Let’s go Scanning: Prepping with X-rays

[BentonlWalters]

Hi all,

 

This is a follow-on from the first post in my ‘Adventures in Thin Sectioning’ thread where I showed this fossil from the Aust bone bed. I wanted to have it scanned so that I have a record of both halves before I try to make histological sections of the ‘offcut’.

 

 

Luckily, my department has a micro X-ray CT scanner (Nikon XT H 225ST) and when there was a gap in demand I was able to book time for a couple hours of scanning. I got three separate scans done, the two pieces of the Aust block done together and then two articulating fragments from the Woodhill Bay Fish Bed at Portishead which are full of upper Devonian placoderm and sarcopterygian fragments. Florists foam is used to hold the pieces in place during scanning as it is easy to press the rocks into and low enough density as to not interfere with the scan.

 

 

The scan for the Aust block took a little over an hour, and after reconstruction the vertebra is differentiable. The scan isn’t brilliant due to the abundance of pyrite in the stone which scatters the X-rays but it should hopefully be good enough to segment out the bone by hand and make a 3D model, so mission accomplished!

 

 

The scans for the Portishead material were much shorter exploratory scans (>30 minutes) but turned out better due to the lower density sandstone matrix and lack of pyrite. Both pieces are full of fragments of scale and bits of bone but the larger of the two has a couple particularly interesting features.

 

A large ?spine which I haven’t yet identified:

 

 

A fragment of jaw with three teeth, likely belonging to the Sarcopterygian Holoptychius:

 

 

Using a free program called Drishti I’ve been able to quickly reconstruct the Portishead scans in 3D and while the differentiation between bone and matrix isn’t fantastic it is good enough to get an idea of the spatial arrangement of the fragments. I intend to spend some time learning to segment out the fragments individually in Dragonfly (another free program for working with slice data) but am currently struggling with a few bugs so that will have to come later.

 

The two fragments as rendered volumes in rough alignment:

 

 

A rough rendering of the locations of the bone/scale  fragments in both blocks. I believe the majority of the scales are Holoptychius as it is the most abundant taxa in this deposit:

 

 

Close up on the area with the fragment of jaw, the three teeth are clearly visible as well as the stumps of two others:

 

 

Thanks for looking, let me know if you have any questions.

Edited September 20, 2023 by BentonlWalters

[FB003]

That's pretty neat. I enjoyed it. Would be interested to see more! Thanks for sharing.

[Tidgy's Dad]

Very interesting. 

[digit]

Very nice! I love it when we can use ultra-modern high tech to work on ancient fossil material. Makes you wonder what tools we'll have one hundred years from now.

 

 

Cheers.

 

-Ken

[sharkdoctor]

What a brilliant thread! Thanks so much for sharing!

[ParkerPaleo]

So jealous, I need a micro CT scanner....

[jpc]

yeah, me too.  Great equipment you've got access to there.

 

[Josesaurus rex]

Of course I would like to see more. It's something quite new to what I had seen.