Titanosaurs (members of the group Titanosauria) were a diverse group of sauropod dinosaurs which included Saltasaurus and Isisaurus. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thriving at the time of the extinction event at the end of the Cretaceous. The group includes the largest land animals known to have existed, such as Patagotitan—estimated at 37 m (121 ft) long with a weight of 69 tonnes (76 tons)—and the comparably sized Argentinosaurus and Puertasaurus from the same region. The group's name alludes to the mythological Titans of Ancient Greece, via the type genus (now considered a nomen dubium) Titanosaurus. Together with the brachiosaurids and relatives, titanosaurs make up the larger clade Titanosauriformes.
|Mounted Patagotitan on display at the Field Museum of Natural History, Chicago, IL|
Bonaparte & Coria, 1993
Titanosaurs had small heads, even when compared with other sauropods. The head was also wide, similar to the heads of Camarasaurus and Brachiosaurus but more elongated. Their nostrils were large ('macronarian') and they all had crests formed by these nasal bones. Their teeth were either somewhat spatulate (spoon-like) or like pegs or pencils, but were always very small.
Their necks were of average length, for sauropods, and their tails were whip-like, but not as long as in the diplodocids. While the pelvis (hip area) was slimmer than some sauropods, the pectoral (chest area) was much wider, giving them a uniquely 'wide-gauged' stance. As a result, the fossilised trackways of titanosaurs are distinctly broader than other sauropods. Their forelimbs were also stocky, and often longer than their hind limbs. Their vertebrae (back bones) were solid (not hollowed-out), which may be a throwback to more basal saurischians. Their spinal column was more flexible, so they were probably more agile than their cousins and better at rearing up. Unlike other sauropods, some titanosaurs had no digits or digit bones, and walked only on horseshoe-shaped "stumps" made up of the columnar metacarpal bones.
From skin impressions found with the fossils, it has been determined that the skin of many titanosaur species was armored with a small mosaic of small, bead-like scales around a larger scale. One species, Saltasaurus, has even been discovered with bony plates, like the ankylosaurs. Studies published in 2011 also indicate that titanosaurs such as Rapetosaurus (on which the examinations were performed), may have used the osteoderms common in the various genera for storing minerals during harsh changes in climate, such as drought. While they were all huge, many were fairly average in size compared with the other giant dinosaurs. There were even some island-dwelling dwarf species such as Magyarosaurus, probably the result of allopatric speciation and insular dwarfism.
The family Titanosauridae was once used for derived titanosaurs, but Wilson and Upchurch (2003) found the type genus Titanosaurus dubious based on the figures and original description. Weishampel et al., in the second edition of The Dinosauria, also did not use the family Titanosauridae, and instead used several smaller titanosaur families such as Saltasauridae and Nemegtosauridae, coining Lithostrotia for derived titanosaurs. A handful of Argentine sauropod workers, however, continue to use Titanosauridae for titanosaurs now placed in Lithostrotia.
In the second edition of The Dinosauria, the clade Titanosauria was defined as all sauropods closer to Saltasaurus than to Brachiosaurus. Subsequent cladistic analyses have defined Titanosauria as including Saltasaurus but not Euhelopus or Brachiosaurus.
Relationships within the Titanosauria have historically been extremely variable from study to study, complicated by the fact that clade and rank names have been applied inconsistently by various scientists. One possible cladogram is presented here, and follows a 2007 analysis by Calvo and colleagues. The authors notably used the family Titanosauridae in a broader fashion than other recent studies, and coined the new clade name Lognkosauria.
In the description of Mansourasaurus, Sallam et al. (2017) published a phylogenetic analysis of Titanosauria including the most taxa of any analysis of the clade. The relationships within Titanosauria can be seen below.
Fossilized dung associated with late Cretaceous titanosaurids has revealed phytoliths, silicified plant fragments, that offer clues to a broad, unselective plant diet. Besides the plant remains that might have been expected, such as cycads and conifers, discoveries published in 2005 revealed an unexpectedly wide range of monocotyledons, including palms and grasses (Poaceae), including ancestors of rice and bamboo, which has given rise to speculation that herbivorous dinosaurs and grasses co-evolved.
A large titanosaurid nesting ground was discovered in Auca Mahuevo, in Patagonia, Argentina and another colony has reportedly been discovered in Spain. Several hundred female saltasaurs dug holes with their back feet, laid eggs in clutches averaging around 25 eggs each, and buried the nests under dirt and vegetation. The small eggs, about 11–12 centimetres (4.3–4.7 in) in diameter, contained fossilised embryos, complete with skin impressions. The impressions showed that titanosaurs were covered in a mosaic armour of small bead-like scales. The huge number of individuals gives evidence of herd behavior, which, along with their armor, could have helped provide protection against large predators such as Abelisaurus.
The titanosaurs were the last great group of sauropods, which existed from about 136 to 66 million years ago, before the Cretaceous–Paleogene extinction event, and were the dominant herbivores of their time. The fossil evidence suggests they replaced the other sauropods, like the diplodocids and the brachiosaurids, which died out between the late Jurassic and the mid-Cretaceous Periods.
Titanosaurs were widespread. In December 2011, Argentine scientists announced titanosaur fossils had been found on Antarctica—meaning that titanosaur fossils have been found on all continents. They are especially numerous in the southern continents (then part of the supercontinent of Gondwana). Australia had titanosaurs around 96 million years ago: fossils have been discovered in Queensland of a creature around 25 metres (82 ft) long. Remains have also been discovered in New Zealand. One of the largest ever titanosaur footprints was discovered in the Gobi desert in 2016. One of the oldest remains of this group was found from the Valley of the Dinosaurs, Paraíba state of Brazil, representing a 136-million-year-old subadult individual.
Aeolosaurini is an extinct clade of titanosaurian dinosaurs known from the late Cretaceous period of Argentina and Brazil. Thomas Holtz (2011) assigned Adamantisaurus, Aeolosaurus, Gondwanatitan, Muyelensaurus, Panamericansaurus, Pitekunsaurus and Rinconsaurus to Aeolosauridae. Rodrigo M. Santucci and Antonio C. de Arruda-Campos (2011) in their cladistic analysis found Aeolosaurus, Gondwanatitan, Maxakalisaurus, Panamericansaurus and Rinconsaurus to be aeolosaurids.Aeolosaurus
Aeolosaurus (; "Aeolus' lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck and tail. Aeolosaurus is well known for a titanosaur, as it is represented by the remains of several individuals belonging to at least three species. However, like most titanosaurs, no remains of the skull are known.
The holotype of Aeolosaurus rionegrinus consists of a series of seven tail vertebrae, as well as parts of both forelimbs and the right hindlimb. It was discovered in the Angostura Colorada Formation in Argentina, which dates from the Campanian stage of the Late Cretaceous, about 83 to 74 million years ago.Atsinganosaurus
Atsinganosaurus is a genus of titanosaurian dinosaur which existed in what is now France during the late Cretaceous period. Well-preserved remains (and the only known) of Atsinganosaurus were collected from the Grès à Reptiles Formation of the Aix-en-Provence Basin. Atsinganosaurus was first described by Géraldine Garcia, Sauveur Amico, Francois Fournier, Eudes Thouand and Xavier Valentin in 2010, and the type and only species is Atsinganosaurus velauciensis.
The generic name is derived from the Greek word "τσιγγάνος" or "αθίγγανος", both meaning "gypsy", which refers to the possible migration from east to west of the species. The specific name is named after its finding place, Velaux - La Bastide Neuve.A 2018 cladistic analysis of Titanosauria places Ampelosaurus, Atsinganosaurus, and Lirainosaurus in the new lithostrotian clade Lirainosaurinae. New estimates suggest a body size of 8–12 meters, perhaps a max length of 14m for especially large individuals, and a weight of 3 to 5.5 tons.Austroposeidon
Austroposeidon is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous Presidente Prudente Formation of Brazil. It contains one species, Austroposeidon magnificus.Brasilotitan
Brasilotitan is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous (early Maastrichtian) Adamantina Formation of Brazil. The type species is Brasilotitan nemophagus.Campylodoniscus
Campylodoniscus is a genus of sauropod dinosaur from the Late Cretaceous Period of what is now Argentina.
The type species was first named and described by Friedrich von Huene in 1929 as Campylodon ameghinoi, the genus name meaning 'bent tooth', from Greek καμπυλος, 'bent' or 'curved' (as of a bow) and ὀδών meaning 'tooth'. The specific name honours Florentino Ameghino. In 1961 Oskar Kuhn noted that the name was pre-occupied by a fish and renamed the genus into Campylodoniscus, the diminutive.The fossil remains of Campylodoniscus were found in the Sierra de San Bernardo and consist of a single jaw bone, the maxilla, holding seven teeth.
The age of Campylodoniscus could be from the Cenomanian, about 95 million years ago, or the Campanian-Maastrichtian, about 70 million years old. It is sometimes estimated as being around twenty meters in length.
Campylodoniscus is probably a member of the Titanosauria. Some researchers consider it a nomen dubium.Epachthosaurus
Epachthosaurus (meaning "heavy lizard") was a genus of dinosaur from the Late Cretaceous. It was a titanosaurid sauropod. Its fossils have been found in Central and Northern Patagonia in South America.Erketu
Erketu is the name given to a genus of dinosaur from the Late Cretaceous (Cenomanian - Santonian). It was a sauropod with the longest neck relative to its body size. Its fossils were found in Mongolia.
The type species, Erketu ellisoni, was described in March 2006 by Daniel Ksepka and Mark Norell of the American Museum of Natural History. Its neck was estimated to be twice as long as its body, which may be a record for neck to body ratio. The exact ratio is unknown, because no dorsal vertebrae of E. ellisoni have been reported, although some hindlimb material suggests the approximate size of the body. The long neck of Erketu is the result of the individual vertebrae being greatly elongated; it is unknown if the number of cervical vertebrae was increased. Erketu is also diagnosed by bifurcate anterior cervical neural spines, another unusual trait for a titanosauriform. A phylogenetic analysis of sauropods indicates that Erketu is a basal somphospondylian (the clade of all macronarians closer to titanosaurs than to brachiosaurs), and is most closely related to Titanosauria.
This particular sauropod species is named after the American Museum of Natural History's resident paleo-artist, and close friend of Mark Norell, Mick Ellison.Futalognkosaurus
Futalognkosaurus ( FOO-tə-long-ko-SAW-rəs; meaning "giant chief lizard") is a genus of titanosaurian dinosaur. The herbivorous Futalognkosaurus lived approximately 87 million years ago in the Portezuelo Formation, in what is now Argentina, of the Coniacian stage of the late Cretaceous Period. The fish and fossilized leaf debris on the site, together with other dinosaur remains, suggest a warm tropical climate in Patagonia during this period.Gondwanatitan
Gondwanatitan (meaning "giant from Gondwana") was a titanosaurian sauropod dinosaur. Gondwanatitan was found in Brazil, at the time part of the southern supercontinent Gondwana, in the late Cretaceous Period (70 mya). Like some other sauropods, Gondwanatitan was tall and ate tough shoots and leaves off of the tops of trees. G. faustoi's closest relative was Aeolosaurus.
The type species is Gondwanatitan faustoi, formally described by Kellner and de Azevedo in 1999.Kaijutitan
Kaijutitan (meaning "Kaiju titan" after the type of Japanese movie monsters) is a genus of basal titanosaur dinosaur from the Sierra Barrosa Formation from Neuquén Province in Argentina. The type and only species is Kaijutitan maui.Lognkosauria
Lognkosauria is a group of giant long-necked sauropod dinosaurs within the clade Titanosauria. It includes some of the largest and heaviest dinosaurs known.Magyarosaurus
Magyarosaurus ("Magyar lizard") is a genus of dwarf sauropod dinosaur from late Cretaceous Period (early to late Maastrichtian) in Romania. It is one of the smallest-known adult sauropods, measuring only six meters in length. The type and only certain species is Magyarosaurus dacus. It has been found to be a close relative of Rapetosaurus in the family Saltasauridae in the sauropod clade Titanosauria in a 2005 study.Mendozasaurus
Mendozasaurus is a genus of sauropod dinosaur. It was a member of Titanosauria, which were massive sauropods that were common on the southern landmasses during the Cretaceous period. The titanosaurian sauropod dinosaur Mendozasaurus neguyelap is represented by several partial skeletons from a single locality within the Coniacian (lower Upper Cretaceous) Sierra Barrosa Formation in the south of Mendoza Province, northern Neuquén Basin, Argentina.
The type species, Mendozasaurus neguyelap, was described by Argentine paleontologist Bernardo Javier González Riga in 2003. Mendozasaurus is the first dinosaur named from Mendoza Province, Argentina.Normanniasaurus
Normanniasaurus ( Normannia lizard) is an extinct genus of basal titanosaur sauropod known from the Early Cretaceous (Albian stage) Poudingue Ferrugineux Formation of Seine-Maritime, northwestern France.Phuwiangosaurus
Phuwiangosaurus (meaning "Phu Wiang lizard") is a genus of titanosauriform dinosaur from the Early Cretaceous (Valanginian-Hauterivian) Sao Khua Formation of Thailand. The type species, P. sirindhornae, was described by Martin, Buffetaut, and Suteethorn in 1994; it was named to honour Princess Maha Chakri Sirindhorn of Thailand, who was interested in the geology and palaeontology of Thailand.
It was a mid-sized sauropod, measuring 15–20 m in length.
Phuwiangosaurus was originally assigned to Titanosauria, but more recent studies have placed it in a more basal position within the Titanosauriformes. Phylogenetic analyses presented by D'Emic (2012), Mannion et al. (2013), and Mocho et al. (2014) resolve Phuwiangosaurus within the Euhelopodidae, alongside genera such as Euhelopus and Tangvayosaurus. Other analyses have failed to find support for such a grouping, including some finding it to be paraphyletic at the base of Somphospondyli.Titanosaurus
Titanosaurus (meaning 'titanic lizard' – named after the mythological Titans, deities of Ancient Greece) is a dubious genus of sauropod dinosaurs, first described by Lydekker in 1877. It is known from the Maastrichtian (Upper Cretaceous) Lameta Formation of India.Triunfosaurus
Triunfosaurus (meaning "Triunfo Basin reptile") is a genus of somphospondylan sauropod dinosaur from the Early Cretaceous of Brazil. It contains a single species, T. leonardii, described by Carvalho et al. in 2017. As a genus, Triunfosaurus can be distinguished from all other titanosaurs by the unique proportions of its ischium. It was initially described as a basal titanosaur, making it the earliest basal titanosaur known; however, subsequent research questioned the identification of the taxon as a titanosaur, instead reassigning it to the Somphospondyli.Yunmenglong
Yunmenglong is an extinct genus of somphospondylan sauropod known from the late Early Cretaceous of Henan Province, central China. Its remains were discovered in the Haoling Formation of the Ruyang Basin. The type species is Yunmenglong ruyangensis, described in 2013 by Junchang Lü et al. on the basis of an incomplete postcranial skeleton. Yunmenglong shares some characters with Euhelopus, Qiaowanlong and Erketu, and a phylogenetic analysis places it as a sister taxon of Qiaowanlong, both grouped with Erketu in a position more derived than Euhelopus but basal to Titanosauria. Yunmenglong represents the first long-necked sauropod dinosaur recorded from central China to date.