery object #234 answer

Last Friday I gave you this mystery skull to identify, which I discovered in a box of unidentified bits and bobs:

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It was pretty obvious that it was the skull of a big cat of some kind, with most of you suggesting a Jaguar or Cheetah (either of which would make me very happy as we have the skull of neither in the Horniman collection). Unfortunately it appears to belong to neither.

As I’ve mentioned  before, cats are quite difficult to differentiate from each other as they haven’t been diverging for all that long and their widespread distributions can mean that populations within a particular species can be quite variable in morphology. Leopards are a good example of this, with a (once continuous) range from Korea to South Africa.

Global distribution of the leopard (Panthera pardus) by Tommyknocker

Global distribution of the leopard (Panthera pardus) by Tommyknocker

As it turns out, this specimen is most likely from a Leopard Panthera pardus (Linnaeus, 1758), since it’s from an adult animal (as is clear from the well formed sagittal crest) but is on the small side for a Lion or Tiger and too big for a Cougar or Cheetah. It also lacks the broad post orbital region seen in the Cheetah and Snow Leopard, and it lacks the concave profile of both the Snow Leopard and Jaguar. All of these identification pointers can be found in this handy pdf by Margaret “Cookie” Sims.

Just to show you what I mean about the variability within a species, here’s a second skull from the same box, that also matches the Leopard identification.

Leopards

I expect the big difference in size is largely down to sexual dimorphism, but as you can see the overall proportions are quite different as well. This may be a difference between widely separated populations, or it could just be individual variation – either way it goes to show that cats are hard to identify.

Friday mystery object #233

This Friday I have a challenge for you. Can you work out which five different species these mandibles come from?

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They are all different sizes and the lack of scale bars is deliberate – this is about trying to find useful features from the shape rather than the size, It’s not easy!

You can put your answers in the comments section below. Good luck!

Friday mystery object #231 answer

Last Friday I gave you this distinctive skull to identify:

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I knew it would be a bit of an easy one, given the highly unusual teeth, but it seemed too interesting a specimen to not use.

As cryptically suggested by many of you (Jamie Revell, Nigel Monaghan, henstridgesj, rachel, cromercrox, Robin Birrrdegg, Allen Hazen and Crispin), this is indeed the skull of a Crabeater Seal Lobodon carcinophaga (Hombron & Jacquinot, 1842).

Jerzy Strzelecki, 2000

These seals are specialised for catching krill, hence the strange shape and tightly fitting nature of their teeth, which act as a filter to strain the tiny crustaceans from ocean water.

Because these seals live in the waters all around the Antarctic, monitoring their population is particularly difficult, so estimates of their numbers vary considerably, from 2 million to 12 million (which is the more likely figure).

As with most abundant animals they have predators, in particular Leopard Seals. Apparently 78% of adult Crabeaters bear scars of Leopard Seal attacks, which can be seen clearly on the live individual in the image above. Most of the attacks happen before the Crabeaters reach a year old and get a bit too big to be easy prey, but in that first year there is apparently a huge mortality rate, with only 20% of seals making it to their first birthday. Good old Mother Nature is never one for sentiment.

Friday mystery object #227 answer

On Friday I asked you to spot the differences between these two cat skulls and I wondered whether anyone could identify them:

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Both henstridgesj and Allen Hazen made some good observations, the first being about the difference in size, then about morphological features that I’ve marked on this image:

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Now henstridgesj also correctly identified one of the skulls – the one on the right of the image is from a Domestic Cat Felis catus Linnaeus, 1758.

As it turns out, this was a bit of a trick mystery object, since BOTH of the skulls belong to Domestic Cats, so this gives us a useful idea of the kind of variation we might expect within a species.

I think that the main cause of variation between these two animals is probably sex, with the male on the left and the female on the right. There may also be differences based on age (although I don’t think that’s a major factor), breed and perhaps disease (the larger specimen looks like it had an infection that affected the surface of the bone).

After taking various measurements, the most useful difference I’ve found between the two skulls is shown with the yellow line. I think that the ratio of these two measurements may provide a way to tell the difference between a male and female cat (in the male it’s around 1 or less than 1, in the female it’s greater than 1) but I’ll need to make a LOT more measurements to test this.

Two other ideas that could be tested were suggested by henstridgesj and Allen Hazen. Allen said: “My impression is that the presence and development of sagital crests, among felidae, correlates pretty strictly with size” and henstridges said: “It seems that if the species of cats are arranged in increasing size order, then the anterior half of the skull (forward of the frontal-parietal suture) seems to increase in size more than the posterior half”.

I’d better take a look to see if this has been tested before…

Friday mystery object #227

This week I thought I should mop up the last of the smaller cats as a spot-the-difference:

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What do you think are the diagnostic features that separate these two skulls (bonus points for species identifications)?

I’m really keen to get your thoughts on this, so please put your observations in the comments section below. Thanks!

Friday mystery object #224

For the last few weeks I’ve been using cat skulls as mystery objects, because they are really hard to tell apart and I was hoping that some useful distinguishing features might get spotted when you try to identify them.

I certainly feel like I’ve learned something, but I’m pleased to say that there aren’t too many more skulls to go, because it’s really difficult. This next one should hopefully be a bit easier than some of the recent cats:

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Any idea what fine felid this skull comes from?

As usual I would really appreciate your thoughts in the comments section below – let’s see if we can crack this!

Friday mystery object #223 answer

Last Friday I gave you this fine feline to have a go at identifying:

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I was a little suspicious of the identification attached to the specimen, but Al Klein suggested the same species – the Jaguarundi Puma yagouaroundi (É. Geoffroy Saint-Hilaire, 1803) [link opens pdf].

My reasons for suspicion were the nature of the post-orbital constriction (the narrowing of the braincase behind the eyes), the nature of the zygomaticotemporal suture between the temporal process of the zygomatic and the zygomatic process of the temporal bone (the bit where two bones meet to make the arch of the cheek) and the shape of the nasal bones where they meet the frontals (the V shaped bones above the nose area).

The observation by henstridgesj that the skull was similar to the previous mystery object (Leopardus tigrinus) was a good one, so I decided to research the genus Leopardus in a bit more detail, to see if there was a better match.

It turns out that the skull I found that matched this one most closely – especially with regard to the relative lack of a post-orbital constriction and the nasal-frontal junction – was the highly arboreal Margay Leopardus wiedii (Schinz, 1821) [link opens pdf].

Margay - Leopardus wiedii, Summit Municipal Parque, Panama. By Brian Gratwicke.

I’m always a bit reticent to re-identify specimens that have original labels from the supplier attached as this one does, but this comes from suppliers (Dr.s Schlüter & Mass) that I know have seriously misidentified or mislabelled specimens in the past (e.g. labelling a African Lappet-faced Vulture as an Andean Condor from Bolivia).

Of course, the real identification may be even more complicated, since the South American cats have a bit of a track record for hybridising to the point of masking distinct species, so any identification I make will be laden with disclaimers and caveats. The joy of real-world animals when contrasted against nice simple biological concepts…

#MuseumSelfie

Today is #MuseumSelfie day as part of #MuseumWeek, so here are few selfies of me trying to recreate the look of specimens from the Horniman’s natural history gallery.

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Utterly ridiculous, but fun nonetheless. If you have some similar selfies why not link to them below in the comments section? After all, I don’t want to be the only one looking silly!

 

Oz carnivores

Here’s an handy guide to the skulls of the carnivores found in Oz, just in case you find yourself in the area and stumble across a large carnivore skull. Natch.

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They are arranged in the order left to right, top to bottom and they follow the sequence of the wild animals of Oz song. If you don’t know the song, it’s here:

Enjoy that little earworm!

Friday mystery object #220 answer

Last week I gave you this lovely skull to identify:

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As I suspected, everyone immediately recognised it as a type of cat. The characteristic two large blade-like premolars with a gap (diastema) behind the long canines and the straight incisor row were a dead give-away.

Then came the difficult bit. There are around 40 living cat species recognised in the world and because they didn’t diverge from a common ancestor until just 10 million years ago (or thereabouts), they all tend to look quite similar.

There were lots of suggestions, ranging from Lynx to Jungle Cat, but only Jake managed to recognise this short and highly domed skull (with impressively long canines) as belonging to a Marbled Cat Pardofelis marmorata (Martin, 1836).

The Marbled Cat is an tree-dwelling species from South and Southeast Asia that isn’t really very well known. They have a ridiculously long and chunky tail to help with their arboreal lifestyle and beautiful patterns on their coat, which gives them their name.

Photo of a Marbled cat (Pardofelis marmorata) spotted in Danum Valley Conservation Area, Borneo, by Johan Embréus 2009

Since cats are so hard to tell apart do you think I should post a few more over the next few weeks? Between us we may be able to spot some useful distinguishing features…

Friday mystery object #219 answer

On Friday 7th Feb I gave you this mystery skull to identify:

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The post got lots of activity from both regulars and biology students from the University of Chicago Laboratory School, which means there were lots of helpful comments!

The specimen was quite clearly from a rodent, due to the paired incisors, but there are a LOT of different rodents out there.

The type of rodent was narrowed down by bugblokenz who suggested the skull was from a squirrel of some sort and Jake pointed out how we know that is the case – the specimen has a spiky postorbital process:

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The presence of a spiky postorbital process (see top skull) suggests that it was from a type of squirrel. Most other rodents either lack this process (see bottom skull), or the process is more stout and blunt.

Narrowing it down to a squirrel is helpful, but there are still around 285 different species to choose from and many squirrels have very similar skulls. This is where the real challenge lay, especially since it clearly wasn’t the British Red Squirrel Sciurus vulgaris or the more widespread Eastern Grey Sciurus carolinensis, as I showed you on Friday 14th. Other suggestions included the Southern Flying Squirrel Glaucomys volans (which is a bit on the small side) and Eastern Fox Squirrel Sciurus niger (which has a really interesting method you can use to identify it).

The relatively narrow zygomatic breadth, combined with a relatively wide breadth between the orbits suggests a ground squirrel of some sort, which many people recognised, leading to suggestions of Poliocitellus frankliniiSpermophilus sp., Otospermophilus sp. and Tamias sp. – for which this useful reference provides some great comparative specimens (huge thanks to Crispin for sharing this).

However, none of the North American ground squirrels quite matched up, with the closest suggestions of Otospermophilus variegatus or Poliocitellus franklinii still being different in a variety of ways, particularly in relation to the width of the skull, relative zygomatic breadth and shape of the postorbital process.

After much consideration it came to me that we may be looking on the wrong continent and it turns out that African ground squirrels are more similar to this specimen. Fortunately, there is a very useful resource providing images of specimens of African rodent species available through the Belgian Biodiversity Platform. This fantastic site has enabled me to make a reasonably confident identification of Striped Ground Squirrel Xerus erythropus (Geoffroy Saint-Hilaire, 1803).

Striped Ground Squirrel (Xerus erythropus) by BOISSEL Philippe

Striped Ground Squirrel (Xerus erythropus) by BOISSEL Philippe

I’d still like to get my mystery skull to a comprehensive physical collection, just to make some fine detail checks (there are some issues with the shape of the posterior margin of the palate I’m not 100% happy about), but overall I’m happy with this – but please let me know if you think I’ve missed something!

Big thanks to everyone who has contributed their ideas on this specimen – let’s see what I can find for you to identify this coming Friday…

[Further information available in this species description PDF]

Friday mystery object #219 answer coming soon…

Apologies for not having the answer to last week’s mystery object posted yet – it’s been a busy week and I simply haven’t had a chance to prepare a decent answer.

However, I have an image of last week’s object alongside a Grey Squirrel (the lighter coloured specimen), to give you an idea of how they differ, so I hope that will prove of interest until I can get a proper post prepared:

Grey_Squirrel_vs_Mystery_219

Friday mystery object #218 answer

Last Friday I gave you this skull to identify:

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There was strong consensus on this being a mustelid – which is good, because that’s what it is. There was also good agreement on it being one of the Martens, which is where things become a bit more difficult.

After looking at a lot of different Marten skulls online without much success in finding a way of telling them apart, this diagram  proved quite helpful.

Images compiled by Mariomassone

Skulls in the sequence: M. zibellina, M. martes, M. foina

If you look at the skull in the middle of the top and centre rows, the auditory bullae (the rounded bones under the skull that house the anatomy used in hearing) have quite distinctive shapes in the three species pictured.

In addition, the the little nub of bone (called the mastoid process) that sticks out behind the ear hole (or external auditory meatus as it’s also known) is very differently developed in the three species. Looking at this character and checking back against other Marten skulls online the clues suggested that the mystery object is the skull of a Pine Marten Martes martes (Linnaeus, 1758).

So well done to everyone who commented – particularly Jake who got the ball rolling with a Martes identification from the start!