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 #197 answer

On Friday I gave you this skull to identify:

mystery197

As I suspected, it wasn’t too much of a challenge. Jake got in quick with the suggestion of a Sri Lankan Python, with Gina Allnatt, Kevin and Rhina Duque-Thues all agreeing with a generic Python sp. identification. Nicola Newton also suggested Python, but she was of the opinion that it was probably a Royal Python or Carpet Python on the basis of the size.

I agree with Nicola and think that this is most likely the skull of a Royal (or Ball) Python Python regius (Shaw, 1802), based on the size of the specimen and the shape of the supratemporal and frontal bones compared to other Pythons I was able to find images for (if you don’t know which bones I mean you can see what I mean on a handy annotated picture of a Python skull from the Digimorph website).

Pet ball python - normal phase, probably an import (rescue). By Mokele

The skull is one of several similar specimens from the old King’s College teaching collection, so it’s a pretty good bet that the skulls came from either research animals or pets. The Royal Python is a fairly small African Python that is commonly sold as a pet because it has a mild temperament – so that helps offer a bit of support for the identification, although what’s really needed is a detailed identification key for Python skulls or access to good comparative material.

The lack of good resources for identifying the skulls of snakes is a bit frustrating. After working with bird and mammal skulls, where there are some amazing resources like Skullsite and the Mammalian Crania Photographic Archive I’m still searching for something similar for reptiles. Perhaps the Deep Scaly Project will deliver the goods one day… here’s hoping!