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Dr. Oliver Demuth

@oliverdemuth.bsky.social

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Dr. Oliver Demuth @oliverdemuth.bsky.social · Nov 15

Let's see if the pastures are greener over here...
Hi everyone I'm Oliver and I'm new here! I am a scientific illustrator and evolutionary biomechanist. I currently study the evolution of bird flight and I also draw and paint dead things ☠🦖🐦. Expect #PaleoArt / #SciArt, #Science and #Fossils!

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

All code (with instructions) is available on my GitHub: github.com/OliverDemuth... and on Zenodo (with additional data): doi.org/10.5281/zeno.... If you have any questions I am more than happy to help and explain the workflow/pipeline! 11/11

GitHub - OliverDemuth/MayaSignedDistanceFields: Signed distance field-based simulations of joint range of motion and path (ligament) wrapping around obstacles (bones) for Autodesk Maya

Signed distance field-based simulations of joint range of motion and path (ligament) wrapping around obstacles (bones) for Autodesk Maya - OliverDemuth/MayaSignedDistanceFields

github.com

Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

These simulations can not only be used to measure the lengths in experimental data, but can also constrain osteological ROM measurements to receive more functionally informative ROM estimates. Importantly, they are applicable to all type of joints and even fossils! 10/11

Soft tissue constrained mobility simulations, where rows represent specimens and columns different thresholds for the ligaments.

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

We calculated ligaments across the whole XROMM dataset and compared them to lengths measuared through dissection. It appears that different ligaments have different amounts of elasticity. Potential differences in (primary?) functions? 9/11

Optimised ligament lengths across the joint mobility and comparison with measurements from dissections. Data points are colour-coded according to the respective ligament and their magnitude

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

Similar to the osteological ROM simulation we used a signed distance field representation of the bones to speed up the optimisation process. The minimal length of each ligament was calculated from origin to insertion without any way points intersecting the bones 8/11

Cost function for the ligament optimisation. The minimal length of a ligament from origin to insertion was optained through minimising the deviations from a straight line while the individual ligament points could not intersect with the bone meshes (i.e., their position in the signed distance fields could not be negative). An additional inequality constraint prevented the ligament from rapidly changing directions and restricted the angular offset between two ligament points to approximately 60°.

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

We were not only interested in the osteological range of motion (ROM) but also in the soft tissues constraints surrounding the joint. We simulated the ligaments of the shoulder capsule that prevent excessive movement while enabling contact between the bones during motion 7/11

Ligaments of the shoulder capsule in the red legged partridge. The ligaments are coloured according to their identity in the different views.

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

Our approach is similar to work by Lee et al. (doi.org/10.1098/rspb...) but implemented in Autodesk Maya with Python. The optimisation approach minimises a cost function that determines joint proximity (cartilage thickness) and congruency (overlap) over a signed distance field 6/11

Cost function for the optimisation of joint articulation. Minimisation of the first term reduces deviation from a previously defined target proximity. The second term improves joint congruency through minimisation of the variance observed in the distance measurements. The minimisation is subjected to the constrain function defined by the signed distance field where measurements could not be negative (i.e., bones intersecting).

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

This made simulations more complicated, as previous pipelines often assumed a static joint centre around which the distal element (e.g., humerus) moves. However our approach automatically optimises joint translations for each rotational joint orientation and it is very fast! 5/11

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

In the shoulder we captured both joint rotations and translations. Our results clearly show that there is no (functional) joint centre in the bird shoulder and the humerus moves dynamically over the glenoid articular cartilage. The joint does not act as a spherical joint 4/11

Joint rotations of three specimens of Red legged partridge (RLP). Different specimens and their trial data are color-coded, RLP2 in red, RLP3 in green and RLP4 in blue. The combined data of all specimens and trials represents the overall partridge joint mobility.

Joint translations within the shoulder joint of the Red legged partridge. Individual panels show the translational offsets in the cardinal axes. Cranio-caudal on the tip, medio-lateral in the middle and dorso-ventral at the bottom

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

We captured the joint motion of Red legged partridge specimens using XROMM (X-Ray reconstruction of moving morphology) and wiggled three specimens in the biplanar X-ray to capture their joint mobility 3/11

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

How do joints move? The articular surfaces between the proximal and distal bones are in contact during motion. However, they are usually not neatly spherical or hinge like but move in complex patterns that include sliding and/or rolling (e.g., in the shoulder joint of birds) 2/11

Figure 4 of Baier DB. 2011. Mechanical properties of the avianacrocoracohumeral ligament and its role in shoulder stabilization in flight. J. Exp. Zool. 317: 83–95.
The figure shows the possible motion of the pigeon humerus relative to the glenoid. Potential glenohumeral motions in frontal view (elevation/depression plane) for the pigeon shoulder. In all views, the glenoid is sectioned at the level of the contact point with the humeral head. (A) Neutral position, the sphere represents the rotation center for a pure spin in elevation/depression. (B) Pure spin is when the contact point of the humeral head changes relative to the same contact on the glenoid. (C) Pure slide occurs when the humeral contact remains the same but the glenoid contact changes. (D) Rolling combines a spin and a slide.

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Dr. Oliver Demuth @oliverdemuth.bsky.social · 8d

Last week our in press manuscript was made available at @jexpbiol.bsky.social with the typeset version following soon. We conducted ex vivo XROMM experiments to determine the joint mobility in Red legged partridges and compared them with in silico simulations: doi.org/10.1242/jeb....

Accepted manuscript. Oliver E. Demuth, John R. Hutchinson, Vittorio La Barbera, Sharon E. Warner, Daniel J. Field; Soft tissue constraints on joint mobility in the avian shoulder. J Exp Biol 2025; jeb.250952. doi: https://doi.org/10.1242/jeb.250952

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Dr. Oliver Demuth @oliverdemuth.bsky.social · Sep 4

More information about the project STEPS can be found here:
www.arch.cam.ac.uk/news/ashleig...

#ERCStG

Dr Ashleigh Wiseman awarded ERC starting grant

www.arch.cam.ac.uk

Dr. Oliver Demuth @oliverdemuth.bsky.social · Sep 4

More information about the project STEPS can be found here: www.arch.cam.ac.uk/news/ashleig...

#ERCStG

Dr Ashleigh Wiseman awarded ERC starting grant

www.arch.cam.ac.uk

Reposted by Dr. Oliver Demuth

Cambridge Archaeology @cam-archaeology.bsky.social · Sep 4

We are delighted to share that Dr Ashleigh Wiseman has been awarded an @erc.europa.eu Starter Grant for her project STEPS: Biomechanical simulations of hominin locomotion across complex terrains.

👉 www.arch.cam.ac.uk/news/ashleig...

#ERCStG

Dr Ashleigh Wiseman awarded ERC starting grant

www.arch.cam.ac.uk

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Dr. Oliver Demuth @oliverdemuth.bsky.social · Sep 4

Very proud of the amazing Dr. Ashleigh Wiseman! Securing an @erc.europa.eu starting grant is a huge achievement! Keep your eyes open for PostDoc opportunities in her new research group at @cam-archaeology.bsky.social @cam.ac.uk!!

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Reposted by Dr. Oliver Demuth

Armita R. Manafzadeh @armanafzadeh.bsky.social · Sep 2

I'm recruiting a PhD student to join the lab at @gtsciences.bsky.social in Fall 2026! Broad taxonomic and topical freedom under the umbrella of vertebrate joint form and function. Information here: www.manafzadeh.com – please share 🦴🩻

Armita R. Manafzadeh @armanafzadeh.bsky.social · Jul 2

✨Some news✨: after finishing my postdoc, I’ll be starting my lab as an Assistant Professor at Georgia Tech. Join us in Atlanta to study how joints work and where they come from!

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Reposted by Dr. Oliver Demuth

Richard Bomphrey @richardbomphrey.bsky.social · Sep 2

🚨 Hiring! We are looking for a postdoctoral researcher with expertise in computational fluid dynamics and structural simulations to investigate biomechanics and mechanosensory feedback in insect flight.

Extreme agility ✔️
Morphological computing ✔️
Meshes! ✔️

jobs.rvc.ac.uk/vacancy.aspx...

a close up of a fly 's head with a blurred background .

ALT: a close up of a fly 's head with a blurred background .

media.tenor.com

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Dr. Oliver Demuth @oliverdemuth.bsky.social · Aug 12

Also asking it to create an image in the style of "paleoart" (see SI) is deeply insulting. Rather than chosing cheap AI slop one should always prioritise palaeoartists - with whom we have been collaborating for centuries. Let's not abandon our principles and our colleagues!

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Dr. Oliver Demuth @oliverdemuth.bsky.social · Aug 12

Generative AI is not science. It is the opposite of objective truth. It is misinformation dressed in a fancy package.

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Dr. Oliver Demuth @oliverdemuth.bsky.social · Aug 12

Interesting study, however, every scientist should stay as far away as possible from #generativeAI! It is literally just making things up with little to no control over the output. No morphology, soft tissues nor anything else can be "reconstructed" or "augmented" with genAI.

Catalina Pimiento 🆓🇵🇸 @pimientoc.bsky.social · Aug 11

Check out our perceptive on the Emerging uses of artificial intelligence in deep time biodiversity research www.nature.com/articles/s44...
#AI #paleontology

Emerging uses of artificial intelligence in deep time biodiversity research - Nature Reviews Biodiversity

This Perspective explores the existing and potential applications of artificial intelligence in deep time biodiversity research as well as offer guidelines on equitable and ethical use of artificial i...

www.nature.com

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Reposted by Dr. Oliver Demuth

Dr Matt Dempsey @sketchy-raptor.bsky.social · Jul 11

Sauropods dared to ask the radical question: "What if dinosaurs were really, really big?"

I will post an ID chart later, but if anyone wants to guess, then feel free to sound off in the comments.

🦕🦕🦕🦕🦕🦕🦕🦕🦕🦕🦕🦕🦕🦕🦕

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Reposted by Dr. Oliver Demuth

Robert Macfarlane @robgmacfarlane.bsky.social · Mar 29

In the 1960s Switzerland had some of Europe's filthiest waterbodies.
Now its cities boast near-pristine rivers & lakes: "We are united by a love of water".
Lessons to learn here, about building emotional connection to water as well as infrastructure investment.
www.theguardian.com/environment/...

From sewage and scum to swimming in ‘blue gold’: how Switzerland transformed its rivers

In the 1960s, the Swiss had some of the dirtiest water in Europe. Now, their cities boast pristine rivers and lakes – and other countries are looking to follow their lead

www.theguardian.com

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Reposted by Dr. Oliver Demuth

Dr Matt Dempsey @sketchy-raptor.bsky.social · Mar 27

I finally got this working. Pro & uropatagium to follow.

Side note, while I'm aware of hypotheses about actinofibril function, I'm not a fan of the trope of pterosaur wing membranes shrinking to almost nothing when grounded rather than just being allowed to fold, even a little bit.

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Reposted by Dr. Oliver Demuth

Dr Matt Dempsey @sketchy-raptor.bsky.social · Mar 2

EEVEE tests 🦖

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Reposted by Dr. Oliver Demuth

Field Palaeobiology Research Group @fieldpalaeo.bsky.social · Feb 4

'Dino Birds' airs on @pbs.org in N. America tomorrow (9pm, 5th Feb.). Follow research from our lab and colleagues around the world revealing the origin of birds. Hope you enjoy it!

www.pbs.org/wgbh/nova/vi...

@stevebrusatte.bsky.social @gnavalon.bsky.social @ksepkalab.bsky.social

Dino Birds

Fossils reveal how birds survived the killer asteroid and became today’s only living dinosaurs.

pbs.org

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