Andrej Spiridonov
@andrejpaleo.bsky.social
Professor of paleontology and Earth systems at Vilnius University. My interests are: theoretical paleontology, evolution, geology, stratigraphy, philosophy of biology and geology, climate at scales great and small.
https://twitter.com/AndrejSpiridon4
https://twitter.com/AndrejSpiridon4
Flags with extinct animals on them:
- California (California grizzly bear)
- Chernyshevsky District, Russia (Kulindadromeus)
- Doronogovi, Mongolia (sauropod)
- Srednekolymsk, Russia woolly (mammoth)
- California (California grizzly bear)
- Chernyshevsky District, Russia (Kulindadromeus)
- Doronogovi, Mongolia (sauropod)
- Srednekolymsk, Russia woolly (mammoth)
January 18, 2026 at 8:24 PM
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
The study: doi.org/10.1130/G537...
🧪 #Geology ⚒️ #Paleobio
January 17, 2026 at 4:01 PM
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
The study: doi.org/10.1130/G537...
🧪 #Geology ⚒️ #Paleobio
January 17, 2026 at 12:12 PM
"Here we document trace fossils of a meiofaunal ecosystem that flourished in the immediate aftermath of the end-Ordovician extinction event...ichnofossils...dominated by nematodes and foraminifera."
www.nature.com/articles/s41...
🧪 #Geology ⚒️ #Paleobio
www.nature.com/articles/s41...
🧪 #Geology ⚒️ #Paleobio
January 17, 2026 at 11:25 AM
"Here we document trace fossils of a meiofaunal ecosystem that flourished in the immediate aftermath of the end-Ordovician extinction event...ichnofossils...dominated by nematodes and foraminifera."
www.nature.com/articles/s41...
🧪 #Geology ⚒️ #Paleobio
www.nature.com/articles/s41...
🧪 #Geology ⚒️ #Paleobio
Always wonderful to learn about the features of the world, which are not so immutable. The geological record reveals the geographically inverted oxygen concentration gradient in the Neoproterozoic oceans.
www.nature.com/articles/s41...
cc: 🧪 #Geology ⚒️ #Paleobio
www.nature.com/articles/s41...
cc: 🧪 #Geology ⚒️ #Paleobio
January 16, 2026 at 5:25 PM
Always wonderful to learn about the features of the world, which are not so immutable. The geological record reveals the geographically inverted oxygen concentration gradient in the Neoproterozoic oceans.
www.nature.com/articles/s41...
cc: 🧪 #Geology ⚒️ #Paleobio
www.nature.com/articles/s41...
cc: 🧪 #Geology ⚒️ #Paleobio
Moments from the Workshop on Mathematical Perspectives on Extinction Dynamics at the International Centre for Theoretical Physics (ICTP), Trieste, Italy.
Sergi Valverde approaches problem of stasis and punctuations across scales, and Ivan Sudakow talks about the opportunities of extinction research.
Sergi Valverde approaches problem of stasis and punctuations across scales, and Ivan Sudakow talks about the opportunities of extinction research.
January 14, 2026 at 1:43 PM
Moments from the Workshop on Mathematical Perspectives on Extinction Dynamics at the International Centre for Theoretical Physics (ICTP), Trieste, Italy.
Sergi Valverde approaches problem of stasis and punctuations across scales, and Ivan Sudakow talks about the opportunities of extinction research.
Sergi Valverde approaches problem of stasis and punctuations across scales, and Ivan Sudakow talks about the opportunities of extinction research.
Contingent responses of diversity and disparity of different animal groups to the P-Tr mass extinction:
"Ammonoids...brachiopods exhibit refilling of vacated morphospace of shell outlines, Ostracods underwent adaptive radiation"
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio #EvoBio
"Ammonoids...brachiopods exhibit refilling of vacated morphospace of shell outlines, Ostracods underwent adaptive radiation"
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio #EvoBio
January 13, 2026 at 9:14 AM
Contingent responses of diversity and disparity of different animal groups to the P-Tr mass extinction:
"Ammonoids...brachiopods exhibit refilling of vacated morphospace of shell outlines, Ostracods underwent adaptive radiation"
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio #EvoBio
"Ammonoids...brachiopods exhibit refilling of vacated morphospace of shell outlines, Ostracods underwent adaptive radiation"
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio #EvoBio
"...occurrence [of SSB] was more likely in species inhabiting drier environments with increased food scarcity and predation pressure, in species with greater size dimorphism and longer lifespans and in those with more complex social structures and hierarchies."
🧪 #EvoBio
🧪 #EvoBio
January 12, 2026 at 8:39 PM
"...occurrence [of SSB] was more likely in species inhabiting drier environments with increased food scarcity and predation pressure, in species with greater size dimorphism and longer lifespans and in those with more complex social structures and hierarchies."
🧪 #EvoBio
🧪 #EvoBio
Crisp and cold weather while driving thorough the winter forest landscapes in the eastern Lithuania.
January 11, 2026 at 5:50 PM
Crisp and cold weather while driving thorough the winter forest landscapes in the eastern Lithuania.
PreꞒ/Ꞓ fundamental change in sedimentation:
"... relatively abrupt shift in the principal locus of CaCO3 burial, from short-lived oceanic crust during much of the Proterozoic to longer-surviving continental crust in the early Paleozoic"
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio
"... relatively abrupt shift in the principal locus of CaCO3 burial, from short-lived oceanic crust during much of the Proterozoic to longer-surviving continental crust in the early Paleozoic"
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio
January 9, 2026 at 10:09 AM
PreꞒ/Ꞓ fundamental change in sedimentation:
"... relatively abrupt shift in the principal locus of CaCO3 burial, from short-lived oceanic crust during much of the Proterozoic to longer-surviving continental crust in the early Paleozoic"
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio
"... relatively abrupt shift in the principal locus of CaCO3 burial, from short-lived oceanic crust during much of the Proterozoic to longer-surviving continental crust in the early Paleozoic"
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio
Weird and wonderful of insect world:
"Titanopterans are spectacular, giant, predatory insects...from the Triassic...the first discovery of a titanopteran fossil outside of Central Asia and Australia, suggesting..circum-Tethys..distribution"
www.cambridge.org/core/journal...
🧪 #Geology ⚒️ #Paleobio
"Titanopterans are spectacular, giant, predatory insects...from the Triassic...the first discovery of a titanopteran fossil outside of Central Asia and Australia, suggesting..circum-Tethys..distribution"
www.cambridge.org/core/journal...
🧪 #Geology ⚒️ #Paleobio
January 9, 2026 at 8:38 AM
Weird and wonderful of insect world:
"Titanopterans are spectacular, giant, predatory insects...from the Triassic...the first discovery of a titanopteran fossil outside of Central Asia and Australia, suggesting..circum-Tethys..distribution"
www.cambridge.org/core/journal...
🧪 #Geology ⚒️ #Paleobio
"Titanopterans are spectacular, giant, predatory insects...from the Triassic...the first discovery of a titanopteran fossil outside of Central Asia and Australia, suggesting..circum-Tethys..distribution"
www.cambridge.org/core/journal...
🧪 #Geology ⚒️ #Paleobio
"to see a world in a grain of sand" quite literally
🧪⚒️ #Geology
🧪⚒️ #Geology
Galaxies and stories tucked away inside a rock. Geology feels like a tiny peep hole into secret land. It makes me think about snorkeling and feeling like you're spying on another world. What a privilege it is to be alive and to see the world on so many beautiful scales.
January 8, 2026 at 9:53 PM
"to see a world in a grain of sand" quite literally
🧪⚒️ #Geology
🧪⚒️ #Geology
Nice essay on the "science after science": numerical prediction and control without explicit understanding.
For me this is not a science, this is 'exo-intuition', or 'exo-skill' at best.
The argument of control of nature over our understanding of it is overstretch.
www.science.org/doi/10.1126/...
🧪
For me this is not a science, this is 'exo-intuition', or 'exo-skill' at best.
The argument of control of nature over our understanding of it is overstretch.
www.science.org/doi/10.1126/...
🧪
After science
Twenty-five years ago, Ted Chiang wrote a prescient science fiction short that began: “It has been 25 years since a report of original research was last submitted to our editors for publication, makin...
www.science.org
January 8, 2026 at 2:03 PM
Nice essay on the "science after science": numerical prediction and control without explicit understanding.
For me this is not a science, this is 'exo-intuition', or 'exo-skill' at best.
The argument of control of nature over our understanding of it is overstretch.
www.science.org/doi/10.1126/...
🧪
For me this is not a science, this is 'exo-intuition', or 'exo-skill' at best.
The argument of control of nature over our understanding of it is overstretch.
www.science.org/doi/10.1126/...
🧪
Reposted by Andrej Spiridonov
I'm giving a talk next week as part of the @sedsonline.bsky.social Webinar series, going into the heart of carbonate sedimentology and core challenges of the field - it's as done and complete as you might think. 🧪⚒️
Join us for the January Seds Online Webinar "Rethinking the meaning of carbonate facies" with @obialik.bsky.social on next Wednesday (14 January) at 4:00 PM UK. Explore the complexity and insights of interpreting carbonate facies, and what we can still learn despite their ambiguity: sedsonline.com
January 7, 2026 at 5:59 AM
I'm giving a talk next week as part of the @sedsonline.bsky.social Webinar series, going into the heart of carbonate sedimentology and core challenges of the field - it's as done and complete as you might think. 🧪⚒️
Interesting!
"Fossils in storm beds plus paleoclimate modelling reveal a seasonal, nearshore setting like that of modern horseshoe crabs."
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio #EvoBio
"Fossils in storm beds plus paleoclimate modelling reveal a seasonal, nearshore setting like that of modern horseshoe crabs."
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio #EvoBio
January 6, 2026 at 9:09 PM
Interesting!
"Fossils in storm beds plus paleoclimate modelling reveal a seasonal, nearshore setting like that of modern horseshoe crabs."
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio #EvoBio
"Fossils in storm beds plus paleoclimate modelling reveal a seasonal, nearshore setting like that of modern horseshoe crabs."
www.sciencedirect.com/science/arti...
🧪 #Geology ⚒️ #Paleobio #EvoBio
Reposted by Andrej Spiridonov
Generally, high extinction rate is followed by high origination rate, but I have also found in some Mesozoic intervals, high origination is followed by high extinction rates in gastropods. It may also point to ecological specialization. In a paper, we have also suggested that...
January 6, 2026 at 11:17 AM
Generally, high extinction rate is followed by high origination rate, but I have also found in some Mesozoic intervals, high origination is followed by high extinction rates in gastropods. It may also point to ecological specialization. In a paper, we have also suggested that...
Creative approach using birth-death mathematical theory in exploring so called "super-progenitor" species. New support for the prevalence of the budding speciation and the 'polytomies-as-signal interpretation'.
doi.org/10.1017/pab....
🧪 #Geology ⚒️ #Paleobio
doi.org/10.1017/pab....
🧪 #Geology ⚒️ #Paleobio
January 5, 2026 at 10:54 PM
Creative approach using birth-death mathematical theory in exploring so called "super-progenitor" species. New support for the prevalence of the budding speciation and the 'polytomies-as-signal interpretation'.
doi.org/10.1017/pab....
🧪 #Geology ⚒️ #Paleobio
doi.org/10.1017/pab....
🧪 #Geology ⚒️ #Paleobio
"diversity peaked before a sharp decline, suggesting a possible link between ecological specialization and extinction risk..aligns with hypotheses proposing that overspecialization limits adaptability, leading to extinction under background conditions"
doi.org/10.1017/pab....
🧪 #Geology ⚒️ #Paleobio
doi.org/10.1017/pab....
🧪 #Geology ⚒️ #Paleobio
January 5, 2026 at 9:39 PM
"diversity peaked before a sharp decline, suggesting a possible link between ecological specialization and extinction risk..aligns with hypotheses proposing that overspecialization limits adaptability, leading to extinction under background conditions"
doi.org/10.1017/pab....
🧪 #Geology ⚒️ #Paleobio
doi.org/10.1017/pab....
🧪 #Geology ⚒️ #Paleobio
Biology student Edgar Žigis created and now has a significantly updated information application "Paleontologas". Please download it!😃Available in English, Lithuanian, Russian, French, Spanish, Italian, Portuguese (Brazilian dialect), German and Slovenian
play.google.com/store/apps/d...
🧪⚒️ #Paleobio
play.google.com/store/apps/d...
🧪⚒️ #Paleobio
January 5, 2026 at 11:52 AM
Biology student Edgar Žigis created and now has a significantly updated information application "Paleontologas". Please download it!😃Available in English, Lithuanian, Russian, French, Spanish, Italian, Portuguese (Brazilian dialect), German and Slovenian
play.google.com/store/apps/d...
🧪⚒️ #Paleobio
play.google.com/store/apps/d...
🧪⚒️ #Paleobio
Sediments and minerals self-organize and create a range of patterns which can be difficult to distinguish from biologically fabricated structures. This review brings significant advancement in understanding the deep time biospheres on Earth and elsewhere.
arxiv.org/abs/2601.00323
🧪 ⚒️ #Paleobio
arxiv.org/abs/2601.00323
🧪 ⚒️ #Paleobio
January 5, 2026 at 8:23 AM
Sediments and minerals self-organize and create a range of patterns which can be difficult to distinguish from biologically fabricated structures. This review brings significant advancement in understanding the deep time biospheres on Earth and elsewhere.
arxiv.org/abs/2601.00323
🧪 ⚒️ #Paleobio
arxiv.org/abs/2601.00323
🧪 ⚒️ #Paleobio
Views on my birthtown of Švenčionys (Pol. Święciany) on the New Year's Eve. It was founded and built in a U-shaped valley which formed during the penultimate glaciation around 150 Ka BP, when a tongue of a giant glacier melted away...
January 1, 2026 at 6:08 PM
Views on my birthtown of Švenčionys (Pol. Święciany) on the New Year's Eve. It was founded and built in a U-shaped valley which formed during the penultimate glaciation around 150 Ka BP, when a tongue of a giant glacier melted away...
Kevin, is that you?
January 1, 2026 at 9:08 AM
Kevin, is that you?
Reposted by Andrej Spiridonov
Congratulations to @nilese.bsky.social for the publication by the @paleosoc.bsky.social's journal Paleobiology of the 50th anniversary punctuated equilibrium symposium organized by Don Prothero & held at the 2022 GSA meeting. @bruceslieberman.bsky.social @andrejpaleo.bsky.social
January 1, 2026 at 2:43 AM
Congratulations to @nilese.bsky.social for the publication by the @paleosoc.bsky.social's journal Paleobiology of the 50th anniversary punctuated equilibrium symposium organized by Don Prothero & held at the 2022 GSA meeting. @bruceslieberman.bsky.social @andrejpaleo.bsky.social
Geologizing biology. Faults over folds.
December 31, 2025 at 3:58 PM
Geologizing biology. Faults over folds.
The New Year, here in Vilnius, will be white and full of snow!
*My son Konstantinas in the playground.
*My son Konstantinas in the playground.
December 30, 2025 at 9:55 PM
The New Year, here in Vilnius, will be white and full of snow!
*My son Konstantinas in the playground.
*My son Konstantinas in the playground.