Extinct Dwarf Emu Egg Discovered in Sand Dune, a First of Its Kind

For the first time, scientists discovered an egg that is thought to belong to an extinct dwarf emu species that once only lived on an island in Australia. The impressively large egg of a dwarf emu that became extinct roughly 200 years ago was just unearthed on the Australian island of Tasmania.

The discovery, written up in the journal Biology Letters, entitled "Eggs of extinct dwarf island emus retained large size" helped researchers in understanding the now extinct dwarf emus and how the birds' eggs evolved to protect the chicks inside.

Understanding the Extinct Dwarf Emus

The world's second-largest bird species is the Emus, measuring roughly at 5.7 feet tall. According to The Smithsonian, there are only one species of emu left alive on the Australian continent, however, this wasn't always the case. Before settlers arrived on the continent, there was a minimum of 3 different emu subspecies living on different islands on the Australian coasts, reported by Phys.org.

Other than the emus we know today, a subspecies known as the Dromaius novaehollandiae, the smaller Tasmanian emu, and the dwarf King Island emu once roamed the continent. Unfortunately, the 3 subspecies became extinct shortly after colonization, primarily due to over-hunting.

Julian Hume, lead author, and paleontologist for the National History Museum, London told Live Science that the emus diverged roughly at the end of the last ice age, about 11,500 years ago when melting glaciers resulted in an increase in sea levels that separated the islands from the Australian mainland. It is a rule that when species are isolated on an island evolution dictates that they will tend to shrink over time, which is the case for the dwarf emus.

The smallest of all emu subspecies was the King Island emu that stood less than a meter tall and is half the weight of the modern emus we know today. Additionally, it is the only emu subspecies that had no egg discovered, until today.

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Discovering the Rare Egg of an Extinct Dwarf Emu

The unique egg was first discovered by Christian Robertson, a natural historian on King Island, in a sand dune. Hume explains that Robertson found broken pieces of the egg in one place and painstakingly glued them back together until he had a unique and rare almost complete emu egg.

The findings weren't as unique on their own, it enabled researchers to compare extinct emu eggs including 6 from Tasmania and 1 from Kangaroo island. Scientists discovered that despite the minuscule size of the bird, the eggs were roughly the same dimensions as larger modern emus. Although, the discovered eggs were slightly less in volume and mass and had a thinner shell.

Researchers theorize that the raiment of large egg sizes could have helped dwarf emus protect the eggs from predatory carnivores and give the chicks time to fully develop before emerging from its shell. The evolutionary strategy is similar to the New Zealand kiwis that lay large eggs relative to their size.