Friday mystery object #302 answer

Last week I gave you this egg to try your hand at identifying:

mystery302

Eggs can be tricky, since they are largely similar in shape and, since egg collecting was banned many years ago, there are few modern resources for identification.

However, you can pick up clues by thinking about colour and pattern and working out what advantage it may have. So you might expect a brightly coloured egg to be laid in a well disguised and deep nest, where it’s unlikely to be spotted except by the parent, whereas a yellowy speckled egg is more likely to be camouflaged if laid in a fairly open, sandy environment.

So this egg was probably laid somewhere near the sea, which means it’s probably from a charadriiform bird (those are the shorebirds).

Now there are a lot of shorebirds, but this egg is pretty big and it lacks the strongly conical shape you’d expect from a cliff-nester like a Guillemot (the shape means it rolls in tight circle, making it less likely to be blown or knocked off a cliff). That actually narrows it down to a handful of birds that makes comparison easier. Curlew eggs, for example, are a similar size, but they tend to be more grey and have larger blotches, plus they’re a bit less elongated.

This particular egg has the shape and colour of a gull egg and large size means it’s almost certainly the egg of a Greater Black-backed Gull Larus marinus Linnaeus, 1758.

I would say more, but at the moment I’m at the natural history highlight of the year – the NatSCA conference. Here’s the Twitter feed in case you’re interested in the discussion:

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 #286 answer

Last week I gave you this mystery object to identify, found on a beach in Ireland:

mystery286

It led to a lot of great cryptic comments relating to marine birds and sternum keels, but Lena was the first to comment and was spot on with the species (or at least as far as I can tell!)

Bird sterna are quite distinctive, with overall shape giving an indicator of mode of life. Long narrow but well-developed keels like this tend to be seen in marine birds that use their wings to fly underwater. The shape of the bottom and sides of the sternum tend to be quite specific to particular genera and species, making sterna pretty good for identification.

Of course that depends on having good comparative material and I was delighted to find John Rochester’s very helpful Flickr page, that has a comparison of British Auks (in this case we’re talking about the geographical British Isles rather than the sociopolitical concept of Britain).

If you take a look at those images you’ll notice that one fits the shape very well indeed – the Guillemot or Common Murre Uria aalge (Pontoppidan, 1763).

1024px-common_murre_rwd2

Guillemot with its meat and feathers on. Image by Dick Daniels, 2011

So that’s the identification I gave to Emer, Ronan, Rory and Paddy who found it on their hols!

 

Friday mystery object #283 answer

Last week I gave you this zoomed in picture of a specimen to have a go at identifying:

mystery283

It was a bit tricky, so I also gave you this bonus clue to help:

mystery283_bonus

I was impressed to see that, despite the limited information available from the images provided, many of you managed to work out that this shows the lightweight ‘honeycomb’ structure that supports the casque of a hornbill.

That was the first challenge but, as ever, I was keen to see if you could get the identification to species – far more of a challenge considering the lack of a side view of the skull and lack of a scale. To make up for that I’ve decided to provide the necessary image here:

Ceratogymna atrata skull

I won’t say what species this is in this post, as I normally would, just to give some more of you a chance to make the identification yourself. However, what I will say is that the very first response by Wood contained a link to an image of the correct species and later to a blogpost featuring this very specimen. In that post there is a discussion about the appearance of the casque, with speculation about whether it had been damaged during preparation, resulting in its appearance. However, as Richard Lawrence pointed out, this appearance is actually normal for the skulls of several species of hornbill.

I will also say that the discussion between Daniel Calleri & Dan Jones and Richard Lawrence about whether it was a hornbill from a genus starting with A or B was interesting and I initially thought it was an A, but am now convinced that it’s a C.

If you’re desperate to know which species it’s from, here’s a link to the skullsite.com page about it.

 

Friday mystery object #279 answer

Last week I gave you this mystery object to identify:

mystery279

It’s the kind of thing you find in museum collections quite often, but it will commonly be misidentified – especially in anthropology collections where (in my experience) it will commonly be referred to as a claw or big cat tooth.

However, nobody who commented went down that route, recognising that the hollow base and well defined crown indicates that it’s an open rooted tooth of some sort. In mammals an open root at this size that would suggest a pig tusk or perhaps a whale tooth, but this isn’t mammalian.

In fact, this tooth is from something even less cuddly than a whale, something crocodilian. This was recognised first by Carlos Grau, but others who came to the same conclusion included Jonathan Larwood, Daniel Jones, palfreyman1414, Wouter van Gestel and Charne. More specifically, this tooth is from a Gharial, Gavialis gangeticus (Gmelin, 1789). This Gharial from the Grant Museum of Zoology in fact:

mystery279_Gharial

Grant Museum of Zoology Specimen LDUCZ-Y215

Gharial teeth are a bit less conical than the teeth of most crocodiles and alligators. Presumably the curve helps prevent their main diet of fish from getting free when caught.

Gharials are sexually dimorphic, with the adult males bearing a big rounded bony  knob on the end of their rostrum, this is where the name Gharial comes from, as this feature resembles a local earthenware pot called a “ghara”. Sadly, these distinctive crocodilians are critically endangered, with just a few hundred left alive in the wild. They are affected by habitat loss, egg theft and use in traditional medicines.

More mysteries next week and if you fancy hearing me talking about animals you might be interested in coming to Animal Showoff at the Grant Museum of Zoology next Thursday evening!

Friday mystery object #278 answer

Last week I gave you this mystery object from the Grant Museum of Zoology to get your thoughts on:

mystery278

Most people spotted that this was a canid of some sort – but there was a lot of discussion about exactly what sort.

Allen Hazen made an interesting observation about the reduced second molar (missing in the specimen, but the socket shows that it was there and smaller than you’d expect from most dogs), plus the remarkably convex facial profile. Useful observations that have a bearing on the identification.

The short and broad muzzle, combined with the convex skull and distinctive molar morphology led Latinka Hristova to suggest Dhole, an identification agreed with by Lupen, palfreyman1414, Richard Lawrence, joe vans, Henry McGhie – and myself as it turns out.

Dhole (Cuon alpinus) by Kalyanvarma

Dhole (Cuon alpinus) by Kalyanvarma

The Dhole Cuon alpinus (Pallas, 1811) is an endangered Asiatic Wild Dog, that hunts in clans and feeds on a variety of medium to large mammals that are usually killed after an extended chase.

I’d not seen the skull of one of these before, but I was aware that they have a convex profile, so it was my immediate suspicion when I saw the mystery object and the species was confirmed by the unusually simple structure of the first molar and very reduced second molar, which are almost cat-like in their adaptation for shearing meat.

All in all, an exciting skull to find – and there are other unidentified canids in the same box that I’m itching to take a look at, so keep your eyes peeled for more mystery mutts.

Friday mystery object #274 answer

Last week I gave you this ungulate skull to try your hand at identifying:

mystery274

It isn’t made any easier by the fact that it’s a female, so it lacks the horns or antlers that make identification easier. As with many ungulates it looks a bit sheepy (as I’ve mention before), but it has some clear indicators that helped you rule out what it’s not.

Jake spotted that the size was about right for a Roe Deer, but the auditory bullae (the bulbs on the underside of the skull that house the ear bones) are too massive and the proportions of the braincase are quite different.

Joe vans also ruled out deer, since it lacks lacrimal pits (large openings in front of the eyes that hold scent glands in cervids). Joe also noticed that the mandible is extremely pinched in just behind the incisors.

The incisors themselves caught the attention of Allen Hazen, who noted the extreme size of the first incisor, which he correctly recognised as being a bit of a giveaway to some people, although only when considered in the context of a variety of other features.

While Daniel Calleri summarised these odd features and added the observation of the decent sized occiptial condyl (the place where the atlas vertebra attaches to the skull) and small paracondylar processes (the bony extensions either side of the occipital condyl and just behind the auditory bullae).

These sorts of observations are exactly what are needed to differentiate between species that are very similar in overall morphology. However, without either an excellent reference collection, or even better, a well researched key, it’s almost impossible.

Fortunately, there is a skull key for a subset of Antelope that occur in Tanzania, created by the Field Museum and the mystery object this week happens to be from a genus present in Tanzania. I’d recommend having a go at using the key, but if you’d rather just find out the answer I’ve provided a link to what it is here. Have fun with the key and enjoy your Easter!