Describer

Deperet, 1896

Time

Cretaceous Late, Campanian

Classification

Saurischia Sauropodomorpha Sauropoda Titanosauria

Diet

Herbivore

Fossilsite

Gres de Maevarano, Majunga, Acanthopholis; Lameta Formation, Maharshtra, India

Fall Under

Isisaurus colberti

Info

Isisaurus colberti (Wilson & Upchurch 2003) > Titanosaurus colberti (Jain& Bandyopadhyay, 1997) > Titanosaurus indicus (Lydekker, 1877)

Titanosaurus indicus (Lydekker, 1877) >> Antarctosaurus septentrionalis (Huene & Matley, 1933) >> Jainosaurus septentrionalis (Hunt, Lockley, Lucas & Meyer, 1995) Titanosaurus blanfordi (Lydekker, 1879) > Titanosaurus madagascariensis (Deperet, 1896).

2 caudal vertebrae, scut.

Extract from the bulletin de la société géplogique de France 3rd series, volume XXIV, page 176, 1896. Note on the suaropod and theropod dinosaurs from the Upper Cretaceous of Ma dagascar by Charles DEPÉRET. Translated by Matthew Carrano Department of Anatomical Sciences SUNY at Stony Brook, September 1999

Titanosaurus madagascariensis, n. sp. Descriptions. — A form of large size is represented by the following elements:

1st. A portion of the shaft of a humerus, 0.32 m long (fig. 2). The bone is filled, with an elliptical cross-section, and is strongly anteroposteriorly compressed, with a transverse diameter of 0.15 m and an anteroposterior diameter of 0.07 m at the midshaft. The olecranon fossa is fairly deep, and well defined on the external side by a strong projection of the humerus behind. This external projection is very well pronounced in Aepisaurus Gervais from the Cretaceous of Mont Ventoux and in Cetiosaurus from England. If its proportions are compared with the humerus of other sauropod dinosaurs, such as Aepisaurus and Cetiosaurus, the Malagasy humerus should measure about 0.90 to 1.0 m in length.

2nd. A vertebra from the anterior caudal region (pl. VI, fig. 1-1a), only the centrum of which is preserved. This centrum is shortened, only 0.16 m in length for a vertical diameter of 0.14 m and a transverse diameter of 0.133 m. It is strongly procoelous and presents a strongly convex articular head behind, forming a veritable cone 0.07 m long. Below, the centrum is hollowed by a deep median furrow, bordered by two crests brought together near the middle, diverging forwards and behind, where they each end in an articular surface for the chevrons; these surfaces are only demi-facets, which permit inferring a double mode of articulation for these chevrons, that is to say each of them rests on two vertebrae at once. The general form of this centrum is nearly circular, and a little compressed on the sides, which show a fairly notable excavation. Several asymmetrical openings for the vascular canals are also visible.

3rd. Another caudal vertebra (pl. VI, fig. 2-2a), smaller and more elongated, which belongs to a more distant region of the tail of the same animal. The strongly procoelous centrum is elongated, 0.11 m long for a vertical diameter of 0.06 m; behind it forms an 0.045 m articular cone, partly corroded on this element. As in the preceding vertebra, a fairly wide longitudinal canal exists below the centrum, bordered by two thick and blunt crests. The articular surfaces for the chevrons have been destroyed by wear. Above the centrum is observed a rounded medullary canal 0.02 m in diameter, surrounded by a neural arch placed very near the anterior border of the centrum, such that the whole posterior part of the centrum is entirely free. The neural arches undoubtedly met above to form a spinous process, which is broken in the described specimen; they probably bore two prezygapophyses in front, of which only the broken insertion base is seen; further, near the junction of the centrum and the neural arches, the insertion base of a transverse process is visible, whose size is impossible to appreciate.

4th. Finally, I refer to the same animal, but without absolute certainty, a large dermal ossification (pl. VI, fig. 3-3a), partly broken on the side, generally rounded or slightly oval in shape, and very thick (0.70 m in the middle) relative to its diameter, which is 0.25 m. The nearly smooth internal face shows a very particular interlaced fibrous structure, whereas the external face, with slightly raised edges towards the center in the form of a subcircular cone, presently a coarsely radiating ornamentation, formed of furrows and areolar cavities of various sizes. These rugosities evidently constitute an insertion base for a horny covering or a sharp spine. The position of this dermal bone on the body of the animal is difficult to specify for the moment; I suppose that it could be placed, as in some other dinosaurs (stegosaurids, ceratopsids), on the posterior part of the back or above the base of the tail.

Relationships and differences

The attribution of this large dinosaur to the sauropod group is proved by the present of a solid humerus, lacking a medullary cavity, as well as by the great size of this humerus (about 1 m), involving a quadrupedal posture. Solid limb bones clearly exist in certain families of orthopodous dinosaurs, such as stegosaurids and ceratopsids, but in these the forelimb is more reduced and implies a bipedal posture; at the same time their vertebrae are platycoelous or amphicoelous, and not procoelous as in the Malagasy form.

The shape of the caudal vertebrae of this latter form is entirely unique: their deeply procoelous formation, as well as the very advanced position of the neural arch on the centrum is only observed among sauropods in the single genus Titanosaurus, established by Mr. Lydekker (1) first after some caudal vertebrae from the Cretaceous of India (Lameta Group), and noted afterwards by the same paleontologist in the Wealden and Upper Greensand of the Isle of Wight. The attribution of the Malagasy animal to the genus Titanosaurus is confirmed by other details of the structure of these caudal vertebrae, such as the presence of a wide median groove under the centrum, the double articulation of the chevrons, the existence of anterior zygapophyses, etc.

Other genera of sauropods (1) whose caudal vertebrae are known show very different characters from Titanosaurus. Cetiosaurus Owen has amphicoelous caudal vertebrae, a little more hollowed anteriorly than posteriorly. Brontosaurus Marsh likewise has amphicoelous caudal vertebrae, and further has chevrons with a simple articulation. Morosaurus Marsh possesses chevrons with a double articulation like Titanosaurus, but much more weakly procoelous anterior caudal vertebrae. The caudal vertebrae of Atlantosaurus Marsh resemble those of Morosaurus. Pleurocoelus Marsh and Diplodocus Marsh have platycoelous caudals. Finally, Macrurosaurus Seeley possesses slightly procoelous caudals, but different from those of Titanosaurus in their elongation, the median position of the neural arch, and the compressed form of the centrum, provided with a simple inferior crest. The form of the caudals in other genera, such as Pelorosaurus Mantell, Ornithopsis Seeley, Thecospondylus Seeley, Aepisaurus Gervais, are ignored.

In summary, the form of the caudal vertebrae and the double articulation of the chevrons seem to refer Titanosaurus to the family Cetiosauridae Lyd. (= [Morosauridae] Marsh) and more specifically to the American genus Morosaurus, perhaps identical to Ornithopsis of England.

However the existence of bony dermal elements, like that which I have figured (pl. VI, fig. 3) and attributed provisionally to the same animal because they were found at the same place as the vertebrae, would give Titanosaurus a special character unknown in other cetiosaurids. It is true that paired (Brontosaurus) or unpaired (Cetiosaurus) dermal sternal ossifications (sternal shield) exist in several genera of this family; but these elements are much thinner and more finely rugose than the Malagasy element, and can, I think, be compared to it neither in form nor in location. The only dinosaurs possessing a true dermal skeleton composed of thick bony plates are several theropods (ceratosaurids) and above all the orthopods (stegosaurids, ceratopsids).

Ceratosaurus Marsh from the Upper Jurassic of Colorado bears, according to Mr. Marsh, a series of bony dermal elements in the neck region supported on the cervical vertebrae; these elements have not been figured, and I cannot say whether they resemble the dermal plate from Madagascar. Stegosaurus Marsh from the Upper Jurassic of Colorado, identical to Omosaurus Owen. from the Kimmeridgian of England according to Messrs. Marsh and Lydekker, was clad in a cuirass of dermal elements, of variable form according to the species. The Malagasy element cannot, in all cases, be compared to the enormous flattened, uneven plates, triangular in profile, that were arranged vertically along the midline of the trunk and tail, and a comparison cannot be imagined with the paired bony plates of the cervical and dorsal region. In particular, Mr. Marsh figured a dermal plate of Stegosaurus ungulatus under the name \\\"tubercular spine\\\", whose general form, although of half the dimensions, resembles the Malagasy element; like in this latter, the inferior face is nearly smooth, the edge is undulating, and the superior surface rugose; but these rugosities do not have the radiating arrangement of the Malagasy form and the center of the plate is elevated into a much more accentuated conical eminence. According to Hulke, in Omosaurus armatus Owen from England, the dermal cuirass was formed from thin plaques and plates.

The family Ceratopsidae likewise presents a strongly developed dermal skeleton, in particular in Ceratops and Triceratops Marsh from the Upper Cretaceous of the Rocky Mountains (Laramie Stage). Some of the dermal elements of Triceratops figured by Mr. Marsh do not lack a certain similarity with the Malagasy element in the general form, undulating border, and more or less conical elevation of the central part; but I found in none of these figures the rugose radiating ornamentation so particular to this latter element. In Nodosaurus textilis Marsh from the medial Cretaceous of Wyoming, there exists a complete dermal cuirass formed by rows of plates, whose entire surface shows a fibrous structure latticed along two directions at right angles, which does not resemble the Malagasy element at all.

A dinosaur from the Upper Cretaceous beds of Neue Welt (Austria) has been referred to the family Ceratopsidae, whose diverse skeletal elements were recognized under the name Struthiosaurus Bunzel, Danubiosaurus Bunzel, and Crataeomus Seeley. This latter paleontologist figured several elements of the dermal armor of this dinosaur; neither the long spines, ornamented at the base with rows of conical polygonal shields, nor the dorso-caudal paired or unpaired plates, 6 to 7 centimeters long, all provided on their external face by a longitudinal carina, can be closely compared to the enormous plate from Madagascar; there is only a certain resemblance between this latter and the dorso-caudal plates of Crataeomus from the point of view of the undulating aspect of the edges and the disposition of the vascular grooves.

The very developed bony plates of the dermal skeleton in Scelidosaurus Owen from the Liassic of England are characterized, as in Crataeomus, by a longitudinal carina that does not exist on the Malagasy element. It is the same with the bony plates, furthermore of small dimensions, of Acanthopholis Huxley (3) from the marly chalk of Folkstone.

To summarize these comparisons, it can be said that the Malagasy dermal element is characterized by its large dimensions, its great thickness, the deep radiating grooves and cavities of its surface, and a slight elevation of the central part into a relatively low cone. It does not resemble any described element of dinosaurian dermal armor. Moreover, it is still the reason that engages me to attribute it to Titanosaurus, whose vertebrae were found in the same locality. It is true that the existence of a dermal skeleton has not been noted in sauropods until here, and it is not impossible that the dermal element in question belongs to some other orthopodous dinosaur, still unknown in Madagascar; this question merits thus still to be reserved.

Specific determination. — Now it remains for me to compare the bones of Titanosaurus from Madagascar with those of other described species of this genus, still incompletely known. The form of the caudal vertebrae will be of great assistance in this. Titanosaurus indicus Lydekker, from the Lameta beds near Jabalpur and Pisdura (attributed to the middle Cretaceous), differs from the Malagasy type by its caudal vertebrae, whose centrum is very transversely compressed in such a way that the sides of the vertebra are not visible when it is examined from below. The size should be fairly similar in the two species, because the type-vertebra figured by Mr. Lydekker (pl. IV) is intermediate in dimensions between the two Malagasy vertebrae and should, in effect, occupy a slightly more distal position in the caudal series than the larger Malagasy vertebrae, because it is more elongated.

Titanosaurus blanfordi Lydekker, from the Lameta beds of Pisdura, is based on two caudal vertebrae whose centra are cylindrical in cross-section, with the transverse diameter is slightly larger than the vertical diameter. In spite of this resemblance in general form, the Malagasy vertebrae differ from these: 1st, because the sides of the centrum are more depressed and excavated, so that there is a more marked angle between the inferior and lateral faces of the vertebrae; 2nd, because the two inferior crests and the medial longitudinal groove of the centrum are much more marked, nearly as much as in Titanosaurus indicus. It can therefore be said that the Malagasy vertebrae represent a particular form that is intermediate between the two Indian species.

Likewise, Mr. Lydekker has made known European forms of the genus Titanosaurus. From the Wealden Clay of Brook (Isle of Wight) comes a caudal vertebra that possesses the strongly procoelous character and the advanced position of the neural arch characteristic of Titanosaurus. It very much resembles the Malagasy vertebra in the degree of compression of the centrum and the projection of the inferior crests; the articular surfaces for the chevrons cannot be estimated. The species, which has not received a specific name, seems to differ very little from the Malagasy species. Another Titanosaurus vertebra from the Upper Greensand of the Isle of Wight is larger than the preceding one and its centrum is more laterally compressed. In summary, the species of Titanosaurus from Maevarana is not identical to any of the forms described from India or Europe, while appearing very close to the Wealden form from the Isle of Wight, at least in the shape of the caudal vertebrae. I will designate it under the name Titanosaurus madagascariensis n. sp.

Titanosaurus madagascariensis, n. sp. — Characterized as a genus by its strongly procoelous caudal vertebrae, whose neural arch is placed very anteriorly on the centrum. The shape of the caudal centra permits distinguishing the Malagasy species from indicus Lydekker, whose caudal vertebrae are strongly transversely compressed, and from blanfordi Lyd., in which the centrum has a more regularly circular cross-section, without trace of the lateral depression shown in T. madagascariensis. Regarding the and degree of compression of the caudal vertebrae, this latter species approaches more the Wealden form from the Isle of Wight, referred by Mr. Lydekker to the Titanosaurus without specific designation. I provisionally attribute to T. madagascariensis a large, thick dermal ossification an external surface slightly elevated into a central cone, ornamented with deep radiating rugosities, which does not resemble any element described among the diverse dinosaurs furnished with dermal armor. However, the fact that sauropods are generally lacking of a cutaneous skeleton renders this attribution somewhat uncertain. It is not impossible that it announces the presence of a large dinosaur from an entirely separate group.

_{Source: Polyglot Paleontologist}

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