Tag Archives for skull

Friday mystery object #232 answer

Last Friday I gave you this nice robust skull to identify:

mystery232

There was a healthy discussion about possible identifications, with the importance of scale mentioned more than once (by Jake, palaeosam, Lena and Robin Birrrdegg). Not only is this a robust skull, it’s also quite large, ruling out the British carnivores – and it clearly is a carnivore judging by the canines and the well-defined sagittal crest.

The lack of cutting and puncturing premolars and molars means that cats, dogs, hyaenas and other very carnivorous large carnivores can be ruled out, narrowing down the likely options in the right size range to the bears, as recognised by palaeosam, Ric Morris, Robin Birrrdegg, Will Viscardi, cromercrox, cackhandedkate, Lena, Daniel Calleri, henstridgesj and Carlos.

The species is a bit more difficult to work out, but the big sagittal crest and fused sutures suggests that this is not an juvenile bear, meaning it’s too small for a bear of the Brown  or Polar variety. That still leaves quite a range of other possible bears, but the pronounced forehead and long square muzzle rules out the Giant Panda, Sun Bear, Spectacled Bear and Asiatic Black Bear, while the big robust incisors rule out the Sloth Bear. That leaves the American Black Bear Ursus americanus Pallas, 1780.

Ursus americanus by Mike Bender/U.S. Fish and Wildlife Service, 2008

Ursus americanus by Mike Bender/U.S. Fish and Wildlife Service, 2008

So well done to cromercrox, Carlos and Robin Birdeggg who all got the species correct!

Friday mystery object #231 answer

Last Friday I gave you this distinctive skull to identify:

mystery231

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 #231

This week I have a very distinctive skull for you to identify:

mystery231

Because I expect some of you to work out what it is straight away, can you make your answer cryptic please, to give other people an opportunity to work it out.

I look forward seeing some cunning and clever hints at what this is!

 

Friday mystery object #230 answer

Last Friday I gave you this skull to identify:

mystery230

It was obvious to everyone who had a go at answering that it was the skull of a marine turtle of some sort, but that’s where it got a bit more tricky. There are only seven species of marine turtle, but their skulls all look quite similar to the untrained eye – mine included.

However, when I found this specimen I decided to improve my skills and I searched for a decent identification guide for turtle skulls, which I was fortunate to find hosted by Florida Atlantic University.

Checking through the characters I discovered that the palate of turtles can be very helpful in identifications, so here’s a colour coded and labelled diagram prepared from the image above that should help illustrate a key diagnostic feature:

Loggerhead_palate

As some of you may have noticed, the maxilla (tinted red) on either side of the palate meet in the middle, which is a characteristic only seen the Loggerhead Caretta caretta Rafinesque, 1814. The other turtles have the maxilla separated by the vomer (tinted green). Well done to  mark b, cromercrox and donald who managed to get the right turtle species!

Loggerhead Turtle. Photo by ukanda, 2006

Loggerhead Turtle. Photo by ukanda, 2006

These large marine turtles will eat pretty much anything they can find, from jellyfish to crabs and sponges. Unfortunately that includes things like plastic, which causes all sort of problems for their digestive system. Just one problem that they face, on top of getting tangled up in fishing tackle and poor survival of their young due to predation from pretty much everything (from foxes to crabs and gulls to sharks). Sadly, it’s not much fun being a turtle.

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:

mystery227

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:

comparing_cats

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:

mystery227

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 #225 answer

Last Friday I gave you this felid skull to identify:

mystery225

As with the other cats over the last few weeks, it’s been difficult to find really clear diagnostic features.

The size helps narrow down the possibilities and the lack of divided auditory bullae rules out some of the species of Lynx, as does the presence of the small first premolar.

However, beyond that there isn’t much to really differentiate this cat from other species, apart from general features of relative proportion (height vs width vs length) and perhaps the angle of the rear part of the sagittal crest (which will probably vary between individuals).

Nonetheless, henstridgesj managed to correctly identify this as an Ocelot Leopardus pardalis (Linnaeus, 1758), one of the largest of the small cats in South America.

Ocelot, 2003 from US Fish & Wildlife Service, Image Archive

My challenge is going to be find a way to pull together the variety of cat skulls we’ve had for the last few weeks, to help make cat skulls a little easier to identify in the future – if that’s even possible. No pressure…

Friday mystery object #224 answer

Last Friday I gave you this felid skull to have a go at identifying:

mystery224

The size was larger than the previous cat skulls I’ve shown you, which helped reduce the possibilities a bit – after all, there are more smaller cats than bigger ones.

As it turns out, Sam Misan and henstridgesj both managed to work out that this is the skull of a Serval Leptailurus serval (Schreber, 1776).

A Serval cat at Serengeti National Park, Tanzania, by Bob, 2007

A Serval cat at Serengeti National Park, Tanzania, by Bob, 2007

These long-legged cats have a relatively small head, but huge ears – and the large external auditory meatus (ear hole) with a very pronounced ridge above for attachment of the muscles of the pinna (the fleshy part of the ear) helps reflect that.

The long legs and the big ears are key to the Serval’s hunting technique in the long grasses of the African savannah, where they listen for the movement of rodents which they dramatically leap on. Probably easier to appreciate this method by seeing it:

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:

mystery224

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:

mystery223

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…

Friday mystery object #223

I hope you’re not all fed up with cats yet, because here’s another:

mystery223

I have concerns about the identification attached to this one, so let’s see if your thoughts agree with what I have written on the label.

As always, you can put your thoughts below and they will be very welcome!

Friday mystery object #222 answer

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

mystery222

No one got quite the right species, but several people (Crispin, manwhohunts, Maxine and Alex Klein) managed to narrow it down to the correct genus.

The flat frontals give the forehead a slope rather than the usual curve we’ve seen in previous cats of this size, making the cranium appear very domed in contrast. The post orbital processes are quite short and gracile (slender). The jaw is quite short while maxilla bone above the canines appears pinched in and the nasals are steep and protruding somewhat.  These are features that appear in the genus Leopardus – the South and Central American small spotted cats.

How to distinguish between different species of Leopadus is more of a problem. Daniel Jones picked up on the incredibly robust bone margin of the foramen magnum (the hole the spinal chord goes into), which may be distinctive, but so far I’ve not seen the underside of other small Leopardus species skulls, so I can’t be sure.

All I know is that this is the skull of an Oncilla Leopardus tigrinus (Schreber, 1775), a small and mainly ground-hunting South American forest cat. I’ve said it before and I’ll say it again, cats are so difficult to identify!

 

 

Friday mystery object #221 answer

Last Friday I gave you this cat skull to identify:

mystery221

It is about the same size as a Domestic Cat and is very similar in morphology. But it’s not a Domestic Cat. 

The auditory bullae (the bulbs under the skull that hold the hearing apparatus) and the external auditory meatus (ear holes) are a bit bigger, the skull is a bit broader and the interpterygoid notch (the gap at the back of the palate that the airway emerges from) is squarer and has a slight ridge in front of it on the palate (and I’m not sure that ANY of these are particularly significant).

There were plenty of suggestions about what this skull might belong to, but only henstridgesj hit the nail on the head with a correct identification of Southern African Wildcat Felis silvestris cafra Desmarest, 1822. So well done Stephen!

Southern African Wildcat (Felis silvestris cafra) in Kgalagadi Transfrontier Park. Image taken by on Johann du Preez 24 December 2007

Southern African Wildcat (Felis silvestris cafra) by Johann du Preez 2008

Friday mystery object #220 answer

Last week I gave you this lovely skull to identify:

mystery220

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…