The Zagaje Formation is a Latest Triassic-Early Jurassic Epoch (Rhaetian-Sinemurian) geologic formation located mostly in Poland with layers also exposed in north Germany. This unit is known for its diverse Ichnofossil assemblages, with traces of invertebrates along vertebrate footprints, as well plants, large coal accumulations, invertebrate remains and ichnofossils.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607. The Zagaje Formation correlates with The lower part of the Höganäs Formation in Scania, as well the Munkerup Member and the Gassum Formation in Denmark.
Paleoenvironment
The Zagaje Formation is particularly visible in the Sołtyków region and is made mostly of Early Jurassic continental mudstone-sandstone deposits linked to the onset of "depositional sequence I". Its age is confirmed as mostly Early Hettangian through stratigraphic and paleontological analyses, including fossil flora and conchostraca findings. Sedimentological studies divide the Sołtyków profile into three parts: ephemeral reservoir deposits, floodplain and lacustrine sediments, and river channel deposits, highlighting dynamic depositional environments influenced by tectonic subsidence and varying hydrological conditions.
Climate wise, the area was located back in the Hettangian around 45°N paleolatitude in Laurasia within a rise of 5–10 °C above present, where it experienced significant climatic and environmental change related with sea-level fluctuations, manifested locally with a notorious retrogradational fluvial-lacustrine sedimentation, with evidence of a humid climate interspersed with drier seasons. Some plant fossils like Hirmeriella mark points of aridity on what was mostly a humid swampy alluvial-lacustrine habitat.
The Zagaje Formation's deposits are known from both outcrops and borehole profiles that consist primarily of sandstones, mudstones, and interspersed coal and siderite layers. It represents a stratigraphic gap with the underlying Upper Triassic formations and is capped by a transgressive contact with the Skłoby Formation. This unit contains freshwater fauna and diverse trace fossils, including vertebrate tracks. The paleoenvironment reflects a dynamic alluvial plain shaped predominantly by high-sinuosity stream processes, transitioning from earlier braided and low-sinuosity stream systems. This evolution is attributed to climatic changes, rising base levels, and decreasing geomorphological gradients. Observations, both from exposures and borehole data, highlight the dominance of avulsion processes, with several depositional subsystems identified. Facies with organic remains are diverse: riverbed biofacies, derived from meandering channels characterized by fining-upward sequences composed of channel lag deposits, point-bar sands, and finer overlying sediments. These deposits exhibit lateral accretion bedding and significant fossil bivalves and large-sized floated plant remains (stems and trunks of large plants) consistent with subaqueous dune migration within the channels; levee deposits derived from successive floods with scarce root traces, while plant remnants are common; Paleosoils with sparse traces of plant roots and remains of floating plants of highly variable size (mainly organic detritus, but also fragments of wood), fragments of bivalve shells and vertebrate remains (amniote bones, tracks, fish scales); the biofacies of the ephemeral water reservoir with plant remains, mainly horsetails, and fossils of insects, ostracods, and conchostraca; The pedogenic soil biofacies with remains of plant roots with preserved organic matter and rhizomes and stems in a living position; Floodplain biofacies with traces of numerous plant roots and plant macroremains, and remains of sedge stems preserved in a living position; Lake-marsh biofacies, dark, laminated mudstones with plant roots and coal, with few fossil bivalves, a large amount of organic matter in the form of plant detritus, and layers of coal and numerous finds of miospores and megaspores. The local presence of charcoal fragments and high concentrations of PAHs, along with possible burnt plants, provides evidence for wildfires in the region, that likely occurred near the surface with charred wood fragments were subsequently incorporated into sediments by river transport.
The high presence of coprolites has allow also to establish the tropic chain of the local biota, with a clear full ecosystemical substitution of the older Triassic archosaurs by Dinosaurs.
Biota
Indet. Invertebrates Several unname Ichnofossils are recovered at Soltyków, including conical domichnia (Conichnus?), bivalve straight to winding linear trails, smooth vertical and subvertical branching tunnels, knob-walled tunnels, mace-shaped or irregular ellipsoid chambers, etc. GenusSpeciesLocationMaterialMade ByCruziana C. problematica cf.C. isp SoltykówDwelling structures Annelids Insect larvae NematodesCochlichnus C. isp. Gromadzice Kontrewers Odrowaz Soltyków Traces Annelids Insect larvae NematodesConichnus C. isp. Gromadzice Kontrewers Odrowaz Soltyków Subcylindrical burrows Annelids Nematodes CrustaceansDiplichnites D. isp. Soltyków Hypichnial trackway Insects Myriapods ArachnidsDiplocraterion D. parallelum Gromadzice Kontrewers Odrowaz Soltyków U-Shaped Burrows Crustaceans Annelids Phoronidans Insects FishImbrichnus I. isp. Gromadzice Kontrewers Odrowaz Soltyków Burrows Annelids Bivalves CrustaceansKouphichnium cf. K. isp. Soltyków V-shaped hypichnial marks Xiphosura MalacostracaPalaeophycus P. isp. Soltyków Straight or slightly curved burrows Annelids Bivalves CrustaceansPlanolites P. isp. Soltyków Horizontal burrows Annelids Bivalves CrustaceansRusophycus R. isp. Soltyków Resting Traces Resting traces of arthropodsScolicia S. isp. Gromadzice Kontrewers Odrowaz Soltyków Moving Traces Locomotion trace of gastropodsScoyenia S. isp. Soltyków Linear slender burrows Beetles?Skolithos S. isp. Gromadzice Kontrewers Odrowaz Soltyków Sac/Bottle shaped burrows Annelids Crustaceans InsectsSpongeliomorpha S. carlsbergi S. isp. Gromadzice Kontrewers Odrowaz Soltyków Sac/Bottle shaped burrows Annelids Crustaceans Insects
Molluscs Indeterminate gastropod egg capsules are known, similar to the ones recovered in the extant Neritina. 4 unnamed morphotypes of freshwater bivalves of the family Unionidae are known. GenusSpeciesLocationMaterialNotesImagesAnodonta A. liasokeuperina SoltykówIsolated ShellsA freshwater mussel, member of the family Unionidae Calceoformites C. uchmani SoltykówClog-shaped protrusionsBivalve estabilization tracesCardinia C. follini C. inglensis C. cf.kullensis Gromadzice Odrowaz Podole Soltyków Isolated ShellsA Carditidae Bivalve. Indicator of oligohaline settings and found also on the younger Skłoby FormationLockeia L. siliquaria L. amygdaloides L. czarnockii Gromadzice Kontrewers Odrowaz SoltykówDwelling tracesResting traces of BivalvesPtychoplasma P. conica SoltykówLocomotion traceGastropod Locomotion tracesScalichnus S. phiale S. isp. Gromadzice Kontrewers Odrowaz SoltykówSac/Bottle shaped burrowsEscape structure of mud-dwelling bivalvesScolicia S. isp. Gromadzice Kontrewers Odrowaz SoltykówTracesLocomotion and feeding trace of gastropodsUnio U. minutus SoltykówIsolated ShellsA freshwater mussel, member of the family Unionidae Viviparus V. spp. SoltykówIsolated ShellsA freshwater snail, member of the family Viviparidae
Crustacea GenusSpeciesStratigraphic positionMaterialNotesImagesBulbilimnadia B. kilianorum Hucisko SoltykówValvesA freshwater Ostracodan of the family BulbilimnadiidaeDarwinula D. sarytirmenensis D. spp. Gromadzice Hucisko Odrowaz SoltykówValvesA freshwater Ostracodan of the family DarwinulidaeEuestheria E. opalina E. loczyi E. brodieana E. minuta Euestheria sp. Gromadzice Hucisko Kontrewers Odrowaz SoltykówValvesA Freshwater Clam shrimp (Phyllopodan) of the family Lioestheriidae. Isopodichnus I. isp. Gromadzice Kontrewers Odrowaz SoltykówHypichnial marksFeeding and moving traces of phyllopod and notostracan crustaceans
Insects Radial chambers around large tunnels have been recovered, they may be arthropod burrows or traces of roots. Large nest structures with septa, similar to nesting behaviour of insects like Cicadas are known. GenusSpeciesLocationMaterialNotesImagesArtematopoditesA. ssp. Odrowaz MPK 5/36, 39, 40A Coleopteran, member of the family PermosynidaeBlattodea indet.Indeterminate Odrowaz MPK 5/54Indeterminate Blattodean remainsBlattulidae indet.Indeterminate Odrowaz MPK 5/1Indeterminate Cockroach remainsCaraboidea indet.Indeterminate Odrowaz MPK 5/12, 15Indeterminate Beetle remainsColeoptera indet.Indeterminate Odrowaz Isolated WingsIndeterminate Beetle remainsHelminthoidichnitescf. H. isp. SołtykówGnawing tracessurficial gnawing traces made by insectsHydrobiitesH. sp. Odrowaz MPK 5/10, 13, 17, 22, 25, 33A Coleopteran, member of the family PermosynidaeLinckichnusL. terebrans SołtykówBoring TracesDetritivorous habitation dwellings or oviposition structures of insects in dead woodMemptusM. sp. Odrowaz MPK 5/44A Coleopteran, Incertade sedisNotocupesN. sp. Odrowaz MPK 5/6A Coleopteran, Incertade sedisOdrowazicorisO. polonicus Odrowaz MPK 5/2A Hemipteran, member of the family BelostomatidaePolysitumP.? sp. Odrowaz MPK 5/14, 29A Coleopteran, Incertade sedisPhoroschizidae indet.Indeterminate Odrowaz MPK 5/4,5, 8, 20, 35Indeterminate Beetle remainsXylonichnusCf.X. isp. SołtykówBoring TracesBorings in the wood made probably by insect larvae
Fish Unidentified Actinopterygian fish scales and teeth were collected from clayish, organic-rich lake deposits, while some coprolites have been referred to Hybodontiform sharks. GenusSpeciesLocationMaterialNotesImagesSemionotusS. cf. bergeriCzarniecka Góra Single specimenA Semionotiform bony fish of the family SemionotidaePaleoniscidae indet.IndeterminateSołtykówScales & TeethIndeterminate Palaeonisciformes specimens
Testudinata GenusSpeciesLocationMaterialNotesImagesChelonipusC. isp.SołtykówFootprintsTurtle TracksTestudinata indet.IndeterminateSołtyków Carapace FragmentsUnidentified Turtle remains, quoted to belong to a large sized taxon
Synapsids GenusSpeciesLocationMaterialNotesImagesAmeghinichnusCf.A. isp.SołtykówFootprintsSmall Synapsid tracks, likely from MammaliaformesBrasilichniumB. isp.SołtykówFootprintsSmall Synapsid tracks, likely from MammaliaformesDicynodontipusD. isp. SołtykówFootprintsTracks referred to Eucynodonts, maybe Tritylodontidae TherapsipusCf.T. isp.Sołtyków FootprintsTracks referred to Eucynodonts
Rhynchocephalia GenusSpeciesLocationMaterialNotesImagesRhynchosauroidesR. isp.SołtykówFootprintsTracks referable to both Sphenodontidae and Lepidosauromorpha
Crocodrylomorphs GenusSpeciesLocationMaterialNotesImagesBatrachopusB. isp.SołtykówFootprintsCrocodrylomorph Tracks, likely of terrestrial taxaCrocodylomorpha indet.IndeterminateSołtykówBones inside a large bromaliteAn Indeterminate Crocodrylomorph, likely preyed on by a large TheropodCrocodylomorpha indet.IndeterminateSołtykówFootprintsUnnamed 3rd type of FootprintMalutitetrapodiscusCf.M. isp.Sołtyków FootprintsProbably left by small terrestrial crocodylomorphs
Pterosauria GenusSpeciesLocationMaterialNotesImagesPteraichnuscf. P. isp.SołtykówFootprintsPterosaur Tracks, the individuals that left them probably had a wingspan of about 30–40 cm
Theropods Some elliptical "post-egg" structures egshells & eggs with embryo remains have been referred to theropods, yet may also belong to Ornithischians. GenusSpeciesLocationMaterialNotesImagesAnchisauripus A. ispp. Cf.A. isp.SołtykówFootprintsAdscribed to smal slender primitive predatory dinosaurs, related with genera such as CoelophysisEubrontes E. isp. Cf.E. isp.SołtykówFootprintsEubrontes is related to the Genus Dilophosaurus, representing a basal NeotheropodsGrallator G. ispp.