Tendaguru Formation in the context of "Unconformity"

Brachiosaurus (/ˌbrækiəˈsɔːrəs/) is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 155.6 to 145.5 million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in the Colorado River valley in western Colorado, United States. Riggs named the dinosaur Brachiosaurus altithorax; the generic name is Greek for "arm lizard", in reference to its proportionately long arms, and the specific name means "deep chest". Brachiosaurus is estimated to have been between 18 and 22 meters (59 and 72 ft) long; body mass estimates of the subadult holotype specimen range from 28.3 to 46.9 metric tons (31.2 to 51.7 short tons). It had a disproportionately long neck, small skull, and large overall size, all of which are typical for sauropods. Atypically, Brachiosaurus had longer forelimbs than hindlimbs, which resulted in a steeply inclined trunk, and a proportionally shorter tail.

Brachiosaurus is the namesake genus of the family Brachiosauridae, which includes a handful of other similar sauropods. Most popular depictions of Brachiosaurus are in fact based on Giraffatitan, a genus of brachiosaurid dinosaur from the Tendaguru Formation of Tanzania. Giraffatitan was originally described by German paleontologist Werner Janensch in 1914 as a species of Brachiosaurus, B. brancai, but moved to its own genus in 2009. Three other species of Brachiosaurus have been named based on fossils found in Africa and Europe; two are no longer considered valid, and a third has become a separate genus, Lusotitan.

Giraffatitan (name meaning "titanic giraffe") is a genus of sauropod dinosaur that lived during the late Jurassic Period (Kimmeridgian–Tithonian stages) in what is now Lindi Region, Tanzania. Only one species is known, G. brancai, named in honor of German paleontologist Wilhelm von Branca, who was a driving force behind the expedition that discovered it in the Tendaguru Formation. Giraffatitan brancai was originally described by German paleontologist Werner Janensch as a species of the North American sauropod Brachiosaurus from the Morrison Formation, as Brachiosaurus brancai. Recent research shows that the differences between the type species of Brachiosaurus and the Tendaguru material are so large that the African material should be placed in a separate genus.

Giraffatitan was for many decades known as the largest dinosaur but recent discoveries of several larger dinosaurs prove otherwise; giant titanosaurians appear to have surpassed Giraffatitan in terms of sheer mass. Also, the sauropod dinosaur Sauroposeidon is estimated to be taller and possibly heavier than Giraffatitan. Most size estimates for Giraffatitan are based on the specimen HMN SII, a subadult individual, but there is evidence supporting that these animals could grow larger; specimen HMN XV2, represented by a fibula 13% larger than the corresponding material on HMN SII, would have measured around 23–26 metres (75–85 ft) long and weighed about 40–48 metric tons (44–53 short tons).

Werner Ernst Martin Janensch (11 November 1878 – 20 October 1969) was a German paleontologist and geologist.

The Lourinhã Formation (Portuguese pronunciation: [loɾiˈɲɐ̃] ) is a fossil-rich geological formation in western Portugal, named for the municipality of Lourinhã. The formation is mostly Late Jurassic in age (Kimmeridgian/Tithonian), with the top of the formation extending into the earliest Cretaceous (Berriasian). It is notable for containing a fauna especially similar to that of the Morrison Formation in the United States and to a lesser extent to the Tendaguru Formation in Tanzania. There are also similarities to the nearby Villar del Arzobispo Formation and Alcobaça Formation. Besides the fossil bones, Lourinhã Formation is well known for the fossil tracks and fossilized dinosaur eggs.

The Lourinhã Formation includes several lithostratigraphic units, such as Praia da Amoreira-Porto Novo Members, Praia Azul Member, the Santa Rita Member, and the Assenta Member. The stratigraphy of the formation is complex and controversial, with the constituent member beds belonging to the formation varying between different authors.