Lithostrotia
With Titanosauridae left as hors de
combat, a
variety of subdivisions have been deployed to organize Titanosauria. The
most successful have been Lithostrotia and Saltasauridae. As mentioned on
the lead-in page, 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.
<--Lithostrotia
|--Malawisaurus
`--+--Epachthosaurus
|--Narambuenatitan
|--Nemegtosauridae
|
|--Nemegtosaurus
| |--Rapetosaurus
| `--Tapuiasaurus
`--Saltasauridae
|--Opisthocoelicaudia
`--+--Neuquensaurus
`--Saltasaurus
Lithostrotia:
| Taxon or Taxa: | Time/Place: | Comments: |
| Malawisaurus dixeyi Jacobs, Winkler, Downs, and Gomani, 1993 (originally Gigantosaurus dixeyi Haughton, 1928) | Aptian (EK) of Malawi | This is one of the earliest definite titanosaurians. It is known from fairly abundant remains, including muzzle bones that show it had a steep face, and armor. |
| Epachthosaurus sciuttoi Powell, 1990 | late Cenomanian-early Turonian (LK) of Argentina | Epachthosaurus is not as well known as some of the others, but new finds including most of a skeleton should change that. It might prove to be an unarmored titanosaurian. |
| Narambuenatitan palomoi Filippi, García, and Garrido, 2011 | early-middle Campanian (LK) of Argentina | Narambuenatitan is known from a partial skeleton including that precious rarity, associated cranial material. Postcranial bones include a handful of vertebrae and representatives of the other major skeletal segments, with a general lack of distal limb bones. |
Lithostrotia i.s.:
| Taxon or Taxa: | Time/Place: | Comments: | |
| Adamantisaurus mezzalirai Santucci and Bartini, 2006 | ?Campanian-?Maastrichtian (LK) of Brazil | Based on six articulated anterior caudals and two chevrons, Adamantisaurus may be related to Aeolosaurus and the so-called "Peirópolis titanosaur" (Trigonosaurus) (which, like the "Shake-n-Bake theropod", the "carcharodontosaurid larger than Giganotosaurus" [Mapusaurus, if I recall correctly] the "EK troodontid", the unnamed dromaeosaurid of Mongolia, the "Fruita Echinodon" [now Fruitadens], the "Proctor Lake hypsilophodont", and the "high-spined Cedar Mountain iguanodont" sometimes identified with "Iguanodon" ottigeri, had taken on mythic stature in the literature). | |
| Aeolosaurus Powell, 1987 (?Gondwanatitan) | A. rionegrinus (type) Powell, 1987 | late Campanian-early Maastrichtian (LK) of Argentina | This is an obscure lithostrotian, with some good remains. It may be synonymous with Gondwanatitan. A. rionegrinus is based on caudal vertebrae, some limb elements, fragmentary scapulae, and ischia; A. colhuehuapensis is known from caudals; and A. maximus is known from partial vertebrae (cervicals, dorsals, and caudals), ribs, limb bones, and a couple of girdle bones. |
| A. colhuehuapensis Casal, Martínez, Luna, Sciutto, and Lamanna, 2007 | Campanian-Maastrichtian (LK) of Argentina | ||
| A. maximus Santucci and Arruda-Campos, 2011 | Campanian-Maastrichtian (LK) of Brazil | ||
| Alamosaurus sanjuanensis Gilmore, 1922 | middle late Campanian-late Maastrichtian (LK) of New Mexico, Texas, and Utah | The only (named) North American lithostrotian, but also
oddly enough one of the better known (although its validity has recently been
challenged), Alamosaurus was likely a southern immigrant, a
representative of a branch of the lithostrotians (possibly close to Neuquensaurus
and some undescribed Brazilian forms) that by the
end of the Maastrichtian was creeping (or stomping, or some other mode of
locomotion more descriptive of a lithostrotian than creeping) steadily
northward. It was one of the last
sauropods, and is not named for the Alamo in San Antonio, but for a
formation (Ojo Alamo). New gigantic LK Texan sauropod remains may belong to this taxon, or may simply be part of what may be better referred to as the "Alamosaurus" complex of titanosaurian remains. It may have been unarmored, which would be unusual for a lithostrotian. |
|
| Antarctosaurus: Huene, 1929a |
A. wichmannianus (type) Huene, 1929 | early-middle Campanian (LK) of Argentina | This sauropod is somewhat controversial because it is not certain how much of the type material belongs in the same taxon. In particular, a square-front lower jaw included in the type material is sometimes suspected to have come from a rebbachisaurid (but the recent discovery of square-jawed titanosaurian Bonitasaura suggests maybe convergence in jaw style between rebbachs and titanosaurians is possible). |
| ?A. brasiliensis Arid and Vizotto, 1972 | Santonian (LK) of Brazil | ||
| Atacamatitan chilensis Kellner, Rubilar-Rogers, Vargas, and Suárez, 2011 | LK of Chile | Atacamatitan is known from a partial skeleton including two dorsals, caudals, ribs, part of the humerus, a possible sternal, the right femur, and lithostrotian debris. It is described as more derived than Malawisaurus but less than saltasaurids. | |
| Bonatitan reigi Martinelli and Forasiepi, 2004 | late Campanian-?Maastrichtian (LK) of Argentina | Described as a small saltasaurid, Bonatitan's material includes at least braincase and caudal remains, but little else is available to me at this time. Don't confuse it with Bonitasaura. | |
| Diamantinasaurus matildae Hocknull, White, Tischler, Cook, Calleja, Sloan, and Elliott, 2009 | Cenomanian-Turonian (LK) of Australia | Diamantinasaurus is a robust derived titanosaurian, known principally from forelimb, hindlimb (minus the foot), and pelvic and pectoral girdle bones. It is unusual in retaining a thumb claw (titanosaurians are known for not even having phalanges on their hands). The species name is a reference to "Waltzing Matilda", which was written in the part of the country where this dinosaur was found. | |
| Elaltitan lilloi Mannion and Otero, 2012 | middle Cenomanian-Turonian (LK) of Argentina | Among the abundance of remains shuffled off as Argyrosaurus or Antarctosaurus over the years was a partial skeleton, including three dorsals, two caudals, the left scapula and arm above the wrist, the right ulna and pubis, and most of a leg (if you combine the right and left elements). Further review showed that it did not belong to either of these two South American titanosaurian stooges (to make three stooges, just add Laplatasaurus; if you want Shemp, there's always Titanosaurus itself). The name refers to the Tehuelche creator god Elal. | |
| Gondwanatitan faustoi Kellner and de Azevedo, 1999 (?Aeolosaurus) | Santonian (LK) of Brazil | This is a recently described titanosaurian (although not particularly large, despite the name). It may be synonymous with Aeolosaurus, and is known from material including two cervicals, seven dorsals, six sacrals, 24 caudals, part of a scapula, much of the hips, humeri, and tibiae. | |
| ?Huabeisaurus allocotus Pang and Cheng, 2000 | Campanian (LK) of China | This is a new, gigantic sauropod, possibly a nemegtosaurid, referred to its own family, Huabeisauridae, but from its description it seems to be close to Opisthocoelicaudia. It has split neural spines in the cervicals, single spines in the dorsals, unforked chevrons, and amphicoelous caudals. Peglike teeth, many verts, girdles, and partial limbs are known. | |
| Isisaurus colberti Wilson and Upchurch, 2003 (originally Titanosaurus colberti Jain and Bandyopadhyay, 1997) | Maastrichtian (LK) of India | This taxon is based on much better material, including much of the postcrania, than most titanosaurians. It looks bizarre, with a short, vertically-directed neck and long forearms. | |
| Lirainosaurus astibiae Sanz, Powell, Le Loeuff, Martinez, and Pereda-Suberbiola, 1999 | late Campanian-?early Maastrichtian (LK) of Spain | This saltasaurid appears to be somewhat less derived than Saltasaurus, possibly as the sister group to Saltasauridae. It is known from the remains of several individuals, including skull material and armor. | |
| Loricosaurus scutatus (N.D.) Huene, 1929 (?Saltasaurus or Neuquensaurus) | early Campanian (LK) of Argentina | At one time considered an ankylosaurian, this armored sauropod may instead be a synonym of Saltasaurus or Neuquensaurus. | |
| Magyarosaurus: Huene, 1932 | M. dacus (Nopcsa, 1915 [originally Titanosaurus]) (type) | early-middle Maastrichtian (LK) of Romania | This small (possibly the smallest known adult
neosauropod) titanosaurian may have remains from several different
sauropods referred to it, a common problem for titanosaurians. It
may be related to Ampelosaurus, and both may be armored dwarf
sauropods. Of the two other species assigned to Magyarosaurus (both Huene, 1932), M. hungaricus may represent a new genus, and M. transsylvanicus may be a synonym of M. dacus. |
| ?M. hungaricus Huene, 1932 | |||
| Maxakalisaurus topai Kellner, Campos, Azevedo, Trotta, Henriques, Craik, and Silva, 2006 | Campanian-Maastrichtian (LK) of Brazil | This possible lithostrotian is based on much of a skeleton, including cranial elements and armor. So far as I can tell, it mostly specializes in being well-publicized, as Google already had 25,500 results a few weeks after it was published. | |
| Muyelensaurus pecheni Calvo, González-Riga, and Porfiri, 2007 | late Coniacian-Santonian (LK) of Argentina | Described as a slender titanosaur, Muyelensaurus is known from a braincase, verts from throughout the column, and various appendicular bones. It may be closest to Rinconsaurus. | |
| Panamericansaurus schroederi Calvo and Porfiri, 2010 | late Campanian-?Maastrichtian (LK) of Argentina | Panamericansaurus is based on five caudals, a sacral, the left humerus, a couple of chevrons, and some fragments of ribs. It is thought to be a close relative of Aeolosaurus, perhaps in a clade with it and Gondwanatitan (Aeolosaurini). | |
| Pellegrinisaurus powelli Salgado, 1996 | early-middle Campanian (LK) of Argentina | This lithostrotian is presently little publicized. It is based on 26 caudals, 4 dorsals, and a partial femur. | |
| Pitekunsaurus macayai Filippi and Garrido, 2008 | early-middle Campanian (LK) of Argentina | Pitekunsaurus is another possible relative of Rinconsaurus, and is apparently from the same area (formational ages are clashing, though, so I'll have to reconcile those). Presacrals, a scapula, a femur, and cranial material are known; odd that it hasn't attracted more attention on that basis. Speaking of which, when will there be a description of that Argentine titanosaur skull that was in a National Geographic article around the turn of the century? | |
| Quaesitosaurus orientalis Kurzanov and Bannikov, 1983 | late Campanian (LK) of Mongolia | Possibly a close relative of Nemegtosaurus, and also based on a skull (although not quite as well-preserved), this also appears to be some sort of lithostrotian. | |
| Rinconsaurus caudamirus Calvo and Riga, 2003 | early-Middle Campanian (LK) of Argentina | Rinconsaurus is based on remains including 13 caudals and a variety of other material; at least three individuals of differing age are known. It may be close to Aeolosaurus. Its caudals include not only the expect procoelous centra, but also amphicoelous and opisthocoelous centra. | |
| Rocasaurus muniozi Salgado and Azpilicueta, 2000 | late Campanian-early Maastrichtian (LK) of Argentina | Rocasaurus may have a good deal of referable material, including juvenile and adult remains. It is based on parts of several verts, much of the hips, and a femur, from a juvenile individual. | |
| Sonidosaurus saihangaobiensis Xu, Zhang X., Tan Q., Zhao X., and Tan L., 2006 | early Maastrichtian (LK) of China | This titanosaurian is based on verts including dorsals, sacrals, and caudals, ribs, a chevron, and most of the pelvis. It was one of the small titanosaurians, around 9 m long (which is in the big iguanodont-average hadrosaurid range). It appears to probably have been a lithostrotian, possibly related to Opisthocoelicaudia. | |
| Trigonosaurus pricei Campos, Kellner, Bertini, and Santucci, 2005 | Maastrichtian (LK) of Brazil | This is the (comparatively) famous "Peirópolis titanosaur" (DGM Series B), about the only case I know of where a taxon was included in definitions of clades without being officially named. It is known from a good chunk of the vertebral column (5 posterior cervicals, 10 dorsals, 6 sacrals, and the left ilium), with a referred group of 10 caudals (I don't know if I necessarily trust this referral, given that the material was found in a bonebed of hundreds of titanosaur bones from at least two taxa [also Baurutitan]). | |
Nemegtosauridae: Originally described as the last diplodocids, then as dicraeosaurids, these sauropods instead appear to be titanosaurians, possibly very derived lithostrotians. Other remains suggest undescribed nemegtosaurines in the ?Aptian-?Albian (EK) of China and the upper Albian (EK) of France.
| Taxon or Taxa: | Time/Place: | Comments: |
| Nemegtosaurus mongoliensis Nowinski, 1971 | early Maastrichtian (LK) of Mongolia | Nemegtosaurus is based on a partial skull with some features similar to Brachiosaurus and others similar to Diplodocus. That it is a titanosaurian was strengthened by the recent discovery of other titanosaurian skulls that closely resemble it. It may represent the skull of Opisthocoelicaudia. A second skull is reported, but I've never seen it figured. |
| Rapetosaurus krausei Rogers and Forster, 2001 | middle Maastrichtian (LK) of Madagascar | Known from material including most of a skeleton and a very distinctive skull, Rapetosaurus (named for a mischievous giant in Malagasy folklore) is extremely important for future titanosaurian studies because of the degree of completeness and the skull. Multiple individuals are known, of different ages. Rapetosaurus was armored, at least as an adult. |
| Tapuiasaurus macedoi Zaher, Pol, Carvalho, Nascimento, Riccomini, Larson, Juarez-Valieri, Pires-Domingues, Silva, and Campos, 2011 | Aptian (EK) of Brazil | Tapuiasaurus is known from much of the front end and limbs of a titanosaur, including a skull (interesting, isn't it, that the titanosaurs with skulls end up in Nemegtosauridae). Other bones include seven cervicals, five dorsals, ribs, a sternal, a coracoid, a humerus, a radius, both ulnae, metacarpals, both femurs, a fibula, and most of a foot. The skull is like that of the other nemegtosaurids; if I had to describe it briefly, I'd say in between the other two skulls, without the curved Nemegtosaurus profile, and without as enormous an antorbital fenestra as Rapetosaurus. |
| Taxon or Taxa: | Time/Place: | Comments: | |
| Opisthocoelicaudia skarzynskii Borsuk-Bialynicka, 1977 | early Maastrichtian (LK) of Mongolia | This sauropod may be a lithostrotian, but it also has a raft of unusual
features (although this may just be a result of having more complete
remains than most lithostrotians). Among these
features is the unique articulation of the tail: the caudal verts have an articulation that is
opposite the regular lithostrotian condition, where a "ball" on the rear of a vert
articulates with a socket on the front of the next vert (procoelous). In Opisthocoelicaudia,
the verts have a "ball" on the front of each vert articulating with a socket on
the rear of its predecessor (opisthocoelous, hence the name). This unique configuration makes this animal's tail both
strong and apparently directed straight out behind the body. This may be related to
the greatly expanded ilium; it has been suggested that the usual muscles for providing
hindlimb movement in reptiles, which are attached to the tail and leg, were either not
present or greatly reduced in this taxon, and the ilium then took over this attachment
function. This may have been to help free up the tail for greater use as a prop in
bipedal feeding (however, much of the hips
were restored, leaving a question as to how much is actually known). Opisthocoelicaudia also
reportedly has some bifurcated presacral
neural spines. It also has six sacrals, like lithostrotians, but the
extra sacral appears to have come from the tail, not the back, as in other
lithostrotians. However, a number of other characters, including form of the arm bones and sternal plates,
show a strong resemblance to those of lithostrotians. It is known from a headless skeleton, and some paleontologists have suggested that it represents the body of Nemegtosaurus, which is known from a partial lithostrotian skull. Originally, it was thought to be closest to Camarasaurus, which isn't a bad guess, comparing the two in general. |
|
| Neuquensaurus: Powell, 1992 | N. australis (Lydekker, 1893 [originally Titanosaurus]) (type) | Santonian-Maastrichtian (LK) of Argentina and Uruguay | This sauropod, closely related to Saltasaurus, is
also known from the remains of several individuals. The specimens assigned to N. australis and N. robustus are a bit of a problem (it was one of those cases where Huene took a bunch of intermixed specimens and parceled them out). Some of the robustus bones look like they should go to australis, and vice-versa. Be that as it may, it does appear that there is more than one taxon in the pot of material originally assigned to South American species of Titanosaurus. |
| N. robustus (?N.D.) (Huene, 1929 [originally Titanosaurus]) | early Campanian (LK) of Argentina | ||
| Saltasaurus loricatus Bonaparte and Powell, 1980 | late Campanian-?Maastrichtian (LK) of Argentina | This rather small sauropod is most famous for the possession of body armor. It is known from the remains of several individuals. | |
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