Monday, 9 April 2012

How The Dinosaurs Shaped Easter Eggs

Across the world people of the Christian faith celebrate Easter. Apart from the cross the other iconic symbol of this is the egg, representing new birth - the chocolate is an added pleasure. Yet new research suggests that the ancestry of the Easter egg, and indeed all bird eggs, may in fact be incredibly ancient.
A useful diagram of links between eggs

Easter eggs and the bird eggs on which they are modeled come in a range of different shapes. Yet as birds all have a single common ancestor in Archaeopteryx, it is likely that their egg shapes have been affected by the dinosaurs' eggs from which their common ancestor is itself descended.

The interesting feature is that dinosaur eggs tend to be very even in shape, with rounded, symmetrical, oblong ends and elongated shells. A classic example of this is top-left, Macroelongatoolithus.

Researchers from the University of Leicester researched these differences by comparing eggs from both animal groups, using a mathematical formula to plot them onto a grid and then examine the similarities and possible lines of ancestry.

Some eggs were so indistinct that it was hard to match them up. Others were a little more obvious, such as the case of the 70 million year old Sankofa pyrenaica, whose eggs have a definite blunt and pointed end, linking it to the common hen. In fact they found that there was a general trend in the links.

The diagram above shows small meat-eating dinosaurs to the left, modern birds to the right, with Sankofa right in the middle. Analysis of the shell from Sankofa eggs found in the Pyrenees showed that they had a structure similar to birds, with two thin hard layers. The only difference was the lack of a third, external water-proof layer, present in all modern birds' eggs. With the link between Achaeopteryx and birds firmly established, further discoveries of dinosaur eggs will reveal more about the ancestry of bird eggs.