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Figure 1. (Above) Titanosaurus colberti, the giraffe of the Cretaceous, sporting its seasonal colors and ready to strut its stuff.

•     Indroduction:

Titanosaurus colberti is a unique sauropod, notable for the extremely short forearms, and the incredible short and deep neck for an animal of it's size. The appears of this animal must have been quite a sight, a titanic body with a short tail, long forelimbs similar to those of brachiosaurs, no claws on the forefeet, and a gigantic neck swinging from the shoulders, held slightly upward and appearing as nothing more than an immense, reptilian giraffe. All currently-recognized valid species of Titanosaurus, including T. colberti, come from India. T. colberti itself, as do many other Titanosaurus species (including the type species, T. indicus) comes from the Late Cretaceous Lameta Formation of central India, in the province of Maharashtra, near the important town of Pisdura, in the locality of Dongargaon. Previously known for fish and gastropods, there is also an unaffiliated braincase referred to the titanosaurids (see Berman and Jain, 1982). This braincase may very well belong to T. colberti, as well as three other sauropods known from near Pisdura, the Titanosaurus species T. indicus, T. madagascariensis, and T. blandfordi. These four species all differ on the form of the middle caudal vertebrae, and are distinct enough to offer that Titanosaurus colberti may be a valid species. It is also the most complete species of Titanosaurus known so far.

Titanosaurus was described by Lydekker in 1877, and comprised the type species T. indicus, for some caudal vertebrae. There has been some debate over the validity of a dinosaur taxon named on just caudal vertebrae, but, as was later found, the caudals of sauropods are highly distinctive, with over 20 distinct traits that can be compared across not just species, but genera and more inclusive taxa. Lydekker also named the species T. blanfordi in 1879 for two types of caudals, but these have been reduced to one type recently. Other Titanosaurus species have been named from abroad, including Madagascar (T. madagascariensis) and Laos (T. falloti). Other species were named to new genera, and include Laplatasaurus and Neuquensaurus from Argentina, and Janenschia from Tanzania; otherwise, there are extensive Indian species of allied taxa, including Antarctosaurus. Some teeth were namd as T. rahiolensis (Mathur and Srivatsava, 1987), but these cannot be compared to the type material used to index Titanosaurus species, caudals, so the species is a nomen dubium and may pertain to a variety of previously recognized species. The systematics of Titanosaurus suffer through lack of good material for more than a few species; while limb material is known for T. indicus, it is not easily compared to other species of scattered limb material, which cannot be assigned to any particular taxon. Thus, Titanosaurus became a wastebasket for unusual sauropods in the Gondwanan continents.

•     Titanosaurs:

Remarkably, this form has received little notice or attention subsequent to its description in 1996. The sauropod is fantastically unique and alters our image of Titanosaurus in general, an animal which does not resemble the similar sauropods, Saltasaurus or Laplatasaurus. In the form of it's pelvis and tail, T. colberti is almost certainly a titanosaurid (saltasaurid of Sereno's usage) of the type Titanosaurus; these forms are distinct in the form of the their caudal vertebrae, which are cupped in the front and ball-shaped in the back, have a ball-shaped articulation for the last sacral vertebra, and mostly have caudal neural spines that incline forwards instead of up or backwards as in other sauropods. The ulna also has a ridge on the medial surface that in proximal aspect give the bone a roughly T-shaped appearance, while in other sauropods this ridge is not as distinct and the ulna looks distinctly triangular in it's proximal aspect.

T. colberti was about 60 feet long, or 18.2 meters, though the tail is incomplete and some dorsal and cervical vertebrae are missing, obscuring the full length of this animal. The arms were certainly long, and would indicate an animal roughly 12.4 feet or 3.75 meters at the shoulder, though this is based on the orientation of the scapula. The scapula is apparently oriented nearly dorsally, as seen in figure 2.

 

Figure 2: The skeleton of Titanosaurus colberti, with missing elements (pes, skull, various vertebrae and ribs, and sternal skeleton) in black. The skull is devised from an undescribed titanosaurid skull from Argentina as well as the titanosauroid Nemegtosaurus. More cervicals and dorsals are known, but are poorly preserved and do not allow more precise placement, thus are not included.

•     Titanosaurus colberti:

Named to honor the late Dr. Edwin "Ned" Colbert, this is the most recently named species of Titanosaurus. A relatively "normal" sized sauropod at around 60 feet or 18.2 meters, this form is unusually massive, especially in the neck, compared to other titanosaurids, including the apparent close relative Saltasaurus from Argentina.

There is only one specimen, labelled ISIR 335, and containing up to 65 elements, including nine cervicals (335/1--9), seven dorsals (335/10--16), fourteen incomplete and nearly-complete dorsal ribs (335/17--30), the complete sacrum (335/31), and sixteen caudals (335/32--47), with nine associated haemal arches (335/48--56); a left scapula and coracoid (335/57 and 58, respectively), and a humerus (335/59) and an ulna (335/60); both ilia are known (335/61--62), as are both pubes (335/63--64) and a right ischium (335/65). No other limb material is known. The specimen is relatively well associated and closely matched, with several elements (left ilium and sacrum; both pubes; and the last three cervicals and the first dorsal) in direct contact. Most ribs were found in the same area, as were most caudals, indicated that while there was posthumous transport of the material, the energy flow was not great, and this animal was probably scavenged before fossilization, as suggested by the lack of hindlimbs and partial forelimbs.

 

in cm	Length	Height	Width
Cervical #10?	26 est.	70	70
Scapula	108		43 (prox)
Humerus	148		21
Ulna	80		36 (prox)
Ilium	925 est.	50	80 (~150 across both)

Table 1. Measurements for Titanosaurus colberti, after Jain and Bandyopadhyay (1997).

This species is probably best distinguished by it's neck, which is very short and deep for a sauropod. Only Amargasaurus, a diplodocoid from Argentina, has as short a neck compared to it's length, but it is also rather small for a sauropod, about half the size of T. colberti in all.

                        

Figure 3. The head and neck of Titanosaurus colberti, illustrating (left) the skeleton of the neck and shoulders surrounded by the flesh, including the extensive fleshy nostril, and (right) the head draped in flesh and skin, ornamented with dermal ossicles (armor), found throughout titanosaurs and known especially among titanosaurids.

While the forelegs are very long and relatively slender, as in other titanosaurids, the forearms (ulna, radius, carpus, and hand) are very short, overall only a little over half the length of the humerus, with a short but compact manus. While the arm is shorter than the leg, it is also bound to the scapula in such a way as to make the forequarters much higher than the hind. The scapula is oriented vertically, based on the orientation of the glenoid facet for the humerus, which is horizontal. Finally, the pelvis is similar to other titanosaurids, with a vertical pubis, and an ilium that is widely splayed to the side but is also relatively horizontal. The pubis is longer than the ischium.  

Glossary of Terms:

• brachiosaurs: a group of sauropods with very long necks probably held about 45°, forelegs as long or longer than the hindlegs, a distinct and wide skull, and very short tail, they are the closest relatives to the titanosaurs, and include such taxa as Brachiosaurus, Sauroposeidon, Sonorasaurus, and Pleurocoelus.
• dermal ossicles: some sauropods had bones imbedded within the skin, rather than next to the bones, and these are normally plate-like with a ridge or keel on the outside that gave the bone a distinct appearance. Many titanosaurs have been found with such bones, including Saltasaurus, so it is not too much to suggest that all titanosaurs probably had them, especially Titanosaurus.
• diplodocoid: a group of sauropods known not just for their long necks but also for their very long tails, short legs, and small, horse-like heads having pencil-shaped teeth restricted to the front of the jaws, a nasal opening in the top of the skull and pulled backwards, without a bar of bone between each bony nostril, and include such taxa as Diplodocus, Apatosaurus, and Amargasaurus, as well as the newly found Nigersaurus (whose skull is highly unusual).
• Gondwana: a paleo-supercontinent formed from Africa, South America, India and Madagascar, Australia, and Antarctica. The continent broke apart by as early as the middle or late Early Cretaceous with the formation of the incipient Atlantic between South America and Africa; later, India broke off by the early Late Cretaceous, and Antarctica and Australia by the late Late Cretaceous. Antarctica did not become totally isolated until the late Paleocene or early Eocene.
• saltasaurid: the "proper" name for the group of sauropods that includes Titanosaurus. See titanosaurid.
• sauropod: a group of dinosaurs having very long necks and tails, short legs, and a very small head, the dorsal vertebrae are much more massive, and the legs built to carry much more weight than in other groups of dinosaurs.
• titanosaurid: a group of sauropods having relatively short necks and tails, long forelimbs, a unique scapula with the distal end at a distinct angle to the proximal end, a manus that has no digits except for maybe a claw on the first finger, dermal armor, and skulls that resemble diplodocoids in being long, low, but with a complete intra-narial bar, and pencil-like teeth, and includes Titanosaurus, Saltasaurus, Laplatasaurus, and Opisthocoelicaudia.
• titanosauroid: the group of sauropods that includes the titanosaurids, as well as a few other forms, such as Andesaurus, Nemegtosaurus, and Rapetosaurus.
• titanosaurs: generally, a group of sauropods with unusual caudal vertebrae having deep yet simple fossae in the sides, cervical vertebrae that are composed of numerous yet very small pockets of air inside (camellae), have dermal ossicles, 

 

References:

• Berman, D.S. and Jain, S.L. 1984. The braincase of a small sauropod dinosaur (Reptilia: Saurischia) from the Upper Cretaceous Lameta Group, central India, with a review of Lameta Group localities. Annals of the Carnegie Museum 51: 405-422.
• Deperet, C. 1896. Note sur les dinosauriens sauropodes et theropodes du Crétacé superieur de Madagascar [Note on the sauropod and theropod dinosaurs from the Upper Cretaceous of Madagascar]. Bulletin de la Société Géologique du France (sér. 3) 24: 176-196. [in French]
• Hoffet, J.-H. 1942. Description de quelques ossements de Titanosauriens du Senoniene du Bas-Laos [Description of dermal ossicles of Titanosaurs of the Senonian of Bas-Laos]. Comptes rendus des séances du Conseil des recherches scientifiques de l'Indochine 1942: 49-57. [in French]
• Jain, S.L. and Bandyopadhyay, S. 1997. New titanosaurid (Dinosauria: Sauropoda) from the Late Cretaceous of central India. Journal of Vertebrate Paleontology 17(1): 114-136.
• Lydekker, R. 1877. Notices of new and other Vertebrata from Indian Tertiary and Secondary rocks. Record of the Geological Survey of India 10: 38-41.
• Lydekker, R. 1879. Indian pre-Tertiary Vertebrata: Fossil Reptilia and Batrachia. Memoirs of the Geological Survey of India, Palaeontologia Indica 4: 1-36.
• Mathur, U.B. and Srivatsava, S. 1987. Dinosaur teeth from the Lameta Group (Upper Cretaceous) of Kheda District, Gujarat. Journal of the Geological Society of India 29: 554-566.
• Sereno, P.C. 1997. The origin and evolution of dinosaurs. Annual Review of Earth and Planetary Sciences 25: 435-490.
• Sereno, P.C. 1998. A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 1998 (189): ?
• Witmer, L.M. 2001. Science...

   

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