Kohei Tanaka, Darla K. Zelenitsky, FranÃois Therrien & Yoshitsugu Kobayashi (2018)
Nest substrate reflects incubation style in extant archosaurs with implications for dinosaur nesting habits.
Scientific Reports 8, Article number: 3170Â
doi:10.1038/s41598-018-21386-x
Dinosaurs thrived and reproduced in various regions worldwide, including the Arctic. In order to understand their nesting in diverse or extreme environments, the relationships between nests, nesting environments, and incubation methods in extant archosaurs were investigated. Statistical analyses reveal that species of extant covered nesters (i.e., crocodylians and megapodes) preferentially select specific sediments/substrates as a function of their nesting style and incubation heat sources. Relationships between dinosaur eggs and the sediments in which they occur reveal that hadrosaurs and some sauropods (i.e., megaloolithid eggs) built organic-rich mound nests that relied on microbial decay for incubation, whereas other sauropods (i.e., faveoloolithid eggs) built sandy in-filled hole nests that relied on solar or potentially geothermal heat for incubation. Paleogeographic distribution of mound nests and sandy in-filled hole nests in dinosaurs reveals these nest types produced sufficient incubation heat to be successful up to mid latitudes (â47Â), 10Â higher than covered nesters today. However, only mound nesting and likely brooding could have produced sufficient incubation heat for nesting above the polar circle (>66Â). As a result, differences in nesting styles may have placed restrictions on the reproduction of dinosaurs and their dispersal at high latitudes.
======
Harsha Dhiman, Guntupalli V. R. Prasad & Anjali Goswami (2018)
Parataxonomy and palaeobiogeographic significance of dinosaur eggshell fragments from the Upper Cretaceous strata of the Cauvery Basin, South India.
Historical Biology (advance online publication)
Â
In the past, fossilised dinosaur eggshells have been extensively documented from the Upper Cretaceous Lameta Formation of Central India and as many as nine oospecies are known at present from this formation. Compared to this, only one dinosaur oospecies has been described from the Cretaceous succession of the Cauvery Basin. However, the first fossil egg from India, identified as a chelonian egg, was documented from the Aptian â Albian Karai Formation of the Cauvery Basin in 1957. Following this, a solitary titanosaurid dinosaur egg was described from the Upper Cretaceous (Lower Maastrichtian) Kallankuruchhi Formation, Cauvery Basin in 1996. More recently, we have recovered isolated eggshell fragments from the marine part of the Upper Cretaceous (Late Maastrichtian) Kallamedu Formation. Based on eggshell morphology, microstructure and ultrastructure, these eggshell fragments are assigned to the oospecies Fusioolithus baghensis. The new find from the Cauvery Basin is important from palaeobiogeographic point of view as the oofamily Fusioolithidae is found in the Upper Cretaceous strata of India, France, Argentina and Morocco. Based on the common occurrence of similar oospecies in South America, Africa, Europe and India, a Late Cretaceous palaeobiogeographic connection between India and South America as well as Europe via Africa is suggested.