Aepyornis maximus – The Elephant Birds
For a long time, Aepyornis maximus was thought to be the heaviest bird ever but it is now thought to have tipped the scales at ‘only’ about 450 kg (almost 1,000 lb) and stood 3 m (10 ft) high.
History of Aepyornis maximus
The three genera of these flightless ratites ( Aepyornis) appear to have been confined to Madagascar and were primitive members of the ostrich-rhea-emu lineage. These giants had strong, conical bills and only vestigial wings.
The four Aepyornis species (there are also three of Mullerornis in the Aepyornithidae) had very stout legs with relatively short leg/foot bones, suggesting that they were rather ponderous forest-dwellers. Their feet appear to have been three-toed.
Radiocarbon dating of eggshell fragments suggests that elephant birds, on which Marco Polo’s legendary roc appears to have been founded, survived well into this millennium. Extinction probably came about through a combination of habitat destruction (deforestation), with ensuing drought, and hunting pressure. Aepyornis laid the largest known egg.
The Largest Egg Ever Laid
Although the ‘elephant’ bird Aepyornis maximus is not quite the heaviest or tallest bird discovered in the fossil record so far, it did lay the largest eggs of which we are aware. However, it is pointed out that we do not know how many Aepyornis species there were and we can only assume that maximus laid the largest eggs found.
Pieces of Aepyornis eggshell and even whole eggs — some containing embryo bones – are quite often washed out of the sand on the beaches or near lakes in Madagascar, where the people use them for carrying water.
Many have found their way into museums and collections around the world. The British Museum has 11, the largest of which is 85.6 cm (33.7 in) around the long axis, with a circumference of 72.3 cm (28.5 in) giving a capacity of 8.88 litres (2.35 gallons), equalling that of 180 hens’ eggs. But there is an even bigger one laid by Aepyornis maximus in the natural history collection at Bristol Museum. It came from the collection of Sir John Henry Greville Smyth in 1926 and its dimensions are: circumference around the long axis — 89 cm (35 in), the circumference around the middle 73.2 cm (28.8 in), length 34.5 cm (13.58 in), width 24.6 cm (9.68 in). Nothing is known of the egg’s history.
Other large Aepyornis eggs include one collected in 1841 and now in the Academie des Sciences, Paris, France. It measures 39 cm (15.4 in) x 32.6 cm (12.8 in) and is said to have weighed about 12.2 kg (27 lb) with its contents. Another in the Western Foundation of Vertebrate Zoology in California, USA measures 32 cm (12.59 in) x 24.2 cm (9.52 in), with the respective circumferences being 88.8 cm (34.96 in) and 72.5 cm (28.54 in).
It has been suggested that such large eggs must have been close to the theoretical maximum size as the pressure of the internal fluid in an even larger cell might be so great that the containing shell would have to be excessively thick, and then the chick would find it very difficult to get out.