As I suspected, everyone figured out that this is the skull of an Alligator Snapping Turtle, but things have become a bit more complicated than they used to be over the last decade, since the single species that used to be in the genus Macrochelys has since been split.
The amount of splitting has varied, but at the moment it seems to have settled on two species being recognised; Macrochelys temminckii (Troost, 1835) and Macrochelys suwanniensis Thomas et al., 2014.
One of the key diagnostic features identified to differentiate between them is the angle of the squamosal (the bit of bone with the arrow pointing it above). In M. temminckii the angle is greater than 90° whereas in M.suwanniensis it’s less than 90°.
That suggests to me that the Dead Zoo specimen is probably the Suwannee Snapping Turtle Macrochelys suwanniensis Thomas et al., 2014. The only problem with this identification is that the collection locality is simply “Mississippi”, which doesn’t fit with the Suwannee river distribution of the species.
I’ll need to go back and look at a few other skeletal characters to confirm the identification once I’m back in the Dead Zoo, but my guess is simply that the collection locality wasn’t accurately recorded, since the specimen came from the natural history supplier Edward Gerrard rather being collected and properly documented by a researcher.
It certainly wouldn’t be the first time a representative locality has been given for a specimen meant for display or teaching rather than research!
Last week I gave you this skull from the Dead Zoo to have a go at identifying:
I think it’s quite a distinctive skull, so I didn’t provide a scale and I asked for cryptic clues to avoid spoiling the challenge.
The overall skull shape is fairly standard for an Artiodactyl, but while this specimen has no incisors in the upper jaw, there are fairly obviously empty alveoli that show where the teeth used to be. That means it’s not a member of the Ruminantia (the deer, antelope, cattle, giraffes and weird deery-antelopey type critters like chevrotains) since they all lack upper incisors.
That leaves the pigs, hippos and camels – and it’s clearly not one of the pigs or hippos.
The camel family is a bit odd. There are three wild species, but then an additional four entirely domesticated species. The proportions of this skull are a bit long for a Llama, Guanaco, Alpaca or Vicuña. That leaves the Dromedary, Wild Bactrian or Domesticated Bactrian camel as possibilities.
Dromedary skulls tend to have a horizontal nasal region then a steep rise to the braincase immediately behind the orbits, but this specimen has a more gentle slope running from the nose to the top of the braincase, so it’s Bactrian.
Unfortunately the Wild Bactrian camel is critically endangered and poorly represented in collections, so it’s hard to find enough comparative material to differentiate the wild and domestic Bactrians.
Well done to everyone who figured out that this is one of the double-humped ships of the desert. There were some great clues in the answers!
Last week I gave you this specimen from the Dead Zoo to have a go at identifying:
It came from a cabinet of cave bones, but Nigel Monaghan (Keeper of the Dead Zoo) wasn’t convinced that this specimen was actually found in a cave.
Partly that’s because it’s a fairly fragile specimen with poorly fused sutures – these don’t usually stay connected in cave deposits, but also because it’s from a species that you wouldn’t expect to find in the kind of caves that the rest of these collections came from. So what is the species?
I don’t think this is a very difficult one since I’ve done very similar specimens before (regular visitors should have had an advantage), so I was looking for cryptic or entertaining answers – and I was not disappointed. Tony Irwin got a great clue in, with a pun that reflected the genus:
I think we need to focus (did I spell that right?) on the shape.
It is of course the skull of a seal in the genus Phoca – and the blunt shape of the anterior portion of the auditory bulla suggests to me that it’s a Harbour Seal Phoca vitulina Linnaeus, 1758 rather than the very similar Spotted Seal, which has a slightly more accute angle on the anterior auditory bulla.
So well done to everyone who figured it out! Now we just need to figure out how it either got into a cave or (possibly more likely) got put into the wrong cabinet.
Last week I gave you this specimen from the “Unidentified” drawer in the collections of the Dead Zoo to try identifying:
I don’t think anyone had much difficulty in identifying it, since it is quite a familiar and characteristic skull, but well done to everyone who worked out that this is a European Badger Meles meles (Linnaeus, 1758).
There are two other species in the same genus – the Asian Badger M. leucurus and Japanese Badger M. anakuma, so they also need consideration (skulls of all three species can be seen in this paper by Andrey Puzachenko). However, the Japanese Badger is a smaller and more delicately skulled animal and the Asian Badger can be distinguised by differences in the shape of the region around the bony bulbs that hold the ear bones (called the auditory bullae – in Asian Badgers they’re more obtuse and have a straighter lateral margin).
So apart from the distinction between two members of the same genus, this is a fairly straighforward specimen to identify, it makes me wonder why it wasn’t recognised in the collection? I think there are a couple of factors, which I’ll outline here.
The first is that the lower jaw (mandible) is missing. This is totally normal for almost any kind of animal skull you find, except these badgers, which have a well-developed bony process that locks the mandible into the long jaw articulation (known as the glenoid fossa).
Badger skull with mandible locked in place.
Detail of jaw articulation showing the main features. Red = mandibular articulation, Blue = inside of glenoid fossa, Green = glenoid process that helps lock the lower jaw in place.
This captive mandible is a dead give-away when you see it, but it does mean that when it’s missing it can be confusing.
A mature adult European Badger like this (as indicated by the well-developed sagittal crest) would also normally have extremely extensive wear on their molar teeth, due to the abrasive grit in the gut of their main diet of Earthworms.
Extensively worn upper molars of an adult European Badger
But the mystery specimen has remarkably little wear on those massive molars. This suggests that it probably had a different diet than is usual for a Badger from northern Europe – and no, not mashed potatoes. The same species in southern Europe has a different diet to their northern counterparts, dominated by insects and fruit, so I wonder if the specimen was collected during someone’s holiday to somewhere in the Mediterranean?
[UPDATE 28th April 2020. Several people have kindly shared images of their badger specimens and it seems that the level of wear in my specimen is not as common as I thought. In one discussion the issue of soil type was raised and I think that may play a big factor. This specimen came from Devon, in an area with sandy soil. Other specimens from areas with muddy or silty soils showed much less wear. This may be coincidence, but it would make sense that Earthworms with coarser soil in their gut would be more abrasive to eat and therefore cause more dental wear. That would be fairly straightforward to test using museum collections. If this hypothesis about wear is correct, then the mystery specimen could be from anywhere with soils that aren’t too sandy.]
I hope you found that useful, or at least a bit of a distraction from lockdown. Stay safe!
Last week I gave you this rather nice, but somewhat tricky mystery object to have a go at identifying:
As well as here on Zygoma, people were checking this out on Twitter, where it was shared under the #GuessTheSkull hashtag started by @Yara_Haridy. I strongly recommend checking it out if you’re on Twitter and also giving Yara a follow as she does some great stuff.
As to this specimen, despite the difficulty, several of you managed to work it out down to species level – which I think deserves a round of applause, because this critter is not very well-known and there are few resources out there with examples of their skulls.
So, working through the options, despite having a whiff of possum about it, it can’t be a marsupial because it doesn’t have holes in the roof of the mouth (aka palatal vacuities), a shelf on the inside of the mandible or a tearduct on the outside of the orbit (aka external lacrimal duct) – all of which are marsupial traits as illustrated on this Tasmanian Devil skull below.
The teeth are those of a carnivore (or perhaps I should say Carnivore) and the auditory bulla is single chambered, so it’s one of the caniform carnivores, rather than one of the feliforms (that long snout suggests the same). This rules out the cats, hyaenas, mongooses and the weird Malagasy carnivores like the Fossa.
From that point on it gets more difficult. Some people thought it was a bit foxy, but the lack of a well-defined post orbital process rules out any of the dogs and it’s clearly not a bear, seal or sealion. That leaves the members of the Superfamily Musteloidea, which includes mustelids, racoons, the Red Panda, and the skunks.
Quite a lot of people got busy searching through possibilities in the largest of those groups – the mustelids. However, most of this family have fairly short, broad skulls. Only the ferret badger skulls come close to this specimen and even they aren’t as narrow. Similarly, the raccoons and Red Panda’s have fairly broad and short skulls.
So that leaves the skunks and relatives in the family Mephitidae. That makes life much easier, since there are only four genera in the family and three of those have wider skulls than this. So that leaves one genus that only contains two species – Mydaus or the Stink Badgers.
That’s where it gets really hard. A few folks on Twitter and Allen Hazen on the blog comments managed to get it to genus (Allen also worked out that it’s female), but I was especially impressed by the efforts of Rémi and katedmonson who went that step further and managed to get the identification to species. Here are the features:
…Comparing the two, M.j. has the slender snout, and a larger infraorbital foramen than the M.m. The big decider for me was the tympanic bulla. They seem to match the M.j. but not the smoother M.m. Also, females in the M.j. are known to lack a sagittal crest, so my best guess is female M. javanensis. About 4 years old. That had just eaten 6 earthworms and two beetles. And she had a limp on her left hind limb. (just kidding about the 6 earthworms, it was only 3)
I’m not sure about the earthworms, beetles or limp and I personally think the age would be a little younger – maybe 2.5 to 3 years since the earthworms have a large amount of grit in their gut and that significantly increases dental wear in animals that eat them. However, I think the rest is spot on – this is indeed the skull of a female Sunda Stink Badger Mydaus javanensis (Desmarest, 1820).
Mydaus javanensis specimen at Museum of Natural History in Vienna. By U.Name.Me, 2018
These odd looking animals have habits similar to the European Badger, foraging on the ground and in the surface of the soil for invertebrates and small prey, and sleeping in burrows during the day. However, while Badgers can be a bit whiffy, these guys have a full-on skunk-like noxious spray from their anal glands.
I hope you enjoyed that challenge, there will be another next Friday and if you want some extra mystery skulls, don’t forget to check out #GuessTheSkull onTwitter.
Last week I gave you this specimen from the Dead Zoo to have a go at identifying:
It was a bit of a tricky one, since the specimen has been sectioned down the midline and the bone of the maxilla has been removed to show the roots of the teeth.
However, many of you were stuck at home and had a chance to get into detail in the comments. There were some fantastic answers where the features were discussed, so I think it’s well worth sharing some of them:
We are confined at home, so we searched together with my 5 years old daughter. Here are our thoughts :
– foramen magnum in a downward position, low-crown teeth, bony part behind orbite, orbites facing toward the front, so we are dealing with a primate
– but a special primate because the orbites are open to the temporal fossa. And also it has a long snout with the orbites below the nasal bone. The orbites are not big enough for a nocturnal monkey. And also the very special lower incisors in horizontal position, also know as teeth-comb. We think it is a lemur-like animal.
The brain case is not round enough for a Lorisidae. We could not find pictures of all the lemur and sportive lemur species. But we saw the picture of a skull of the cat-ish one and it fits very well.
Second thoughts: we cannot quite see this but in my own notes on lemur;
Canine often incisiform and procumbent, arranged laterally with incisors in toothcomb, creating array of 3.
Ist mandibular premolar often caniniform
This would then be 3 premolar, 3 molar and therefore not Varecia but more probably Eulemur….
While some lemurs don’t have upper incisors, this one has small peg-like ones. A Ruffed lemur (Varecia variegate), while having the same dentition, has more of an orbital thickness.
Since the skull has been dremeled out, I am not sure how much of a diastema was between the canine and upper premolars. If there was one there, I will vote for a Ring tailed lemur (Lemur catta), female, because of the smoother occipital and more slender lower mandible. The size fits as well.
These comments all highlight features of the skull that belong to lemurs, but there is a little confusion caused by the bone removed from around the teeth.
Ring-tailed Lemur was the most popular answer, but the diastema (or gap) between the upper canine tooth and the first upper premolar that katedmonson mentioned would not be present on this specimen, even if the bone was still there. Also, that lower first premolar has a fairly simple conical/triangular shape with just one cusp – which makes it caniniform, as mentioned by steveryder.
Rather than the Ring-tailed Lemur, this is the skull of a Ruffed Lemur Varecia variegata Kerr, 1792. I think it’s probably from a female or young animal (or both) as it’s more gracile than some other specimens I’ve seen. This accounts for the reduced orbital thickness, slender mandible and smoother occipital mentioned by katedmonson.
Black and white ruffed lemur by Charles J Sharpe, 2018
I should say, on Twitter Michael English and Gabriella Κογντογριδη also recognised this as a Ruffed Lemur. Worth mentioning that if you use Twitter and you like identifying skulls (well OBVIOUSLY you like skulls if you’re reading this) then it’s well worth checking out the #GuessTheSkull hashtag started by Yara Haridy.
A new mystery object next week – stay safe and healthy!
This week I’ve gone for a slightly more artsy image for the mystery object than usual:
You can click on the pictures to get a large version, which you might find useful.
I foolishly forgot to measure the specimen or include a scale bar, so I’ll update with a length as soon as I get back to the specimen. Sometimes it’s nice to rely just on morphology, so let’s see if anyone can work out what this is before I provide more information. [UPDATE: it’s 84mm long]
However, it didn’t take long for you to work out what it was and, if I’m honest, you beat me to it, so well done on that and thanks for your contributions!
Clearly it’s a carnivore as it has well-developed carnassial teeth. However, immature animals with a mix of deciduous and permanent teeth can be confusing. It also doesn’t help when the skull shape is still forming.Fortunately, to help narrow it down there is the auditory bulla and that molar tooth just behind the carnassial. The shape of these features suggest that it’s a mustelid.
There was some discussion about badgers and otters, but Bob Church settled it by providing a very useful reference containing this image:
Figure from Long, Charles A. 1965 Comparison of Juvenile Skulls of the Mustelid Genera Taxidea and Meles, with Comments on the Subfamily Taxidiinae Pocock. American Midland Naturalist 74(1)225-232.
As you can see, this is an excellent match for the mystery specimen, both in dental morphology, auditory bulla shape and even scale, allowing us to make a confident identification of juvenile American Badger Taxidea taxus (Schreber, 1777).
So well done to Jeanie, katedmondson, Bob Church and Rémi, and my thanks to you all for your help in identifying this tricky specimen.
Last week I gave you this unidentified skull from the collections of the Dead Zoo in Dublin to have a go at identifying:
I wasn’t sure how difficult this would be – I know carnivore skulls can be a bit of a challenge, but this is a critter that’s come up as a mystery object a couple of times before. As such, I did expect a few of the regulars to recognise this, but it proved more difficult than I thought.
That said, nobody got it. Well, somebody got it, but that person was nobody with the simple statement:
I’m guessing coati 🤔
Of course, there’s more than one kind of coati, in fact there are four: the Ring-tailed, the White-nosed (or Coatimundi), the Eastern mountain and the Western mountain.
The mountain coatis are in the Genus Nasuella and they have a very narrow and gracile rostrum (that’s the muzzle area) – so this is not one of them. The other two are in the Genus Nasua and they are recognisable by their upward tilted nasal area and their upper canines which are very tusk-like – projecting forward and triangular. The mature adults of both species have a big sagittal crest, which this lacks, but that’s probably because it’s not a mature adult.
The slightly more inflated auditory bullae and the angle of the mastoid process (where the muscles that control the movements of the outer part of the ear attach to the skull) tells me that this is most likely to be the White-nosed coati Nasua narica (Linnaeus, 1766).
I hope that helps in case you need to identify another of these any time soon.