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 #425

One of the things I get asked to identify a lot in my job are bits of bone that people have found on the beach. I’ve decided to give you an idea of what that’s often like, with this small section from a skull as this week’s mystery object:

I hope you have some fun figuring out what this bone belongs to – I usually find it to be quite a rewarding experience.

As ever you can pop your thoughts in the comments box below. Enjoy!

Friday mystery object #424 answer

I hope that you had a very merry festive season and that you didn’t spend too much time contemplating last week’s mystery object from a dig by Irish Archaeological Consultancy that’s been taking place in Dublin:

Because the object is still partly in the soil and I was unable to get images from every angle and I think that there are some helpful features still buried, so I apologise for that. Still, we can take a look at what we know and start narrowing down possibilities.

First of all, we know that this is the lower part of the hind limb of a bird. That much is clear due to the shape of the articulations, in particular the lobed shape of the distal end of the tarsometatarsus (or TMT, which is the long bone in the image that is intact apart from a hole in the midshaft).

Considering that based on the scale bar the total length of the TMT must be around 380mm, this is clearly from a VERY big bird. The largest bird species occurring in Ireland would be the Great Bustard, which has a TMT length of between 138 and 176mm in the males (which are significantly larger than the females). So that’s not even close.

There are birds common to Ireland which are smaller, but with longer legs, such as the Grey Heron. However, their TMT would seldom be greater than 210mm. Even the Common Crane, which has historcially be reported in Ireland, only has a TMT in the 200-250mm range – about the same as a Greater Flamingo, which is the kind of exotic bird that may have been brought to Ireland by humans as an ornamental in the last few hundred years. We need to look further afield.

The next obvious stop has to be the largest bird, to at least get a sense of just how big the TMT is likely to get. Ostriches have a TMT in the region of 448mm, so we’re not quite up to that size, but we’re also not all that far away. On a side note, as we mentioned earlier, the mystery object probably still has part of the distal articulation buried in the soil – but if it didn’t then it would be a good contender for a small Ostrich, since they only have two toes and their TMT would be missing the section of articulation that is likely buried here.

The next largest bird to consider would be the Emu, which has a TMT around 400mm. This is getting into the right sort or size range, but we should consider the other possible candidates. Staying with Antipodean species, the Southern Cassowary has a TMT in the region of 325mm long and the Northern Cassowary is around the same size. Then we jump over to South America and the rheas. The largest is the Greater Rhea, for which I could only find a measurement of 320mm, which was taken from one male specimen.

Based on size alone this suggests that Emu is the most likely option, but we all know how size can be a bit unreliable. The next thing to look at is probably the shape of the unguals (those are the ends of the digits where the claws would attach):

In most ratites the ungual on the middle digit seems to have quite a flat profile, but from the images I’ve seen of skeletons, the Emu appears to be the only one with a similarly curved middle ungual.

On balance (and I’d be happy to reconsider if I can get my hands on the fully excavated specimen) I think this is most likely to be the leg of an Emu Dromaius novaehollandiae (Latham, 1790) – an opinion shared by Adam Yates.

I realise there are some other extinct large ratites (various moas and the elephant birds) that may have found their way to Ireland as fairly complete fossils, but the lack of holes for wiring, and with the bones still in their correct orientation suggests that this specimen went into the ground with its skin still more or less intact.

I’d like to thank everyone for their suggestions – I’m not sure I’d call this a cut-and-dried answer, but hopefully I’ll get a chance to take a closer look at the specimen in 2022 and confirm the identity with more certainty.

Happy New Year to everyone!

Friday mystery object #424

This week I thought it would be nice to have something seasonal and festive for Christmas Eve, but I couldn’t think of anything that I haven’t done before, so you’re getting a genuine mystery object that came to light on an archaeological dig in Dublin by Irish Archaeological Consultancy:

I’ve been thinking about a possible identification for this specimen (and I’ve ruled out a LOT of possibilities), but I’ve not had much time to check on comparative material, so I’d be keen to hear your suggestions about what you think this leg might have come from in the comments below.

Have a Merry Christmas and try not to spend too much time thinking about this 😉

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!

Friday mystery object #421 answer

Last week I gave you another genuine mystery object to have a go at identiftying, from an archaeological dig by Irish Archaeological Consultancy:

As I suspected, quite a few people recognised this specimen. It’s a humerus with the distal articulation (that’s the elbow bit) intact and the proximal articulation (where it meets the shoulder) broken off.

The size and overall shape is similar to a small, robust human humerus, so at first glance it might suggest a primate, like a Chimpanzee or maybe a small Orangutan. However, the olecranonon fossa (the groove at the back of the elbow joint that the olecranon process on the ulna bone of the lower arm/forelimb locks into when the arm/forelimb is straight) is far too deep for it be from an ape.

Baboons, Geladas and Mandrills have a deep fossa, but the overall shape of their articulations is more cuboid than this, so there aren’t really any other primates large enough.

The shape is all wrong for an ungulate and most carnivore humeri have a different articulation shape and some diagnostic features that are lacking here. But, there is one type of carnivore that has a humerus this shape. This was not lost on many of you, both in the comments here and on Twitter.

The general similarity in shape with a primate humerus is due to a functional similarity in the use of the fore limbs. Unlike most carnivores, the animal this came from can stand bipedally and use its arms. Obviously I’m referring to a bear of some kind.

The type of bear is a bit harder to pin down definitively. It’s unlikely to be a Brown Bear, since it’s not really big enough. That also rules out Polar Bear. I think it’s most likely to be from an American Black Bear Ursus americanus Pallas, 1780, since the other species of a similar size have somewhat better developed supracondylar crests (the ridges on the sides that the muscles of the forearm attached to) it could be from, like the Asiatic Black Bear or Sun Bear.

Thanks for all your observations on this – I hope there will be some more exciting archaeological mysteries to come!

Friday mystery object #420 answer

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

It was picked up on the Porcupine Bank, which is a raised area of the Irish shelf around 200km off the west coast of Ireland, just before the drop off into the abyssal depths of the Atlantic.

Although it’s a little hard to tell from the photo, the object is around 1m long. It has a conical cavity at the base, but it’s fairly shallow, extending only about 20cm before fully closing up.

The fact this isn’t a tube allows us to rule out the possibility that this is from some unholy giant scaphopod:

Or indeed a particularly well-formed giant ship-worm, like one I’ve featured before:

You can’t tell from the photo, but it’s very dense and heavy. What you can see is that it has some quite well defined longitudinal ridges:

This isn’t something you normally find in horns, but you do find in tusks. So the question has to be, what kind of tusk is this?

I’ve talked about tusks before on this blog, and I’ve spent a lot of time identifying ivories over the years, after learning key diagnostic features from the wonderfully knowledgable Dr Sonia O’Connor, both in her training courses and working alongside her when I was at the Horniman Museum and she was visiting to do some research. This tusk reminds me of one of the more tricky ones we looked at.

The marine location suggests it could be from a Walrus. The overall shape isn’t bad, but Walrus tusks tend to be no more that about 75cm long at their longest. They also have a more squared-off section at the base and often a deeper groove on the sides partway along the length from the base, so it seems unlikely.

Really that just leaves something proboscidian – but here we hit the difficult bit. Mammoth tusks have been dredged from the sea many times, from fossils in sediments that became covered by sea level rises after the melting of glaciers around 11,500 years ago. However, Elephant tusks were transported in huge nubers to Europe by ship to supply the demands of the ivory trade between the late 18th and early 20th Century, so it is entirely possible that this is a relic of that trade (as suggested by Chris Jarvis).

In my experience, submerged Mammoth tusks are seldom in such good condition as this. While there is some degration and flaking towards the tip, there is much less of the deep staining or separation of dentine fibrils that I would normally expect from Mammoth tusk submerged for several thousand years.

However, if it was more deeply buried until recently it may have avoided the worst of that degradation, so that expectation isn’t good enough.

There is a method for distinguishing between Mammoth and Elephant ivory, that relies on an artefact of the tooth development process. This involves measuring the intersection angle of Schreger lines (an optical feature resulting from light interacting with dentine tubules) in a polished section of the tusk:

In Elephants the angle of intersection tends to be obtuse (>90o), whereas in Mammoths they are more acute (<90o). Of course, to see this would require cutting a section of tusk, so it may have to remain a mystery until the desalination treatment has been completed and I can see if there is an opportunity to check any broken surfaces or prepare a small sample.

The question in this case has to be, how important is it to know the identity, compared to the importance of keeping the specimen as intact as possible? That is a bigger conversation that will need to be had with my colleagues.

Thanks for your thoughts everyone!

Friday mystery object #420

This week I have another real mystery object for you to have a go at identifying. This was dredged off the sea floor, on the extreme western edge of the European continental shelf where it meets the Atlantic Ocean:

There are a few possibilities, so I’d be interested to hear what you think. You can leave your suggestions, observations and questions in the comments box below.

Have fun!

Friday mystery object #419 answer

Last week I gave you a genuine mystery object from an archaeological dig in Dublin to have a go at identifying:

There were several suggestions, both in the comments here and on Twitter. They can’t all be right, so this seems like a good opportunity to look at the skulls of a variety of different species, so we can narrow it down.

Scale is important in this, since the mystery object is quite large, despite being just a section of the braincase from the rear of the skull, made up of parts of the parietal bones (on either side) and part of the occipital bone (the bone that forms the back wall of the skull). This is an area of convergence on the skull – a meeting point for the bony sagittal crest associated with attachment of the temporalis muscles (used in operating the jaw) and the nuchal crest associated with the nuchal ligament that connects the trapezius muscles of the neck (used in moving the head) to the skull.

1. Deer.

Deer skull
Deer skull

Cervids lack the well-developed sagittal crest seen in the mystery object. They also have a broad triangular scar for the attachment of the nuchal ligament – presumably relating to the high forces that the nuck muscles have to deal with due to the carrying of and fighting with antlers. In females the shape of the nuchal scar is very similar, although it’s less well defined. So the mystery, with its strong sagittal crest and neat occipital crest is not from a deer.

2. Bovids.

Sheep, cows and other bovids are similar to deer – with a broader nuchal scar (presumably for similar reasons to the deer). Their reliance on masseter muscles more than the temporalis muscles when chewing also means that their sagittal region doesn’t match our mystery critter, with the temporalis scars usually not meeting the midline of the skull:

Sheep skull

2. Pig.

In profile the pig skull looks like a pretty good match, with scars from quite well-developed temporalis muscles just behind the eye socket:

Pig skull

But the Suidae actually have a very distinctive spatulate shape to the rear part of their skulls, presumably for incredibly hefty nuchal ligament attachment to help power their rooting activity:

Pig skull

That results in a very distinctive shape in the dorsal view, so the mystery object is clearly not a pig:

Pig skull

3. Horse.

Horses can have a fairly well-developed sagittal crest and I don’t feel like I can entirely disregard the possibility that this mystery specimen may be from a mature Equid, although the shape looks somewhat off to me – a bit flatter and angled more downwards:

Horse skull

The horse specimens I’ve seen also have more of a nuchal ‘knot’ rather than a defined ridge in the midline of the occipital:

Horse skull

4. Camel.

Camels have very strongly developed sagittal crests, but this is parly due to the short and narrow area to the rear of the braincase, so the crest rises sharply. The nuchal crest is also much more prominent, forming a continuous sharp line right into the zygomatic arch:

Dromedary camel skull

The mystery object could be from a camel, but I think it lacks the strength of the camel’s nuchal region and the braincase seems broader than that of the camels.

5. Badger.

There was a suggestion of badger, but that can be ruled out simply because of the size. This section of mystery bone is about as long as a badger’s entire skull:

Badger skull

While the size is off, the suggestion does have merit in terms of morphology, as the broad braincase does hint at a member of the Carnivora and in Ireland there aren’t many large carnivores – at least not any more.

6. Seal.

One type of large carnivore still found around Ireland would be the seals. However, the need for extreme flexibility in their head movements while resisting drag from their watery environment gives them a very characteristic shape to their nuchal region:

Seal skull

7. Dog.

Dogs are always worthy of consideration in these instances. They can be small or large, their skull shape can vary hugely and they are found everywhere that humans are found.

Dog skull

This does seem a bit more like it, although size is still an issue. Even the biggest dog – and the skull shown above is from a BIG dog – struggles to be close to the right size. Also, the nuchal crest in dogs tends to taper to a point fairly evenly, whereas the mystery bone has a nuchal crest that has ‘shoulders’ for want of a better term. Dog is possible, but I’m not convinced.

8. Cat.

There is no way a domestic moggie could come close to big enough, but there are big cats that come surprisingly close:

Tiger skull
Tiger skull

The nuchal crests of lions and tigers have those ‘shoulders’ and a well defined occipital crest down the midline. They are also closer in size and the braincase and sagittal crest are about right.

9. Bear.

Of course, we can’t talk about lions and tigers without also considering bears.

Bear skull

Again, the nuchal crest ‘shoulders’ are there, the size is perfect and the sagittal crest and braincase are close. However, the occipital crest seems a little less well-defined.

So these are the species I’ve been considering and at the moment I’m thinking big cat or bear for this mystery object. I know there are other large carnivores, like hyenas, but they have an unmistakable sagittal/nuchal region:

Hyena skull

I will need to have the specimen in my hand with a good range of comparative specimens available to get a more conclusive identification. One significant factor will be that as animals mature, their muscle scars tend to become more rugged and this changes their appearance, so I will need specimens from animals of different ages and life histories to help consider those factors.

Sorry I’m not giving you a definitive answer this week, but I hope you’ve enjoyed the process!

Friday mystery object #419

This week I have a very real mystery object for you to have a go at identifying, that was recently excavated in Ireland by archaeologists from Irish Archaeological Consultancy and they very kindly let me take a look and share it with you:

I have an idea of what this is, but I’d be keen to hear what you think it might be.

You can put your thoughts in the comments below and hopefully between us we’ll figure it out!

Friday mystery object #418 answer

Last week I gave you this Blaschka model to have a go at identifying:

It certainly has a bit of a Christmas decoration vibe about it, which in my experience means it must be a radiolarian. These models were made later than the models I’ve shared before, so they don’t appear in the 1878 H.A. Ward catalogue that I’ve linked to previously. They do appear in the 1888 catalogue however, but that has proved difficult to track down online.

Regardless, the Corning Museum of Glass has an impressive archive of Blaschka art works and a bit of careful image searching can yield some very helpful clues to the identity of this specimen.

As you can see from this artwork (which itself was presumably copied from the Report of the United States Geological Survey of the Territories ; v. 12: Fresh-water rhizopods of North America (with thanks to Emmanuel for the pointer to this publication on Twitter), the species is Raphidiophrys elegans Hertwig & Lesser 1874 (emended Penard 1904) and its number in the 1888 Ward catalogue was 636.

The Blaschkas regularly copied illustrations as a basis for their models, often sticking very closely to the source material. I expect Rudolf Blaschka did much of this copy work, since he seems to have had a finer hand than his father Leopold. The accuracy of the copies and the fact that they are often mirrored from the original work does suggest that Rudolf used a glass plate to assist with the copying process.

If you’re not familiar with how that works, here’s a old skool explanation:

I know doing image searches doesn’t really count as an honest biological method of identifying the type of radiolarian depicted in the model, but quite frankly I’m primarily a zoologist – I have my limits and if the method works, why not use it?

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 #416 answer

Last week I gave you an anatomical specimen to have a go at identifying:

It proved a popular object, perhaps unsurprisingly given its unusual condition. This becomes a bit clearer when seen the specimen is seen from the back:

The fact that it’s conjoined at the head and chest is fairly obvious, but what kind of animal is it?

This is where the discussion got interesting, with a variety of different aspects of the morphology being discussed, ranging from number of vertebrae to shape of the rostrum (or nose if you prefer). Generally the conversation went back and forth between dog and cat (although sloth also came up).

For me, a handy place to check when trying to differentiate juvenile cats and dogs is the unguals – the tips of the toes. The claws of cats and dogs are quite different. If you look more closely at the image above, you can see that the unguals in this animal are deep-bellied at the base and steeply curved:

This claw shape is functionally well adapted to climbing and the broad base relates to a retractile mechanism – something very feline. Here’s an example from a much bigger felid – a Tiger.

So this is the skeleton of a conjoined kitten. Well done to Chris Jarvis, who was the first to comment and he correctly spotted the feline nature of this specimen.