Sneaky crocodiles occupied sauropod hatcheries
The nesting grounds of sauropod dinosaurs where absolutely astonishing, covering hundreds of square miles in cases, forming vast playgrounds to rear their young. Some of the most exquisitely preserved sauropod hatcheries are from Jabalpur in India, and offer a unique window into investigating the reproductive and parental behaviour of these magnificent giants
|Sarcosuchus [Credit: (c) Nicholls. 2015]|
At a superficial level, the eggs of reptiles might all appear to be quite similar to each other. However, we can actually gain a lot of insight from detailed examination of their chemistry and ultrastructure, and scientists now know that different groups of reptiles have very different egg types.
|Nesting site and some of the fossilised eggs [Credit: Srivastava et al. 2015]|
This is based on several delicate details of the eggshell, including a sub-spherical to ellipsoid shape, a smooth and uneven external surface texture, and distinctly shaped shell units typically found in crocodilian eggs.
|Different types of reptilian eggs in cross section [Credit: Srivastava et al. 2015]|
Dyrosaurids were quite common in South-East Asia towards the closing of the Cretaceous, and even survived the mass extinction that saw the demise of the non-avian dinosaurs. The nesting site is fossilised in rocks that represent an ancient estuarine environment, not too far from the shoreline, so perhaps young dyrosaurids were born on land, taking to the waters only at a later age when they had levelled up their swimming abilities.
|Sections of the crocodylomorph eggs, including under-crossed polars to give some funky colours! |
[Credit: Srivastava et al. 2015]
The findings appear in the PLOS ONE.
Author: Jon Tennant | Source: Public Library of Science [January 21, 2016]