It’s been a big week for big prehistoric creatures. First, the Zoological Society of London’s Institute of Zoology confirmed once and for all that Madagascar’s Vorombe titan, which reached a weight of 800 kg (1763 lbs.) and height of three meters (9.85 feet) was the largest bird ever. Then, researchers in South Africa announced the discovery of a cousin of the brontosaurus that may have been bigger than its relative and was possibly able to stand on two legs. If Fred Flintstone were alive at the time, he’d be drooling over a steak the size of a butcher shop and wings the size of buffaloes.
The Royal Society Open Science journal brings the story of Vorombe titan, which means 'big bird' in Malagasy and Greek, out of the backrooms of dusty museum and into the competition to move up from ‘big’ to ‘biggest’. The common belief has been that there were 15 species of elephant birds under the genera Mullerornis and Aepyornis. Zoologists led by study author James Hansford opened up museum collections of elephant bird bones, measuring and cataloging them and eventually identifying a third genus, Vorombe, that was the biggest bird of all. Not surprisingly, the giant was flightless. What is surprising is the impact of its extinction on Madagascar, as Dr. Hanson told Science Daily.
"Elephant birds were the biggest of Madagascar's megafauna and arguably one of the most important in the islands evolutionary history -- even more so than lemurs. This is because large-bodied animals have an enormous impact on the wider ecosystem they live in via controlling vegetation through eating plants, spreading biomass and dispersing seeds through defecation. Madagascar is still suffering the effects of the extinction of these birds today."
Because many of the bones were found with tool marks, it’s believed that extinction was caused by humans killing the birds and eating their eggs until they disappeared somewhere between 120 CE and 1000 CE).
Moving to the category of biggest brontosaurus, the largest of the thunder lizards is believed to be the B. excelsus, which weighed up to 15 long tons and measured up to 22 m (72 ft) from head to tail. However, a newly-discovered species considered to be a predecessor and close cousin of the brontosaurus may deserve a category of its own as the ‘biggest brontosaurus still trying to walk on two legs’.
Found in 2012, it has taken this long to carefully remove enough fossils from the discovery site on the border of South Africa and Lesotho to identify as a new species in the sauropodomorpha category called the Ledumahadi mafube, which means "a giant thunderclap at dawn" in the Sesotho indigenous language of South Africa.
While not the biggest brontosaurus ever, Ledumahadi mafube was the biggest of its time between 195 million and 200 million years ago, placing it at the start of the Jurassic Period and before the brontosaurus. The specimen found would have weight about 14 tons and been about double the size of one of today’s large elephants.
The research, led by University of the Witwatersrand palaeontologist Professor Jonah Choiniere and published in the current edition of the journal Current Biology, shows that L. mafube walked on four legs but, because it was isolated from other similar species, had forelimbs shaped more for crouching, leading them to believe it may have been a transitional species in the move from two legs to four. (An artist's interpretation can be seen here.) Study lead author, Dr. Blair McPhee, describes the differences in Phys.org.
"The first thing that struck me about this animal is the incredible robustness of the limb bones. It was of similar size to the gigantic sauropod dinosaurs, but whereas the arms and legs of those animals are typically quite slender, Ledumahadi's are incredibly thick. To me this indicated that the path towards gigantism in sauropodomorphs was far from straightforward, and that the way that these animals solved the usual problems of life, such as eating and moving, was much more dynamic within the group than previously thought."
When it came to dinosaurs and flightless birds, bigger was not necessarily better. Will the same ultimately be true of modern humans?