Vorompatra Lore

from

The Origin and Evolution of Birds

by Alan Feduccia

(Yale University Press, 1996: pp.283-285)

Elephantbirds. While the Pleistocene radiation of moas in New Zealand produced the tallest bird, the heaviest, the elephantbird, evolved during the same era on Madagascar. In the thirteenth century, Marco Polo recorded that the legendary roc came from Madagascar. This part of the roc tale may not have been so legendary, but if Sinbad the Sailor was borne off by huge flying birds, the elephantbird cannot be blamed; it was wholly earthbound.

The seven species of elephantbirds, some the size of a cassowary, were still present less than two millennia ago, when humans arrived on Madagascar. Radiocarbon dates of eggshell fragments (Burger et al. 1975¹) indicate that the birds were widespread as late as the tenth century. Their extinction probably took place gradually over many centuries because they had no major enemies--the only large predators, until humans arrived, were crocodiles and two eagles. Under these conditions, the adaptive radiation of elephantbirds produced a variety of species, though only one attained elephantine proportions, Aepyornis maximus ("largest tall bird"). This ponderous giant with elephant-style legs stood 2.7 to 3 meters (9-10 ft.) tall, and Dean Amadon (1947²) of the American Museum of Natural History has calculated that its weight approached 450 kilos (1,000 lbs.). By contrast, a large ostrich may attain a height of 2.4 meters (8 ft.) and weigh about 135 kilos (300 lbs.). Like the moas of New Zealand, the elephantbirds were grazers, and probably, as Alexander Wetmore (1967³) noted, they also cropped the lower branches of shrubs and trees, which they could easily reach with their long necks. Somewhat similar to moas in their graviportal posture, the elephantbirds differed from them in having vestigial wings and a pygostyle.

The elephantbird is first mentioned in a book by the French traveler E. de Flacourt in 1661, but the most vivid early descriptions appear in the diary of Mr. Joliffe, surgeon of H.M.S. Geyser, which was cruising off Madagascar in October 1848 with a French merchant named Dumarele on board.

M. Dumarele casually mentioned that some time previously, when in command of his own vessel trading along the coasts of Madagascar, he saw at Port Liven, on the North-west end of the island, the shell of an enormous egg, the production of an unknown bird inhabiting the wilds of the country which held the incredible quantity of 13 wine quart bottles of fluid!!! he having himself carefully measured the quantity. It was of the colour and appearance of an ostrich egg, and the substance of the shell was about the thickness of a spanish dollar, and very hard in texture. It was brought on board by the natives...to be filled with rum, having a tolerably large hole at one end through which the contents of the egg had been extracted, and which served as the mouth of the vessel. M. Dumarele offered to purchase the egg from the natives, but they declined selling it, stating that it belonged to their chief, and that they could not dispose of it without his permission. The natives said the egg was found in the jungle, and observed that such eggs were very very rarely met with, and that the bird which produces them is still more rarely seen. (Strickland 1849, 338-339⁴)

Many eggs have now been recovered, and about thirty unbroken Aepyornis eggs are known to exist, some weighing more than 9 kilos (20 lbs.), measuring up to 33 centimeters^A (1 ft.) in length, and equal in volume to seven ostrich eggs. One actually contains an embryo, revealed by X-rays^B. The eggs of Aepyornis are the largest birds' eggs known, and as Joselyn van Tyne and Andrew J. Burger (1976⁵) have noted, "such an egg would hold the contents of seven ostrich eggs or 183 chicken eggs or more than 12,000 hummingbird eggs" (1976, 31).

The probable fossil record of elephantbirds is confined to the Pleistocene and Recent remains known from Madagascar, but this has not stopped paleontologists from assigning fragmentary material to the elephantbirds. Two pieces of leg bones from the Fayum of Egypt, a region south of Cairo, have been identified on totally insufficient grounds as belonging to the Aepyornithiformes, the order containing elephantbirds^C. One of these is a small fragment of tibiotarsus in the British Museum of Natural History named Eremopezus, and the other is a piece of tarsometatarsus from the Oligocene named Stromeria. Even an eggshell fragment, called Psammornis, from the Eocene of southern Algeria has been assigned to the elephantbird. Moreover, Franz Sauer (1976⁶) has reported "aepyornithoid" eggshells from the Miocene and Pliocene in Turkey, and Sauer and Peter Rothe (1972⁷) have described eggshells from Miocene and Pliocene deposits on the Canary Islands as being "aepyornithoid." These attributions are based on the shells' relatively large pore size, and there is no valid evidence that these specimens are from elephantbirds; they could all easily be eggshells of other large flightless birds, paleognathous, gruiform, or of other unknown affinity.

There are no confirmable Tertiary elephantbird fossils, and in the absence of a reliable fossil record extending beyond the Pleistocene, it is difficult to explain the existence of elephantbirds on Madagascar. The separation of Africa and Madagascar began in the medial Jurassic, which was about the same time as the initial breakup of Gondwanaland, and Madagascar assumed its present position in the early Cretaceous (Rabinowitz, Coffin, and Falvey 1983⁸). To view elephantbirds as flightless passengers on the ancient drifting landmass of Madagascar can only stretch credulity to its outer limits. The ancestors of elephantbirds, like those of the moas, must have flown to Madagascar and become flightless later, perhaps as late as the Miocene or even Pliocene^D.

Footnotes

1. Burger R., K. Ducate, K. Robinson, and H. Walter. 1975. "Radiocarbon Date for the Largest Extinct Bird" Nature 258:709.
2. Amadon, D. 1947. "An Estimated Weight of the Largest Known Bird" Condor 49:159-164.
3. Wetmore, A. 1967. "Re-creating Madagascar's Giant Extinct Bird" National Geographic 132:488-493.
4. Strickland, H.E. 1849. Supposed Existence of a Giant Bird in Madagascar. Annals and Magazine of Natural History, 2d ser., 4:338-339.
5. Van Tyne, J. and A.J. Burger. 1976. Fundamentals of Ornithology . 2d ed. New York: John Wiley and Sons.
6. Sauer, E.G.F. 1976. "Aepyornithoid Eggshell Fragments from the Miocene and Pliocene of Anatolia, Turkey" Palaeontographica 153:62-115.
7. Sauer, E.F.G., and P. Rothe. 1972. "Ratite Eggshells from Lanzarote, Canary Islands" Science 176:43-45.
8. Rabinowitz, P.D., M.F. Coffin, and D. Falvey. 1983. "The Separation of Madagascar and Africa" Science 220:67-69.

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Notes on this text

1. There is apparently at least one specimen 34 centimeters long. This is a quibble, even for me--I'm just trying to keep these sources honest!



2. In 2000, the University of Texas at Austin did a CT scan of the smaller of two eggs obtained by the National Geographic Society: an image can be viewed here. This brings the number of eggs containing subfossil embryos to two, at least; a 1967 x-ray of the one the author mentions in this text can be seen here.



3. It appears the author is not convinced these fossils represent Aepyornithid birds. If his suspicions are correct, the order's fossil record is even spottier than it is usually given credit for, undermining the Gondwanan origin theory of ratite phylogeny.



4. Another vote for flight as the means by which the Vorompatra's ancestor reached Madagascar. The late arrival would certainly account for the dearth of palæogenic (i.e., pre-Pliocene Tertiary) fossil ratites on the island.