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Jean-François Cudennec

@limpetnerd.eurosky.social
3.1K followers 707 following 1.3K posts

🔬 Limpet scientist (PhD) | Marine biology, paleontology & coastal archaeology 📸 Also nature photographer www.instagram.com/jfcudennec?igsh=M…

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Jean-François Cudennec @limpetnerd.eurosky.social · 07/10/2026
The only official penis of the European map is this one
A 2€ coin
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Jean-François Cudennec @limpetnerd.eurosky.social · 07/10/2026
I thought had an agile mind before seeing this
A map of Europe, but there’s something off
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Jean-François Cudennec @limpetnerd.eurosky.social · 03/10/2026
« Two Earthlings » John Brosio (2009)
Oil painting by John Brosio of a dimly lit museum. A massive dinosaur (T-rex ?) skull stands tall inside a towering glass display case, while a solitary feminine human figure stands besides looking up.
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Jean-François Cudennec @limpetnerd.eurosky.social · 02/10/2026
Another cool find for #FossilFriday: 66 Mya, a theropod dinosaur munched on a toothed diving bird, and we know it because its feathers were preserved in the dino's 💩 #PaleoSky ⚒️🧪🦕
While some dinosaurs are thought to have had ‘fuzzy’ or ‘downy’ feathers (shown in this illustration as the yellow spikes on a Nanotyrannus’ neck), ancient birds (such as the one in the Nanotyrannus’ mouth) were more likely to have had feathers that look similar to the birds of today. Image credit: Andrey Atuchin.The fossilized feather of a hesperornithiform bird exposed on the surface of the 66-million-year-old coprolite. Image credit: O’Connor et al., doi: 10.1016/j.cub.2026.08.054.Evolution of feathers structures
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Jean-François Cudennec @limpetnerd.eurosky.social · 02/10/2026
A gorgeous specimen for #FossilFriday : the internal cast of a Jurassic bivalve (Pleuromya cf. uniformis), turned into a talisman with a religious Islamic inscription : ‘There is no god but Allāh [and] Muḥammad is His Prophet’ #PaleoSky ⚒️🏺🧪🦑🦕
Fig. 1. Pleuromya cf. uniformis (Sowerby 1813), Jurassic, Morocco. Internal mould of articulated specimen bearing a religious inscription in high relief. Museo Geominero, Madrid, catalogue number MGM-7809X. (a) Left valve view; (b) right valve view; (c) anterior view; (d) dorsal view; and (e) detail showing striations visible on the surface of the letters (left arrow) and how a fissure in the rock also affects the letter (right arrows), indicating that the letters were carved in high relief and do not represent surface adherences of any foreign material. The thick patina of dirt that covered the specimen, originally dark grey in colour, was removed by washing with detergents, alternating with immersions in hydrogen peroxide.

Source : https://www.lyellcollection.org/doi/full/10.1144/jgs2026-014
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Jean-François Cudennec @limpetnerd.eurosky.social · 27/09/2026
So a bird (wood pigeon ?) crashed into our window, and the detail of the feather structure imprinted on the glass is just… 🤯🦉
The marks left by the bird on the window : the silhouette and wing can clearly be seen Details of the wing's feathers
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Jean-François Cudennec @limpetnerd.eurosky.social · 23/09/2026
Casual Anthropocene wednesday
The Guardian headline : « Huge El Niño projected to cause 450,000 deaths in next six months »
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Jean-François Cudennec @limpetnerd.eurosky.social · 23/09/2026
I’ve been quiet lately: fieldwork on an uninhabited island, workshops with students, buying our dream house (and its forest), moving in 2 dogs + 2 kids, a baby due this winter… Not much time left for shitposting. The hardest part? Staying focused while limpets still occupy 99% of my brain.
Two kids looking at lush trees through a large windowHand-drawn plans of the houseProspection on Beniguet island, the Britton flag proudly displayed on the dGPSAn infant jawbone, dated back to early middle age
Béniguet - France
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Jean-François Cudennec @limpetnerd.eurosky.social · 24/07/2026
The vertical design (D) has a very cool detail : the species’ call is also represented
Ten euros - KingfisherDetail of the 10 euros banknote, with a sonogram of the species vocalisation
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Jean-François Cudennec @limpetnerd.eurosky.social · 24/07/2026
The bluest blue I’ve ever seen 💙 Gentiana sp. (Brachyphylla maybe?)
A small patch of deep blue flowers growing among the rocks, somewhere in the Vanoise massif, at 2800 m asl
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Jean-François Cudennec @limpetnerd.eurosky.social · 24/07/2026
Completely obsessed by these euro banknote design proposals 🦉 Ursula, give us the bird money !
20 euros - Bee eater10 euros - kingfisher100 euros - Avocet
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Jean-François Cudennec @limpetnerd.eurosky.social · 20/07/2026
This summer the fields turned yellow, the beaches turned green and the only thing left to harvest is what rots in the sand. But Argentina lost, so it’s all good.
A beach in Brittany, covered by a green tide (Ulva sp.). A tractor is collecting the rotting sea weed to prevent sanitary issues.
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Jean-François Cudennec @limpetnerd.eurosky.social · 19/07/2026
Yeah intensive livestock farming may be a monstrosity against animal welfare and both a climatic sanitary plague, but at least coastal ecosystems are devastated.
A spectacular green tide (Ulva sp.) in the bay of Douarnenez, Brittany, France.
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Jean-François Cudennec @limpetnerd.eurosky.social · 15/07/2026
Anthropocene is cancelled. Welcome to Pyrocene 🔥
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Jean-François Cudennec @limpetnerd.eurosky.social · 15/07/2026
Limpets graze biofilm using their radula, a tongue like structure covered in tiny teeth, leaving specific markings on the rocks. Modelling works shows that these animals are close to the optimum when it comes to cover a surface by crawling, and without passing two time on the same spot 🦑🌊🌍🌿
Grazing marks from common limpets on a rock. 

Credit : Laetitia BeauvergerSource : https://www.pnas.org/doi/epdf/10.1073/pnas.1405966111
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Jean-François Cudennec @limpetnerd.eurosky.social · 13/07/2026
End of heatwave has been postponed, again. And another one has been scheduled for the end of July. Dreaming of « The atrium of a Roman house during heavy rain » by Luigi Bazzani, 1882.
« The atrium of a Roman house during heavy rain » by Luigi Bazzani, 1882.
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Jean-François Cudennec @limpetnerd.eurosky.social · 10/07/2026
Here's a paper (in French) about the ornaments on the kid from La Madeleine cave (Upper Palaeolithic) journals.openedition.org/paleo/1058?l...
a-b: plan and stratigraphy of the La Madeleine site with location of the burial; c: sketch of the burial indicating the arrangement of the personal ornaments.

After Capitan and Peyrony 1928.Ornaments associated to the La Madeleine child.
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Jean-François Cudennec @limpetnerd.eurosky.social · 10/07/2026
Let’s go clamposting 🦑🌊
Chamelea gallina
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Jean-François Cudennec @limpetnerd.eurosky.social · 10/07/2026
Scaphopods were also widely used as ornaments by prehistoric people: with an opening on both ends of the shell, they are particularly convenient to hang on a thread. But since they’re underwater critters, they were usually digged from fossil beds (happened at least in France and N. America)
Scaphopods ornaments in prehistoric grave
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Jean-François Cudennec @limpetnerd.eurosky.social · 10/07/2026
3/ cold spells would still occur, long enough to allow the establishment of sub-boreal biota, in a sort of glacial/interglacial oscillation, but with a poorly understood kinetic. A truely fascinating formation, were Mediterranean and Subpolar species co-occurs in single fossil beds !
A) Glycymeris obovata, warm-temperate
B) Centrocardita squamulosa ampla, subtropical 
C)Arctica islandica, subpolar
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Jean-François Cudennec @limpetnerd.eurosky.social · 10/07/2026
2/ refining our climatic forecasts. My postdoc at @derbyuniearth.bsky.social was specifically about palaeothermometry and palaeobiology of this Crag, and with absolute seawater temperature derived from isotopic data collected on fossils, we showed that even during a « warm » period,
The Sudbourne Park excavation of the Ramsholt member of the Coralline Crag.

Suffolk, 2023
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Jean-François Cudennec @limpetnerd.eurosky.social · 07/07/2026
Look at these 🏺 pictures 🤩
Mosaic of the Knidos F shipwreck off the Datça Peninsula. Credit: Ocean Exploration Trust / Türkmenoğlu, E., & Davis, D., Heritage (2026)

https://archaeologymag.com/2026/06/three-byzantine-shipwrecks-found-off-turkey/Two representative views of Günsenin Type I amphorae on the Knidos F site. Credit: Türkmenoğlu, E., & Davis, D., Heritage (2026)

https://archaeologymag.com/2026/06/three-byzantine-shipwrecks-found-off-turkey/Secondary amphora type at Knidos L site. Credit: Türkmenoğlu, E., & Davis, D., Heritage (2026)

https://archaeologymag.com/2026/06/three-byzantine-shipwrecks-found-off-turkey/
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Jean-François Cudennec @limpetnerd.eurosky.social · 01/07/2026
Just vibing
Screenshot from Ctenoides ales Wikipedia page
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Jean-François Cudennec @limpetnerd.eurosky.social · 01/07/2026
Disco clam remains unmatched
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Jean-François Cudennec @limpetnerd.eurosky.social · 30/06/2026
You liked the flash flood ? I hope you’ll like the flash drought
Source : @tleilax___ (Twitter)
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Jean-François Cudennec @limpetnerd.eurosky.social · 30/06/2026
France: just endured two consecutive historic heatwaves, with a third on the way (and it’s not even July yet) French authorities: don’t address the criticism about mass mortality and lack of preparation, but give the green light to a controversial climate-wrecking highway project.
« final go-ahead for this controversial project: the Council of State has approved the environmental permit for the A69 motorway »
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Jean-François Cudennec @limpetnerd.eurosky.social · 25/06/2026
Knowledge is power (France is bacon)
Maximal temperatures in France today, June 25, 2026
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Jean-François Cudennec @limpetnerd.eurosky.social · 19/06/2026
Looking at these graphs, thinking of my kids
Daily mean temperature, year 2026, France.

Almost always over the decadal average, with already one strong heatwave, and a second one being forecasted to be even way more hot
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Jean-François Cudennec @limpetnerd.eurosky.social · 08/06/2026
Fresh off the bench: a very cool pot base with classic Bell Beaker decoration, from last year’s excavation on our island shell middens. #PaleoSky 🏺
A pot shard standing on a pile of limpet shellsDetail of the pot shard, with distinct decoration
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Jean-François Cudennec @limpetnerd.eurosky.social · 29/05/2026
Also, hovering over a species opens a panel describing its relationships (XX pollinates YY and is eaten by ZZ). There's a lot to be said about gen AI, but I definitely wouldn't have managed to do this on my free time, with my poor coding skills, and surely not in half an hour or so.
The bumblebees box, witha all the plant it polinates, and the predators
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Jean-François Cudennec @limpetnerd.eurosky.social · 29/05/2026
As an amateur naturalist, I listed the species found in my area and asked Claude to build a 3D model of the interactions between them. The ecosystem is nicely structured around the two large green balls (oak and beech). It looks messy, but you can navigate through it and add taxa manually.
The ecosystem reconstruction : dots of different size/colors linked by arrows of different colors representing the different types of interactions
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Jean-François Cudennec @limpetnerd.eurosky.social · 26/05/2026
Wait, what ?
Top 50 rising in Science leaderboard on Substack. 
The Limpet Doctrine (my newsletter) is 48
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Jean-François Cudennec @limpetnerd.eurosky.social · 25/05/2026
The sea surface temperature in the Bay of Brest with see a 10°C increase in just one week. The usual summer temperature maximum is somewhere around 20 °C, and is normally reached in August. One of the most studied coastal ecosystem in the world, turned into a hot marine stew. shorturl.at/Sg8ss
Top : iroise sea/bay of Brest sst for the 20/05/2026, at 13 degrees Celsius 
Bottoms : the same map, but for the 27/05/2026, reaching 23 degrees.
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Jean-François Cudennec @limpetnerd.eurosky.social · 24/05/2026
Having a cnidarian (Velella velella, the purple sail) using the winds to sail across the ocean is already cool, but TIL that this species has different morphs to catch the dominant winds (east/west) in the Pacific Ocean. (Also, have you seen these growth rings ?? 👀)
https://bioobs.fr/blog/fiche-espece/?id_espece=202Figure from Cameron et al (2023)

https://www.researchgate.net/publication/372860179_Strong_chiral_optical_force_for_small_chiral_molecules_based_on_electric-dipole_interactions_inspired_by_the_asymmetrical_hydrozoan_Velella_velella
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Jean-François Cudennec @limpetnerd.eurosky.social · 23/05/2026
My daughter, 5yo, to the other kids at the playground : « so, the radula is like a tongue for the snails, but covered in teeth ! »
A kids hand pointing to radula grazing marks from snails or slugs on the playground structure
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Jean-François Cudennec @limpetnerd.eurosky.social · 11/05/2026
Facebook meme groups may not be completely dead
Cartoon displaying the absurd complexity of the « simplified northwest Atlantic food web »
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Jean-François Cudennec @limpetnerd.eurosky.social · 05/05/2026
The area alone is worth the visit. Incredibly powerful environment. The fossil are sitting just above the waves, and yesterday’s weather wasn’t even that bad according to our guide…
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Jean-François Cudennec @limpetnerd.eurosky.social · 05/05/2026
Yesterday we wandered in the « Eastern hyper-oceanic barrens ecoregion » of Newfoundland to walk in socks on the oldest animal ever known (Ediacaran fauna, Avalonian period) at Mistaken Point. And this Beothukis ? The holotype, still in situ. What a day ! #PaleoSky ⚒️
The eastern hyper oceanic barren ecoregion : no trees, but a lot of wind Beothukis holotypeThe fossil surface of Mistaken point. The sea floor was covered in ash layer, preserving the fossils
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Jean-François Cudennec @limpetnerd.eurosky.social · 30/04/2026
What do "mama" and "cuckoo" have in common? Both are Lallwörter : onomatopoeic words reinvented by every generation of speakers, which resist the regular laws of phonetic evolution. The cuckoo's call pulls the word back into shape faster than cultural change can erode it.
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Jean-François Cudennec @limpetnerd.eurosky.social · 29/04/2026
In his "gourmet almanac", a reference for gourmets published in 1807, Grimod de la Reynière provides a demanding recipe: the "Rôti Sans Pareil". It is made of a bustard stuffed with a turkey stuffed with a goose stuffed with a pheasant stuffed with a
Drawing of all the 17 birds stuffed one in anotherBirding list of the recipeA lighter version, with only 12 birds
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Jean-François Cudennec @limpetnerd.eurosky.social · 29/04/2026
Understandable
"Cuckoo takes one look at UK and flees to France"
Source : https://www.bbc.com/news/articles/c145mmez57yo
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Jean-François Cudennec @limpetnerd.eurosky.social · 28/04/2026
It's absolute dating a least
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Jean-François Cudennec @limpetnerd.eurosky.social · 28/04/2026
1/ Are Pokémon named after their call ? Or do they shout their name after learning it from us ? Is there a relationship between "les mots et les choses" ? Or language is purely arbitrary?
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Jean-François Cudennec @limpetnerd.eurosky.social · 24/04/2026
One of the four horsemen of nature slop enjoyers, alongside the green 'solar powered' sea slug, the 'QT mold spore' sea bunny, and the "dark academia" skull orchid
Costasiella kuroshimae, also known as a leaf slug, sea sheep, or leaf sheepJorunna parva, the sea rabbitAristolochia salvadorensis, the "Darth Vader orchid"...
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Jean-François Cudennec @limpetnerd.eurosky.social · 24/04/2026
1/2 When I say science is a creative act, just like any other art form, this is what I mean: In the 60s a paleontologist asked himself: what if I modeled every mathematically possible coiled shell? He did, and realised nature only uses a tiny corner of that space. 🧪🦑🌊🌍🌿🐚
Raup's (1966) morphospace of coiled shells. He used three out of several parameters in a geometric model simulating shell geometry to define the axes of his space. Many existing taxa can be placed within this space, but most parts of the space remain "empty" (the white regions).
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Jean-François Cudennec @limpetnerd.eurosky.social · 22/04/2026
Since y'all liked the 290 million years old fossilized butthole from last month, here's a Messapicetus (Miocene beaked whale) that got fossilized in its own puke. Gross, really. Also incredible, but mostly gross.
Figure 2 from Lambert et al., 2015

Figure 2. Fossil remains of the extinct beaked whale Messapicetus gregarius and associated clupeid fish Sardinops sp. cf. S. sagax found in Cerro Colorado. (a) Photograph and line drawing of the articulated caudal portion of a skeleton of Sardinops sp. in left lateral view (note the typically clupeid urostyle supporting the caudal fin complex), with a complete skeleton of the modern sardine S. sagax for comparison (adapted after [21]). (b) Imbricated large cycloid scales of Sardinops sp. in right lateral view showing tubercular protuberances in their central region and curved radii-like lines in their lateral fields, with a body of S. sagax for comparison reporting the putative collocation of the scale set. (c) Dolomite concretion with the skull and mandibles of M. gregarius in ventral view; occipital region, hamular processes of the pterygoids, posteroventral and apical regions of the mandibles emerge from the concretion. bv, articulated bivalve shells; mda, apex of mandibles; mdp, posteroventral part of mandibles; ph, hamular processes; wd, fragment of fossilized wood. (d) Line drawing of the skull of M. gregarius inside the concretion with a reconstructed outline of its body. Multiple individuals of Sardinops sp. found around the head and in the chest region are schematically represented. Stippled line marks the outline of the concretion.
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Jean-François Cudennec @limpetnerd.eurosky.social · 21/04/2026
Just cleaned my eBird from several hundred flagged lists from Merlin and launched a new streak. Wish me luck !
A house sparrow, standing on a plant stem, eating a cereal grain
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Jean-François Cudennec @limpetnerd.eurosky.social · 20/04/2026
Reading tip
Front page of the article "Holocene climate variability", with the mention "Harry Potter and the" written above with a pencil
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Jean-François Cudennec @limpetnerd.eurosky.social · 09/04/2026
10 followers on Medium but two articles boosted in a row? Turns out writing about limpets for a living might not be a career dead-end after all. Who knew there was a market for brainless mollusc content ? medium.com/@jf.cudennec...
Front page of my article about convergent evolution among gastropods.
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Jean-François Cudennec @limpetnerd.eurosky.social · 09/04/2026
Phare de la Jument Brittany, France
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