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
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:
|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|
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
was. However, it is now obvious that this cannot be. Skulls for
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 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.|
|?Agustinia ligabuei Bonaparte, 1999 (originally Augustia Bonaparte, 1998)||Aptian-Albian (EK) of Argentina||This is a very unusual sauropod. It appears to have
had plates not unlike Stegosaurus, only oriented with the faces
forward and backward rather than side to side. Spines are also
present. The original name turned out to be
preoccupied (Zariquiey, 1927) by an insect, necessitating the name change. Some
researchers have linked it with rebbachisaurids.
An osteoderm from the Hauterivian-Barremian (EK) of Croatia is similar.
|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" giganteus (N.D.) Huene, 1929||Coniacian (LK) of Argentina||As the name suggests, this is a large animal. It probably is not Antarctosaurus.|
|"Antarctosaurus jaxartensis" (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.|
|Austrosaurus mckillopi (N.D.) Longman, 1933||late Albian (EK) to perhaps Cenomanian-Turonian (LK) of Australia||Unusual for being so basal so late, Austrosaurus has auditioned with Brachiosauridae, Camarasauridae, "Cetiosauridae", and "Titanosauridae", without finding a good fit. New study puts it as a titanosaurian, more derived than Malawisaurus. Brachiosaurid-like material from the Cenomanian (LK) of Australia, including some referred to informally as the "Hughenden sauropod," was traditionally referred here, but the description of Diamantinasaurus and Wintonotitan muddies those waters.|
|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 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.|
|?"Nurosaurus qaganensis" (N.N.) in press? described? named as something else? out to lunch?||EK of China||Known from most of a skeleton (or so we've been led to believe), this animal has been awaiting official description for a while. It is a very large animal, with bifid neural spines.|
|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.|
|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.|
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