The basin extends from Hanöbukten, a bay in the Baltic Sea, in the east to the town of Hässleholm in the west and ends with the two horsts Linderödsåsen and Nävlingeåsen in the south.

The Kristianstad Basin has also yielded fossils of several varieties of reptiles, including plesiosaurs, turtles and crocodylomorphs, as well as one of the most diverse mosasaur faunas in the world and some of the few non-avian dinosaurs known from Sweden.

The Kristianstad Basin is located in northeastern Skåne, the southernmost province of Sweden, extending from Hanöbukten, a bay in the Baltic Sea, in the east to the town of Hässleholm in the west.

[2] The basement is overlaid by approximately 250 metres (820 feet) of mainly shallow water or marine sediments from the Cretaceous, ranging in age from the Barremian to the earliest Maastrichtian.

Conglomeratic beds are also common, typically consisting of belemnite rostra or bivalve shells and coarse terrigenous clastic rocks.

Nilsson's work was followed by further investigations by physicist and chemist Wilhelm Hisinger in 1837, archaeologist and bibliographer Johan Henrik Schröder in 1885 and paleontologist Carl Wiman in 1916.

Later studies on marine reptile fossils were also conducted by J. Christian Moberg in 1884 and 1885, Bernhard Lundgren in 1888, Anders H. Hennig in 1910, Alf Lundegren in 1934, Gustaf Troedsson in 1946 and 1954 and prominently in a series of publications of paleontologist Per-Ove Persson, who described several species of mosasaurs and plesiosaurs alongside sea turtles and the crocodylomorph Aigialosuchus, from 1954 to 1996.

[15] Fossil material conclusively identified as dinosaurian was recovered only relatively recently, with the earliest discovery being two teeth from a small Ornithopod, similar to those of Hypsilophodon, being found at Ivö Klack in 2001.

Leptoceratopsid fossils include four maxillary teeth, a dentary tooth, two caudal vertebrae and one right manual phalanx, recovered at Åsen and Ullstorp.

[3][15] The discovery of the leptoceratopsid remains were scientifically significant as they represented the first record of ceratopsians in Europe and also contradicted the previously prevailing hypothesis that more primitive members of that group preferred semi-arid and arid environments rather far away from coastal regions.

[15] The first fossil of a carnivorous dinosaur in Sweden was discovered by high school student Clarence Lagerström in 2015 at the Ugnsmunnarna site on Ivö island.

Despite being fragmentary and few in number, they are scientifically important as they represent some of the few remains of the poorly known dinosaur fauna of the Baltic Shield, which was an isolated landmass during the Late Cretaceous.

[15] The warm shallow seas of the Kristianstad Basin were inhabited by a variety of marine reptiles, with several mosasaurs and plesiosaurs present.

[9] The mosasaurs were large, carnivorous reptiles at the top of the food chain and since all the Campanian species are known from several sites, it is likely that all of them lived in the entire basin.

The high diversity of mosasaurs in the basin can be explained by the dissimilarity in dentition and body size between the species, meaning that they would not have competed with each other for food.

Among the hybodonts were the genera Polyacrodus and Meristodon, which went extinct in the early Campanian, before the time when a majority of the local fossil fauna lived.

[5] All shark species found in the Kristianstad Basin were active predators, but many of them only fed on smaller food items such as bony fish and various invertebrates.

Local chimaerids, adapted to eat hard-shelled organisms with their flattened and crushing dental plates, include the genera Amylodon, Edaphodon, Elasmodus and Ischyodus.

[5] The local echinoderm fauna, which also included starfish and crinoids, was dominated by sea urchins, which occur in many different genera, the most common of which are Cidaris, Echinocorys, Echinogalerus, Holaster, Micraster, Phymosoma and Salenia.

Belemnites were a basic part of the food web and likely served as prey for many of the vertebrates in the basin, such as fish, plesiosaurs and the smaller mosasaurs.

[5] Fossil wood has been recovered from late Middle Santonian to earliest Campanian-age deposits at Åsen, representing the tree genera Pinus, Platanus, Scandianthus, Silvianthemum and Actinocalyx.

The jaws of Aigialosuchus are long and thin, suggesting a diet mostly composed of fish, but its teeth are unusually robust, meaning that it might also have fed on shelled invertebrates or larger animals.

[5] During the transgressions experienced during the Late Cretaceous, the inland sea within the Kristianstad Basin remained very shallow, and its northern parts formed an archipelago with several low islands and a number of small peninsulas.

[2] Remnants of these islands and peninsulas remain today in the form of rocky hills and mounts throughout northeastern Skåne, such as the Ivö Klack site, Fjälkinge backe, Kjugekull, Oppmannaberget, Vångaberget, Västanåberget and Ryssberget.

Modern great white sharks are known to patrol around small islands inhabited by seals, possibly a behavior also present in the similar Cretoxyrhina.

[4] The high diversity of sharks and mosasaurs recovered at Ivö Klack shows that large predators frequented the rocky coastline.

It is probable that the richness of the environment also made Ivö Klack a nursery and feeding ground for migratory species, similar to rocky shores today.

The discovery of the basin's only crocodylomorph at Ivö Klack might indicate that Aigialosuchus preferred to live in coastal waters, where it could lay its egg on adjacent land, rest and heat up, similar to modern crocodilians.