Turonian marine amniotes from the Bohemian Cretaceous Basin, Czech Republic

Abstract

Despite being known for over 155 years, the Late Cretaceous marine amniotes of the Bohemian Cretaceous Basin in the Czech Republic have received little recent attention. These fossils are however significant because they record a diverse range of taxa from an incompletely known geological interval: the Turonian. The presently identifiable remains include isolated bones and teeth, together with a few disarticulated skeletons. The most productive stratigraphical unit is the Lower–Middle Turonian Bílá Hora Formation, which has yielded small dermochelyoid sea turtles, a possible polycotylid plesiosaur and elements compatible with the giant predatory pliosauromorphPolyptychodon. A huge protostegid, together with an enigmatic cheloniid-like turtle,Polyptychodon-like dentigerous components, an elasmosaurid and a tethysaurine mosasauroid have also been found in strata corresponding to the Middle–Upper Turonian Jizera Formation and Upper Turonian – Coniacian Teplice Formation. The compositional character of the Bohemian Cretaceous Basin fauna is compatible with coeval assemblages from elsewhere along the peri-Tethyan shelf of Europe, and incorporates the globally terminal Middle–Upper Turonian occurrence of pliosauromorph megacarnivores, which were seemingly replaced by mosasauroids later in the Cretaceous.

Spatiotemporal Distributions of Non-ophidian Ophidiomorphs, With Implications for Their Origin, Radiation, and Extinction

“…Whereas the bivalve larvae would have floated on prevailing currents, it is more likely that the actively swimming dolichosaurs followed either the southern coastline of the Atlantic along western Africa to South America, or the northern coastline through the Baltics and along eastern North America (Caldwell and Cooper, 1999). The migration pattern also compares well with that proposed for the Turonian distribution of russellosaurines and aigialosaurs (Bell, 1997;Bardet et al, 2008;Kear et al, 2013).…”

“…The CTBE, which restructured marine ecosystems globally, could easily have affected dolichosaur ecosystems and thus populations, causing an extinction or near-extinction of dolichosaurs outside of their population centers: the Tethys and the Western Interior. The radiation of mosasauroids in the Tethys during the Turonian (Bardet et al, 2008;Kear et al, 2013) likely exacerbated the situation, possibly putting competition and predation pressures on any surviving dolichosaur populations.…”

The shell bone histology of fossil and extant marine turtles revisited

“…These taxa are not closely related to the modern chelonioid taxa (Kear & Lee, ; Benson et al ., ). The second phase occurred mainly in North America and Eurasia, starting in the late Early Cretaceous and reaching a diversity peak in the Late Cretaceous (Hirayama, ; Lapparent de Broin & Werner, ; Bardet et al ., ; Lapparent de Broin, ; Kear, ; Kear & Lee, ; Sato et al ., ; Kear et al ., ). It includes more open marine forms such as Protostegidae, Cheloniidae sensu lato ( s.l. )…”

Cretornis hlavaci Frič, 1881 from the Upper Cretaceous of Czech Republic (Pterosauria, Azhdarchoidea)

“…The Jizera Formation is a part of a transgressiveeregressive cycle deposited during the regressive phase after the maximum transgression characterized by the Bíl a Hora Formation, which is composed of marlstones, micritic limestones and spongolites. The vertebrate fauna of the Jizera and Teplice formations, except the pterosaur Cretornis, consist of diverse chondrichthyan and osteichthyan fishes and marine reptiles (Fri c, 1883;Ekrt et al, 2008;Kear et al, 2014).…”