Friday mystery object #283

This week I have a mystery object for you that’s a bit different from the usual. Any idea what this zoomed in picture is showing?

mystery283

It’s probably a bit of a tricky one, so if you want an extra image that makes it much easier you can click on this link for a bonus clue.

Please leave your suggestions in the comments below – I’d love to find out your thoughts and let me know if you needed the clue. Have fun!

Friday mystery object #282 answer

Last week I gave you this mystery object supplied by Dr David Hone:mystery282

This is the premaxilla of a fish, but that doesn’t narrow things down much, since there are 28,000 species of bony fish, leaving a huge range of possibilities.

There were several suggestions of Wolf Fish, which is what I originally thought it was myself, but that’s not what it is. Then the suggestions of various Wrasse species started cropping up – which is a lot more likely.

My first look at Wrasse teeth came when I tried to identify the fish used in the Horniman’s Merman:

SONY DSC

There are a lot of Wrasse, over 600 species in fact, so it can be hard to narrow down the species, especially when few comparative specimens are available.

One very helpful osteology resource for identifying fish from their bony bits is Osteobase which lets you pick a bone and start making comparisons. It’s worth keeping in mind that you need to really explore the taxonomic tree on the left of the page to get a real appreciation of how useful it is – so for example, after selecting the premaxilla, if you look at the Perciformes (the Order containing the Wrasse) you see a huge range of premaxilla specimens that help narrow down the bone you’re trying to identify.

This clearly shows that the Labridae is definitely the right family for the mystery object and the Mexican Hogfish Bodianus diplotaenia (Gill, 1862) is a very close match.

So congratulations to Richard Lawrence who I think has it right, especially since the specimen was found within the range of this species. I hope you all enjoyed the challenge!

Friday mystery object #282

This week I have a mystery specimen from Dr David Hone who showed me it when he came and spoke about Tyrannosaurus at PubSci the other night (if you want to see the talk take a look at the Periscope feed from the evening). Here it is:

mystery282

Do you have any ideas of what bone it is and from which family of animals? If you can work out the species I will be both surprised and very impressed.

As usual if you think it’s too easy, please be sure to leave a cryptic clue in the comments section below. I hope you have fun with this!

Friday mystery object #281 answer

Last week I asked for your opinion on this mystery object:

mystery281

It had originally been identified as Boa constrictor and then reidentified as Green Anaconda, but I didn’t believe either of those options.

There was some activity in the comments, from the initial observation that it’s a snake from Wood, to Andy Mills’ suggestion of Python, with palfreyman1414 and Daniel Jones and Daniel Calleri’s discussing how to tell whether it’s a boid or pythonid.

In fact, palfreyman1414 did some sterling work tracking down characteristics to help distinguish between these commonly confused groups, with this handy comment:

“The postfrontal bone, usually present, borders the orbit behind, rarely also above, and in the pythons a supraorbital bone is intercalated between it and the prefrontal bone.”

And..

“Boids are, however, distinguished from the pythons in that none has postfrontal bones or premaxillary teeth”

The character of the presence or absence of teeth in the premaxilla (the frontmost bone of the upper jaw in the midline of the skull) is particularly useful, although it’s not unusual for the premaxilla to fall out of snake skulls.

The postfrontal character is a bit less obvious and I’m not fully convinced by it – not because there isn’t an extra bone in the pythons compared to the boas (there is), it’s just whether it’s a postfrontal, a supraorbital or a post orbital. That depends on the reference you read. To help get an idea of the bits we’re talking about, I’ve highlighted them here (purple for premaxilla, pink for the bit missing in boids, call them what you like):

mystery281_bones

It’s probably worth mentioning that Anacondas are members of the boid family, so it’s clear that this specimen is a pythonid rather than a boid. But that doesn’t tell us what species it is (if you want to see a Boa constrictor skull there’s a video of one here).

Comparing overall skull shapes in snakes is not very effective, since the skull is very loosely articulated to allow it to deform when swallowing large prey, so when mounted they can be very variable in shape. Because of this you need to compare the shapes of the various bones that make up the skull to narrow it down.

There is a very helpful image resource called BioLib that has validated photos of skulls amongst other images, so it’s well worth checking out. Trawling through I didn’t manage to find a species with the same shapes in the nasals, prefrontals, frontals, parietals and supratemporal – but I did discover a specimen photo by Jean-Christophe Thiel that fit (not to mention a previous mystery object) – so I’m fairly confident that this is a Royal Python Python regius (Shaw, 1802).

Many thanks to everyone for their comments – it’s been a fun challenge where I know I’ve learned an awful lot. I hope you have too!

Friday mystery object #280 answer

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

mystery280

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

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

Croc_development

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

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

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

Friday mystery object #280

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

mystery280

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