Andrej Spiridonov

@andrejpaleo.bsky.social

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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

PDI data for four cores that span the end-Triassic mass extinction.
Geologist with it's sample
Sculpture of a sitting metal man holding erratic boulder
Smallest and the largest estimated Liopleurodon ferox tooth specimens.
Proportion of shifts in speciation rate
. Photographs of the Middle Devonian Hujiersite amber.
Comparison of squared chord distance (SCD) for (a) temperature, (b) total organic carbon (TOC), and (c) antelope-sterol concentrations from Lake Zonag, revealing pronounced variability during 9000–7000, 4000–2500, and 500–0 years
Professor X with mind rays: "Analytical Paleobiologists doing research"
Charles Darwin saving evolutionary biologist from learning more than 1 scientific name
Climate response to thermogenic carbon and sulfur emissions.
Sam Neil as dr. Allan Grant in the "Jurassic Park" scene
A reconstruction of the Ajimu giant salamander, which is believed to have inhabited the lakes and marshes of the Ajimu region approximately 3.5 million years ago when its environment was warmer and more humid. Today, this area is home to Andrias japonicus, the Japanese giant salamander endemic to Japan. (Kanon Tanaka)
Examples of Lithuanian terms for horses depending on their hide patterns and colors.
Model predictions for the interaction between mean annual temperature and richness on population-level ITV of (a) Plethodon sala-manders, (b) birds, and (c) small mammals, with all other predictors held at their means. For birds, the support for the interaction was weak (95% CI overlapped 0) compared to the other taxonomic groups.
Depositional model and facies details of the VdP deposits. (A) Reconstructed sequence of events: (Top) High-energy cyclonic events transport terrigenous debris, plant matter, and tetrapod carcasses across undisturbed tidal flats. (Middle) Coarse sediment settles to form a storm layer, rapidly stabilised by microbial mat draping; sinking vertebrate carcasses create impact deformation structures in the soft substrate. (Bottom) Resumption of tidal rhythms immediately buries isolated bones and debris, while articulated carcasses retain soft tissue, progressively buried by onlapping laminae over multiple tidal cycles. (B) Photomicrograph showing the typical fine, undisturbed rhythmic couplets. (C) A photographic detail illustrating an event bed, overlain by distinctive microbial draping structures. (D) A reddish, oxidised plant leaf transported from the hinterland, representing material delivered by flood pulses. Scale bars: 1 mm.
EAVP23, Vilnius. Talk by Justyna Slowiak.
Mandible of Feliopsis piriyai, occlusal view.
Match between rates of environmental change and evolutionary adaptation.
Trophic structure of the Paja formation
Evolution on a curved manifold and its implications for evolutionary rate estimates
Regression of bite force as a function of snout–vent length, with species ecological traits indicated, including a 95% confidence interval around the regression line and extrapolation of bite force for Megalania (Varanus priscus).
Ancestral state reconstruction and transition dynamics of skull roof rugosities.
Large angiosperm diaspore volume in the late Campanian DT flora. Cretaceous-Quaternary trends of diaspore volume are represented by 59 carpofloras. Dots and bars represent means and ranges, respectively, in each flora
The extended self-similarity (ESS) plots. The scaling of the q th order moments (S q q =log〈Δ ρ (Δt) 〉) as functions of the first order moments (M 1 ) for moments order q = 0.1, 0.3, …1.9 (top to bottom).
Graphical abstract of the "From eons to epochs: multifractal geological time and the compound multifractal - Poisson process"
Main panels: quantile-quantile (Q-Q) plots for the sample distributions of observed survivorship incremental slopes vs. the slopes generated by the randomized null models. Because the randomized data are based on 1 Myr cohorts, the comparisons shown here use observed data from those runs that employ 1 Myr cohorts—i.e., runs 1 and 2aggregated.Theanalysesarepartitionedintothe“pK-Ordovician”(Floian to mid-Katian)(A,C,E)and“K-Silurian”(lateKatiantoend-Silurian)(B,D,F)time intervals and,for each of these, into background extinction(A, B),extinction events (C, D),and the Late Ordovician Mass Extinction (LOME)(E, F)
Amazing diamond patters of the silver poplar (Populus alba) bark
Per-stage estimates of median genus age and γ- andβ-diversities of Phanerozoic mega-assemblages (PMAs) of three hierarchical levels along their respective scaled durations, where 0 is the beginning and 1 the end of the duration of a PMA. Each dot represents one per-stage estimate of one PMA at the respective level (PMA1st level n=4;PMA2ndlevel n = 16; PMA3rd level n = 50). Black lines are the estimates, averaged in 10 time bins. Shaded areas are the 95% confidence intervals of the binned averages.
Reddish 'Sahara dust'
Figure 3. Illustrative example: Part 1. Schematic illustration of model performance relative to the oracle model for increasing true effect size in the finite-data regime, comparing the full (true-structure) model (M1), the intercept-only model (M0), Bayesian model averaging and stacking, as well as selecting a model with Bayes factor or PSIS elpdloo. This is a simplified summary based on the results of simulated experiments in Appendix D. For small true effect sizes, the true-structure model can overfit, but, over the considered range, the full model has the best expected performance.
Schematic plate diagram of Pentremites spicatus showing placement of bitemarks in black.
Variations in branch length ratio (l ) and branch diameter ratio (r) of canopy tree and understory sapling branches across branch orders.
Books authored by Fred L. Bookstein
Founding figures of the geometric morphometrics by Fred Bookstein
Cepaea nemoralis
The procedure of true elliptic Fourier descriptor normalization, using the graphics of a turtle (blue line) as an example
Liudas Daumantas digging Šventoji formation (mid- upper Devonian).
The increase of the normalized perceptual distance σ* (A) and actual perceptual distance σ (B) over Ediacaran–Cambrian transition.
The normalized mean Haar fluctuation <Δρ(Δτ)>, the logarithmic slope of which gives an estimate of H.
Classification of characteristics of ecosystem, community, Linnaean (genealogical), geological time scale/paleogeography, and Bretskyan (holobiont geobiome) scalar hierarchies.
The bachelor of science diploma ceremony of the Vilnius University Faculty of Chemistry and Geosciences
Pollen counts of five key species in Sunfish Pond: Fagus, P. strobus, Quercus, Tsuga and Betula
Workflow for the production and analysis of the datasets.
MCT and biogeographical reconstruction employing BAYAREA + J model.
Timetree with modeled mass extinction events.
Fossil crania of Ziphiidae from the Diamantina Zone.
Björn Kröger
Euchromius bella or similar Crambidae.
the skulls of the auroch (Bos primigenius) on the right, and it's descendant - the domestic cattle (Bos taurus) on the left.
Triassic Smaug (Smok wawelski) - large bodied bipedal theropod-like archosaur of disputed affinities found in Silesia, Poland.
Megaloceros skull with the horns
Hypergaph perspectives in ecosystem restoration.
Title of the lecture
Body masses of individual Ursus arctos from Western Iberian Peninsula
Triassic paleogeography and major Earth system perturbations.
Paleogeographic maps, stratigraphic columns, and δ13C-δ18O-δ7Li data from late Ediacaran carbonates of the Patom section, Siberia and the Jiulongwan section, South China.
Species diversity of Ordovician–Silurian trilete spores
Timeline of select major events in the development of phylogenetic comparative methods, sorted by discrete trait models, continuous trait models, and tree models. We elaborate on some of these methods in the main text.
Hominin dentitions have changed in relation to dietary changes over the past 10 million years.
Membranous sacs preserved in situ in the autozooid cystids of P. gatehousei and D. hexaclitia gen. et sp. nov. and colonial growth reconstruction of P. gatehousei.