Lusotitan

Chapter • Meet the dinosaur

Overview

Lusotitan atalaiensis was a large brachiosaurid sauropod: a long-necked plant-eater with forelimbs longer than its hindlimbs, giving it a sloping back and a neck that was carried high like a living crane. Length estimates usually fall between about 20 and 25 metres, with body mass estimates ranging from roughly 15 to 30 tonnes depending on the method used. The humerus of the type specimen is a little over two metres long, one of the largest sauropod upper arm bones known from Europe. No skull has been found, but in close relatives such as Giraffatitan the head was small, with an arched snout and broad, spatulate teeth crowded at the front of the jaws. Lusotitan walked on all fours on pillar-like legs and held its tail clear of the ground. Like all sauropods it was a bulk feeder on a colossal scale. It probably browsed high in conifers, araucarias, ginkgos and tree ferns, stripping foliage with its sturdy teeth and swallowing it with almost no chewing. Digestion happened slowly in an enormous fermenting gut, much as in modern elephants but scaled up dramatically. An animal of this size would have needed hundreds of kilograms of plant matter a day and must have moved regularly between feeding grounds on the coastal floodplains. Bone microstructure in related sauropods shows rapid early growth, with near-adult size reached in a few decades before growth slowed. The fossils come from Atalaia, near Lourinhã on the Portuguese Atlantic coast, and were excavated in the 1940s and 1950s. In 1957 Albert-Félix de Lapparent and Georges Zbyszewski described the material as a new species of Brachiosaurus, B. atalaiensis. The specimen is a partial skeleton without a skull: dorsal and caudal vertebrae, ribs, a scapula, the humerus, parts of the pelvis and hind limb elements. Only in 2003 did Miguel Telles Antunes and Octávio Mateus recognise that the animal differed enough from North American Brachiosaurus to deserve its own genus, naming it Lusotitan, the 'titan from Lusitania' — the Roman name for Portugal. Subsequent analyses, including work by Philip Mannion and colleagues, have supported a brachiosaurid identity for Lusotitan, although its precise position within the family shifts between studies. The material is housed at the Museu Geológico in Lisbon and remains key evidence that brachiosaurids lived on both sides of the young Atlantic during the Late Jurassic.

Chapter • Where it lived

Habitat

Lusotitan lived in the Late Jurassic, in the Tithonian around 152–145 million years ago, in what is now western Portugal. The Lourinhã Formation preserves broad floodplains, meandering rivers, lagoons and sandy coastal plains along the rift of the opening North Atlantic, clothed in forests of araucarias, ginkgos, cycads and ferns under a warm, seasonally dry climate. The type material comes from Atalaia and Peralta near Lourinhã, and additional sauropod remains attributed to the same type of animal have been reported from the coastal cliffs between Lourinhã and Torres Vedras.

Chapter • Family life

Breeding

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy