Ibirania

Ibirania is an exceptionally tiny saltasaurine titanosaur discovered in the Late Cretaceous rocks of Sao Paulo State, Brazil. Measuring less than six metres in total length and weighing roughly one to two tonnes, it was no larger than a modern draft horse, making it one of the most miniaturised sauropods known to science. Bone histology of the type specimens confirmed that these fossils belonged to fully mature adult individuals rather than juveniles, evidencing extreme dwarfism. While dwarfed dinosaurs are typically associated with isolated islands, Ibirania evolved its reduced stature within an inland continental setting, probably driven by prolonged seasonal aridity and scarce local food resources. Its small frame allowed it to browse efficiently on low vegetation and thrive where colossal sauropods could not find sufficient sustenance.

It is one of the smallest sauropods ever discovered, displaying true nanism in an inland continental setting.

Where and when

Ibirania lived in the Late Cretaceous, from 83.6 to 72.1 million years ago (Campanian age). Its remains come from Brazil, in the Sao Jose do Rio Preto Formation.

The numbers

Length 5.8 m (estimates run from 5.5 to 6 m). Mass about 1.7 t. Hip height about 1.5 m. That is 3.4 human-lengths, or 0.52 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

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