Andrej Spiridonov

Exploring Temporal Fluctuations in Multifractal Geochronologies In a groundbreaking study set for publication in the journal Commun Earth Environ in 2026, researchers led by Lovejoy, S., along with Davies, R., and Spiridonov, A., delve into the intricacies of time

Popular article on our recent discovery of the scaling laws of empirical geochronologies:
scienmag.com/exploring-te...
🧪 ⚒️ #Geology #Paleobio #Climate

Survival bias of the ocean floor certainly affects our perception on the igneous sources of global perturbations, including mass extinction events. There are no strict rules on why only terrestrial LIPs could trigger catastrophes.
The study itself:
doi.org/10.1130/G534...
🧪 #Geology ⚒️ #Paleobio

We all know that the taxonomic interest and effort of description in different taxonomic groups is rather obvious. But how severe it is, and how should we mitigate this ever-present bias?

🧪 #Geology ⚒️ #Paleobio #EvoBio

Pathological specimen of the belemnite Hibolithes hastatus (Montfort, 1808), GIUS 8-3798/1, upper Callovian of Poland.

Parasite-induced rostra of Jurassic belemnites:
"The absence of any external injury corroborated by high-resolution computed tomography suggests parasitism as the most probably cause for shell deformation."
app.pan.pl/archive/publ...
🧪 #Geology ⚒️ #Paleobio

Digital reconstruction of beaks in fossil coleoids.

This digital machine learning reconstruction could be a real breakthrough in the specimen paleontology. A good use of AI.
"The oldest sepioid cephalopod from the Cretaceous discovered by Digital fossil-mining with zero-shot learning AI"
www.nature.com/articles/s42...
🧪 #Geology ⚒️ #Paleobio #EvoBio

Yes, the durations of gaps are affected by noise as well as the structure of sampling. Either way, this is the data you actually have at hand before the more advanced derivative analyses. The point here is that the structure of gaps have very specific form: it shows scaling with multiple regimes.

RMS fluctuations in the carbonate d18O and their measurement densities, as well as the scale-by-scale correlations of fluctuations of d18O and their measurement densities.

At time scales of hundreds of millions to billions of Ma correlation between temperatures and measurement densities becomes increasingly close, thus highlighting the possibility that we should pay special attention in trying to reconstruct trends at the longest time scales.
5/5

This suggests that there is a common cause and a very specific bias in the distribution of gaps or conversely paleoclimatological measurements, directly related to the tempos of geodynamic, sedimentological functioning, and stratigraphical reflections of the planet Earth.
4/5

Scaling regimes in measurement densities and temperatures as a function of time scale.

What is more interesting these gaps in sections reveal similar scaling regimes to that of surface temperatures, with scaling breaks and crossovers between macroweather-climate, climate-macroclimate, macroclimate-megaclimate time scales.
 3/5

Probability distribution of intervals between consecutive datapoints.

The gaps are neither uniform nor Gaussian. As it turns out, they are scaling, and multifractal, meaning that the moments of their distributions diverge as we zoom-inn.
2/5

Paleotemperatures through the Phanerozoic and the variation of measurement densities through time.

I'm glad to share our new study on the nature of distributions of gaps in empirical geochronologies of geological section as a function of time scale. Measurements of proxies are highly uneven if measured through time.
1/5
 www.nature.com/articles/s43...

🧪 #Geology ⚒️ #Paleobio #EvoBio

"Network analysis reveals close faunal connections between the Huayuan and Burgess Shale biotas, indicating transoceanic dispersal. Dated shortly after the Sinsk event..."
🧪 #Geology ⚒️ #Paleobio #EvoBio

Fuck off

Andrej drinking "workahole"

Workahole and the deep passion for science, nature and the world helped me cope through some very difficult moments in my life (e.g. recent loss of my mother). I know it is a poison. But for a time being, poison can also serve as a medicine.
Grok image of me in a natural setting.

Photo of the last page of the Vilnius University magazine "Universitas Vilnensis" featuring intellectual tournament "Protmušis", with the photo of our team (top left).

Moments from the "Protmušis" (BrainBattle) intellectual tournament 21 years ago at VU. Here is our team (top left picture). From the left: Bronė L, me, Norbertas Noreika, Darius Kazlauskas @dariusbio.bsky.social . We were the first team who broken-even with undefeated team of mathematicians.

Third principal stress in 2D planar models of tyrannosaurids.

First principal stress in 2D planar models of tyrannosaurids

Cladogram showing the average von Mises stress present in the theropod crania and their respective theropod clades.

Creativity of scientific illustrations trying to convey complex multidimensional data sometimes is really stunning. Physical fields as topographic anatomical maps and phylogenies 👇

anatomypubs.onlinelibrary.wiley.com/doi/epdf/10....
🧪 #Geology ⚒️ #EvoBio

Temporal trends in coastline geometry and extinction risk across the Phanerozoic.

Interesting article exploring the role of the shapes of paleogeographies of coastlines as determinants of the extinction risk:
"Taxa...that occur along east-west– oriented coastlines, islands, or inland seaways—consistently exhibit higher extinction risk"
www.science.org/doi/full/10....
🧪⚒️ #Paleobio

Giant stegosaurs from the Crichton's/Spielberg's "Jurassic World"

Application of allometric equation to the giant stegosaur material, where it was shown, the probable weight of the animal was around 7 tons.

So the "Lost World: Jurassic Park" sized stegosaurs were real all along?!
Seven ton "sub-adult sauropod" sized stegosaurs apparently is a new thing on the block.
www.researchgate.net/publication/...
🧪⚒️ #Paleobio

Comparison of Ceratosaurus maxilla with teeth and teeth of Smilodon amd Homotherium.

Intriguing idea, that Ceratosaurus of the Morrison Formation, was a sabertooth cat analogue in its teeth shape and hunting patterns. I knew that their teeth were dagger-like, but here they are essentially the same size as in Smilodon, and they for the whole battery!
t.co/JLD4aB4OGG
🧪⚒️ #Paleobio

It's amazing how the Cambrian fossil record can overturn our understanding on the disparity, ontogeny and evolution of key groups!
🧪 #Geology ⚒️ #Paleobio #EvoBio

Ha, I just wanted to forward this article to you! I think currently, science, and paleontology in particular, is concentrated on highly detailed description/exploration/modeling of specific cases, and much less so in the discovery and testing of general principles, but still, there is a room ;-)

Meme making joke of physicists simplifying complex things to the simplest possible abstractions (e.g. nuanced body modelled as a particle).

Photo of the Thomas J. M. Schopf (1939-1984) from his obituary.

Excerpt from the T. J. M. Schopf article on the comparison of deterministic and stochastic approaches in paleontology, one of the first uses of the term "species as particles".

Thomas J. M. Schopf (1939-1984) was this kind of person. He was orthodox in some areas and a visionary in others (established "Paleobiology). The stochastic paleontology is the way in understanding the evolution of life.
doi.org/10.1017/S009...
🧪 #Geology ⚒️ #Paleobio #PhilSci #EvoBio #Macroecology

Thank you, Peter!

Andrej Spiridonov: How Will the Anthropocene Be Remembered? Geological Time Scales, Pragmatic Boundaries, and the Ultimate Causes „Athena: filosofijos studijos“ yra kartą per metus leidžiamas filosofijos žurnalas, kurį rengia Lietuvos kultūros tyrimų instituto Šiuolaikinės filosofijos skyrius.

Glad to share my new article dedicated to the Anthropocene from the perspective of broader stratigraphy and the practice of geologists, published in philosophy journal "Athena"
athena.lt/atsisiusti/c...
Special issue on the Anthropocene:
athena.lt/naujausias-nr
🧪 #Geology ⚒️ #Paleobio #PhilSci

Great to see this hierarchical (Bretskyan hierarchy) approach to the scaling of marine biodiversity through seascapes. But why limit systemic dissection and set the outer scale to the 1 km (where the fun stuff begins)?
🧪 #Geology ⚒️ #Paleobio #Macroecology

Main shell features of a radiolitid bivalve. The right valve is conical to cylindrical while the left valve is usually opercular (modified from Cestari & Sartorio, 1995).

They are weird! Bivalve which looks like a giant singular coral polyp.

Radiolitidae

When you visit Trieste, Italy, you and you go and buy tickets for bus, in the buss station ticket office you can find this beautiful two projection section of Cretaceous rudist bivalve mollusk from the Radiolitidae family, which converged in their for with corrals!
🧪 #Geology ⚒️ #Paleobio

If you are a grad student in paleo-sciences, don't miss a chance to upgrade your quant skills! 👇
🧪 #Geology ⚒️ #Paleobio #EvoBio

Flags with extirpated and extinct animals on them 👇
🧪 #Geology ⚒️ #Paleobio

Cool story (here it is freely archived archive.is/45tQd ) which combines fossil record and the stratigraphy of lahars in estimating giant mudflow risks.
The study: doi.org/10.1130/G537...
🧪 #Geology ⚒️ #Paleobio