Titanosaurus

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Titanosaurus
Drawings of a distal caudal vertebra of the holotype of T. indicus in different views

Drawings of a distal caudal vertebra of the holotype of T. indicus in different views

Temporal occurrence
Upper Cretaceous ( Maastrichtian )
72 to 66 million years
Locations
Systematics
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Sauropodomorpha
Sauropods (Sauropoda)
Titanosaurs (Titanosauria)
Titanosaurus
Scientific name
Titanosaurus
Lydekker , 1877

Titanosaurus is a dubious genus of sauropod dinosaur from the Titanosauria group . It was described with the species Titanosaurus indicus in 1877 by Richard Lydekker using a few fossil remains from India . In the followingyears, Titanosaurus was assigned a mass of further fossil material - a total of 14 species were described, the fossils of which come from India, Laos , Argentina , Madagascar and Europe andcover60 million years within the Cretaceous period .

The whole group of Titanosauria is still systematically unexplained, and the term Titanosaurus is now considered a dubious genus ( noun dubium ).

About the generic term

The characteristic features of the original material ( holotype material) specified by Lydekker - which only comprises two central caudal vertebrae - have now been proven in many other titanosaurs and in some cases also in other sauropods outside the titanosauria. Since from today's point of view there is no feature that clearly characterizes the species ( autapomorphism ), the type species Titanosaurus indicus is considered invalid.

Of the 14 species, only five were found valid in a study published in 2003. However, these have inevitably lost any connection with the undiagnosed Titanosaurus type material. The genus Titanosaurus is thus a noun dubium, so the individual species names are only provisional.

Titanosaurus is the namesake for several higher-level taxa , such as the Titanosauridae , the Titanosauroidea and the Titanosauria . He has long been considered a central, important representative of these groups in science. This view is no longer shared today - many researchers also question the Titanosauridae family, which no longer appears in many cladistic analyzes. Taxa such as Titanosaurus and Titanosauridae are now often referred to as "trash taxa", to which masses of bones have been assigned that are usually not particularly similar to the original material. The systematics of the Titanosauria is still very controversial and is described by Wilson (2005) as “one of the last fronts in dinosaur phylogenetics ”.

With over 30 known genera, the Titanosauria are geographically the most widespread and diverse group of sauropods. They differ from other sauropods e.g. B. through their "broad corridor", which is also evident in their fossil footprints. They had their heyday in the Cretaceous and were, together with the Rebbachisaurids , the last surviving sauropods.

History of the Discovery - Titanosaurus indicus

William Henry Sleeman found two vertebrae in 1828 that were later described as Titanosaurus indicus.
The Scottish paleontologist Hugh Falconer made the first scientific description of the vertebrae in 1862, but without naming them.

Although the genus was described in 1877, the first two bones were discovered as early as 1828 by British officer William Henry Sleeman in a small hill called Bara Simla, near Jabalpur in central India. After the bones had changed hands, they came to the Indian Museum in Calcutta in 1832 .

In 1862 they were first described scientifically by the Scottish paleontologist Hugh Falconer , who recognized them as the vertebrae of a reptile. He recognized three diagnostic features and described the vertebrae as caudal vertebrae, which were once located in the middle third of the tail. However, even Falconer could no longer determine the exact location - only one origin from the Lameta formation is certain . Sleeman wrote that the site is located directly under the basalts of the Dekkan-Trapp volcanism , which cover the hill, which speaks for a layer within the Lameta formation called "Upper Sands"; in any case, later authors disagreed, and today a layer called the “sauropod bed”, from which many other sauropod bones would later emerge from Bara Simla, is considered to be the most likely source of the bones.

However, the new species was not named until Richard Lydekker's description in 1877. Lydekker assigned a fragmentary femur bone (thigh bone) from the same site as well as a femur and several vertebrae from Pisdura 300 kilometers to the south to the two vertebrae and named the bones Titanosaurus indicus . He found further characteristic features on the vertebrae and pointed out that they belong to the sauropods. Later (1879) he found some differences between the finds from Pisdura and Bara Simla and ascribed the Pisdura finds to a species of their own: Titanosaurus blanfordi . He only assigned the femur bone from Bara-Simla to the genus because of the same location. In any case, studies by Matley (1921) showed that the femur comes from a completely different stratigraphic layer (the "green sand"), which is why it was excluded from the genus Titanosaurus by Huene and Matley in 1933 and assigned to the South American Antarctosaurus . Titanosaurus indicus is based only on the two caudal vertebrae already described by Falconer and now considered non-diagnosable.

In the following years, Matley collected a mass of further sauropod material in Bara Simla (1917-1919), Pisdura (1920), and Chota Simla (1932-1933), a small hill that is half a kilometer from Bara Simla. These bones came from at least four different titanosaur species. However, to this day no bones are known from the region that overlap the type material of Titanosaurus indicus , which makes the assignment of further material to this species impossible. The only overlapping finds come from Chota Simla (Swinton, 1947) but have never been described. The majority of the bones found in this location went to the sponsor of the excavations - the Natural History Museum in London - but the overlapping finds could not be found later in the collections.

"Titanosaurus" species

Titanosaurus egg

Since the description of Titanosaurus indicus , 13 more species have been described, but they are now classified outside of Titanosaurus .

Titanosaurus blanfordi

Titanosaurus blanfordi (1879), another Indian Titanosaurus species, was described on the basis of two caudal vertebrae discovered by WT Blanford near Pisdura . Although Lydekker ascribed them to Titanosaurus indicus in 1877, the latter described them as a new species three years later due to some different surface structures. However, Lydekker did not specify which of the two vertebrae was the holotype material (the material which refers to the taxon) should apply, which is why both vertebrae were initially considered together as a holotype. However, in 1929 von Huene noticed significant differences in size and proportions between the vertebrae, which is why he assigned the smaller, poorly preserved vertebra to the Laplatasaurus madagascariensis . Thus, only the larger, better preserved vertebra (to which a large part of Lydekker's investigations referred) remained as Titanosaurus blanfordi .

Huene and Matley (1933) ascribed other bones to the species - a tail vertebra fragment, a hand bone fragment (metacarpal), a partial tibia and possibly a shoulder blade . Today the assignment of these bones to Titanosaurus blanfordi is considered invalid. The vertebral fragment differs from the holotype material, and the remaining material does not overlap with the vertebrae; only the tibia can be assigned to the Titanosauria group.

The holotype material was believed to be a mid-tail vertebra that was twice as long as it was high. It has clear similarities to other titanosaurs such as Pellegrinisaurus or Gondwanatitan ; however, since no autapomorphy (unique characteristic) is known, Titanosaurus blanfordi is also considered invalid.

Titanosaurus rahioliensis

Titanosaurus rahioliensis (Mathur and Srivastava, 1987) has been described on the basis of some unusually shaped teeth that were discovered near the village of Rahioli in the Gujarat province of the West Indies, a locality particularly known for finds of dinosaur eggs. The teeth were thin and slightly arched and have some similarities with the Diplodociden Nigersaurus ; the assignment to Titanosaurus is, however, invalid from today's point of view, since there is no connection to the other material. Today it is classified as an indeterminate neosauropod . Although postcranial (non-skull) bones were found in the same site in addition to the eggs, which presumably came from titanosaurs, these have not yet been described. The original teeth have been lost today, but photographs still exist.

Titanosaurus colberti ( Isisaurus colberti )

This species is known for a partial skeleton that was discovered near Dongargaon (south of Jabalpur , near Pisdura) in central India. The description was made in 1997 by Jain and Bandyopadhyay, who consider four Indian Titanosauria to be valid in the description: Titanosaurus indicus , Titanosaurus blanfordi , Titanosaurus madagascariensis and Titanosaurus colberti . The species "Antarctosaurus" septentrionalis , to which a large part of the sauropod material from Bara Simla was ascribed (Huene & Matley, 1933), described it as a juvenile representative of Titanosaurus indicus . However, this view was rejected by later authors.

The partial skeleton, which is one of the few connected dinosaur skeletons from India, is characterized by various autapomorphies. It overlaps the caudal vertebrae of Titanosaurus indicus , but the two vertebrae differ in essential points, which is why Titanosaurus colberti is considered a valid species, but must be classified outside of Titanosaurus .

In 2003 the species was rewritten as a separate genus by Wilson and Upchurch under the name Isisaurus .

Titanosaurus australis and Titanosaurus robustus ( Neuquensaurus )

Between 1893 and 1894, Lydekker carried out studies on the fossils of the State Museum in La Plata , Argentina - a museum that in previous years housed a handsome number of fossils collected by the director himself. In addition to two new sauropod genera ( Argyrosaurus and Microcoelus ), Lydekker described the two new Titanosaurus species Titanosaurus australis and Titanosaurus nanus .

Titanosaurus australis (Lydekker, 1893) was described on the basis of leg and arm bones, interconnected vertebrae and a few other bones. A caudal vertebra, which overlapped with the Titanosaurus indicus vertebrae from India, was taken as an occasion for an assignment to Titanosaurus due to similarities . Slight differences in the vertebrae, along with the geographical distance, should justify the distinction between the two species. In any case, Lydekker noted in his description his uncertainty about the assignment to Titanosaurus :

"Accordingly, the reference of the latter [ Titanosaurus australis ] to Titanosaurus must be regarded as a more or less provisional measure, rendered necessary by our very incomplete knowledge of the type species [...]"

In German, for example: "Accordingly, the assignment to Titanosaurus must be viewed as a more or less provisional measure, due to our very incomplete knowledge of the type species".

Von Huene (1929), who visited La Plata between 1923 and 1926, attributed various vortex sequences and numerous limb remains to the species, and published the first attempt at reconstruction of a Titanosauria based on Titanosaurus australis . Some arm and leg bones, which Lydekker had assigned to Titanosaurus australis but not described, he took as the basis for the new species Titanosaurus robustus due to differences in the limbs .

However, later authors recognized clear differences between the Indian Titanosaurus and the South American species Titanosaurus australis and Titanosaurus robustus . Powell (1986) proposed the new genus Neuquensaurus on the basis of these findings , while McIntosh (1990) subordinated the two species to the already existing genus Saltasaurus . Newer authors agree with Powell, which is why Neuquensaurus as a genus - with Neuquensaurus australis as the type and Neuquensaurus robustus as the noun Dubium - is generally recognized.

Titanosaurus nanus

In 1893 Lydekker described two interconnected sacral vertebrae , which he tentatively described as the new South American Titanosaurus species, Titanosaurus nanus . In any case, Powell (1986) classified this species as the noun dubium because the vertebrae are poorly preserved and, apart from their smaller size, do not reveal any special features that could justify a species of their own.

Titanosaurus araukanicus ( Laplatasaurus )

In 1929 von Huene described the new genus of titanosaurs Laplatasaurus on the basis of new material from Cinco Saltos and Rancho de Avila as well as bones which Lydekker had previously assigned to the species Titanosaurus australis . Laplatasaurus differed from Titanosaurus (according to Huene) in its larger size and slimmer proportions. However, some of the Laplatasaurus bones were attributed by Powell (1986) to the Titanosaurus , as a new species Titanosaurus araukanicus - due to similarities to Indian bone material from Chota Simla, which was ascribed to Titanosaurus indicus . However, this material was not clearly compared with the type material of Titanosaurus indicus , and the corresponding bones can no longer be found today - which is why they cannot be reliably attributed to Titanosaurus indicus . This also makes Titanosaurus araukanicus appear questionable.

Titanosaurus sp.

Titanosaurus sp. was described by Powell (1987) on the basis of 18 well-preserved, connected caudal vertebrae and the last sacral vertebra, which, together with two other finds of connected vertebrae, were discovered in the Baurú Group in Brazil . The caudal vertebrae overlap with the type material of Titanosaurus indicus ; however, later authors consider the assignment to Titanosaurus questionable. Apparently Powell didn't compare the bones to Laplatasaurus , Neuquensaurus, or Titanosaurus robustus . In addition, the common characteristics of Titanosaurus indicus and Titanosaurus sp. Described by Powell apply. also to other titanosaurs, including Andesaurus and Aeolosaurus . However, the vertebrae are diagnosable and are currently waiting for a new description.

Titanosaurus madagascariensis

Titanosaurus madagascariensis is based on bones discovered in the Maevarano formation in Madagascar. The animal was described by Depéret in 1896 using two tail vertebrae, an incomplete humerus (upper arm bone) and dermal bone plates - this is the first armored sauropod described. Other material - well-preserved caudal vertebrae and fragmentary limb bones - were ascribed to this species by Thevenin in 1907. Von Huene (1929) considered the differences between the Malagasy form and Titanosaurus indicus to be too great and ascribed the species to the South American Laplatasaurus - as Laplatasaurus madagascariensis .

Better preserved sauropod finds from Madagascar appeared only a few years ago; Mention should be made of Rapetosaurus krausei (Rogers and Forster, 1999/2002), which is known among other things for its connected skull material. The descriptors of Rapetosaurus consider ( Titanosaurus ) Laplatasaurus madagascariensis as a noun dubium, this view was shared by later authors.

Titanosaurus falloti

In 1942 Hoffet described the new Titanosaurus species Titanosaurus falloti from Muong Phalane, Laos. The species is based on a complete femur and three femoral fragments; However, since there is no overlap with the Titanosaurus type material, the species must be classified outside of Titanosaurus from today's perspective . Allain et al. (1999) described a new titanosaur from Tang Vay (a little south of Muong Phalane) as Tangvayosaurus hoffeti . They examined Titanosaurus falloti again, but found no autapomorphies (unique selling points) and assigned it to Tangvayosaurus hoffeti . Later authors see this assignment as too premature, since the material from Titanosaurus falloti is considered undiagnosed.

Titanosaurus valdensis and Titanosaurus lydekkeri ( Iucitosaurus )

Two tail vertebrae (BMNH R146a, R151) from the middle section of the tail, which were described by Lydekker in 1887, come from the early Cretaceous ( Barremium ) layers of the Wessex Formation (a formation of the English Wealden ) of the Isle of Wight , England. Lydekker noted that the vortices were similar to those of Titanosaurus indicus and Titanosaurus blanfordi ; nevertheless he described the new genus Ornithopsis on the basis of these vertebrae . Both Ornithopsis and Titanosaurus formed the new family Ornithopsidae (Lydekker, 1887).

Lydekker's assignments, however, met with criticism, for example Hulke said that the English and Indian finds belong to the same species. In 1888 Lydekker attributed the two vertebrae to the Titanosaurus and introduced the new species Titanosaurus' sp. a on. Another, geologically younger ( Cenomanium ), eddy from the upper Greensand Formation of the Isle of Wight he described as Titanosaurus' sp. b .

In 1929 von Huene established species names for the two as yet unnamed species. Titanosaurus' sp. a he described as Titanosaurus valdensis and remarked that this was the oldest known Titanosaurus species. Titanosaurus' sp. b got the name Titanosaurus lydekkeri, however von Huene expressed doubts about the correctness of the assignment to Titanosaurus and noted that only additional, better bone material could bring clarity.

Later authors saw Titanosaurus valdensis as its own genus of titanosaurs. This view was taken by McIntosh (1990) and later implemented by Le Loeuff (1993) who found the two Titanosaurus valdensis vertebrae together with a third find (BMNH R1886), which also comes from the Wealden of the Isle of Wight, as Iuticosaurus valdensis rewrite. Le Loeuff described two autapomorphies; later authors, however, considered this to be inadequate; so both features were later found in other titanosaurs. Naish & Martill (2001) therefore consider Iuticosaurus valdensis as a noun dubium - this view is shared by later authors.

Titanosaurus lydekkeri was ascribed to Macrurosaurus semnus by McIntosh (1990) , but Le Loeuff (1993) ascribed the species to Iuticosaurus (as Iuticosaurus lydekkeri ) and regarded it as the noun dubium. Later authors (Naish and Martill, 2001) confirmed the dubious character of Iuticosaurus ( Titanosaurus ) lydekkeri .

Titanosaurus dacus ( Magyarosaurus )

Titanosaurus dacus is based on two eddies that were found in layers of the Late Cretaceous ( Maastrichtian ) near Hațeg , Romania and described by Nopcsa in 1915. Later, however, the species - along with a large number of other bones - was described as the new genus Magyarosaurus (von Huene, 1932), since the vertebrae had little resemblance to the Indian pieces. Von Huene described a total of four species - Magyarosaurus dacus , Magyarosaurus hungaricus , Magyarosaurus trannsylvanicus and Magyarosaurus sp. ; however, later authors (McIntosh, 1990, and Le Loeuff, 1993) only considered Magyarosaurus dacus to be valid.

cf. Titanosaurus sp.

This species is based on the caudal vertebrae and leg bones (femur and humerus), which come from late Cretaceous deposits (Maastrichtian) from Saint Chinian ( southern France ) and are now stored in the University of Lyon . However, the bones were only mentioned briefly by Depéret (1899) and assigned to the genus Titanosaurus , and later - without any further description - named by Huene (1929). A scientific description is still pending , and there have not yet been any comparisons with the Titanosaurus indicus vertebrae.

cf. Titanosaurus indicus

Lapparent (1947) described another French Titanosaurus species from Fox-Amphoux using vertebrae and leg bones. Later authors noted, however, that there was no evidence that the bones actually belonged to the same individual, nor clear references to Titanosaurus indicus , since the common characteristics mentioned by Lapparent are not genus-specific, but are widespread among sauropods.

supporting documents

Main source

Much of the information comes from the following treatise:

Individual evidence

  1. ↑ a b Jeffrey A. Wilson: An Overview of Titanosaur Evolution and Phylogeny. In: Fidel Torcida Fernández-Baldor, Pedro Huerta Hurtado (eds.): Actas de las III Jornadas Internacionales sobre Paleontología de Dinosaurios y Su Entorno. = Proceedings of the 3rd International Symposium about Paleontology of Dinosaurs and their Environment Paleontología de dinosaurios y su entorno. Salas de los Infantes (Burgos, España), 16 al 18 de septiembre de 2004. Colectivo arqueológico-paleontológico de Salas, Salas de los Infantes (Burgos, España) 2006, ISBN 84-8181-227-7 , pp. 169-190 .