Here’s the Friday feline for this week:
Any idea what species this skull is from?
As usual you can put your questions, comments and suggestions below and I’ll do my best to respond. Good luck!
Last week I gave you this lovely skull to identify:
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.
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…
On Friday 7th Feb I gave you this mystery skull to identify:
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:
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 franklinii, Spermophilus 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 Thomas, 1909.
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…
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:
Last Friday I gave you this skull to identify:
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.
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!