Tag Archives for skull

Friday mystery object #280 answer

Last week I gave you this crocodilian skull from the Grant Museum of Zoology to see if you had any thoughts about which species it might be:

mystery280

It turns out that you did indeed have some excellent thoughts about the identification, with Cindy Nelson-Viljoen immediately getting it right, with astute observations from David Godfrey and palfreyman1414, plus another correct responses from Joe Vans (as well as Tone Hitchcock and Henry McGhie not via the comments section).

This is a skull of the Dwarf Crocodile Osteolaemus tetraspis Cope, 1861. It’s small size is the first clue, but given how crocodiles grow this could pass as the skull of a young individual of a much larger species. As David Godfrey pointed out, there may be some paedomorphism (where adults look like juveniles) in effect in this species, since the adults as well as being small, have relatively short snouts and big eyes – which are features of juvenile animals as you can see in this display of crocodile development I did for Dinosaurs! Monster Families just before leaving the Horniman:

Croc_development

Part of my reason for wanting to show you this specimen was to force myself to look for some good online resources to get more familiar with crocodilian morphology. As it turns out, I did find a very useful comparative image, which shows the size and shape of the mandibular foramen (a large gap between the bones in the side of the lower jaw) is a helpful feature:

In this species the foramen is small, which when considered with the overall proportion is quite distinctive. Of course, this image does not include all 24(ish) living crocodilian species, but it does provide a pretty good range. Hopefully this will help speed up future croc skull identifications, at least allowing certain species to be discounted.

If you have any good tips for crocodile identification please share below!

Friday mystery object #280

Last week the answer to the mystery object was a Gharial – a very weird crocodilian from India. I realised that I didn’t know much about identifying the Crocodyliformes, so I thought it might be fun to have a go at working out what this species might be:

mystery280

As always, I would love to hear your thoughts below and let’s see if we can find some good diagnostic features!

Friday mystery object #277 answer

Last week I gave you this pretty cool skull from the Grant Museum of Zoology to identify:

mystery277

On Twitter the prevailing hypothesis was that this is the skull of an Alien Xenomorph, which was also proposed by Daniel Calleri, but most the comments here on Zygoma were a bit more down to Earth.

The identification started being narrowed down by Sisyphus47 and palfreyman1414 who recognised it as a reptile, which was narrowed down further by joe vans to a fossorial (or burrowing) lizard.

Allen Hazen, John D’Angelo and Daniel Calleri took it another step further and identified this as an amphisbaenian or worm lizard, but Rebecca Watling went even better and identified it as the skull of a Red Worm Lizard Amphisbaena alba Linnaeus, 1758. The morphology is very close and the size is right, so that’s the identification I’d also reached.

Amphisbaena alba by Diogo B. Provete

Amphisbaena alba by Diogo B. Provete

I’ve talked about Amphisbaenia before, but this one is a good bit bigger than most other species and the skull is oddly similar to that of a Weasel. I’m not really sure why, because the diet of these strange reptiles is very poorly known. It seems likely that they’ll eat invertebrates and small vertebrates, presumably in burrows, which does actually sound similar to a Weasel.

Weird, but pretty awesome!

Friday mystery object #277

This week I have a pretty interesting little skull from the Grant Museum of Zoology for you to try your hand at identifying:

mystery277

Any ideas what this might be from?

As usual you can leave your answers below – I have a feeling that some of you will find this easy, so please try to be a bit cryptic with your suggestions. Have fun!

Friday mystery object #275

This week I have a genuine mystery skull for you to identify from the Grant Museum of Zoology:

mystery275

I think I know what it is, but I’d be keen to see if you agree with me.Probably a bit on the easy side, so please keep your answers cryptic to avoid spoiling the fun for others!

Oh and apologies for the substandard photos – I used my phone with a tripod, which sort of worked, but it’s not ideal. Hope it’s good enough for you to make an identification!

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!

Friday mystery object #274

Last week I talked about ungulates in collections being incorrectly identified as sheep. This week I have a specimen for you that is also not a sheep, although it does look a bit sheepish. Can you work out what it is?

mystery274

You can leave your thoughts in the comments section below – I’m not sure they need to be cryptic, but it certainly adds to the fun!

Friday mystery object #272 answer

Last Friday I gave you this skull to identify:

mystery272

It was a bit of mean one, because although the family is fairly distinctive, it has poor species representation in online resources or indeed the literature.

The cranium is quite low and long, with some similarities to an otter, but the rostrum (or muzzle) is a bit too narrow and the teeth aren’t quite the right shape. Also the orbits are orientated more vertically, whereas otters have orbit that are at more of an angle so the eyes are closer to the top of the head.

The overall shape, dental configuration and median lacerate foramen all suggest it’s a member of the Herpestidae.

Narrowing down the species was a step too far however, after all, there are around 34 species spread across Africa, Madagascar and Asia and Europe and they are generally quite similar in cranial morphology, with only a few species having good descriptions of the skull.

To help challenge the lack of images of mongoose crania online, I’m pleased to say that this specimen does have an identification – it’s a Ruddy Mongoose Herpestes smithii Gray, 1837. While the name Ruddy Mongoose makes it sound like it’s annoyed me, it actually refers to the reddish-brown of its coat.

A Ruddy mongoose from Daroji wildlife sanctuary in Karnataka, India. By Kalyanvarma, 2009

A Ruddy mongoose from Daroji wildlife sanctuary in Karnataka, India. By Kalyanvarma, 2009

This species is endemic to India and Sri Lanka, where it lives in dry, forested hills and feeds on pretty much anything it can get hold of, from snakes to bird eggs. As with other mongooses (or should that be mongeese?), they have a mutation that prevents snake neurotoxins from bonding at receptor sites, meaning that they are immune to some types of venom – pretty handy if you’re going to eat snakes!

Friday mystery object #272

This week I have another specimen from the Grant Museum of Zoology for you to try your hand at identifying:

mystery272

I have a feeling that it may be easy to get this identification to Family level, but species may prove a little bit more tricky.

I’d love to hear what you think it might be, so leave your suggestions in the comments box below. Have fun!

Friday mystery object #271 answer

Last Friday I gave you this odd looking V-shaped bone to identify:

mystery271a

It led to a lot of speculation on Facebook and Twitter, with ideas including a bird wishbone, hyoid or mandible. However, the comments on the blog tended to be a little more focussed in the area of the mandible of an ant-eating mammal.

The two little prongs at the anterior of this lower jaw are a bit of a give-away about which type of ant-eating mammal it is, as they are only seen on one family. When you look at the additional image I provided it becomes even easier to work out which:

mystery271b

As most of you correctly worked out, this is a specimen of Pangolin, of which there are four species in the genus Manis (thanks Allen Hazen for the correction – there are more like eight species in the family). I found this nice illustration of the skulls of the various species, to help narrow it down even further:

Anatomical and zoological researches: comprising an account of the zoological results of the two expeditions to western Yunnan in 1868 and 1875; and a monograph of the two cetacean genera, Platanista and Orcella. John Anderson, 1878.

Anatomical and zoological researches: comprising an account of the zoological results of the two expeditions to western Yunnan in 1868 and 1875; and a monograph of the two cetacean genera, Platanista and Orcella. John Anderson, 1878.

So it appears from the morphology of the premaxilla, zygomatic region and nasals that this is a Sunda Pangolin, Manis javanica Desmarest, 1822.

Manis javanica by Piekfrosch, 2006

Manis javanica by Piekfrosch, 2006

These unusual scaly insectivores are critically endangered due to poaching for their meat, skin and scales for the Chinese market, with their population suspected to have declined by 80% in the last 20 years, despite having a protected status. Sad to say that their ability to roll into an armoured ball does nothing to protect them from people.

Friday mystery object #269 answer

Last week I gave you this mystery object from the Grant Museum of Zoology to have a go at identifying:

mystery269

If you’ve been checking the mystery object recently you’ll notice that this specimen has a feature of the palate that I made reference to in the answer to mystery object #267 – the Tasmanian Devil. It’s incompletely ossified, which is a characteristic of marsupials.

The large curved canines and pointed premolars suggest some predatory activity, while the flattened molars suggest some grinding of vegetation, making this one of the marsupial omnivores, in the Order Peramelemorphia.

The large size of the skull and the long curved canines make this specimen rather distinctive – as first spotted by Richard Lawrence, this is indeed a Continue reading →

Friday mystery object #268 answer

Happy New Year! I hope everyone had a lovely festive period.

I gave you this distinctive specimen from the Grant Museum of Zoology to try your hand at identifying:

mystery268

Despite being distinctive, it raised some discussion about the identification, because there are few resources available for comparison.

Phil Cox was the first to get the right Family (at least in the comments – @MelanieGbones got it on Twitter) – the Chrysochloridae or Golden Moles. Then the discussion got a bit more involved as species were discussed and the possibility of the convergent Marsupial Moles was considered.

There are 21 species of Golden Mole, all of which occur in southern Africa, which could have made this a very difficult identification to species, if it wasn’t for the large size of the skull and the very characteristic large and vertically-posteriorly flaring zygomatic arch that continues round to near the back of the skull. This narrows it down to one of two species in the genus Chrysospalax.

The extent of this feature in this specimen, plus the shape of the palate, suggest to me that this particular specimen is from the

Continue reading →

Friday mystery object #268

Merry Christmas mystery solvers!

This week I have an unusual object from the Grant Museum of Zoology for you to identify:

mystery268.jpg

It’s pretty distinctive, but I’ve not seen many of these, so hopefully it’ll make an interesting object to identify. As usual, if you think you know what it is, please leave a hint or cryptic clue rather than just writing down the answer – it makes it more fun for other people that way.

Have fun!

Friday mystery object #267 answer

Last Friday I gave you this specimen to identify:

mystery267

It was a pretty distinctive one, but a great specimen – and a nice robust example of this particular species.

The partially ossified palate and nasolacrimal (or tear) duct on the external border of the orbit shows that this is a marsupial, and the pointy, robust teeth suggest that it’s highly carnivorous with a penchant for carion, which narrows down the options pretty effectively.

As many of you recognised, this is a Tasmanian Devil Sarcophilus harrisii (Boitard, 1841) – so well done to Tone Hitchcock, Chris, Cindy Nelson-Viljoen, Ric Morris, henstridgesj, palfreyman1414, Lauren McCafferty, joe vans, Daniel Jones and Daniel Calleri, Allen Hazen and Michelle for getting this one right. The key was definitely in those marsupial characters, which immediately ruled out any of the highly diverse placental carnivores.

Tasmanian Devil (Sarcophilus harrisii), Tasmanian Devil Conservation Park, Taranna, Tasmania, Australia by JJ Harrison 2010.

As several of you alluded to, the Tasmanian Devil is undergoing a major decline in population at the moment, mainly due to a particulary nasty transmissible disease that causes tumours to develop on the face, preventing feeding. The tumours are spread between individuals when they bite each other, especially when feeding, which is pretty common Devilish behaviour.

In fact, Devils are pretty rough and tumble creatures in many of their behaviours. When breeding they have a large litter of up to 30 young, which have to compete for just 4 nipples in the pouch. Unsurprisingly, few of the litter survive and presumably those that do are pretty pushy.

Hopefully the Devils will survive their current population crash. There are some individuals who show some resistance to the facial tumour disease, which reflects the importance of genetic diversity within populations. It would be a great shame if the Devils went the same way as the other large marsupial carnivore, the Thylacine.

Friday mystery object #266 answer

Last week I gave you this distinctively weird looking skull to identify:

mystery266

As I suspected, many of you worked out what it was straight away, but I wonder if it would have been as easy if the side view hadn’t included the mandible?

The upper dentition, especially the pair of incisors, is somewhat similar to that of a rodent, but that mandible is ludicrously massive and could only really belong to the weirdest primate in the world: the Aye-aye Daubentonia madagascariensis É. Geoffroy, 1795

So very well done to Tone Hitchcock, henstridgesj, Chris, Cindy Nelson-Viljoen, Daniel Jones, steve torna, Agata Stachowiak, palfreyman1414, boneman2014Lee Post, joe vans, Allen Hazen, Dave Taylor, Michelle, witcharachne, and Daniel Calleri.

The Aye-aye’s incisors are an adaptation for gnawing holes in wood to get at grubs inside. It finds these tasty morsels using a tapping finger and crazy bat-like ears to detect the tunnels the larvae create when feeding, with a system a bit like seismic ground response analysis.

Aye-aye by Frank Vassen 2008

Aye-aye by Frank Vassen 2008

 

Once the squishy prey has been detected and an entry point has been gnawed, the Aye-aye fishes it out using a specially adapted long, thin finger with a hooked claw.

Aye-aye fingers by Dr. Mirko Junge 2009

Aye-aye fingers by Dr. Mirko Junge 2009

Basically, the Aye-aye feeds rather like a woodpecker, but with the benefit of fingers and teeth. Perhaps it’s weird, but it’s most definitely wonderful!Aye_aye