An introduction to the Mesozoic biotas of Scandinavia and its Arctic territories

Abstract

The Mesozoic biotas of Scandinavia have been studied for nearly two centuries. However, the last 15 years have witnessed an explosive advance in research, most notably on the richly fossiliferous Triassic (Olenekian-Carnian) and Jurassic (Tithonian) Lagerstätten of the Norwegian Arctic Svalbard archipelago, Late Cretaceous (Campanian) Kristianstad Basin and Vomb Trough of Skåne in southern Sweden, and the UNESCO heritage site at Stevns Klint in Denmark -the latter constituting one of the most complete Cretaceous-Palaeogene (Maastrichtian -Danian) boundary sections known globally. Other internationally significant deposits include earliest (Induan) and latest Triassic (Norian-Rhaetian) strata from the Danish autonomous territory of Greenland, and the Early Jurassic (Sinemurian-Pliensbachian) to Early Cretaceous (Berriasian) rocks of southern Sweden and the Danish Baltic island of Bornholm, respectively. Marine palaeocommunities are especially well documented, and comprise prolific benthic macroinvertebrates, together with pelagic cephalopods, chondrichthyans, actinopterygians and aquatic amniotes (ichthyopterygians, sauropterygians and mosasauroids). Terrestrial plant remains (lycophytes, sphenophytes, ferns, pteridosperms, cycadophytes, bennettitaleans and ginkgoes), including exceptionally well-preserved carbonized flowers, are also world famous, and are occasionally associated with faunal traces such as temnospondyl amphibian bones and dinosaurian footprints. While this collective documented record is substantial, much still awaits discovery. Thus, Scandinavia and its Arctic territories represent some of the most exciting prospects for future insights into the spectacular history of Mesozoic life and environments.

Geological control on dinosaurs’ rise to dominance: Late Triassic ecosystem stress by relative sea level change

“…Because of generally high sedimentation rates and stressed marginal marine conditions, deltaic successions in TBO only comprise cm‐scale coal beds, and bay deposits dominate over lacustrine (Klausen, Ryseth, Helland‐Hansen, Gawthorpe, & Laursen, 2015), making the fossil preservation potential low. Except for a 3‐m‐long temnospondyl amphibian (Vigran et al., 2014), ichthyosaurs (Kear, Lindgren, Hurum, Milàn, & Vajda, 2016) and unspecified ‘vertebrate’ (Fefilova, 2005) fossils found in prodelta to shallow marine deposits, body fossils are rare, and few potential fossil sites exist—placing extra emphasis on the palynological record for understanding the evolution of terrestrial life in TBO. Since floral species are fundamental building blocks of the food chain, it is natural to assume that the importance TBO deltas had for terrestrial plants is transferrable to the fauna.…”

The marine conservation deposits of Monte San Giorgio (Switzerland, Italy): the prototype of Triassic black shale Lagerstätten

“…Our list is not intended to be all inclusive for global Lagerstätten but was assembled with the intention of assessing the characteristics of the Triassic Monte San Giorgio in a global framework. For the Early Triassic, we included the Paris biota (Thaynes Fm) from Idaho, USA (Brayard et al, 2017 ; Doguzhaeva et al, 2018 ), the fauna from Kap Stosch, Greenland (Wordie Creek Fm; Brinkmann et al, 2010 ; Kear et al, 2016 ), the famous fish nodules from the Middle Sakamena Formation of Madagascar (Beltan, 1996 ; Brinkmann et al, 2010 ; Kogan & Romano, 2016 ), the ichthyosaur- and thalattosaur-bearing faunas of the Sulphur Mountain Formation from British Columbia and Alberta, Canada (Bastiaans et al, 2023a , 2023b ; Neuman, 1992 , 2015 ) and of the Vikinghøgda Formation in Svalbard (Hurum et al, 2018 ).…”

“…We complemented that list with some European Lagerstätten such as the Swiss Ducanfurgga (Prosanto Fm; Scheyer et al, 2017 ), which yielded some amazing vertebrate fossils recently (Cavin et al, 2017a , 2017b ; Ferrante et al, 2023 ; Scheyer et al, 2017 ). Furthermore, we included data from the conservation deposits of the Prida Formation of Fossil Hill, Nevada (Kelley et al, 2016 ; Sander et al, 1994 , 2021 ), Edgeøya, Svalbard (Botneheia Fm; Engelschiøn et al, 2023 ; Kear et al, 2016 ) and the Eosauropterygia-rich strata of the Gailtal in Carinthia (Partnach Fm; e.g., Rieppel, 1994 ; Tichy, 1998 ; Zapfe & König, 1980 ).…”

Marine reptiles from the Jurassic/Cretaceous transition at the High Andes, Mendoza, Argentina

“…Benson and Druckenmiller, 2014;Fischer et al, 2012;Tennant et al, 2016Tennant et al, , 2017Zverkov et al, 2018). Marine reptile-bearing localities documenting this transition are still scarce and/or poorly studied with a remarkable exception concerning the northern high latitude Slottsmøya Member Largestätte (SML) of the Agardhfjellet Formation (Spitsbergen, Svalbard archipelago, Norway) (Delsett et al, 2016(Delsett et al, , 2017Druckenmiller et al, 2012;Hurum et al, 2012;Kear et al, 2015;Knutsen et al, 2012a, b, c;Roberts et al, 2014). From southern latitudes, rich Tithonian marine reptile faunas from the Vaca Muerta Formation (Neuquén Basin, Argentina) have been extensively reported (e.g.…”