Andrej Spiridonov

Vilnius University · Department of Geology and Mineralogy

Analysis of fossil assemblage structure can help illuminate the processes shaping the assembly of ecological communities. Using Bayesian network analysis methods, we investigated patterns of association between presences and abundances of 12 large-bodied mammal clades at Pleistocene fossil localities and their dependence on local environment types,...

Giant rhinoceroids were once named as the largest land mammals ever imagined. They lived in Eurasia during the Eocene and the Oligocene, and they could have potentially lived in the area of present-day Helsinki, Finland. We, however, may never know this with certainty because not only have no fossil remains of those animals been found in what is no...

Punctuated equilibria is a theory of evolution that suggests that species go through periods of stability followed by sudden changes in phenotype. This theory has been debated for decades in evolutionary biology, but recent findings of stasis and punctuated change in evolutionary systems such as tumour dynamics, viral evolution, and artificial evol...

The objective determination of boundaries of bioregions is a nontrivial problem. Here we present a new method family, HespDiv, and an algorithm for its implementation in a new R package: hespdiv. The hespdiv algorithm performs iterative hierarchical nonlinear spatial subdivisions of taxic data into topologically contiguous geographic regions. Biore...

For five decades, paleontologists, paleobiologists, and ecologists have investigated patterns of punctuated equilibria in biology. Here, we step outside those fields and summarize recent advances in the theory of and evidence for punctuated equilibria, gathered from contemporary observations in geology, molecular biology, genetics, anthropology, an...

The Ludlow epoch of the Silurian period was a time of significant geobiological perturbations, the most significant being the mid-Ludfordian Lau Event and associated huge positive carbon isotopic excursion. On the other hand, the impact of the Lau Event on ecosystems is far from understood, with the majority of studies being concentrated on conodon...

Scaling fluctuation analyses of marine animal diversity and extinction and origination rates based on the Paleobiology Database occurrence data have opened new perspectives on macroevolution, supporting the hypothesis that the environment (climate proxies) and life (extinction and origination rates) are scaling over the “megaclimate” biogeological...

Milaičiai-103 borehole is located in the southwestern part of Lithuania. Stratigraphically, the core of Milaičiai-103 is represented by rocks from the Pridoli, Upper Silurian. Previous research examining conodont and brachiopod fossil material from Milaičiai-103 revealed a new "Šilalė Event" extinction (Spiridonov et al., 2020). In this study, we f...

The process of evolution and the structures it produces are best understood in the light of hierarchy theory. The biota traditionally is described by either the genealogical Linnaean hierarchy or economic hierarchies of communities or ecosystems. Here we describe the Bretskyan hierarchy—a hybrid eco-genealogical hierarchy that consists of nested se...

Permian fishes and their isolated microremains are known from many localities in the Zechstein Basin. However, up to date the vertebrates have never been revealed in the southeasternmost part of this ancient sea. The new material consists of euselachian-type dermal denticles,?Listracanthus sp. dermal denticle,?Omanoselache sp. tooth, actinopterygia...

Biodiversity is a fundamental concept in biology. By biodiversity scientists usually mean taxic richness, i.e., the number of species, genera, or other higher taxonomic categories. Diversity sometimes is equated to the complexity of biological systems, but at the higher hierarchical level of observation (in: McShea DW, Brandon RN (2010) Biology's f...

The Late Pleistocene to the Holocene is a time interval that covers the climate transition from a cold to a warm interglacial regime. In the Baltic region, many studies have focused on estimating environmental responses to climatic forcing using palynological and stratigraphic proxies of glacial and periglacial settings. Herein we describe the mixe...

In recent years it has become commonplace to formalize chemostratigraphic units and identify isotopic zones (chemo­stratigraphic units) from excursions. Stable carbon isotopes have been used in solving stratigraphic problems in the Silurian for more than 30 years. δ13C data supplement other stratigraphic proxies, allowing the subdivision of geolo...

The brachiopods constitute one of the major components of the marine metazoan fossil record. On the other hand their apparent decline in importance in forming benthic communities through the Phanerozoic is one of the most striking macroevolutionary and macroecological patterns. Here we analyzed changes in average latitudinal and longitudinal ranges...

The diversity of life on Earth is controlled by hierarchical processes that interact over wide ranges of timescales1. Here, we consider the megaclimate regime2 at scales ≥1 million years (Myr). We focus on determining the domains of ‘wandering’ stochastic Earth system processes (‘Court Jester’3) and stabilizing biotic interactions that induce diver...

The monograptids from the Wenlock and Ludlow (mid-to late Silurian) of the palaeo-tropical Baltic Basin exhibit thickened ring structures (sicular annuli) over their initial phase of growth. Appearing before the lundgreni extinction event, they persisted throughout the remainder of the Silur-ian, fluctuating in number over that period. To better un...

The Mulde event was one of several significant turnover events during the Silurian. This event is mostly recognized in the fossil record of graptolites and conodonts, as well as stable carbon isotopic data. Therefore, the ostracods – a significant part of the benthos – comprise a new and important dimension in understanding this global geobiologica...

Dinosaurs are one of the most spectacular discoveries that paleontology ever uncovered through its history. The fossils of skeletons (and on the rare occasions their soft tissues) reveal the appearance and functional capabilities of ancient beasts. Despite the richness of preserved body fossils, the behavior of extinct animals is strongly underdete...

The late Permian time was a transformative period before the most severe mass extinction known. Even though fishes constitute a key component of marine ecosystems since the Silurian, their biogeographic patterns during the late Permian are currently insufficiently known. The new ichthyofaunal material described here comes from the southeastern part...

High spatial resolution diatom and loss-on-ignition analyses were carried out on the surface sediments of a shallow, medium-sized lake in north-eastern Lithuania to examine the degree of spatial heterogeneity of diatom assemblages in the lake, as well as the influence of water depth on diatom compositions. The compositional properties of sediments...

The International Meetings of Early-stage Researchers in Palaeontology (IMERP) are aimed at early-stage palaeontologists, from undergraduate students to recent post-doctoral researchers. Geologists, biologists or any scientist with research topics related to palaeontology, as well as palaeoartists, are also welcome. The IMERP has two main objective...

Four new brachyuran species, assigned to two new genera and one existing genus, are recorded from Lower and Upper Cretaceous strata of Moscow Oblast (Moskovskaya Oblast) and Dagestan, Russia. Three new taxa, Personadorippe levashiensis gen. et sp. nov., Levashidromites cornutus gen. et sp. nov. and Vectis collinsi sp. nov., were recovered from Apti...

The Late Pleistocene and Early Holocene were time periods of significant transitions between glacial and warm climate states. In this contribution, a study of changes of diatom assemblage compositions in recurrence plots, rarefaction models, and their rank abundance distributions (Fisher's alpha) in the Southeast Baltic is presented. Three sites we...

The late Permian was a transformative time, which ended with one of the most significant extinction events in Earth's history. Fish assemblages are a major component of marine food webs. The macroevolution and biogeographic patterns of late Permian fish are currently insufficiently known. In this contribution, a late Permian ichthyofauna from the K...

Settlement distribution modelling assumes that human spatial behaviour can be revealed by using the correct set of variables. However, the regional variables of large-scale gradients are only considered rarely. Also, settlement modelling applications are often impeded by fragmentary and error-prone datasets. Thus, in current-day Lithuania, in order...

The upper Silurian, and especially Pridoli epoch is a critical interval for the understanding the evolution of Earth’s biota, since it witnessed series of powerful extinction events, global reorganizations of paleocommunities, and expansion of new clades, which assumed dominance in the subsequent Devonian period. The stratigraphic record of the eas...

On a distal part of the outwash plain in the several sites of Ūla River valley, South East Lithuania, the organogenic sediments (gyttja) are found at the different depth buried under the lacustrine and aeolian sand. The Late-Glacial is indicated as the sedimentation time by the results of a palaeobotanical analysis, 14 C and OSL dating. During the...

Iterative evolution has proved a difficult evolutionary phenomenon to study and interpret. Inferences of causality vary from study to study and quantitatively based phylogenetic reconstruction has never been attempted. In an effort to better understand iterative evolution we employed stratocladistics, gap analysis and disparity analysis to study th...

[Naujojo Sibiro salų mamutas Goša ir pleistoceno megafaunos ekspozicija Vilniaus universitete] Mammoth Gosha and the Pleistocene megafauna exposition from New Siberian Islands at Vilnius University

The Earth’s biota originated and developed to its current complex state through interacting with multilevel physical forcing of our planet’s climate and near and outer space phenomena. In the present study, we focus on the time scale of hundreds to thousands of years in the most recent time interval – the Holocene. Using a pollen paleocommunity dat...

The mid-late Homerian Age of the Silurian Period was a time of intense changes in biota, oceanic chemistry, and sea level and is known as the lundgreni extinction (for the graptolite extinctions), the Mulde bioevent (for the conodont turnover event) or the Homerian carbon isotope excursion (CIE) probably related to glacially influenced climate pert...

The Homerian to Ludfordian interval of the mid to late Silurian Period was a time of significant changes in conodont communities, global climate, oceanographic patterns and biogeochemical cycles. The Mulde and the Lau events are preeminent examples of globally recognized conodont extinction episodes from this interval in Earth’s history. The Siluri...

The late Permian is a transformative time, which ended in one of the most significant extinction events in Earth's history. Fish assemblages are a major component of marine foods webs. The macroevolution and biogeographic patterns of late Permian fish are currently insufficiently known. In this contribution, the late Permian fish fauna from Kūmas q...

A recent book by Yale ornithologist Richard Prum (2017) is an excellent example of the Victorian era-style "popular| expositions of innovative ideas in the form of a book-long argument, which are easily understandable for an educated person and of great interest for an expert. In his quest to explain the myriad of intricate and seemingly evolutiona...

Conducting cladistic analyses using exclusively fossil data presents a slew of unique challenges. The absence of genetic material and loss of morphological characters during preservation greatly reduces the amount of available usable characters, giving results more susceptible to convergence biases. Stratocladistic builds on traditional morphologic...

The Cenomanian–Turonian transition marks one of the most important extinction episodes of the Mesozoic era. This extinction event was associated with the development of widespread oceanic anoxia and pronounced stable carbon isotopic excursion. Despite its importance, the effects of the perturbation on higher latitude biotas, and from the Baltic reg...

The upper Wenlock epoch (Homerian age) of the Silurian period was an interval of intense changes in biotic composition, oceanic chemistry and sea level, which also witnessed a double-peaked positive stable carbon isotopic excursion. These biotic and environmental perturbations are thought to have originated due to reorganizations of the ocean syste...

The Silurian period, and the Wenlock epoch in particular, experienced a series of powerful bioevents, among which was the Mulde event (upper Homerian). Here, the results of a study of the mid- to late Wenlock conodont paleocommunities in the shallow platform environments of the Lithuanian part of the Silurian Baltic basin are presented. The analyse...

The Ludlow Epoch (Silurian) was marked by several globally recognized but mechanistically poorly understood biotic events. The most pronounced of them was the Lau Event, which strongly decimated conodont, graptolite, and brachiopod faunas. Additionally, this event coincides with the largest positive stable carbon isotopic anomaly in the whole Phane...

The assemblage of rare fish microremains of chondrichthyans and actinopterygians from Upper Permian de pos its in Karpėnai Quarry in northern Lithuania is described in detail for the first time. The deposits are characterized as reflecting a rapid phase of deposition of the Zechstein Limestone, in terpreted as on a shallow shelf above storm-wave ba...

The Gėluva regional stage stratigraphically corresponds to the late Wenlock. This time interval witnessed significant graptolite extinctions and turnovers of conodont faunas, as well as a large positive Mulde carbon isotopic excursion. Thus, the development of a detailed stratigraphy is a necessary step in understanding the complex patterns of regi...

In our paper (Spiridonov and others, 2016, v. 316, p. 363– 400), please replace autocorrelated random walk formula (on the lower part of the page 374) for the one presented here: Y t =ρY t-1+ X t

One of the severest perturbations of the Silurian marine environment is the mid-Homerian Mulde bioevent. This event proceeded in several temporal steps, which, according to some authors, implies possible globally synchronous perturbation. The dynamic pace and consequences of these perturbations, as well as their effects on conodont community dynami...

The Gėluva regional stage stratigraphically corresponds to the late Wenlock. This time interval witnessed significant graptolite extinctions and turnovers of conodont faunas, as well as a large positive Mulde carbon isotopic excursion. Thus, the development of a detailed stratigraphy is a necessary step in understanding the complex patterns of regi...

The Pridoli epoch is one of the most geobiologically unstable intervals in the Silurian period. However, the ecological and evolutionary dynamics of the biota from this time are still poorly understood. Here we present a comprehensive quantitative time-series analyses of conodont abundances during the middle and the upper parts of the Pridoli epoch...

The fossil record, it is known, is the only direct source of information on the past biotic change as well as its connection to the changes in terrestrial and cosmic environments. In the past several decades there was constant growth in recognition that quasiperiodic changes in the Earth’s orbital parameters (eccentricity, obliquity and precession)...

Mizarai impact crater is located in Southern Lithuania, near the resort Druskininkai. It is regularly rounded depression, 6 km in diameter, 500 m deep, while the impact breccias layer is up to 2000 m thick. The type of impactorasteropid is not known. The cosmogenic origin of the crater is confirmed by set of indices used for the recognition of such...

New data on the Upper Homerian and Ludlow (Silurian) stratigraphy of the shallow water sedimentary and biotic succession of the Lithuanian part of the Silurian Baltic basin are presented here based on detailed analysis of the Vilkaviškis-134 core. Four formations: the Riga, Gėluva and Širvinta formations of Wenlock age and the Neris Formation of Lu...

The Pridoli series is one of the thickest and most complete stratigraphic intervals of the Silurian as well as other systems of the Lithuanian part of the Baltic sedimentary basin. In this study we present a sequence stratigraphic model of the sedimentary succession in the Milaičiai-103 core section. High resolution trend of concentrations of total...

The Ireviken event was one of the most intense extinction episodes that occurred during the mid-Paleozoic era. It had a strong global effect on a range of clades, with conodonts, grap-tolites and chitinozoans affected most. Using geophysical proxies and conodont species parameters of their temporal abundance structure we investigate how they affect...

Abstract—The morphology of Pa elements of the Ozarkodina remscheidensis s. l, species group (Ozarkodina remscheidensis eosteinhornensis (Walliser), Ozarkodina remscheidensis remscheidensis (Ziegler) and Ozarkodina inordinata Viira) from the southeastern part of the Silurian (Upper Ludlow and Pridoli) of the Baltic Basin is statistically analyzed. M...

Based on the integrated chemostratigraphic and lithostratigraphic studies, as well as biostratigraphic and palaeoecological analyses of conodonts in the Ledai-179 core, we present a combined model of change in the upper Wenlock and lowermost Ludlow strata of the inner shelf settings in the eastern part of the Baltic Basin. The comparison of the δ13...

Integrated lithostratigraphical, cyclostratigraphical, graptolite and conodont biostratigraphical and chemostratigraphical (δ13C) data are presented from the upper Jaagarahu, Gėluva and Dubysa regional stages, including the lundgreni Event (middle Homerian) in the Viduklė-61 well, Lithuania. The Viduklė-61 well is located in the west of Lithuania i...

The Gėluva age (late Homerian: Silurian) is an important interval of time during which one of the major episodes of mass extinction occurred, affecting many clades of marine organisms. In this study, we investigated a stratigraphic series of gamma logs in the Viduklė-61 well. To test the possible presence of sedimentary cycles, we applied wavelet a...

Anotacija Kojelė A., Radzevičius S., Spiridonov A., Brazauskas A. Gėluvos regioninio aukšto (viršutinis homeris, silūras) ribos stratotipas // Geologijos akiračiai. ISSN 1392–0006. 2014, Nr. 1, 10–21 p. Suaktyvėjus silûro uolienų tyrimams Vakarų Lietuvoje, būtina revizuoti visą silūro stratigrafinę schemą, naujai aprašyti stratigrafinius padalinius...

Ireviken event (Early Silurian) is one of the most prominent early paleozoic species turnovers identified by now. Earlier investigations showed that during considered biotic crisis large number of conodont species became extinct. Just twelwe out of sixty globally known species survived (Calner, 2008). A lot of attention concerning Irreviken event h...