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[dinosaur] Dinosaur biogeographic structure and Mesozoic continental fragmentation + Scandinavian fossils

Ben Creisler

This paper is not yet officially online, but info and press releases are already out:

A.M. Dunhill, J. Bestwick, H. Narey,  and J. Sciberras (2016)
Dinosaur biogeographic structure and Mesozoic continental fragmentation: a network-based approach. 
Journal of Biogeography (advance online publication) 


Aim: To reconstruct dinosaur macro-biogeographic patterns through the Mesozoic Era using a network-based approach. We test how continental fragmentation affected dinosaur macro-biogeographic structure and evolutionary rates. 

Location: A global occurrence database of dinosaur families from the Late Triassic to the end-Cretaceous was used for this study. 

Methods: Biogeographic and geographic network models were constructed. Continental landmasses were linked by direct continental contact and sea level conditioned connections in geographic networks, and by shared dinosaur families in biogeographic networks. Biogeographic networks were run with raw, novel and first-step connections for all dinosaur, ornithischian, theropod, and sauropodomorph taxa. 

Results: Geographic connectedness declines through time, from peak aggregation in the Triassic-Jurassic to complete separation in the latest Cretaceous. Biogeographic connectedness shows no common trend in the raw and novel connection network models, but decreases through time whilst showing some correlation with continental fragmentation in most of the first-step network models. Despite continental isolation and high sea levels, intercontinental faunal exchange continued right up to the end of the Cretaceous. Continental fragmentation and dinosaurian macro-biogeographic structure do not share a common pattern with dinosaurian evolutionary rates, although there is evidence that increased continental isolation resulted in increased origination rates in some dinosaurian lineages. Spatiotemporal sampling biases and early Mesozoic establishment of family-level distribution patterns are important drivers of apparent dinosaur macro-biogeographic structure. Main conclusions There is some evidence to suggest that dinosaur macro-biogeographic structure was influenced by continental fragmentation, although intercontinental exchange of dinosaur faunas appears to have continued up to the end of the Cretaceous. Macro-biogeographic patterns are obscured by uneven geographic sampling through time and a residual earlier Mesozoic distribution which is sustained up to the end of the Cretaceous.





A paper in open access:

Benjamin P. Kear, Johan Lindgren, Jørn H. Hurum, Jesper Milàn, and Vivi Vajda (2016)
An introduction to the Mesozoic biotas of Scandinavia and its Arctic territories.
Geological Society, London, Special Publications, 434,  Mesozoic Biotas of Scandinavia and its Arctic Territories. (advance online publication)

Free pdf:

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.