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 #436 answer

Last week I was in the lovely city of Edinburgh, catching up with many of my wonderful natural history colleagues from around the world at the Society for the Preservation of Natural History Collections (SPNHC) conference. While I was there, I spotted this object and thought it might pose an interesting mystery object:

Interesting perhaps, but clearly not very challenging, since I think everyone managed to figure out what it is, despite the unusual viewing angle. Well done to Wouter van Gestel for being the first to comment.

Here’s an image of the same object from a couple of different (and somewhat more common) angles:

The large size and that very distinctive lower jaw, where the two halves of the mandible meet and run parallel for over half the length of the jaw, are unmistakeable (as noticed by Adam Yates). This is the skull of a Sperm Whale Physeter macrocephalus Linnaeus, 1758.

Nearby, I noticed a much smaller version of this specimen, housed in a much smaller version of the National Museums Scotland, which definitely deserves a mention:

The teeth of a Lego whale are probably not as efficient at keeping hold of a squid as the robust curved teeth of the real animal, and the skull is a bit less impressively huge, but it certainly has charm.

If you get a chance to visit Edinburgh I definitely recommend a trip to National Museums Scotland – not just for the Sperm Whale and the Lego, but also for one of the most impressive taxidermy dioramas I’ve ever seen. Here’s a small section to give you an idea:

Friday mystery object #436

This week I have been in the beautiful city of Edinburgh at the conference of the Society for the Preservation of Natural History Collections (SPNHC), Biodiversity Heritage Library (BHL) and the Natural Sciences Collections Association (NatSCA) hosted wonderfully by National Museums Scotland (NMS).

It’s been a fantastic opportunity to catch up with natural history colleagues from around the world and to learn what everyone has been busy doing over the last few years. I also got to see some fantastic specimens held by NMS and I thought I’d set one of them as this week’s mystery object:

Do you have any idea what this might be?

As ever, you can leave your thoughts in the comments box below. Have fun!

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 #417 answer

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

Pretty much everyone recognised it as a marsupial, thanks to the palatal vacuities and inflected angular of the mandible (as Allen Hazen alluded to).

The size, general shape of the skull and tooth shape narrows down possible species very quickly, as it’s quite large (at around 17cm) and quite kangeroo-shaped. That leaves the likely options as Eastern-grey, Western-grey or Red kangaroos.

Red Kangaroo skulls tend to average around 205mm long, Greys tend to average in the region of 145mm, so this falls between the two – either a small Red or a large Grey.

The sutures of the skull seem well-fused and there are quite robust muscle scars, suggesting a well-developed adult animal. For me this hints that it would probably be in the large end of the size range of its species, rather than at the small end of the size range – hinting at it being a Grey.

Another feature that hints at Grey Kangaroo is the crown of the third upper incisor, which in Red Kangaroos tends to be slightly broader than it is long, whereas in Greys it tends to be longer than wide.

Unfortunately, I’ve so far failed to find good enough verified images or specimens of Western Grey Kangaroo skulls to differentiate from the Eastern Grey.

I do know that this mystery specimen is identified as an Eastern Grey Macropus giganteus Shaw, 1790, but I am also aware that the taxonomy of these animals has been complex and confusing, especially since their ranges overlap so I don’t fully trust that identification. Sometimes a dose of scepticism is important when dealing with historic collections, so I think I’ll just leave it there after the tough week I’ve had.

Friday mystery object #412 answer

Last week I gave you this rather nice skull to identify:

I was hoping that it would catch some of you out, since at first glance it looks like the skull of some kind of canid. I thought I had caught out Joe Vans, but then he noticed one of the features that sets this skull apart from dog skulls – the pinched-in section in the mid-muzzle area. Then everyone started piling in with their observations and my hopes of being tricksy were fully dashed.

This is of course the skull of that paragon of convergent evolution, the Thylacine (AKA the Tasmanian Wolf or Tiger) Thylacinus cynocephalus (Harris, 1808).

I’ve written fairly extensively about convergent evolution between Thylacines and canids before, when I worked at the Grant Museum of Zoology, so I won’t go into huge detail here, but I will give you an annotated image showing some of the features to look for that help distinguish these marsupial carnivores from their placental dopplegangers:

A= 8 incisors vs 6 in canids
B= Lacrimal duct on outside of orbit
C= Inwardly deflected angular process
D= “Pinched” midsection of rostrum
E= Palatal vacuities

These physical differences between the Thylacine and the Eutherian canids are features common to many marsupials and they act as reminders that evolution is limited by what it has to work with. At the most fundamental level that means DNA.

In recent years the methods for successfully extracting and sequencing DNA from museum specimens has moved on in leaps and bounds. In 2018 these advances allowed the Thylacine’s genome to be assembled, allowing comparison with their morphologically similar, but taxonomically distant counterparts.

The team that did this went looking for similarities between protein coding genes in the different lineages at first, to understand what was driving the morphological convergence – but it seems that they were looking in the wrong place.

When they looked more closely, it was actually in the cis-regulatory elements (the non-coding DNA that used to be considered “junk”, but which is now recognised as playing a vital role in regulating development) that genetic convergence was seen. It turns out that these elements were also driving convergence in brain development between Thylacines and canids.

It seems that protein coding genes are quite stable – if they mutate they usually stop working properly, so the mutation often doesn’t persist. But mutations in cis-regulatory elements can change gene expression with less risk of catastrophic consequences. Unsurprisingly that means they are increasingly being seen as the main drivers in evolutionary adaptation. If you’re interested in finding out more about this fascinating research, a pdf of the 2019 paper on Thylacine/canid genetic convergence by Feigin, Newton & Pask can be accessed here.

I hope you enjoyed this short trip down the road of convergent evolution, with a hat-tip to the genetic drivers involved.

Friday mystery object #412

After last week’s foray into insects, I have a nice chunky vertebrate skull to for you to have a go at identifying:

Any idea what this might be from? I have a feeling this may be way too easy for some of you, so let’s keep the answers cryptic or perhaps poetic, so everyone gets a chance to figure it out for themselves. Have fun!

Friday mystery object #410 answer

Last week I gave you this rather fishy skull to have a go at identifying:

There was a lot of discussion about what it could be, which is unsurprising, since there are a LOT of fish species – with over 34,000 possibilities. This one proved additionally confusing, since it seems to have no teeth, as mentioned in the comments by Adam Yates. Fortunately, Wouter van Gestel flagged that some species with several rows of teeth tend to lose those teeth during preparation if it’s not done with sufficient care, which is useful to know.

I picked this object because I get a lot of requests for identifications of fish skull bones and this specimen is helpful, as it has the various bones of the skull labelled individually:

This specimen also happens to be a fish from a family that often comes up for identification. The neurocranium (or braincase) has a fairly characteristic shape in these fish, which is best seen from above on the skull (although unfortunately it’s not labelled in the image below):

The neurocranium tends to be a bone that gets found on beaches quite commonly. In fact, I have had a similar neurocranium as a mystery object in the past, so you may have seen one here before:

This shape is what I expect to see from members of the True Cod family, the Gadidae. Clearly a lot of other people recognised this as well, since Chris kicked off the comments with references to Gadus, Cod and Pollock and there were lots of suggestions of Cod and Pollock (AKA Saithe) on Twitter:

Unfortunatley, this is where it gets more complicated. Differentiating between different Gadids isn’t always easy. The size suggests it will be one of the larger members of the family – Cod, Haddock or Pollock being the main focus. Haddock is easy enough to dismiss, since they have small mouths, with lower jaws (composed mainly of the dentary and articular bones) that don’t project as far as we see in this specimen.

After that it gets really quite tricky – to the point where I am now doubting the original identification we have for the mystery object. This specimen was labelled as an Atlantic Cod Gadus morhua, although the original identification when acquired from Rowland Ward was Pacific Cod Gadus macrocephalus. But after a lot of searching of images from some pretty reliable online resources, I’m increasingly convinced that the specimen is a Pollack, Pollock or Saithe Pollachius pollachius (Linnaeus, 1758) – N.B. I’m ruling out P. virens since the lower jaw proportions are wrong.

The reason I’m thinking Pollack is based around a few small features of a couple of the bones of the skull. In particular, I’m interested in the shape of the hyomandibular and the opercular (Osteobase has these elements for Cod, but unfortunatley not Pollack). To give you an idea of the differences, here are the Cod elements (superimposed in blue) alongside the same bones of the mystery object (tinted red):

These differences are consistent across the skull specimens of Cod and Pollack that I’ve managed to find. The Cod has notch in the upper leading edge of the hyomandibular, unlike the Pollack, which has a more obtuse smooth line along the leading edge. The Cod also has a notch in the trailing lower edge of the opercular, that is just seen as a slight concavity in the Pollack.

I’d be interested to hear what you think about these suggested features!