Friday mystery object #233 answer

Last Friday I gave you a variety of mandibles to have a go at identifying. They lacked a scale bar and represented a range of different species that have similarities in mandible shape.

There were some great cryptic suggestions of identities, but it must be said that Jake came through with a really clear and pretty much spot-on list of suggestions. So here are the answers in a handy form that might be useful for reference:

mystery233b

The Sheep and Cow have a distinctive upward inflexion at the end of the mandible, with the Cow’s being so strong that the incisors start above the level of the top of the molar tooth row – unlike the Sheep’s.

This inflexion is much less marked in the Red Deer, which has a narrower body of the mandible, presumably relating to the less intensive chewing of a browser compared to grazers (grass is tough stuff). The Deer also has a notch along the bottom of the jaw, which Jake pointed out as a useful feature.

The Pig mandible tapers less overall, but is thicker at the end with the articulation – presumably because the omnivorous Pig is chewing differently, using the temporal muscles more than the masseter muscles and therefore needing a different area of the jaw for muscle attachment. The teeth are also pretty distinctive. Like the Pig, the Donkey mandible lacks the long and hooked coronoid process, but is also very triangular in shape with quite squared teeth – features typical of an equid.

So hopefully that gives you some pointers for telling some common herbivore mandibles apart when you don’t have a scale bar – a more common problem for some of us than you might think…

Bonus mystery object

I usually offer up a mystery object on Friday, but here’ a bonus object that landed on my desk this morning.

image

Apparently it was found in a horsefield in Kent, I have narrowed down the likely species of the animal that ‘donated’ the bone to a couple of options, but thought you might like to have a go as well, before the specimen is handed over to our Anthropologists to inspect the engraved designs.

As usual can can leave your comments below. Have fun!

Friday mystery object #228 answer

Last Friday I gave you these bits of mystery forelimb (scapula and humerus) to identify:

mystery228

I thought it would be an easy one, since it’s from a very common species with a near global distribution – plus the humerus has quite a characteristic crest along the proximal end, from the shoulder articulation to the middle of the bone.

Most people who commented noticed this crest and Jake suggested that it had adaptive features (along with the scapula), maybe for a specialised way of life.

As it turns out, these bones come from an animal that is probably best described as a specialist generalist – a Brown Rat Rattus norvegicus (Berkenhout, 1769).

Rattus norvegicus, the Brown Rat. Image by National Park Service

These versatile and intelligent animals are very good climbers and brilliant swimmers, using their forelimbs to both get around and manipulate food.

This particular rat was a male pet rat purchased from Harrods in October 1960 – I get the impression it didn’t survive for that long, since the humerus head hasn’t fully fused. You can’t buy pets from Harrods any more, so this specimen not only shows us what a rat’s humerus and scapula look like, but it also represents a teeny-tiny piece of British history.

Friday mystery object #228

This week’s mystery object is a bit of a break from the cat skulls. Any idea what these two bones are and what species they’re from?

mystery228

As always, you can put your thoughts and suggestions in the comments section below, but if you think it’s easy please try to be a bit cryptic in your response, to give other people a chance. Enjoy!

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!