Friday mystery object #446 answer

Last week I gave you this mystery object from the collection of the late Dr Don Cotton to have a go at identifying:

It led to some really interesting discussion in the comments, which converged on this being a whale vertebra. More exactly, one of the cervical (neck) vertebrae from the neck of a smallish to medium-sized whale.

Whale necks are very short and the bones are a bit odd, as in they can be fused together in the adults and sometimes in juveniles (but not always), and depending on the species they might not fuse at all. This one is not fused, but you can see facets just above the solid centrum section, where the vertebra in front of this one would have snugly nestled.

It looks like the lateral processes (bits that stick out to the side) that would have extended from the facets, but have broken off, presumably due to the action of the waves on the shore where this specimen washed up. This makes it even harder to identify which of the cervical vertebrae this is or the species that it came from. However, the squared centrum and spur-like lower processes make me think that this is probably from one of the cervicals nearer the thoracic (chest) region – my guess would be cervical number 6 (cervical 7 often lacks the lower processes while 3,4 and 5 tend have better developed lower processes).

In the comments the discussion focussed on large dolphins, like the Beluga or Narwhal, but the shape reminds me more of the cervicals I’ve seen from baleen whales like the Fin Whale, although the size is all wrong. However, there is a much smaller member of the Balaenoptera species complex that inhabits Irish waters: the Northern Minke Whale Balaenoptera acutorostrata Lacépède, 1804 – which is what I think this mystery object probably came from.

I could be wrong and this could possibly be from a large dolphin that occurs around Ireland, like an Orca or Long-finned Pilot whale, but these have extensive fusion of the neck vertebrae, so I’m going to stick my neck out with the Northern Minke.

Northern Minke Whales are well documented in the waters around Ireland, especially during the spring and summer months. Don Cotton was a founding member of the excellent Irish Whale and Dolphin Group, which is the source of much of the information we have about the occurrance of these otherwise enigmatic animals in Irish waters.

Friday mystery object #444

This week I finally had a chance to look at some skulls in the Dead Zoo collections, and I thought I’d share the joy of that with you here:

Do you have any idea which two species these skulls might be from?

As ever you can leave your thoughts, questions and suggestions in comments box below. If you find this too easy, maybe make your answer cryptic, to give other people a chance to work it out for themselves. Enjoy!

Friday mystery object #441 answer

Last week I gave you this rather impressive spider to have a go at identifying:

The huge size had a several people on Twitter and in the comments here suggesting it’s a Goliath Birdeater Theraphosa blondi. It is big, with a leg span of around 19-20cm, but not quite as big (or as chunky) as the Goliath.

Also, although it’s probably not easy to see from the main image, this specimen has tibial spurs on the first pair of legs – which are absent in Goliath Birdeaters:

Tibial spurs on first pair of legs (don’t confuse them with the hooked mating organ at the end of the pedipalp)

Another thing that’s not easy to see in the main image is some subtle purple iridescence on the first three legs, pedipalps and chelicerae:

This is something I only noticed after looking for it with a light and it offers some support for the identification on the side of the box:

This label suggests the specimen is Bolivian (or in this case Peruvian) Blue-leg Birdeater Pamphobeteus antinous Pocock, 1903, but that species (as hinted at by the name) has quite distinctly blue legs:

There are fourteen other species in the genus Pamphobeteus, some of which also display some degree of iridescence on the same parts of the body, so I suspect that what we have here is one of the other species. I’m wondering if it might be Pamphobeteus grandis Bertani, Fukushima & Silva, 2008, which is very similar in appearance to P. antinous, except it has purple iridescence rather than violet/blue.

Unfortunately, I’m no spider expert and I don’t have time at the moment to go through the diagnostic features of P. grandis and relatives under a microscope, but when I get a chance I’ll check my tentative identification!

Friday mystery object #440 answer

Last week I gave you this piece of bone to have a go at identifying:

It was a particularly difficult challenge and I’m still not 100% sure of what it is, but I was very interested to hear your thoughts.

There was a general leaning towards one of the (many) bones of the skull – although since there’s a suture running through the middle of this, it must consist of at least two different bones that have fused.

This feels right to me, since there aren’t many other parts of the skeleton consisting of fused bony plates containing foramina. But as to which bones of the skull and which animal, that’s a much more difficult identification prospect.

Unfortunately this kind of identification usually depends on a combination of familiarity with a range of skulls and comparative collections to figure it out and, I’m sad to say, that I’ve had very little opportunity to immerse myself in cranial collections for several years now and I rarely get a chance to work on comparative material these days.

The best I could come up with is this being a section from the upper internal portion of the orbit of a Sheep Ovis aries Linnaeus, 1758 (or something quite similar).

I’m thinking this partly due to the V-shaped notch in the margin of the bone, which can be hard to spot in the initial photos, so here it is from the side:

This notch is something I think of as being present in some (but by no means all) Sheep specimens (e.g. take a look at the dorsal view in Mike Taylor’s fantatsic SV-POW! blogpost featuring a very helpful Sheep skull multiview). When I checked with a couple of my own specimens, I think I can just make out where this mystery section might sit – but it’s very hard to be sure since the region is quite variable between individuals (or perhaps breed) by the looks of my specimens:

I hope that wasn’t too disappointing as a challenge, and I apologise for not offering a definitive answer, but if I manage to track down some old specimen that is missing this exact section of bone, I’ll be sure to share it here!

In the meantime, please feel free to offer more suggestions and, if you have comparative material of your own, maybe see what you think? Thanks everyone!

Friday mystery object #438 answer

Last week I gave you this closeup of a mystery object from the Dead Zoo:

I thought it might be a bit too easy, so I asked for cryptic clues – and I was neither wrong, nor disappointed.

There were a variety of comments both here on the blog and on Twitter, and it was fairly clear that some key ideas emerged. Termites and ants were mentioned a lot (in relation to diet), but it was one of the seven deadly sins that was most often referenced. Clearly this sin is Sloth, but the animal is also clearly not a Sloth, since it has five claws and not just two or three. Plus, Sloths eat leaves rather than invertebrates.

However, there is of course a termite hunting critter with five toes and “Sloth” in its name – the Sloth Bear Melursus ursinus (Shaw, 1791).

Like their cousin the Giant Panda, the Sloth Bear has veered off the quite generalist diet of most bear species and focused on something locally abundant and easy to access – assuming you have the right equipment. In this case the equipment is a set of absolutely MASSIVE claws, long lips and tongue and no teeth in their upper jaw.

Sloth Bears are somewhat lanky looking compared to their similarly-sized Black Bear cousins and while they are less carnivorous, they can be quite formidable when faced with another predator thanks to a their large canine teeth and those impressive claws.

This particular specimen has been displaced from its usual location thanks to building works taking place in the Dead Zoo. Unfortunately, the wild living population is also being displaced due to habitat loss and degradation.

My thanks to everyone who commented on the mystery object – there were some great cryptic answers and while I’m a bit put out because so many of you figured it out, I’m happy that so many of you clearly know about these somewhat odd – but in my opinion, very interesting – members of the bear family.

Friday mystery object #437 answer

Last week I gave you this mystery bone to have a go at identifying:

It’s clearly a scapula (aka a shoulder blade), and it’s quite large. There were plenty of suggestions, which generally leaned towards a large cervid – such as a Giant Deer.

Giant Deer at the Dead Zoo

The general shape isn’t far off, but there are a few details that are different. One is the size – a Red Deer scapula is smaller maybe around 20-23cm long, but Giant Deer scapulas are even bigger than the mystery object.

But also the shape of the scapula spine isn’t quite right, especially the wobble just visible halfway down and at the acromion process, where the scapula spine ends near the articulation with the humerus.

That acromion process also helps us rule out Horse, as Adam Yates pointed out in the comments.

This scapula most closely matches that of a Cow Bos taurus Linnaeus, 1758.

So well done to palreyman1414 and katedmondson, who spotted the bovine nature of this bone.

Friday mystery object #432 answer

Last week I gave you a mystery object from the Grant Museum of Zoology, UCL, with this old photo from my time as the Curator there:

This is one of those species that I have a bit of a soft spot for, due to the general weirdness of the skull. That does however make it quite recognisable as a specimen, even in a photo that hasn’t been taken for the purposes of identification – like this one.

Everyone who commented recognised that this is some sort of turtle, and thanks to that very flat skull with all the features towards the very front end, most people worked out that it’s a from a Mata-mata Chelus sp. Duméril, 1806.

Illustration of Chelus fimbriatus, by R. Mintern, 1885

Back in 2016, when I took the photo of the specimen, that would have been enough for a species identification (which would have been Chelus fimbriata), but today it’s simply not good enough, since molecular taxonomists determined a species level split in populations from the Amazon and Orinoco basins in 2020. Darn.

Fortunately, morphological differences between Mata-mata from different basins have been recognised for a while (link opens a pdf of ), reflecting the molecular split between species. Unfortunately, the main area of morphological difference is in the carapace, which isn’t in the photo I provided (if only I’d known that the species was going to split back in 2016…).

But fear not – back in 2018 Hannah Cornish did a Specimen of the Week blogpost about this very specimen, with some more useful images. The overall outline of the Grant specimen seems more rectangular than oval, which may indicate that it is an Amazon Mata-mata, making the original identification of Chelus fimbriata (Schneider, 1783) still correct – although a proper examination of the specimen would be needed to confirm that.

So a hearty congratulations to everyone who figured out what this was – and I would suggest taking a look through the comments from the mystery object, as there are some very interesting observations and discussions about that strange skull which are well worth a read. That’s the kind of thing that I love most about running this blog!

Friday mystery object #431 answer

Last week we had a genuine mystery object to identify from the Andalusian coast, which was found and photographed by Paula Burdiel:

Image by Paula Burdiel, 2022

When Paula contacted me, she also provided links to some useful resources, including the Fishbase list of all the marine fish found in Spain (which is fantastic for narrowing down the list of likely suspects) and the #ScanAllFish digitisation project, which has the ambitious and laudable aim of scanning all fish species (although unfortunately it looks like they haven’t got around to this species just yet).

Any extra information is useful when trying to identify fish, since there are so many species, but sometimes a bit of familiarity is what you really need to start narrowing down options, which makes the Zygoma community a helpful resource when dealing with an identification like this. And you did not disappoint!

Tony Irwin, jennifermacaire and Wouter van Gestel all came through with excellent observations on the species. This object is a neurocranium (we’ve talked about these before) with a very pronounced supraoccipital crest (the big fin-like crest on top), which combined with the overall shape of the neurocranium suggests it’s a member of the Sparidae (the family containing the Porgies and Seabreams).

Knowing this, and having the Fishbase list, makes it much easier to narrow down the likely species. Unfortunately, there is no single resource to make comparison easy, but a lot of trawling through a variety of images of skulls and neurocrania will yield results (Flickr has some useful images for example).

Image by Paula Burdiel, 2022

From my searches, the shape of the supraoccipital, vomer/prevomer (the beaky-looking bit) and that impressive set of supraorbital crests (those frills of bone above the eye sockets) suggest that this mystery object is probably the species suggested by Tony Irwin – the Gilt-head Seabream Sparus aurata Linnaeus, 1758. I’m not 100% sure of this identification, but it’s the best fit I can find.

Thanks to Paula for sharing this object and thanks to eveyone for your thoughts on this specimen – it’s always valuable to get your input!

Friday mystery object #431

This week I have another guest mystery object for you to have a go at identifying, this time it’s from Paula Burdiel, who found the specimen in summer 2020 while beachcombing in Islantilla, Huelva (Spain):

Image by Paula Burdiel, 2022
Image by Paula Burdiel, 2022
Image by Paula Burdiel, 2022
Image by Paula Burdiel, 2022
Image by Paula Burdiel, 2022
Image by Paula Burdiel, 2022

With this fantastic array of images and clear locality information, I’m hoping that we can figure out which species we have here. Let’s hear what you think it might be in the comments below – between us I think we can identify this fishy mystery object!

Friday mystery object #430 answer

Last week we had a second guest mystery object from Rohan Long, who is based at the Harry Brookes Allen Museum of Anatomy and Pathology at the University of Melbourne.

Image by Gavan Mitchell, 2022

It was a genuine mystery object and it certainly proved quite tricky. There were quite a few suggestions of gibbon, but the proportions of the long bones aren’t right, with gibbon radius and ulna bones proportionally far longer in relation to the humerus or any of the the bones of the legs than what we see above. The skull does look quite gibbony gibbonesque gibbon-like, but generally gibbons have an auditory bulla (the region on the underside of the skull that houses the hearing apparatus) that strongly curves, almost like a boomerang, whereas here the feature is much straigher.

Image by Gavan Mitchell, 2022

The teeth tell us that the mystery object is from one of the Cercopithecidae (Old World Monkeys) since there are only two premolars instead of the three that you find in the Platyrrhini (New World Monkeys). That helps a bit, but there are still over 150 species in the Cercopithecidae to consider.

Some can be ruled out fairly easily, such as members of the Papionini, like baboons and macaques, which have adults that are more prognathic (their jaws jut forward) that this specimen. This is less true for juveniles (jaws jut more as the animal grows and matures), but we can ignore that here, since the mystery specimen has well-fused sutures and visible wear on the teeth, so we know it’s an adult.

Image by Gavan Mitchell, 2022

One thing that can be useful to consider when trying to identify primate skulls is the shape and position of the nasal opening. This can vary within species and it can be a feature sensitive to the angle at which a photograph is taken (making it more difficult to assess from images), but overall it can help narrow down possibilities without having to get into too much fine detail early in the identification process.

Image by Gavan Mitchell, 2022

The Mammalian Crania Picture Archive has well standardised images, including a reasonable variety of primates with males, females and animals of different ages represented. They also provide some measurements for each specimen, that may be useful when making comparisons. The primate page is here in case you’re not familiar with this very valuable resource.

Over the last week I’ve taken a look through a wide variety of skulls from different primate taxa and I’m confident that the mystery specimen is from the Colobinae. I think the position of the nasal opening (especially the top part of the opening in relation to the eyesockets) is helpful in distinguishing possible species within the subfamily. This makes sense when you consider that a third of the genera in the Colobinae are in a group known as the “odd-nosed monkeys”.

In this specimen the nasal opening forms a shield shaped hole with a flat top that starts quite high in relation to the eye sockets. In most species it starts lower, sometimes well below the line of the bottom margin of the eye socket. The Red Colobus is superficially quite similar, but when you look at other features it doesn’t look right – for example, if you look at the underside of the skull it has several different features, include a differently shaped incisor arcade and the pterygoids (the wing-shaped bits of bone that spread to either side, just behind the palate) are a different shape.

However, I did find a species which matches much better, so I am tentatively suggesting that the mystery object may be a Black-crested Sumatran Langur (AKA Mitred Leaf Monkey or Sumatran Surili) Presbytis melalophos (Raffles, 1821). If not that species I think the mystery specimen will be in the same Genus. There will undoubtedly be additional species with similar skulls that I’ve not seen, but within the limits of the resources at my disposal I don’t think I can do any better than that.

Oddly enough, I have had a skull of this species as a mystery object before, but it appears to be from a much younger individual, so at first glance it looks quite different, but the general features of the nose still remain:

My thanks to everyone for your suggestions and many thanks to Rohan for sharing this mystery object. It’s been an interesting one and has reinforced my conclusion that primate skull identification can be REALLY difficult!

Friday mystery object #430

This week we have another guest mystery object from Rohan Long:

Today’s mystery object is another item from the Harry Brookes Allen Museum of Anatomy and Pathology at the University of Melbourne. In contrast to our last offering – a partial skull with most of the diagnostic features frustratingly absent – this is a full skeleton of a small primate. We have many classroom sets in our collection comprising complete, disarticulated skeletons of mammals, mostly marsupials and primates. The primate sets overwhelmingly consist of macaques (Macaca sp.) which I presume were lab animals from the University. Additionally, there are sets of a few baboons, a few chimpanzees, and one Sacred Langur (Semnopithecus entellus). Then there’s this one.

Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022

I had originally described it as, “large macaque”, but after cataloguing dozens of macaque skeletons, it stood out as something different. It kept bugging me, and I had committed myself to giving every specimen in our comparative anatomy collection a proper identification. I had found some previous blog posts by Paolo while researching how to identify primate specimens, and that’s what prompted me to initially get in touch. In regards to provenance, our comparative anatomy collection was mostly amassed in the early 20th century, and many specimens are associated with Frederic Wood Jones, Anatomy Department Head from 1930-1937. Wood Jones and his colleagues had strong international networks, and there are species in this collection from all over the world.

As ever you can leave your observations, thoughts and suggestions about which species this might be in the comments section below. Have fun with this one!

Friday mystery object #428 answer

Last week we had a guest mystery object from Rohan Long, Curator of the Harry Brookes Allen Museum of Anatomy & Pathology at the University of Melbourne:

Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022

It is not an easy one. This part of the mammalian skull contains very few helpful diagnostic features – as pointed out by Kenny Travouillon:

Plus this is from a juvenile animal, and we all know how that can cause problems when making an identification.

Thanks to everyone for your comments – Rohan was keeping and eye on them here and on Twitter, so I’ll hand over to him to wrap this one up:

Well, it’s been a week, and many identifications for the mystery skull were offered on Twitter and in the Zygoma comments. Some suggestions were silky anteater, marsupial mole, pangolin, armadillo – but the focus quickly turned to marsupials. On Twitter, mammal curator Kenny Travouillon said it was not peramelemorphian or macropod, zooarchaeologist Jillian Garvey said that it could be macropod. Early on, biology lecturer Robin Beck said that it was definitely a phalangerid, and that it was probably a juvenile common brushtail possum (Trichosurus vulpecula). Robin identified the specimen as phalangerid based on the restriction of the mastoid exposure to a ventral strip on the occiput, and then narrowed down to trichosurine, rather than a phalangerine, due to the relatively flat dorsal profile of the skull. The bone texture indicates a juvenile specimen. (Richard came to the same conclusion in the Zygoma comments.)

I went digging around in our comparative anatomy collection to investigate this and then clouded matters a bit, as I found a partial skull of a juvenile common ringtail possum (Pseudocheirus peregrinus) which was superficially similar to the mystery skull. I thought this was the real identity of the skull, but Robin pointed out that the ventrally restricted mastoid exposure, more recessed stylomastoid foramen, and a well-developed pterygoid fossa all point to Trichosurus rather than Pseudocheirus.

Image by Rohan Long, 2022
Image by Rohan Long, 2022

I think this partial skull is conclusively identified to genus. I have already identified a number of (less ambiguous) Trichosurus specimens within the comparative anatomy collections. Although it would take more work to definitively ID the species, I think it is likely to be vulpecula – a very common and widely distributed species in Australia. As you may have noticed from the original images, the specimen has sand grains adhering to it. Based on this, I’d say that this was collected in the field, probably by Frederic Wood Jones (or members of the McCoy Society for Research and Investigation, which he founded) in the 1930s.

Thank you all for your suggestions and discussion!

Finally, I’d like to add my thanks to Rohan for giving us this mystery object to mull over. If anyone else fancies doing a guest mystery object, please do get in touch.

Friday mystery object #428

This week I’m delighted to have a guest mystery object for you, presented by Rohan Long, Curator of the Harry Brookes Allen Museum of Anatomy & Pathology at the University of Melbourne (who is on Twitter as @zoologyrohan) and photographed beautifully by his colleague Gavan Mitchell:

This is a skull from the Harry Brookes Allen Museum of Anatomy and Pathology at the University of Melbourne. Although the focus of our museum is on human anatomy, we have a significant comparative anatomy collection, which comprises hundreds of specimens of vertebrate animals – skeletal material, skulls, and potted specimens. Occasionally, I’ve encountered animal specimens that are very difficult to definitively ID, and this partial skull is one of them.

Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022
Image by Gavan Mitchell, 2022

Our comparative anatomy collections date from the earliest 20th century and are predominantly native Australian mammals and domestic animal species. However, the academics at the University have always had international networks, and there are species represented in the collection from all over the world. Many have been prepared in a lab for class specimens, many have been collected in the field. The latter are assumed to have been associated with Frederic Wood Jones, a British anatomist with a fondness for comparative anatomy and island collecting trips who was head of our Anatomy Department from 1930 to 1937.

Do you have any ideas what this portion of skull might be from? I don’t think we need cryptic answers for this one. Rohan will be keeping a close eye on the comments, so do feel free to ask questions.

I hope you have fun with it!

Friday mystery object #427 answer

Last week I gave you a nice skull to have a go at identifying:

It proved to be more tricky than I thought, but I think that may be because there is a skull image on Wikimedia that may have misled people searching for a comparative skull of this species.

This is the skull of the humble Guinea Pig Cavia porcellus (Linnaeus, 1758), but if you tried searching for Guinea Pig skull, you may have seen this image:

Clearly this is not the same species as our mystery object – the incisors alone are an absolute give-away, with their striking orange enamel and the their much greater size. Those big incisors also bed deeply into the mandible, creating a pronounced ridge at the base of the mandible that props the entire skull at an angle. This one is the skull of a Coypu, regardless of the Guinea Pig identification given on the Wikimedia page.

There were also quite a few suggestions that the mystery object might be a Capybara, or one of several other South American rodents. The size suggests it’s not Capybara – I suppose a very young Capybara might just about be small enough, although they would certainly have less pronounced muscle scars and more open sutures.

There are plenty of other South American rodents, but most of those of a similar size and overall shape have a much more V-shaped exit to the nasal passage in the palate, rather than this very open and U-shaped structure.

When identifying skulls, it’s generally best to rule out the most common and likely species first, since this can significantly speed up the identification process. This is why misidentified comparative specimens can be a problem, so always try to check more than one example. I’ll certainly be suggesting an edit to the misleading Wikimedia entry to help prevent this issue in future, but this isn’t a criticism, since nobody is perfect and I know I’ve made mistakes myself in the past, especially early on, so I’m trying to fix them retrospectively!

Friday mystery object #425 answer

Last week I decided to give you a taste of the kind of identification I often get asked to do. One bone with no scale and a photo from just one angle that doesn’t quite show what you’re looking at very clearly:

I must admit that I was suitably impressed with the responses though, since the very first response by Chris was cryptic yet absolutely spot-on.

As you probably figured out, this is the upper front section of jaw (or premaxilla if you’re feeling fancy) from a fish.

The more difficult bit is working out which fish, since there are plenty to choose from – over 28,000 species.

This is where knowing where the specimen came from can be helpful, since it can help narrow down the likely possible options. However, morphology is always the most important thing to consider and I find that locality is more useful for figuring out species than the higher taxonomic group – and higher taxonomy is really helpful for narrowing down options.

Of course, to do this you need good comparative morphological specimens to help steer you in the right direction. This can be difficult when working with fish, since there are so many species and they have skeletons that tend to be poorly fused, so there are many separate bony elements for each animal.

However, there are some great resources out there that are helping address this problem. The Florida Museum has a really helpful resource with images of bony elements of fish, listed by taxonomic group and Osteobase is a similar resource that is even more useful for identification as it’s more image-led.

The premaxilla isn’t always the easiest element to differentiate, but there are a few things to look for:

The teeth. You do need to be careful with these as a feature, since they can break off and look quite different between individuals. Check out the teeth in this specimen and notice there is a line partway down each tooth. This is a weak point that the teeth can break along quite easily and I’ve seen examples of premaxillae from this species that have mainly squarish, blunt looking teeth because the sharp cusps have come off.

General shape. Some Orders of fish have premaxillae that are almost solid triangles (like the Tetraodontiformes), others are long, thin and quite straight – looking almost like just a shard of bone (like some Beloniformes). It’s worth taking a good look at the shape and trying to spot processes and articulation points, since these provide clues to the taxonomy.

Processes on the rear of the premaxilla. These can be present or absent, well defined, poorly defined, high, low, long, short, simple, complex etc. The thing to remember about this mystery specimen is that the rear of the premaxilla curves downward with no processes on the upper surface – so its close relatives are also unlikely to have processes, or if they have them they are unlikely to be well-developed.

Processes in the middle of the premaxilla. Some groups have a process like a fin in the middle of the premaxilla (e.g. Esociformes and Osmeriformes). The mystery has no process here.

Processes on the front of the premaxilla. Many groups do have at least one process on the upper surface at the front of the premaxilla, but the number and shape are important for identification. The mystery specimen has two – the first is tall and shaped a bit like a bat-ear the second is not fully separate from the first and it is lower and quite squared off:

When you start to put all of these features together it becomes easier to narrow down possibilities. If you use Osteobase to scan through images of premaxilla you’ll find that the premaxillae that are closest (although none are identical) are from the Pleuronectiformes – or the Flatfish.

Knowing this one is from Irish waters (which I admitted in the comments) helps narrow down options to 22 species (things like Turbot and flounders) and with a bit of searching online and especially checking specimens in the Archaeological Fish Resource at the University of Nottingham you can narrow down the possible species to one good option.

This is the premaxilla of a Halibut Hippoglossus hippoglossus (Linnaeus, 1758). These large flatfish undergo a strange developmental distortion of the head that allows them to lie on their side on the seabed without having their left eye sitting in the sand.

Illustration of Atlantic Halibut Hippoglossus hippoglossus by Marcus Elieser Bloch (1723–1799), via rawpixel.com.

This asymmetry is far more obvious in the whole animal than it is when just looking at the skull.

As you can hopefully make out, the jaws are reasonably symmetrical and the distortion is mostly in the area of the frontals and ethmoid bones, which have shifted to allow the eye to move. Here’s a more complete view of the right side of the Halibut skull to finish up with:

I hope you enjoyed the challenge!

Friday mystery object #423 answer

Last week I gave you this fishy looking critter to identify:

It wasn’t an overly difficult one for most of you, since it is a very distinctive and somewhat unusual animal with some immediately recognisable features. Most obvious are the gills.

Bony fish only have one visible external opening on either side of their head where water exits after it’s flowed over the gills, and this is well hidden when the gill flap (or operculum) is closed. So this is clearly not a bony fish.

Most modern sharks have 5 external visible gill slits, but this one has six. That makes it a bit of an evolutionary anachronism. There are only seven species of shark with more than 5 gills and they are all in the Order Hexanchiformes, which narrows down the possibilities considerably. Of those, two have seven gills, leaving just five possible species.

Those five species sit in just two families – the Cow Sharks and the Frilled Sharks. These can be separated based on a variety of features, but the most obvious is that the Cow Sharks have fusiform (or spindle-like) body shapes with a very pointed nose to help them move efficiently through the water by minimising drag. The Frilled Sharks have more anguilliform (eel-like) bodies with a blunter head and mouth set further forward in relation to the eyes – a feature about the mystery object picked up on by Allen Hazen.

There are only two species of Frilled Shark to choose between and I’m not sure I could tell the difference between them based on the photo provided. However, one species is only found off the coast of South Africa, and in last week’s post I dropped a (hopefully) helpful clue – this specimen was caught off the coast of Ireland.

That means this can only be the Frilled Shark Chlamydoselachus anguineus Garman, 1884. Well done to Adam Yates for being the first to get it spot on. This specimen was caught off the coast of County Donegal at a depth of 390 fathoms (or 713 metres in standard units) just over 21 years ago. A special mention to Pete Liptrot on Twitter who managed to identify this mystery object to the actual specimen – not just the species!

Friday mystery object #422 answer

Last week I gave you this rather fishy looking mystery object to have a go at identifying:

With that prominent lure it was fairly obvious to everyone that this is an anglerfish of some sort, but there are somewhere in the region of 286 different species, so it needs some narrowing down.

That bulbous body shape is pretty distinctive though, so a lot of people both in the comments and on Twitter quickly identified this as one of the football fish in the genus Himantolophus.

Narrowing down to species is perhaps a bit tricky from just this photo. There are 22 species in the genus and thanks to the deep sea habitat these fish inhabit they aren’t commonly seen, so photos for comparison can be hard to find.

However, the double bony ridge on the head (that makes it look like it’s frowning) is very prominent in this specimen, which isn’t the case for all of the football fish species. However, it is particularly notable in the Pacific and Atlantic Football Fish species.

I have to admit that I’m just not good enough with fish identification to tell the difference based on specimens I’ve seen. However, since this specimen is in the Dead Zoo in Dublin, it seems unlikely (although not impossible) to be from the Pacific.

In the words of our youngest commenter:

It is indeed an Atlantic Football Fish Himantolophus groenlandicus J. C. H. Reinhardt, 1837, so very well done to E and everyone else who managed to work it out!