Pasha van Bijlert
@pashavanb.bsky.social
Evolutionary biomechanist & Paleontologist 🇳🇱
Interested in how animals move
PhD candidate at @uugeo.bsky.social & @naturalis.bsky.social
📷:Tom Brown
Interested in how animals move
PhD candidate at @uugeo.bsky.social & @naturalis.bsky.social
📷:Tom Brown
Made it to the Sunshine Coast to visit @cjclemente.bsky.social and (soon) @taylorjmdick.bsky.social for the next three months! We'll full be doing physics simulations and robot experiments in Chris's lab, and even some fieldwork studying the locomotor biomechanics of wild emus and kangaroos
September 18, 2025 at 6:11 AM
Made it to the Sunshine Coast to visit @cjclemente.bsky.social and (soon) @taylorjmdick.bsky.social for the next three months! We'll full be doing physics simulations and robot experiments in Chris's lab, and even some fieldwork studying the locomotor biomechanics of wild emus and kangaroos
We were recording an outreach video at @naturalis.bsky.social, when I realised we accidentally recreated the T rex chicken meme (with an emu of course ❤️ 🐦❤️)
August 21, 2025 at 7:25 PM
We were recording an outreach video at @naturalis.bsky.social, when I realised we accidentally recreated the T rex chicken meme (with an emu of course ❤️ 🐦❤️)
For everyone at #ISB2025 interested in musculoskeletal modeling, I'm giving a talk about MuSkeMo, my model construction and visualization tool, Tuesday 11:30 in Room A1 (Session 6A - Musculoskeletal Model Personalization).
MuSkeMo is my tool for musculoskeletal model construction in Blender.
MuSkeMo is my tool for musculoskeletal model construction in Blender.
July 28, 2025 at 7:19 PM
For everyone at #ISB2025 interested in musculoskeletal modeling, I'm giving a talk about MuSkeMo, my model construction and visualization tool, Tuesday 11:30 in Room A1 (Session 6A - Musculoskeletal Model Personalization).
MuSkeMo is my tool for musculoskeletal model construction in Blender.
MuSkeMo is my tool for musculoskeletal model construction in Blender.
Here's the segment (in Dutch), at approx. 8:20 - www.rtl.nl/nieuws/uitze...
And as a bonus, the most Dutch picture I've ever taken of Ash
And as a bonus, the most Dutch picture I've ever taken of Ash
June 27, 2025 at 6:04 PM
Here's the segment (in Dutch), at approx. 8:20 - www.rtl.nl/nieuws/uitze...
And as a bonus, the most Dutch picture I've ever taken of Ash
And as a bonus, the most Dutch picture I've ever taken of Ash
Enigmacursor, the new neornithischian dinosaur described by @tweetisaurus.bsky.social & @profpaulbarrett.bsky.social, made the Dutch news today! Here's me miming approximately how much bigger Enigmacursor would be than my dog Ash (in his TV debut!)
@naturalis.bsky.social
@naturalis.bsky.social
June 27, 2025 at 6:04 PM
Enigmacursor, the new neornithischian dinosaur described by @tweetisaurus.bsky.social & @profpaulbarrett.bsky.social, made the Dutch news today! Here's me miming approximately how much bigger Enigmacursor would be than my dog Ash (in his TV debut!)
@naturalis.bsky.social
@naturalis.bsky.social
Here's me at the Netherlands Society for Evolutionary Biology meeting 2025 (with excellent alignment with a seagull, by Barbara Gravendeel), and the award ceremony at Fysica 2025 (📷 =Nederlandse Natuurkundige Vereniging)
June 5, 2025 at 3:15 PM
Here's me at the Netherlands Society for Evolutionary Biology meeting 2025 (with excellent alignment with a seagull, by Barbara Gravendeel), and the award ceremony at Fysica 2025 (📷 =Nederlandse Natuurkundige Vereniging)
Recently, the NL Society for Evolutionary Biology awarded me the "Best Paper Award", and Dutch Physics Magazine gave me the "Picture your research" award, both for our grounded running paper. I often worry that evo biomechanics is too niche for both fields, so this was very encouraging!
June 5, 2025 at 3:15 PM
Recently, the NL Society for Evolutionary Biology awarded me the "Best Paper Award", and Dutch Physics Magazine gave me the "Picture your research" award, both for our grounded running paper. I often worry that evo biomechanics is too niche for both fields, so this was very encouraging!
New paper in @cellpress.bsky.social Current Biology by Karl Bates ea. Karl's physics simulations (validated in a human model) suggest that although Lucy could run - top speed was limited, not leaving much headroom for endurance running.
www.cell.com/current-biol...
www.cell.com/current-biol...
January 7, 2025 at 2:16 PM
New paper in @cellpress.bsky.social Current Biology by Karl Bates ea. Karl's physics simulations (validated in a human model) suggest that although Lucy could run - top speed was limited, not leaving much headroom for endurance running.
www.cell.com/current-biol...
www.cell.com/current-biol...
If you've made it this far, allow me to show you the progression my ratite models have made. Thanks for reading!
18/18
18/18
December 30, 2024 at 4:10 PM
If you've made it this far, allow me to show you the progression my ratite models have made. Thanks for reading!
18/18
18/18
I'll be cross-posting my other twitter threads here on Bluesky soon as well, so stay tuned if you're interested in animal and dinosaur biomechanics!
16/18
16/18
December 30, 2024 at 4:10 PM
I'll be cross-posting my other twitter threads here on Bluesky soon as well, so stay tuned if you're interested in animal and dinosaur biomechanics!
16/18
16/18
Many thanks to the people listed here!
15/18
15/18
December 30, 2024 at 4:10 PM
Many thanks to the people listed here!
15/18
15/18
I assembled and visualized the model in @blender3d.bsky.social, using my plugin MuSkeMo:
github.com/PashavanBijlert/MuSkeMo/
Compatible (so far) with OpenSim and Gaitsym.
Preprint here: doi.org/10.1101/2024...
(Yes the model has joints for each neck vertebrae, use it for reaching sims 😅)
13/18
github.com/PashavanBijlert/MuSkeMo/
Compatible (so far) with OpenSim and Gaitsym.
Preprint here: doi.org/10.1101/2024...
(Yes the model has joints for each neck vertebrae, use it for reaching sims 😅)
13/18
December 30, 2024 at 4:10 PM
I assembled and visualized the model in @blender3d.bsky.social, using my plugin MuSkeMo:
github.com/PashavanBijlert/MuSkeMo/
Compatible (so far) with OpenSim and Gaitsym.
Preprint here: doi.org/10.1101/2024...
(Yes the model has joints for each neck vertebrae, use it for reaching sims 😅)
13/18
github.com/PashavanBijlert/MuSkeMo/
Compatible (so far) with OpenSim and Gaitsym.
Preprint here: doi.org/10.1101/2024...
(Yes the model has joints for each neck vertebrae, use it for reaching sims 😅)
13/18
Optimizations were done in @opensim.bsky.social Moco. These are all direct collocation simulations. All models, simulator outputs, and several code examples are available on our project page:
simtk.org/projects/emi...
(Emily stands for Emu Model for Investigating Locomotor dYnamics)
12/18
simtk.org/projects/emi...
(Emily stands for Emu Model for Investigating Locomotor dYnamics)
12/18
December 30, 2024 at 4:10 PM
Optimizations were done in @opensim.bsky.social Moco. These are all direct collocation simulations. All models, simulator outputs, and several code examples are available on our project page:
simtk.org/projects/emi...
(Emily stands for Emu Model for Investigating Locomotor dYnamics)
12/18
simtk.org/projects/emi...
(Emily stands for Emu Model for Investigating Locomotor dYnamics)
12/18
We didn't prescribe postures: the optimizer was free to select any, but selected these postures in response to anatomical changes.
By sequentially increasing the target speed, we simulated a full walk-to-run transition, and a run-to-walk transition (from top speed down).
6/18
By sequentially increasing the target speed, we simulated a full walk-to-run transition, and a run-to-walk transition (from top speed down).
6/18
December 30, 2024 at 4:10 PM
We didn't prescribe postures: the optimizer was free to select any, but selected these postures in response to anatomical changes.
By sequentially increasing the target speed, we simulated a full walk-to-run transition, and a run-to-walk transition (from top speed down).
6/18
By sequentially increasing the target speed, we simulated a full walk-to-run transition, and a run-to-walk transition (from top speed down).
6/18
So we did an experiment that's impossible outside the computer: we built a bird, and systematically changed its muscle and tendon anatomy. The muscles were tuned to generate peak forces at columnar, intermediate, and crouched postures, with both rigid and elastic tendons.
5/18
5/18
December 30, 2024 at 4:10 PM
So we did an experiment that's impossible outside the computer: we built a bird, and systematically changed its muscle and tendon anatomy. The muscles were tuned to generate peak forces at columnar, intermediate, and crouched postures, with both rigid and elastic tendons.
5/18
5/18
Birds have two related features: long tendons (that store energy like springs), and crouched leg postures (so foot-to-hip distance can change, which can "look" like a spring). In a real bird, you can't isolate these two features, making it hard to explain their running style
4/18
4/18
December 30, 2024 at 4:10 PM
Birds have two related features: long tendons (that store energy like springs), and crouched leg postures (so foot-to-hip distance can change, which can "look" like a spring). In a real bird, you can't isolate these two features, making it hard to explain their running style
4/18
4/18
What is running, actually? In humans, running has an aerial phase, a moment without ground contact. But that's neither true for birds, nor many quadrupedal animals - they sometimes run without an aerial phase, maintaining ground contact with at least 1 foot.
2/18
2/18
December 30, 2024 at 4:10 PM
What is running, actually? In humans, running has an aerial phase, a moment without ground contact. But that's neither true for birds, nor many quadrupedal animals - they sometimes run without an aerial phase, maintaining ground contact with at least 1 foot.
2/18
2/18
Most birds use a funny running style: grounded running. It's a paradox: GR costs more energy than normal running, but animals usually minimize costs.
Do birds waste energy? We resolve this with a model of the emu (the best bird).
Published in @science.org Advances last Sept
(reposting my x 🧵s)
1/18
December 30, 2024 at 4:10 PM
Most birds use a funny running style: grounded running. It's a paradox: GR costs more energy than normal running, but animals usually minimize costs.
Do birds waste energy? We resolve this with a model of the emu (the best bird).
Published in @science.org Advances last Sept
(reposting my x 🧵s)
1/18
Trix the T. rex is feeling festive
December 25, 2024 at 4:02 PM
Trix the T. rex is feeling festive
Haven't logged on here in a while, but for some reason my follows jumped up. Thanks a lot!
I'm going to be more active here - expect 3D physics simulations of how modern animals and fossils move, and other sciencey things!
For now - here's my emu blooper reel from our recent bird running study
I'm going to be more active here - expect 3D physics simulations of how modern animals and fossils move, and other sciencey things!
For now - here's my emu blooper reel from our recent bird running study
December 8, 2024 at 1:49 PM
Haven't logged on here in a while, but for some reason my follows jumped up. Thanks a lot!
I'm going to be more active here - expect 3D physics simulations of how modern animals and fossils move, and other sciencey things!
For now - here's my emu blooper reel from our recent bird running study
I'm going to be more active here - expect 3D physics simulations of how modern animals and fossils move, and other sciencey things!
For now - here's my emu blooper reel from our recent bird running study
The figures from Allen et al 2015 were a fantastic resource!
@johnrhutchinson.bsky.social
@johnrhutchinson.bsky.social
November 6, 2023 at 9:25 AM
The figures from Allen et al 2015 were a fantastic resource!
@johnrhutchinson.bsky.social
@johnrhutchinson.bsky.social
November 6, 2023 at 9:24 AM
Spent last week doing a muscle dissection of a crocodile at NHM Denmark - thanks a lot
@markscherz.bsky.social for enabling this! This big boy had a Caudofemoralis of over 300g!
Thanks also to
@lauraminifera.bsky.social for letting me take over your couch 😅🐕
@markscherz.bsky.social for enabling this! This big boy had a Caudofemoralis of over 300g!
Thanks also to
@lauraminifera.bsky.social for letting me take over your couch 😅🐕
November 6, 2023 at 9:23 AM
Spent last week doing a muscle dissection of a crocodile at NHM Denmark - thanks a lot
@markscherz.bsky.social for enabling this! This big boy had a Caudofemoralis of over 300g!
Thanks also to
@lauraminifera.bsky.social for letting me take over your couch 😅🐕
@markscherz.bsky.social for enabling this! This big boy had a Caudofemoralis of over 300g!
Thanks also to
@lauraminifera.bsky.social for letting me take over your couch 😅🐕
Trix the T. rex vs the JP jeep - who would win? Come to my talk at #SVP2023 to find out what my newest musculoskeletal (physics) simulations suggest. I'm on Saturday at 9:15
(Fair warning: I'm not actually going to animate the jeep in front of T. rex. Probably)
#FossilFriday
@naturalis.bsky.social
(Fair warning: I'm not actually going to animate the jeep in front of T. rex. Probably)
#FossilFriday
@naturalis.bsky.social
October 20, 2023 at 3:31 PM
Trix the T. rex vs the JP jeep - who would win? Come to my talk at #SVP2023 to find out what my newest musculoskeletal (physics) simulations suggest. I'm on Saturday at 9:15
(Fair warning: I'm not actually going to animate the jeep in front of T. rex. Probably)
#FossilFriday
@naturalis.bsky.social
(Fair warning: I'm not actually going to animate the jeep in front of T. rex. Probably)
#FossilFriday
@naturalis.bsky.social