Titanosauria

    Titanosauria is composed of a large number of poorly known sauropods, among the last animals of their kind to have existed. The animals listed here are traditionally listed as titanosaurids, but since it's recognized that Titanosaurus itself is based on dubious material that cannot be classified beyond Titanosauria, Titanosauridae is not particularly useful. Titanosaurians commonly are either very large for sauropods or very small, often with armor set in the skin (which when found disassociated earlier was assumed to belong to ankylosaurians). Titanosaurian armor comes in three general forms: mound-like, bulb-like, and disc-like.
    Another characteristic just now becoming appreciated is the wide gauge hips, implying a somewhat different muscle arrangement and gait for these animals compared to other sauropods. Wide gauge sauropod trackways show up in the Jurassic, establishing the presence of titanosaurian-style walking a bit before the actual titanosaurians show up. Their teeth are somewhat peglike, like diplodocid teeth, but this is virtually their only similarity. Here is a chart showing some important differences between the two groups:

Character: Group: Titanosauria Diplodocidae
Armor present in some none has been found
Cervical/Dorsal Neural Spine generally unsplit split
Sacrum 6 verts 5 verts
Tail like Brachiosauridae whip-lash ending
Chevrons simple skid-like

    For a time, however, titanosaurians and diplodocids were considered to be very closely related, which was excusable then, because no one was really sure what a "titanosaurid" was. However, it is now obvious that this cannot be. Skulls for titanosaurians were not known until this decade, although Mongolian sauropod skulls from the Seventies and Eighties are now known to belong to probable derived titanosaurians, not to diplodocids as they were first described.
    Titanosauria is divided into several families by some workers, including Saltasauridae and Andesauridae, which supposedly contains certain closely-related "basal titanosaurid"-type sauropods.
    Many titanosaurians come from LK South American formations whose ages have not been pinned down yet. Also, several titanosaurians (Antarctosaurus especially) are based on arbitrary assortments of remains, which may or may not all belong together. Some actually were titanic in size, but there were also "pygmy" titanosaurians, especially in areas thought to have been islands. Titanosaurians are still rather poorly known, and a lot of the taxa aren't especially well defined.
    As an interesting bit of trivia, a taxon named Succinodon was once thought to be a member of Titanosauria, until it was discovered that the holotype "jaw" was actually the filled burrowings of a mollusk.
    Phytoliths (bits of silica that plants grow within themselves to make them less palatable) have been found in LK Indian coprolites attributed to titanosaurians. The interesting part about them is that grass phytoliths are among them. Grass was long thought to have not appeared, or at least not been of any importance, until the early Cenozoic, but these phytoliths indicate diverse grasses formed part of the diet of titanosaurians. These grasses were probably not really common yet. Other finds in South America suggest that grasses first appeared in the southern continents in the Cretaceous, which may explain some of the current blindness about them: Southern Hemisphere continents have not been explored as well as the northern continents when it comes to paleontology.

<--Titanosauria
      |--Andesaurus
     
`--+--Argentinosaurus
           `--+--Malarguesaurus
                 `--+--Lognkosauria
                      |     |--Drusilasaura
                      |     |--Futalognkosaurus
                     
|     `--Mendozasaurus
                      `-->Lithostrotia

Titanosauria and Lognkosauria: As you can see by scrolling down the page, Titanosauria is one of the largest groups of classic dinosaurs. It will likely continue to grow for a while, as titanosaurian finds seem to be greatly increasing. They also have an unusual tendency to have generic names starting with the letter A. A vast nesting colony of titanosaurians has recently been discovered in Argentina, with some specimens showing skin impressions, and another such possible colony was uncovered in Spain. Numerous undescribed forms are turning up at a frightening pace, some including cranial material. Argentina is particularly rich.
    Now, for a bit of definitions: Technically, Titanosauria is composed of all sauropods closer to Saltasaurus than to Euhelopus or Brachiosaurus. Within Titanosauria, Lithostrotia is composed of Saltasaurus, Malawisaurus, and all descendents of their most recent common ancestor. Similarly, Saltasauridae is Saltasaurus, Opisthocoelicaudia, and all descendents of their most recent common ancestor. Note, though, the effects of the Titanosaur Uncertainty Principle (the more titanosaurs that are observed, the less higher-level classification resolution is achieved; this differs from other situations where the more taxa you have, the clearer things are supposed to be).

Taxon or Taxa: Time/Place: Comments:
Andesaurus delgadoi Calvo and Bonaparte, 1991 early Cenomanian (LK) of Argentina This sauropod is the best-known example of a basal titanosaurian. It shows some resemblance to Argentinosaurus and, interestingly, Haplocanthosaurus.
Argentinosaurus huinculensis Bonaparte and Coria, 1993 late Cenomanian (LK) of Argentina This basal titanosaurian, known from limb bones and vertebrae, is among the largest known dinosaurs.
Malarguesaurus florenciae González-Riga, Previtera, and Pirrone, 2008 late Turonian-early Coniacian (LK) of Argentina Malarguesaurus is based on partial postcranial remains including caudals, chevrons, and partial humerus and femur. Although the caudals had the standard titanosaurian procoelous fronts, the rear surfaces of the proximal and middle caudals were flat. Malarguesaurus was a robust titanosauriform, and may have been closest to Phuwiangosaurus.
Drusilasaura deseadensis Navarrete, Casal, and Martínez, 2011 late Cenomanian-Turonian (LK) of Argentina Drusilasaura is known mostly from vertebrae (four dorsals, a sacral, and six caudals) and a scapula. It was a large titanosaurian, and appears to have been a lognkosaurian.
Futalognkosaurus dukei Calvo, Porfiri, González-Riga, and Kellner, 2007 late Turonian-early Coniacian (LK) of Argentina Also known as the more pronounceable "Futalongkosaurus", this is currently the most completely known giant sauropod, with all of the cervicals, dorsals, and sacrals accounted for. It would have been around 32 to 34 meters long, with a hefty neck. Phylogenetic analysis puts it closest to Mendozasaurus, and the two may form a cozy little Lognkosauria with Malawisaurus as sister group.
Mendozasaurus neguyelap Gonzalez Riga, 2003 late Turonian-Coniacian (LK) of Argentina Mendozasaurus is a titanosaurian based in large part on 22 caudals and limb material. It is armored, and may be a basal titanosaurian, but more derived than Malawisaurus. More material has been found from the type locality, including short wide cervicals as in Isisaurus. The two may be related. Futalognkosaurus also appears to be related.

Titanosauria i.s.: The taxa here display great diversity for large sauropods. Some of the more basal species are brachiosaurid-like, while other are close to the base of Saltasauridae, with everything in between covered. A titanosaurian braincase from the late Aptian or early Albian (EK) of Texas has recently been described. At the early end, Bathonian (MJ) tracks from England appear to be titanosaurian in origin.  

Taxon or Taxa: Time/Place: Comments:
Aegyptosaurus baharijensis Stromer, 1932 Albian-early Cenomanian (EK-LK) of Egypt This average titanosaurian is based on a partial skeleton, including most of the limbs, which allow us to know about the relative ratios of the limb bones in titanosaurians. Unfortunately, we have to go on figures, as the type material was destroyed in WWII.
Amargatitanis macni Apesteguia, 2007 Barremian (EK) of Argentina Known from six caudals, a scapula, a femur, and an astragalus, Amargatitanis (not to be confused with Amargasaurus) is an early titanosaur. Its scapula was wide, flat, and robust.
Ampelosaurus atacis Le Loeuff, 1995 late Campanian (LK) of France This basal titanosaurian is known from copious material from several individuals that comprises most of a skeleton. A number of interesting types of armor have been found from it. Several other undescribed titanosaurians are known from the same area.
"Antarctosaurus": "A." brasiliensis Arid and Vizotto, 1971 (or 1972; 1971 is more common) Santonian (LK) of Brazil "A." brasiliensis is based on a partial humerus, partial femur, and a dorsal.
"A." giganteus (N.D.) Huene, 1929 Coniacian (LK) of Argentina As the name suggests, this is a large animal. It probably is not Antarctosaurus.
"A." jaxarticus (N.D.) Riabinin, 1939 Turonian-Santonian (LK) of Kazakhstan Vast differences in location and time make it unlikely that the femur for which this name was intended belongs to Antarctosaurus.
Argyrosaurus superbus Lydekker, 1893 Campanian-?Maastrichtian (LK) of Argentina This titanosaurian has historically been difficult to pin down, with a number of specimens (including what is now the holotype partial skeleton of Elaltitan) assigned to it over the years. The only elements that can be definitely assigned are the bones of the type specimen, most of the left arm of a large titanosaur. It is notable for, among other features, its elongate metacarpals.
Atsinganosaurus velauciensis Garcia, Amico, Fournier, Thouand, and Valentin, 2010 late Campanian (LK) of France Atsinganosaurus, the "gypsy reptile" in reference to possible migrations between western and eastern Europe and an inferred relationship with a far-flung genus (Malawisaurus), is known from vertebrae, limb bones, and teeth.
Balochisaurus malkani Malkani, 2006 Maastrichtian (LK) of Pakistan Balochisaurus is based on caudal verts and was assigned to the Balochisauridae (saltasaurids).
Barrosasaurus casamiquelai Salgado and Coria, 2009 early-middle Campanian (LK) of Argentina Barrosasaurus is a large titanosaurian known from three partial vertebrae. Do not confuse it with Barosaurus (easier to remember if you don't misspell it Barrosaurus, as I keep doing).  
Baurutitan britoi Kellner, Campos, and Trotta, 2005 Maastrichtian (LK) of Brazil This titanosaur is known from a sacral and 18 caudals, referred to in earlier works as "DGM Series C", a less-famous neighbor of the "Peirópolis titanosaur" (Trigonosaurus).
Bonitasaura salgadoi Apesteguia, 2004 Santonian (LK) of Argentina Bonitasaura was a smallish titanosaurian (on the order of 7 meters long as a subadult). Known from bones from most of the major parts of the body and belonging to one individual, its lower jaw suggests the presence of a keratinous beak; teeth are peglike and confined to the rostral tip of the squared-front jaw, while a sharp "guillotine" ridge runs along behind the teeth, on the bone making up the lateral sides of the jaw.  This throws an interesting wrench in the interpretation of Antarctosaurus as a chimera made up of saltasaurid postcranial material and a rebbachisaurid jaw (rebbachisaurids are also known to have jaws with strongly squared-off front margins): perhaps the jaw and postcrania really do go together, with the jaw form just an example of convergence to address similar niches. Rebbachisaurids appear to have had more replacement teeth set for action (remember, dinosaurs replaced teeth continuously) than Bonitasaura, giving a way to tell the two jaw types apart (well, that and the sharp ridge on Bonitasaura, too).
Borealosaurus wimani You, Ji, Lamanna, Li J., and Li Y., 2004 Cenomanian-Turonian (LK) of China This sauropod is based on an opisthocoelous mid-distal caudal from Liaoning Province, and referred to the Titanosauria. Possible remains from the same locality include a tooth crown, another caudal, and a right humerus.
Chondrosteosaurus gigas (N.D.) Owen, 1876 Barremian (EK) of England Another indeterminate Wealden sauropod, based on two cervical centra, this one was once tentatively synonymized with Regnosaurus, which later turned out to be a basal stegosaurian.
Gobititan shenzhouensis You, Tang, and Luo, 2003 Aptian-Albian (EK) of China Based on caudal vertebrae and a left hindlimb, this sauropod was described as a basal titanosaurian. It is said to be close to Tangvayosaurus.
Hypselosaurus priscus (N.D.) Matheron, 1869 Maastrichtian (LK) of France Based on disassociated remains, it is difficult to tell what Hypselosaurus constitutes, beyond a titanosaurian of some sort. Sometimes large eggs from France are referred to this taxon, without much evidence.
Jainosaurus septentrionalis Hunt, Lockley, Lucas, and Meyer, 1995 (originally Antarctosaurus septentrionalis Huene and Matley, 1933) Maastrichtian (LK) of India This sauropod, based on material including a braincase, shoulder girdle, and forelimb, has been considered a giant individual of Titanosaurus, but since the latter is so poorly defined, we may never be able to know for certain.   
?Jiangshanosaurus lixianensis Tang, Kang, Jin, Wei, and Wu, 2001 late early Albian (EK) of China This new sauropod is allied with the titanosaurians because of the structure of its shoulder girdle and vertebrae. It is not to be confused with the prosauropod Jingshanosaurus. Parts of the pelvic girdle and femur are also known.
Karongasaurus gittelmani Gomani, 2005 EK of Malawi A contemporary of Malawisaurus, this titanosaurian is based on a partial lower jaw and some referred teeth. It may have been fairly derived, given that the form of the teeth and their position in the mandible suggests a longer, lower skull than that of Malawisaurus, which would be more in line with lithostrotians like Nemegtosaurus and Rapetosaurus. It could also conceivably be a diplodocoid, but no diplodocoid postcranial remains are known from the area.
This may also be the first classical dinosaurian taxon published in an electronic-only format.
Khetranisaurus barkhani Malkani, 2006 Maastrichtian (LK) of Pakistan Khetranisaurus is another of a group of apparent titanosaurians from the Maastrichtian of Pakistan, based on caudals. There is a dichotomy of what are called balochisaurids (saltasaurids) and pakisaurids (titanosaurids) with these genera, and Khetranisaurus is grouped with the pakisaurids by the describer. 
Laplatasaurus araukanicus Huene, 1929 early-middle Campanian (LK) of Argentina A large titanosaurian, Laplatasaurus is known from a large number of elements that may or may not belong to the same taxon. Some workers have suggested referring it to Titanosaurus, but I am refraining because of the taxonomic fuzziness of T. indicus.
Marisaurus jeffi Malkani, 2006 Maastrichtian (LK) of Pakistan Marisaurus, based on caudals, was aligned with the balochisaurids (saltasaurids) by its describer.
Microcoelus patagonicus (N.D.) Lydekker, 1893 (?Neuquensaurus) Santonian-Maastrichtian (LK) of Argentina Microcoelus is an obscure titanosaurian usually thought to be the same as Neuquensaurus, although strictly speaking the two are not directly comparable at this time (Microcoelus is based on a dorsal, while Neuquensaurus has no reliably assigned dorsals).
Mongolosaurus haplodon Gilmore, 1933 ?Aptian-Albian (EK) of China (Inner Mongolia, so not a misnomer) Based on cervicals, a partial braincase, and unusual teeth, Mongolosaurus has been considered as everything from a diplodocid to (unofficially) a therizinosaurian, and now nests within Titanosauria (although exactly where is still up for grabs). It possessed split neural spines.
Normanniasaurus genceyi Le Loeuff, Suteethorn, and Buffetaut, 2013 Albian (EK) of France Normanniasaurus (from Normandy, as suggested by the name) is a basal titanosaurian based on a partial skeleton consisting of fragmentary vertebrae, parts of the shoulder and pelvic girdles, and parts of a femur and fibula. A somewhat younger caudal centrum has also been assigned to it.
Pakisaurus balochistani Malkani, 2006 Maastrichtian (LK) of Pakistan Next in the caudal-based titanosaurians of Pakistan, Pakisaurus was identified as a pakisaurid.
Paludititan nalatzensis Csiki, Codrea, Jipa-Murzea, and Godefroit, 2010 early-mid Maastrichtian (LK) of Romania Paludititan is known from a partial articulated skeleton (verts and partial pelvis), an uncommon occurrence for a Haţeg sauropod. It was described as a relatively derived titanosaurian.
Paralititan stromeri J. B. Smith, Lamanna, Lacovara, Dodson, J. R. Smith, Poole, Giegengack, and Attia, 2001 early Cenomanian (LK) of Egypt An extremely large titanosaurian, Paralititan is based on material including a humerus, shoulder girdle, and caudal verts. It apparently lived in an ancient mangrove environment.
"Pelorosaurus" becklesii Mantell, 1852 late Berriasian-Valanginian (EK) of England Based on a partial forelimb with skin impressions, this animal is, based on the proportions of limb bones, a titanosaurian, not a basal titanosauriform/brachiosaurid-type animal like true Pelorosaurus.
Petrobrasaurus puestohernandezi Filippi, Caundo, Salgado, Garrido, García, Cerda, and Otero, 2011 late Coniacian-early Santonian (LK) of Argentina Petrobrasaurus is known from a partial associated skeleton, including teeth, a cervical, several partial dorsals and caudals, a humerus, much of a hand, sternals, both femurs, partial tibiae, a pubis, ribs, chevrons, and fragments. It is similar to Mendozasaurus, and may be a lognkosaurian.
Puertasaurus reuili Novas, Salgado, Calvo, and Agnolin, 2005 early Maastrichtian (LK) of Argentina Puertasaurus is based on most of a cervical, a dorsal, and two caudal centra, and really came out of left field for me. I don't have much information to put up here right now, except that it was regarded as a titanosaurid, was apparently very large (absurdly large vertebrae), had large neural spines on the cervicals, and had short (length) anterior dorsals. It may be close to the lognkosaurians (Futalognkosaurus and Mendozasaurus). 
Qingxiusaurus youjiangensis Mo J., Huang C., Zhao Z., Wang W., and Xu X., 2008 LK of China This titanosaurian is represented by limited postcranial material, including a caudal neural spine, humeri, and sternal plates.
Quetecsaurus rusconii González Riga and Ortiz David, 2014 mid or late Turonian (LK) of Argentina Quetecsaurus is known from a partial skeleton including a postorbital, teeth, a handful of vertebrae (well, if you have big hands), ribs, a coracoid, and a fair portion of an arm. It appears to have been related to the lognkosaurians.
Sulaimanisaurus gingerichi Malkani, 2006 Maastrichtian (LK) of Pakistan The final (alphabetically speaking) caudal-based titanosaurian from Pakistan, Sulaimanisaurus was aligned with Pakisauridae.
Titanosaurus indicus (N.D.) Lydekker, 1877 Maastrichtian (LK) of India This sauropod is based on caudals and a femur. Obviously, these remains are somewhat sparse for founding a genus, let alone a family. Some of the referred material may not even be titanosaurian.
"Titanosaurus": "T." blandfordi (N.D.) Lydekker, 1879 Maastrichtian (LK) of India Indeterminate titanosaurian caudals.
"T." falloti (N.D.) Hoffet, 1942 Aptian-Albian (EK) of Laos This poorly known sauropod seems to be close to (?is) Tangvayosaurus and its allies.
"T." lydekkeri (N.D.) Huene, 1929 ?Albian (EK) of England This obscure possible titanosaurian is based on a vertebra.
"T." madagascariensis Deperet, 1896 mid Maastrichtian (LK) of Madagascar; ?Maastrichtian (LK) of ?India This sauropod is based on caudals with associated armor (one of which turning out to be Rapetosaurus), making it the first titanosaurian to be considered to have body armor. It is sometimes referred to Laplatasaurus, for no apparent reason
"T." nanus (N.D.) Lydekker, 1893 (?Neuquensaurus) Santonian-Maastrichtian (LK) of Argentina See Microcoelus (seriously, they have the same citation); the difference is it's known from a cervical and a dorsal, which Nequensaurus australis is both currently lacking.
"T." valdensis (N.D.) Huene, 1929 Barremian (EK) of England This sauropod, also known as Iuticosaurus, based on worn caudals, is one of the few definite examples of Wealden titanosaurians.
Traukutitan eocaudata Juárez Valieri and Calvo, 2011 Santonian (LK) of Argentina Traukutitan, a possible lognkosaurian, is known from both femurs and 13 caudals. Notably, the more distal of the caudals are not procoelous.
Uberabatitan ribeiroi Salgado and Carvalho, 2008 Maastrichtian (LK) of Brazil Uberabatitan is known from vertebrae, pelvic bones, and limb bones.
Vahiny depereti Curry Rogers and Wilson, 2014 mid Maastrichtian (LK) of Madagascar Vahiny is based on a Jainosaurus-like braincase, selected out of the rare non-Rapetosaurus titanosaurian fossils sometimes known under "Malagasy Taxon B". As such, it may eventually prove to be the same as "Titanosaurus" madagascariensis, or it may be that there are more than two titanosaurians in the Maevarano Formation.
Xianshanosaurus shijiagouensis Lü J., Xu L., Jiang X., Jia S., Li M., Yuan C., Zhang X., and Ji Q., 2009 early LK of China Xianshanosaurus is as-yet obscure. It is based on caudals, a coracoid, a femur, and ribs.

 

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