Excavations
Earlier limited works in Krasiejów were focused on one meter thick claystone layer containing accumulations of bone fossils. Fine-graininess of the bone bearing sediment, high organic matter content and constant thickness of the layer indicate its lacustrine origin.
Single bone findings below this layer proved that the vertebrate community had been living in this area for a long time. However, environmental conditions favouring fossilization of their remains were rare. This could occur when the hypoxia and toxicity of sediment caused by decaying bacteria protected corpses from scavengers, and a flow of highly mineralised waters counteracted humic acids, protecting bones from dissipation. Krasiejów claystone contains numerous characean gyrogonites - resting stages of green algae with calcareous walls found only in low-salinity and fresh waters, shells of freshwater crustaceans - conchostracans, and shell moulds of unionid bivalves. Stratification and composition of sediment above and below the bone-bearing layer indicate its fluvial origin. The environment of a river's delta evidently did not favour fossilization of vertebrate remains.
The most important achievement of this year's excavations was the discovery of a small area of lacustrine sediments containing accumulations of bones and skeletons about 7 meters above the main layer. Species composition of this community is the same as in the lower level, but with domination of terrestrial animals (aetosaurs, capitosaurs and early dinosaurs) and low participation of strictly aquatic animals (metoposaurs and phytosaurs). This, and also the abundance of freshwater bivalves' remains, type of sediment and its stratification, suggest an environment of a small, isolated pool where partly decayed carcasses were deposited by flood waters.
Following months of excavations brought about discoveries of various fossils. The works, supervised by Prof. Jerzy Dzik, were led by assistants: Tomasz Sulej (Institute of Palaeobiology), Mariusz Lubka (Wrocław University), Andrzej Kaim (Institute of Palaeobiology) and Agnieszka Kapuścińska (Faculty of Geology of the Warsaw University graduate).
June: - The most important of the initial findings was an incomplete skeleton of a phytosaur. It contains pelvis and thirteen trunk vertebrae, seven of them preserved in life position. It is possible that a fragment of neck spine found nearby during initial works in 1999 belongs to the same individual. This skeleton is the least displaced set of remains of an adult phytosaur from Krasiejów.
July: - A complete skull of a young metoposaur and a complete but poorly preserved ganoid fish were among the important discoveries of the month. For the first time identifiable plant remains were found in Krasiejów. The most valuable are scales and leafed twigs of a coniferous tree allied to Voltzia.
Towards the end of the month the works were moved to the upper bone-bearing level, discovered in spring and located 7 meters above the main layer. Here, over a dozen vertebrae and most importantly a complete pelvis and a limb of a small bipedal archosaur were uncovered. Its dinosaur affinity is suggested by an ossified buttress over a hip joint socket (acetabulum), against which the head of a vertically orientated femur was loaned, and by a three-digit foot. However, the acetabulum is fully calcified in its center, as opposed to open sockets of dinosaurs.
August: - Numerous aetosaur remains, including skulls, were found. They are the most complete among the oldest fossils of this group of animals.
September: - Skull fragments of a capitosaurid amphibian were found in the upper level. The remains were identified as Cyclotosaurus, an animal which had its ear-drums located in oval openings near the posterior margin of the skull roof.
An accumulation of dinosaurid remains, including a crushed skull, was found in the second half of the month.
