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Superfamily Titanosauroidea

the Titanosaurs and their relatives

Late Jurassic to Late Cretaceous
(Kimmeridgian to Maastrichtian)

Saltasaurus loricatus, illustration by Steve Kirk - Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals, ed.. Barry Cox

While other sauropod groups died out during the late Jurassic or Middle Cretaceous, the titanosaurs continued roight until the end of the period. And not only continued, but flourished. They have been found almost worldwide; only central to northern North America westerrn "Asiamerica" was probably free of them (I wouldnt be surprised if - on the weight of purely biogeographical reasons - the strangely primitive Australian Austrosaurs turn out to be abberent titanosaurs; after all, titanosaurs were common everywhere else in Gondwana)

All titanosaurs were rather primitive and unspecialised sauropods, for a long time considered on the basis of their peglike teeth and badly reconstructed skulls, to be cousins of the diplodocids. It is now known that they are related rather to brachiosaurs and camarosaurs, being grouped with them in the clade Macronaria. They ranged in size from realtively small sauropods to some the hugest animals that ever walked on land.

For a complete anatomical definition, see Titanosauria; for a very readable essay and commentary on titanosaur physiology and lifestyle, and the problems of gigantism, see Titanosaur Notes

A number of Middle Creteacous forms previously considered to be brachiosaurs now seem to be titanosaurs. Although they do not have the distinct characteristics of the family Titanosauridae, they are certainly representative uncles and aunts; earlier forms continuing to exist alongside their more recent relatives.

Chubutisaurus insignis Corro, 1974

Comments: Previously considered among the brachiosaurs, this huge animal seems to be a representative basal (ancestral) type, closely related to the Titanosauridae. The only "official" member of the family Chubutisauridae

Aegyptosaurus baharijensis Stromer, 1932 Horizon: "Continental intercalaire"
Age: Cenomanian
Place: north-central Gondwana (Egypt)
Length:Length: 15m
Remains: Remains: leg bones, fragmentary vertebrae (destroyed in WW2)

Comments: An early representative of the Titanosaur group. It's relationship to later members are not known.

Paralititan stromeri J. B. Smith, Lamanna, Lacovara, Dodson, J. R. Smith, Poole, Giegengack, and Attia, 2001

Comments: A huge animal, Paralititan apparently lived in a swampy mangrove environment. It is not clear how it avoided becoming mired

Venenosaurus dicrocei Tidwell, Carpenter & Meyer, 2001

Comments: May be closely related to Cedarosaurus, if so, the latter is not a brachiosaur, but a titanosaur

A paraphyletic, or maybe even polyphletic, family of mostly gigantic proto-titanosaurids. The family was named by Jose Bonaparte, the great Argentine paleontologist, and includes the genera Phuwiangosaurus, Andesaurus, Argentinosaurus, Malawisaurus, and perhaps Iuticosaurus (formerly Titanosaurus valdensis Huene - DinoData page) . Many workers now consider Andesauridae an invalid taxon and its representative forms as simply generic early/basal titanosaurids. In any case, these animals belong at the base of the titanosaurid tree, intermediate between contemporary forms like Chubutisaurus and more advanced Titanosaurs. In asmuch as true Titanosaurids seem to have evolved as early as the late Jurassic, that means that the Andesauridae also extend back equally as far, and continued alongside thioer descendents for some 50 million years or so.

Malawisaurus dixeyi (Haughton, 1928)

Comments: originally known as Gigantosaurus - not to be confused with the Carcharodontosaurid carnivore Giganotosaurus. It had a steep face and armor plates.

Andesaurus delgadoi Calvo and Bonaparte, 1991

Comments: This gigantic primitive titanosaur shows some resemblance to Argentinosaurus, and shares a similar vertebral structure

Argentinosaurus huinculensi Bonaparte & Coria, 1993

Comments: possibly the largest known dinosaur. It may be related to Andesaurus. In any case it lived in teh same geographic region, and only some 10 million or so years later.

This is one of the largest families of dinosaurs. Because Titanosaurus is based on poor materials, it has been suggested that the name be changed to Saltasauridae. Titanosaurids are mostly known from the Cretaceous of Gondwana, especially South America, but they were also representative of India, Madagascar, and even Europe. While some were as huge in size a stheir name indicates, many were of moderate proportions, and there were also dwarf forms that seem to have been island-dwellers. Many titanosaurids are rather poorly known, and it is not unlikely that - as is usually the case - a lot of the taxa based on fragmentary material will turn out to be invalid. It used to be thought that the Titanosauridae were cousins to the Diplodocids. More recent study reveals that the skulls of titanosaurid skulls were not diplodocid-like (as restored by von Huene, an early but influential worker in this field) nor extremely-flat (as has also been suggested), but were instead similiar to Camarasaurus and Brachiosaurus, although not as high (see illustration of Rapetosaurus). The way that the teeth mesh together is different from that of other sauropod groups, especially diplodocoids. The head is surprisingly small, even by sauropod standards. (say around 30 cm for a 14.5 meter long animal)

A vast nesting colony of titanosaurids has been discovered in Argentina recently, with some fossilised embryos showing skin impressions, and another such possible colony was uncovered in Spain. The embryo skin impressions indicates (according to the placement of these scales) that these titanosaurs would not have sported the keratinous dorsal spikes found associated with a diplodocid specimen (see "Skin" in Currie and Padian's Encyclopedia of Dinosaurs). Neither were the juveniles feathered

The existence of nesting grounds indicates that these were sociable animals, perhaps congregating and nesting in large heards. Possibly the safety of numbers protected them from the carnivorous Abelisaurs that were their main predator.

Some representative Titanosaurs:

Subfamily Unknown

Janenschia robusta (Fraas, 1908)

Comments: this waste basket taxon species is composed of all sauropods that couldn't be placed in the other Tendaguru sauropod taxa (including some genuine Titanosaurids that are the earliest representatives of the group). Also previously known as Gigantosaurus

Epachtosaurus sciuttoi Powell, 1990

Comments: a primitive late surviving form, this species seems to lack the typical titanosaur osteoderms. Originally thought to be Cenomanian (mid Cretaceous, it appears to be later Cretaceous instead, making it a sort of "living foossil" existing alongside more advanced Saltosaurid titanosaurs.

Subfamily Titanosaurinae

A small group of rather primitive, closely related titanosaurids, these evolved in isolation on the "island ark" of India, which had by now seperated from the rest of gondwana and was moving slowly northward.

Jainosaurus septentrionalis Hunt, Lockley, Lucas, and Meyer, 1995

Comments: probably should be included under the genus Titanosaurus.

Titanosaurus indicus Lydekker, 1877

Comments: The femur is much morte slender than those of Saltasaurus and Alamosaurus, indicating a more lightly built animal. Otherwise this is a poorly known form, which served as the basis of the family Titanosauridae. Not surprisingly, some workers wish to change the name to Saltasauridae, as Saltosaurus is much better known. As with Megalosaurus and Megalosauridae, I am in favour of keeping the old name; call me sentimental.

Titanosaurus colberti Jain and Bandyopahday, 1997

Comments: better material than T. indicus

European Titanosaurs

A rich but poorly known assemblage of titanosaurs inhabited Europe during the end of the Cretaceous. Many of these animals were island dwellers. None were large, and maany became dwarf forms

image © Le Musée des Dinosaures

Ampelosaurus atacis Le Loeuff, 1995

Comments: A primitive titanosaurid known from good material. A number of types of armor have been found with it, indicating that primitive as well as advanced titanosaurs possessed bony plates in the skin.
 Dinosaur hunting in the South of France

Hypselosaurus priscus Matheron, 1869

Comments: The remains are not sufficient to identify Hypselosaurus beyond a general titanosaurid. Large fossil eggs from France are referred to this taxon, but there is no guarantee they actually come from the same animal (although they are probably dinosaurian). These animals probably inhabited a large island

Magyarosaurus dacus Huene, 1932

Comments: the smallest known adult sauropod, this little animal would seem to have been an island dweller. Often limitations of food, and absense of large preditors, on islands result in previously large animals evolving into smaller forms (like the dwarf elephant (Elephas falconeri) of Pleistocene Malta). As the remains include both robust and slender humeri, it is likely that these are from several different species of dwarf sauropods

Modestly-sized specialised sauropods from the late Cretaceous of western Asiamerica. Originally believed to be aberrant dicraeosauran diplodocids, they are now considered aberrent titanosaurs. Most likely through geographic isolation these animals evolved in their own way. Their main predators were Tyrannosaurids. Rapetosaurus from Madagascar may belong to the same group, although the geographic distance makes me think it actually belongs to a different subfamily (perhaps one indigenous to Madagascar, at that time, like now, an island and hence with its own unique fauna).

Nemegtosauridae

Nemegtosaurus mongoliensis Nowinski, 1971

Comments: based on a partial skull with some features similar to both Brachiosaurus and Diplodocus, Nemegtosaurus was for a long time associated with the latter (specifically under the subfamily (now family) Dicraeasaurinae), in part because of poor reconstruction. There followed some indecisiveness among dinosaurologists as to whether Nemegtosaurus should be considered an aberrant titanosaur or an aberrant diplodocimorph. The discovery of Rapetosaurus finally showed without a doubt Nemegtosaurus' titanosaurid affinities. But Nemegtosaurus's problems did not end there. Early on, a headless skeleton found nearby was named Opisthocoelicaudia skarzynskii and classified as a Camarasaurid. This was during the period in which Nemegtosaurus was thought to be a Dicraeasaur. It was then suggested that the skull and skeleton belong to the same animal. However, while the skull is now safely ensconed among the Nemegtosauridae/inae/ini, the skeleton is still often included with the Saltasaurinae (I am not sure, not having the journal at hand, but I think the reference here may be Upchurch). Following the dictum of the Franciscan monk  William of Occam (c. 1280/5-1349) that entia non sunt multiplicanda praeter necessitatem (No more things should be presumed to exist than are absolutely necessary) I would rather retain the Nemegtosaurus head firmly on the Opisthocoelicaudia body.

Quaesitosaurus orientalis Kurzanov and Bannikov, 1983

Comments: A close relative of Nemegtosaurus mongoliensis, it lived in the same locality but several millions of years earlier, possibly an ancestral form. In all probablility this species should better be considered a species of Nemegtosaurus, rather than a distinct genus.

Subfamily Uncertain

Reconstruction of the skeleton of Rapetosaurus, with body outline.
Image © Mark Hallett/State University of New York (SUNY) at Stony Brook.

Rapetosaurus is often included with the Nemegtosauridae/Nemegtosaurinae, on the basis of similarity of skull features. However, because so little is known of Titanosaur skulls, it may well be that this was simply the standard skull morphotype. The Rapetosaurs and Nemegtosaurs had been geographically isolated for many millions if not tend of millions of years, and one would expect a lot of divergence, perhaps even upto subfamily grade.

Rapetosaurus krausei Rogers and Forster, 2001

Comments: "the most complete titanosaur yet discovered, provides a view of titanosaur anatomy from head to tail. A total-evidence phylogenetic analysis supports a close relationship between brachiosaurids and titanosaurs (Titanosauriformes). The inclusion of cranial data from Rapetosaurus also lays to rest questions concerning the phylogeny of the enigmatic Mongolian genera Nemegtosaurus and Quaesitosaurus. In spite of their elongated, diplodocoid-like skulls, all three taxa are now firmly nested within Titanosauria." (reference)
Rapetosaurus skull (left) from Neuer Titanosaurier identifiziert

Subfamily Saltasaurinae

The Saltasaurs, here taken to include the Saltasaurs and Alamosaurs - i.e. the "crown titanosaurids" - were advanced latest Cretaceous forms were apparently limited to west Gondwanaland and south-west Asiamerica. These were stocky animals of medium to very large size. When these armor nodules were first found they were assumed to belong to ankylosaurians. In fact, no ankylosaur is known from South America (west Gondwana). however, primitive abarrent ankylosaurs did inhabit Australia (south-east Gondwana) . For a while the Saltasaurs were the only sauropod known to have armour plates in the skin (osteoderms), but it has recently been found that other (possibly most, although not all) titanosaurids, and possibly some other sauropod lineages, were also so equipped.

Alamosaurus sanjuanensis Gilmore, 1922

Comments: these huge advanced titanosaurs migrated north across a land-bridge and invaded southwest Asiamerica, where they were preyed on by Tyrannosaurus (and you think you've got troubles...). This genus was larger but more lightly built than Saltasaurus. Also, unlike its South American cousins, it seems to have lacked large osteoderms, no armor has ever been found for this species.
Trivia note: This evocatively named genus is not called after the Alamo, a sone may think, but was originally described from the "Ojo Alamo Sandstone," strata now assigned to the Kirtland Shale (the "Ojo Alamo Formation" is currently used for Paleocene deposits). This in turn is named after a trading post in New Mexico -- Ojo Alamo -- where it was first found. The trading post in turn was named after a large cottonwood tree, called alamo in Spanish, that grew next to the spring nearby (info from  Alamosaurus!, and Dinosauria Translation and Pronunciation Guide A (Ben Creisler)

Neuquensaurus australis Powell, 1992

Comments: originally known as Titanosaurus. A modestly sized, advanced form, very like Saltasaurus loricatus, although apparently somewhat earlier in time (possibly an ancestor?), and should go in the same genus. However dinosaurologists have a penchant for creating as many genera as possible.

Saltasaurus loricatus Bonaparte and Powell, 1980

Comments: This rather small sauropod caused a stir in the paleontological world when it was discovered to possess of body armor (up until then all sauropods were believed to be smooth-skinned and rather defenseless). Since then, other titanosaurs have been found that are similarly equipped. Dermal scutes are present in many sauropods, and in diplodocomorphs takes the form of a crest along of the back, But in many titanosaurids these spines developed into or were replaced by armoured scutes. There is no compelling evidence to believe the scutes formed a dorsal carapace. In his doctoral dissertation, Jaime Powell (the co-discoverer of this species) arranged them along the back in two parallel rows in Saltasaurus
[ref: Dinogeorge Re: Utahraptor vs Tyrannosaurus Newsgroups: sci.bio.paleontology Date: 1996/02/23]

cautionary note (please read before using this page as reference material!)

Books and Web Links

Book and Journal References

McIntosh, J. S., 1990: Sauropoda. pp.345-401, in Weishampel, D. B., Dodson, P., & Osmólska, H. (eds.), 1990: The Dinosauria. University of California Press, Berkley, Los Angeles, Oxford, 1990

Kristina Curry Rogers and Catherine A. Forster, "The last of the dinosaur titans: a new sauropod from Madagascar" Nature 412, 530 - 534 (2001)

Upchurch, P., 1998: The Phylogenetic relationships of sauropod dinosaurs. -Zoological Journal of the Linnean Society of London: Vol. 128, 1, pp. 43-103

Chiappe, L. M., R. A. Coria, L. Dingus, F. Jackson, A. Chinsamy, and M. Fox. 1998. "Sauropod dinosaur embryos from the Late Cretaceous of Patagonia" Nature Volume 396, 258-261: - describes the fossilized remains of the titanosaur embryos

Shreeve, James, Uncovering Patagonia's Lost World, National Geographic, December 1997, pp. 120-137.

Web Sites

Earth History Portal

Titanosauria - Palaeos - detailed technical diagnosis, lots of links

Titanosauridae - Fred Bervoets' DinoData - lists every genus and species

Titanosauridae - Mikko Haaramo's phylogeny pages

Other

Titanosauridae (Saltasauridae) - Justin Tweet's Thescelosaurus! - excellent short intro of group as a whole, along with good short summary of each genus and species, including poorly known forms

Ameghiniana Round Up, Pt. II - by Thomas R. Holtz

Face of the Titanosaur by Ralph Miller III

TITANOSAUROIDEA - Diosauricon, listst every genus and species

Dinosaur embryos egg-site - scanned newspaper article on discover of titanosaur embryos

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