Titanosaurs

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Titanosaurs
Hypothetical reconstruction of the skeleton of Argentinosaurus in a special exhibition at the Senckenberg Natural History Museum

Hypothetical reconstruction of the skeleton of Argentinosaurus in a special exhibition at the Senckenberg Natural History Museum

Temporal occurrence
Upper Jurassic to Upper Cretaceous ( Tithonian to Maastrichtian )
152.1 to 66 million years
Locations
  • worldwide
Systematics
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Sauropodomorpha
Sauropods (Sauropoda)
Titanosaurs
Scientific name
Titanosauria
Bonaparte & Coria , 1993
Live reconstruction of Diamantinasaurus . From Hocknull and colleagues, 2009.
Tapuiasaurus skull . Photographs and drawings from Zaher and colleagues, 2011.

The titanosaurs ( Titanosauria ) were a species and shape-rich group of sauropod dinosaurs . They lived mainly during the Cretaceous Period , when they were the dominant group of sauropods, and became the last group of sauropods to become extinct only about 66 million years ago on the Cretaceous-Tertiary boundary , along with all other non-avian dinosaurs. Fossils have been discovered on every continent.

So far, almost 70 genera have been recognized, which make up more than a third of the known species of sauropods. The blueprint of these herbivores as indicated in all sauropods by a barrel-shaped body, a long neck and a very small relative head. Various genera of the Titanosauria had skin bone plates (osteoderms), but they were probably not used for defense. Finds of eggs and nests provide clues about developmental and reproductive biology . These dinosaurs are named after the titans found in Greek mythology . In fact, they included some of the largest and heaviest land animals of all time, such as the Patagotitan , Dreadnoughtus , Argentinosaurus or Paralititan , but dwarf forms such as Magyarosaurus are also known.

Most genera are poorly documented due to the very patchy fossil record . Skull bones and parts of the skeleton that were still anatomically connected when they were discovered are very rare. The family relationships within the group have only been seriously discussed since 2001 and remain highly controversial to this day. Together with the Brachiosaurids and related genera, the Titanosauria form the group Titanosauriformes , which belongs to the Macronaria .

features

skull

Almost complete skulls are known only from Rapetosaurus , Nemegtosaurus , Quaesitosaurus and Tapuiasaurus . These skulls were similar in shape to those of the Diplodocidae : the snout was elongated, while the nostrils were high up on the skull at the level of the eye sockets. Nevertheless, these skulls showed common features that were lacking in Diplodocidae and other groups of sauropods. For example, the squamous bone (squamosum) does not adjoin the supratemporal window , a skull window on the rear upper side of the skull. Furthermore, the snout, i.e. the intermaxillary bone (premaxillary) as well as the front parts of the upper and lower jaw, has numerous openings ( foramina ). To date, however, too little skull material is known to be able to use features of the skull to define groups within the Titanosauria.

Nemegtosaurus probably had 13 teeth on each side of the upper and lower jaws, making a total of 52 teeth. The crowns were long and thin and resembled the even thinner, pin-like crowns of the Diplodocidae; in both groups, however, this morphology developed independently of one another ( convergent ). More original sauropods such as Camarasaurus or Omeisaurus have spatula-shaped tooth crowns, while more original titanosauriformes such as Brachiosaurus show an intermediate shape between the more original, spatula-shaped tooth crowns and the thinner tooth crowns of the Titanosauria.

whirl

The vertebrae of the Titanosauria were generally wider and lower than those of other sauropod groups. The front caudal vertebrae of all Titanosauria except Opisthocoelicaudia were procoel, that is, concave on the front . The lateral cavities (pleurocoele) of the vertebrae were eye-shaped in contrast to those of other sauropods. So far, there is no evidence of connected spinal columns, which is why the general number of cervical, back and tail vertebrae is unknown. However, many more strongly derived titanosaurs showed an additional, sixth sacral vertebra. Other neosauropods typically had five sacral vertebrae; in very primitive sauropods like Barapasaurus there were only four. Furthermore, some more derived (more modern) titanosaurs such as Opisthocoelicaudia had a significantly shorter tail. If the tail of more primitive sauropods consisted of about 50 and of diplodocids about 80 caudal vertebrae, these derived titanosauria only had 35.

The vertebrae were characterized by a reduction in the mechanical connecting elements , especially in the more derived Titanosauria such as the Saltasaurids , which led to greater flexibility of the spine. This trend was even evident in the caudal vertebrae. The absence of the hyposphene-hypantrum connections of the dorsal vertebrae is particularly significant in all Titanosauria except for some original forms such as Andesaurus and Phuwiangosaurus . In other sauropods, these connecting elements led to additional stabilization of the spine and probably supported increasing body size.

The vertebrae in front of the sacrum (presacral vertebrae) and occasionally the sacral vertebrae are criss-crossed with a complex, honeycomb-like structure made up of numerous chambers, some of which were filled by the animal's air sac system and which reduced the weight of the spine. Such a complex internal structure of the vertebrae is also found in the Diplodociden and Mamenchisaurus , while less derived sauropods showed a simpler chamber system. The evolution of this complex chamber system into different groups of sauropods is probably related to increasing body size and neck length.

Shoulder girdle, pelvis and limbs

Hand skeleton of Diamantinasaurus . This find is the only evidence so far of a hand claw in titanosaurs (right in the picture). From Hocknull and colleagues, 2009.
Femur bone of a non-titanosaur (left, Diplodocus ) and a titanosaur (right, Diamantinasaurus ) in comparison. The blue lines mark the horizontal and vertical, the red line marks the shaft axis. While with other sauropods like Diplodocus the shaft axis corresponds to the vertical orientation, the thighbone of the titanosaur was slightly splayed to the side and is thus at an angle of about 10 ° to the vertical orientation.

In the appendicular skeleton - the shoulder girdle, the pelvis and the limbs - a significant part of the characteristics important for the classification of the Macronaria and especially the Titanosauria can be found. Many of these features are probably related to the evolution of a further leg position within the Titanosauria: The legs were not column-like straight under the body, as in more primitive groups of sauropods, but were slightly curved outwards when viewed from the front. Thus, the feet touched the ground at some distance from the center line of the body and were not close to or on the center line, as in more primitive groups of sauropods. Analogously, fossil tracks of sauropods can be classified into two groups, the "narrow-track" type, Parabrontopodus , which probably shows the original constellation of more primitive sauropod groups, and the "broad-track" type, brontopodus , which reflects the constellation of titanosaurs and possibly other macronarians.

The shoulder girdle was characterized by a long compared with other sauropods coracoid (coracoid) and a larger, crescent-shaped breastbone (sternum) made, resulting in a total of broader chest led. The limbs were generally robust and relatively shorter than other sauropods. Various features of the front legs of the Titanosauria were found in other groups of Saurischia , but are absent in the other sauropod groups. These are regressions of features that emerged early in the evolution of the sauropods and were related to the evolution of columnar legs. The upper arm bone (humerus) showed a pronounced deltopectoral ridge as well as divided and anterior (forward) enlarged distal (lower) articular knots . Furthermore, a bone spur at the upper end of the ulna ( olecranon ) extended over the articular surface of the ulna. These features suggest that the front legs are bent outward. The forearm, consisting of ulna and radius (radius), was also extremely robust - for example, the thickness of the spoke at its upper (proximal) end was at least a third of its entire length, a jointly derived feature (synapomorphism) of the Titanosauria. The metacarpal bones were shorter and more robust than the greatly elongated metacarpal bones of more native Macronaria such as Brachiosaurus . The carpal bones (carpalia) seem to have been completely absent, while only extremely reduced remnants of some phalanxes (phalanges) remained of the fingers. Claws (unguals) on the forefoot have not been found in any Titanosauria except Diamantinasaurus .

The ilium of most sauropods showed a distinctive, rounded crest on the upper side of the anterior (pre-acetabular) half. The titanosauriformes this comb was higher and club-like, so that the iliac its highest point far ahead of the acetabulum showed (acetabulum). In some Titanosauria, for example Neuquensaurus or Alamosaurus , this club was turned outwards and formed an almost horizontal platform. The pubic bone (pubis) was in many ways much longer than the ischial (ischium), unlike other sauropods experiencing this size ratio was mostly reversed. The shorter ischial bone of the Titanosauria was usually wider than that of other sauropods.

The thigh bone (femur) was not oriented vertically as in other sauropods, but slightly splayed outwards, which led to the typical further leg position. This can be seen on the one hand in the inwardly curved proximal (upper) third of this bone. On the other hand, the distal (lower) articular knots were not perpendicular to the shaft axis, as in other sauropods, but were inclined laterally by 10 ° relative to the perpendicular orientation. In cross-section, the shaft of the femur of most sauropods was wider mediolaterally than anteroposterior ; When viewed from the front, the bone was wider than when viewed from the side, and the cross-section appears as an ellipse. In the Titanosauria, this ellipse was significantly more eccentric than in the other sauropod groups. This adaptation probably counteracted the greater flexion moment caused by the further leg position.

In contrast to the hands, the feet had curved claws. So far, only three complete and articulated foot skeletons have been found, which vary greatly in their structure. The number of phalanges (phalanges) of each of the five toes can be described by so-called phalangeal formulas : Epachthosaurus shows a phalangeal formula of 2-2-3-2-0, while in Opisthocoelicaudia it is 2-2-2-1-0 and in one skeleton recently discovered in Patagonia is 2-2-2-2-0.

Paleobiology

Giant growth and dwarfing islands

This fragment of the thigh bone of the gigantic titanosaur Argentinosaurus in the Museo de La Plata (Argentina) measures 1.18 meters in length. A full femur would have been eight feet long.

Sauropods, the largest land animals of all time, were estimated to average between 15 and 60 tons, while very few species are estimated to weigh less than 5 tons. Particularly huge forms developed several times independently of one another within different lines of development, both in basal forms such as Turiasaurus , in Diplodocidae such as Supersaurus , in Brachiosauridae such as Sauroposeidon and - probably also independently of one another - in different forms within the Titanosauria. The largest known titanosaurs include Argentinosaurus , estimated to be 30 meters long and weighing 60 to 88 tons. The Egyptian Paralititan is estimated to be 26 meters or longer and about 50+ tons in weight, while the equally gigantic forms Antarctosaurus giganteus with an estimated 60 tons and Puertasaurus are little known. However, there are indications that the formulas used may significantly overestimate the body mass; other allometric formulas result in body masses in the range of 30 to 40 tons for the same skeletons. While most of the largest sauropods are only known from very fragmentary remains, almost 27% of the body structure of the approximately 30 meter long Futalognkosaurus was predictable. Dreadnoughtus , whose skeleton is known to over 70%, was about 26 m long and 30 tons in weight, which makes it the most fully recorded gigantic sauropod. The specimen that has survived in fossil form is likely not yet fully grown, as the scapula had not yet fused with the coracoid .

In contrast to these giant forms, the titanosaurs also include some of the smallest known sauropods. The Romanian Magyarosaurus only reached a length of about five meters. This comparatively small size is attributed to island dwelling - for example, Europe was an island archipelago in the Cretaceous period . In rapetosaurus from Madagascar and for Ampelosaurus from Western Europe it could have also acted to island shapes.

nutrition

The thin tooth crowns of the more derived Titanosauria as well as the Diplodocida suggest that these sauropods could not chop their food in the mouth, unlike early Macronaria and more primitive sauropods, which probably with their spatula-shaped tooth crowns could process food to some extent. Dinosaur faunas, each with several titanosaurs living at the same time, are known from South America, India, Madagascar and Europe. This suggests that different titanosauria occupied different ecological niches for foraging in order to avoid competition .

Prasad and colleagues (2005) report on coprolites (petrified dung) from the Upper Cretaceous India, which was discovered together with the remains of titanosaurs. These coprolites contain the remains of conifers , dicotyledonous plants , palm trees and various groups of grasses , so the diet of the titanosaurs consisted of a wide range of different plants. The assignment of these coproliths to the Titanosauria remains uncertain.

Function of the tail

The tails of sauropods belonging to the group of Diplodocidae ended in a characteristic whip tail , which was possibly used for defense or to generate noise. Some authors see the increased flexibility of the tail as well as the biconvex rear caudal vertebrae of the titanosaurs, as is the case with diplodocids, as an indication that titanosaurs could also have had such a whip-like tail end. Other authors contradict this hypothesis and state that the series of these biconvex vertebrae was significantly shorter than that of the Diplodocidae, which is why one cannot speak of a whip tail. The hypothesis of a whip-like tail appeared as early as the 1980s, but was due to the incorrect classification of the titanosaurs as close relatives of the Diplodocids.

In the Saltasauriden, the tail was significantly shortened with only 35 vertebrae. According to some researchers, this shortened tail could have served as a kind of third hind leg while the animals stood up to eat or mate.

Eggs and nests

Titanosaurs dug nest pits with their flexible hind feet. The clutch typically consisted of 20 to 40 eggs. Figure from Vila et al. , 2010
Titanosaurus egg
Megaloolithus -Nestgrube ( clutch ) from Pinyes (Spain). Illustration from Vila et al., 2010
A suspected nest predator, the snake Sanajeh indicus . On the right an associated sauropod egg, including a newly hatched or still embryonic titanosaur. From Wilson et al., 2010
The diagram shows the position of the serpent in the fossil shown above. Egg 2 is missing in the above illustration of the original fossil. From Wilson et al., 2010

To date, numerous sites with fossil eggs of the type ( Oogenus ) Megaloolithus , which are traditionally attributed to sauropod dinosaurs, have been discovered. These eggs are characterized by a rounded shape, a relatively thick egg shell consisting of a single layer of calcite, and a tubercle-like surface of this egg shell. Well-researched sites are mainly found in Upper Cretaceous rocks in southern France, northern Spain, India and South America. With the discovery of reference Auca Mahuevo 1997 in northern Patagonia , a vast nest colony with thousands Megaloolithus -Eiern, the assignment could at least this nest colony to be confirmed to the titanosaur. In some eggs, for example, well-preserved skeletons of embryos were found that show some synapomorphies of the Titanosauria. Many authors write other Megaloolithus -Nestkolonien due to the similarity with the finds from Auca Mahuevo also titanosaurs to. However, other authors emphasize that the evidence is insufficient to assign all Megaloolithus finds to the Titanosauria. So were found in Romania Megaloolithus newborn grade eggs near the remains hadrosaur the type telmatosaurus transylvanicus . It is therefore possible that some Megaloolithus finds actually belonged to other groups.

The locations of the eggs in Auca Mahuevo extend over six different stratigraphic layers, which suggests that Titanosauria nested at this location for at least six different periods of time. The large number of clutches suggests that these sauropods live in the herd, at least during the breeding season. Although brood care has been demonstrated in other dinosaur groups such as the ornithopods and theropods and the closest relatives of the sauropods living today, the birds and crocodiles, also do brood care, many researchers suspect that the sauropod nests were no longer cared for after the eggs were laid. This is indicated by the huge size of the adult animals and the high concentration of nests in a relatively small area in Auca Mahuevo. In addition, there is no evidence in Auca Mahuevo of surfaces trampled by the sauropods ( dinoturbation ).

The eggs are typically 13 to 15 centimeters in diameter, while the eggshell is approximately 1.3 mm thick. They are found in clusters of mostly 20 to 40 eggs that are stacked in up to three layers. However, the actual nest is rarely preserved, which is why we only speak of clutches and not nests. However, some clutches show indications of the architecture of the nest: They are located within elongated, elliptical to kidney-shaped impressions in a base layer of sandstone that are around 100 to 140 centimeters long and 10 to 18 centimeters deep. A wall of structureless sandstone around the impressions was probably created when these nests were excavated by the titanosaurs. Similar elongated impressions found in some other Megaloolithus -Nestkolonien in South America, Europe and India. A recent study suggests that titanosaurs dug these pits with their flexible hind feet by digging.

Most studies on Megaloolithus suggest grade eggs, the eggs were buried. This interpretation is supported by the number of pores in the egg shell and the resulting permeability for water vapor (G H 2 O ). The eggs of today's birds are mostly exposed to the atmosphere, which is why their eggs have relatively few pores in order to avoid possible water loss. The eggs of today's reptiles, on the other hand, are often buried in the ground or in vegetation and are characterized by numerous pores. Many Megaloolithus -Eierschalen show a water vapor permeability, but something is significantly higher than with modern birds, smaller than with today's reptiles. Eggs found near Pinyes in northern Spain, for example, show ten times more water vapor permeability than today's bird eggs. The eggs from Auca Mahuevo seem to be an exception, for which only twice as much water vapor permeability was calculated as compared to bird eggs. The Auca Mahuevo eggs, unlike other Megaoolithus eggs, could therefore have been incubated in open nests. This is supported by the fact that the nest pits at this site are not filled with the sandstone in which the nests would have been dug, but with the clay siltstone that was only subsequently entered by a flood . Grellet-Tinner and colleagues (2004) suspect that the titanosaurs from Auca Mahuevo covered their nests with plant material. This is suggested by the tubercle-like surface of the eggshell, which probably had the function of preventing particles from blocking the pores of the eggshell. Since the bumps are between 0.6 and 1.6 millimeters apart, they could only keep away particles that were larger than 0.6 millimeters, which is why only plant material is considered as a cover. This interpretation is supported by the discovery of carbon residues in the nest pits, which presumably originate from plant material.

In the Upper Cretaceous India there were indications of a nest predator: The skeleton of the 3.5 meter long snake Sanajeh was found in association with three eggs and the front part of the trunk of a either newly hatched or embryonic titanosaur. One of the eggs is wound around and crushed by the snake's body, while the other two eggs are intact. From this, researchers conclude that the titanosaur skeleton could belong to the same animal that hatched from the now crushed egg. The remains of the sauropod belonged to an animal about 0.5 meters long.

Individual development

In some eggs of Auca Mahuevo, almost complete and anatomically connected embryo skulls were discovered. These skulls represent the currently most complete known Titanosauria skulls and give insights into the individual development of these sauropods. The embryo skulls were broad and roughly triangular when viewed from the side. They showed large, round eye sockets and a short snout with a large, triangular antorbital window. On the snout there was an egg-tooth- like tip, which was formed by the intermaxillary bone (premaxillary) and probably served to break open the eggshell. As comparisons with the best-preserved skulls of adult titanosaurs show, the skull bones changed drastically during growth: the snout was significantly elongated, while the upper jawbone (maxillary) developed a connection with the square jugal , which the cheekbone (jugal) from the underside developed the skull parted. The nostrils became larger and wandered over the eye sockets. The eye sockets took on an inverted teardrop shape. The frontal bone and parietal bone were greatly reduced in size, resulting in a narrower skull.

Osteoderms and skin prints

Ampelosaurus atacis cutaneous bone plate .

In 1896 Charles Depéret attributed a large, cylindrical plate to the titanosaur "Titanosaurus" madagascariensis and was the first to suspect armor in a sauropod. Long disregarded, Depéret's hypothesis was only confirmed in 1980 with the discovery of armor near Saltasaurus . A skeleton of this genus shows small, rounded bones that are in contact with one another and form a mosaic-like surface. In addition, there were larger, oval plates with a conical outer surface. Since this discovery, further skeletons with associated osteoderms as well as isolated, individual osteoderms have been discovered, mainly in South America, but also in Africa, Madagascar and Europe. Osteoderms have been identified for 10 of the 40 currently recognized titanosaur genera. As connected (articulated) skeletons of different genera without associated osteoderms show, the armor was missing in at least some genera. The previously known osteoderms vary in size from a few millimeters to a few decimeters; the largest find shows a diameter of 59 centimeters. The Titanosauria are the only sauropods of which there are reliable finds of osteoderms, although there are indications of possible osteoderms in some genera from other groups, such as "Pelorosaurus" becklesii .

Finds of titanosaur osteoderms are very sparse compared to bone finds: Currently, only almost 90 titanosaur osteoderms are known, in connection with skeletal finds there are at most a few, regardless of the degree of articulation of the skeletons. In contrast, osteoderm finds from other groups, such as the crocodiles or the thyrophore dinosaurs, are very common. This suggests that the osteoderm-bearing titanosaurs were only weakly armored. Leonardo Salgado (2003) notes that the osteoderms he examined are either asymmetrical or bilateral symmetrical, with the bilateral symmetrical clearly predominating. In contrast, the osteoderms of today's alligators , which run across the back in horizontal stripes, are not bilaterally symmetrical. From this he concludes that the symmetrical osteoderms ran in a row on the midline of the body over the vertebral spines, while the asymmetrical osteoderms were distributed on the flanks of the animals. Michael D'emic and colleagues (2009) found that armored titanosaurs were generally smaller than unarmored ones - armored species showed an average femur length of 87 centimeters, while the femoral length of unarmored species averaged 149 centimeters. The evolutionary history of the osteoderms within the Titanosauria is not known.

Various authors have tried to divide the known osteoderms into groups (morphotypes) based on their shape. The most recent approach comes from Michael D'emic and colleagues (2009) and provides for four morphotypes: The ellipsoidal type (Morphotype 1), the most commonly found morph, which is found among others in Saltasaurus , is often made up of large, oval plates convex surface and occasionally shows a thorn-like elevation. The keeled type (morphotype 2) shows an elongated crest on the surface. The cylindrical type (Morphotype 3) is characterized by round to oval, flat plates, but is only known from four specimens. The mosaic type (Morphotype 4) is assigned to the small, mosaic-like arranged platelets that occurred, for example, in Saltasaurus , as well as irregularly shaped osteoderms that cannot be assigned to any other type.

Skin imprints were found inside some of Auca Mahuevo's eggs, showing that, like other dinosaurs, the surface of the skin was covered with tubercle-like scales that did not overlap. The skin impressions of the embryos from Auca Mahuevo also showed elongated and rosette-shaped structures that were formed by closely spaced scales. Some researchers suggest that these structures ossified and became osteoderms in later stages of development. These osteoderms could have protected young titanosaurs from small predators. For adult titanosaurs, however, the number of osteoderms appears to be too low to have offered effective protection against predators - it is therefore considered that the osteoderms in adult titanosaurs have been converted into calcium reserves.

Origin and paleobiogeography

The oldest known Titanosauria is Janenschia from the Upper Jurassic ( Tithonium ) of Tanzania , although the assignment of this genus to the Titanosauria is not recognized by all researchers. Undoubted titanosaurs first appear in Lower Cretaceous rocks in Europe, North and South America, Africa and Australia. Tracking of the broad type, which many researchers attribute to titanosaurs, could indicate that titanosaurs have existed since the middle Jurassic.

Lydekker (1895) assumed that titanosaurs only emerged on Gondwana after the separation of the northern ( Laurasia ) and southern land masses ( Gondwana ), which took place in the Upper Jurassic, and that their distribution was limited to Gondwana. Although some titanosaurs were also found in the northern continents in the following years, these finds were often viewed as exceptions, which resulted from independent advances by some populations from south to north. Numerous recent finds, which have since been made on the continents of the former Laurasia, show, however, that titanosaurs were not restricted to Gondwana. Today, many researchers assume that titanosaurs spread around the world even before the supercontinent Pangea finally collapsed, when connections between the large land masses still existed.

Research history

William Henry Sleeman found two vertebrae in 1828 that were later described as Titanosaurus indicus .

As early as 1828, the British officer William Henry Sleeman discovered two eddies in central India near Jabalpur . These bones came to the Museum of Calcutta in 1832, where they were described by the Scottish paleontologist Hugh Falconer in 1862 . Falconer recognized that it was the tail vertebrae of a reptile and gave diagnostic features but did not come up with a new name. Thus, Richard Lydekker only described a new species and genus, Titanosaurus indicus, from the same site in 1877 on the basis of these vertebrae and a fragmentary thigh bone . Other Titanosaurus species were described a few years later from Madagascar and South America. In the period that followed, Titanosaurus and the Titanosauridae became so-called wastebasket taxa, to which almost all sauropod finds from the Cretaceous were ascribed, even if no similarities with other known titanosaur remains could be established. It was not until the 1970s that other important finds were made, particularly in South America, such as Saltasaurus . Some original genera, such as Andesaurus, were similar to other titanosaurs, but lacked important common derived features of the more derived titanosaurs, such as procoele (front concave) caudal vertebrae. To include these original forms, the group was named Titanosauria in 1993. With Rapetosaurus , an almost complete skeleton of a titanosaur including skull was discovered for the first time at the beginning of the 21st century. This find showed, among other things, that Nemegtosaurus and Quaesitosaurus , which are known for isolated, diplodocid-like skulls, were not diplodocids, but titanosaurs. The discovery of well-preserved embryonic skulls within eggs in Auca Mahuevo was also important for understanding the evolution of skull features and individual development. Recent finds include Diamantinasaurus from Australia and Atsinganosaurus from southern France, which were described in 2009 and 2010, respectively. The dreadnoughtus found in Patagonia was first described in 2014 .

Systematics

definition

The Titanosauria group was established in 1993 by Bonaparte and Coria. Although these authors list the genera that they want to group within the Titanosauria, they do not give an exact definition of this group. Thus it remains unclear whether newly discovered, original forms should be included in this group or not. Later authors propose different definitions, but they remain controversial. The first definition provide Salgado and colleagues (1997): According to these authors, the titanosaur are a node-based taxon ( node-based definition ) that the last common ancestor of Andesaurus delgadoi includes and Titanosauridae and all descendants of this ancestor with. Sereno and Wilson (1998) criticize this proposal because Andesaurus delgadoi is little known and other genera such as Chubutisaurus , which were previously considered to be representatives of the Titanosauria, were possibly more basal than Andesaurus . These authors therefore put forward an alternative stem-based definition : According to this definition, the Titanosauria include all taxa that are more closely related to Saltasaurus loricatus than to Euhelopus zdanskyi and Brachiosaurus brancai . Furthermore, these authors name a new group, the Somphospondyli , which should include all taxa that are more closely related to Saltasaurus loricatus than to Brachiosaurus brancai . According to these definitions, the Somphospondyli, in contrast to the Titanosauria, does not exclude Euhelopus . The most recent definition is from Upchurch and colleagues (2004). These authors criticize the definition of the titanosauria established by Sereno and Wilson because it contains three reference taxa, which they consider to be impractical and confusing. In addition, the distinction between Somphospondyli and Titanosauria is based on the systematic position of Euhelopus , which is highly controversial. Consequently, these authors synonymize Symphospondyli and Titanosauria and give the same definition for the titanosauria that was used by Sereno and Wilson for the Symphospondyli: a stem line-based taxon that includes all taxa that are more closely related to Saltasaurus than to Brachiosaurus .

External system

The Titanosauria form together with the Brachiosauridae and some original forms the group Titanosauriformes . Some authors see the genus Euhelopus as close relatives of the Titanosauria and summarize both within the group Somphospondyli - this group is however controversial (see below). The Titanosauriformes in turn form the Macronaria group together with the Camarasauridae . At this level, too, another group is inserted by some authors, the Camarasauromorpha , which excludes some of the original Macronaria. The Macronaria form together with the Diplodocoidea ( Diplodocidae , Dicraeosauridae and Rebbachisauridae ) the group Neosauropoda . An example system follows (simplified from Upchurch and colleagues, 2004).

 Sauropoda  

 Vulcanodon


  Eusauropoda  

 Shunosaurus


   

 Barapasaurus


   

 Cetiosaurus



  Neosauropoda  

 Diplodocoidea


  Macronaria  

 Camarasaurus


  Titanosauriformes  

 Brachiosaurus


   

 Titanosauria





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Template: Klade / Maintenance / Style

Until the late 1990s titanosaurs were considered close relatives of the Diplodocidae. A closer relationship between these two groups was first suggested in 1929 by Friedrich von Huene in his description of the Antarctosaurus skull : This skull shows the narrow tooth crowns typical of diplodocids and the nostrils located high on the skull. Werner Janensch (1929) divided the sauropods into two groups based on their tooth morphology - the narrow-crowned species (Titanosauridae and Diplodocidae) and the broad-crowned species (e.g. Brachiosauridae). Some authors classified the Diplodocidae within the Titanosauridae (Romer, 1956, 1966, 1968), others summarized both groups in a group called Atlantosauridae (Steel, 1970). It was only the work of Salgado and colleagues (1997) and Wilson and Sereno (1998) that showed that titanosaurs were closely related to Brachiosaurus- like forms.

Internal system

The internal systematics of the Titanosauria is still highly controversial today. There are a number of suggestions that often contradict each other in the structure and naming of the clades . To make matters worse, many analyzes only consider a few genera, while many other, valid genera have not yet appeared in any analysis. The paleontologist Jeffrey A. Wilson writes: "The interrelationships of Titanosauria remain as one of the last frontiers in dinosaur systematics" ("The relationships of the Titanosauria are one of the last fronts of the dinosaur systematics"). Nevertheless, the analyzes agree on some points: Saltasaurus is always considered to be the most derived genus, while Neuquensaurus is mostly treated as a sister taxon of Saltasaurus . Both genera are often grouped together as Saltasaurinae - often together with Rocasaurus and sometimes additionally with other genera. Almost all analyzes see Alamosaurus and Opisthocoelicaudia as close relatives of the Saltasaurinae, sometimes both genera are compared as Opisthocoelicaudiinae of the Saltasaurinae. The Opisthocoelicaudiinae and the Saltasaurinae are often grouped together as Saltasauridae . Andesaurus is usually considered to be the most original representative of the Titanosauria. Also Malawisaurus is considered by many to be very original analysis titanosaur, although some authors (Upchurch, 1995 and Rogers, 2005) suggest a more derived position of this genus and suspect that Malawisaurus , Saltasaurus and neuquensaurus are more closely related to each other than with opisthocoelicaudia .

The question of whether there were monophyletic groups of original titanosaurs is a matter of debate . Bonaparte and Coria (1993) divide the Titanosauria into two families, the original Andesauridae, consisting of Andesaurus and Argentinosaurus , and the more derivative Titanosauridae. Upchurch (1998) retains the Andesauridae as the original titanosaur group and assigns it to the genera Andesaurus , Malawisaurus and Phuwiangosaurus . In contrast, Salgado and colleagues (1997) and many later studies consider the Andesauridae to be paraphyletic and thus invalid. With the Lognkosauria, Calvo and colleagues (2007) set up a new group of original titanosaurs that is said to contain Mendozasaurus and the newly discovered Futalognkosaurus . Furthermore, proposals are discussed that include other groups of derived titanosaurs in addition to the Saltasauridae. Wilson (2005) summarizes Quaesitosaurus and Nemegtosaurus together with Rapetosaurus within the Nemegtosauridae . Quaesitosaurus and Nemegtosaurus were often considered to be representatives of the Diplodocoidea, but are considered to be representatives of the Titanosauria in many more recent analyzes.

There is disagreement about the naming of groups within the Titanosauria. Many analyzes use the name Titanosauridae to summarize more derived titanosaurs, excluding basal forms such as Andesaurus . Wilson and Upchurch (2003) published a revision of the genus Titanosaurus and declare the type species Titanosaurus indicus as invalid because it is based only on two caudal vertebrae that show no diagnostically usable features. Consequently, these authors consider rank-based taxa based on Titanosaurus as a nominotypical taxon - the Titanosauridae, the Titanosaurinae and the Titanosauroidea - also as invalid. Titanosauria remains valid as a ranked taxon after this proposal. Upchurch and colleagues (2004) summarize the more strongly derived Titanosauria in a new group corresponding to the Titanosauridae, the Lithostrotia . While this name has been adopted by some recent analyzes, Calvo and colleagues (2007) continue to use the name Titanosauridae for the same group. Some authors also use the name Eutitanosauria for derived titanosauria.

This cladogram follows Calvo and colleagues (2007):

 Titanosauria  

Andesaurus


  Titanosauridae (= Lithostrotia )  


Malawisaurus


  Lognkosauria  

Mendozasaurus


   

Futalognkosaurus




   

Epachthosaurus


  Eutitanosauria 


Rapetosaurus


   
  Aeolosaurini  

Gondwanatitan


   

Aeolosaurus



   

Rinconsaurus


   

Loma Lindero sp.




   

Lirainosaurus


   
  Opisthocoelicaudiinae  

Opisthocoelicaudia


   

Alamosaurus



 Saltasaurinae 

Neuquensaurus


   

Saltasaurus


   

Rocasaurus






Template: Klade / Maintenance / 3





Template: Klade / Maintenance / Style
Genus list of the Titanosauria (modified from Upchurch and colleagues, 2004)

Genera with a reliable assignment to the Titanosauria

Genera with controversial assignment to the Titanosauria

dubious genera ( noun dubia )

literature

  • Luis M. Chiappe , Frankie Jackson, Rodolfo A. Coria , Lowell Dingus : Nesting Titanosaurs from Auca Mahuevo and Adjacent Sites: Understanding Sauropod Reproductive Behavior and Embryonic Development. In: Kristina Curry A. Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. a. 2005, ISBN 0-520-24623-3 , pp. 285-302, doi: 10.1525 / california / 9780520246232.003.0011 .
  • Kristina Curry A. Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. a. 2005, ISBN 0-520-24623-3 .
  • Leonardo Salgado , Rodolfo Anibal Coria, Jorge Orlando Calvo : Evolution of Titanosaurid Sauropods. I: Phylogenetic Analysis Based on the Postcranial Evidence. In: Ameghiniana . Vol. 34, No. 1, 1997, pp. 3-32, digitized version (PDF; 4.42 MB) .
  • Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. a. 2004, ISBN 0-520-24209-2 , pp. 259-324.
  • 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 .
  • Jeffrey A. Wilson, Paul Upchurch: A Revision of Titanosaurus Lydekker (Dinosauria - Sauropoda), the first dinosaur genus with a 'gondwanan' distribution. In: Journal of Systematic Palaeontology. Vol. 1, No. 3, 2003, ISSN  1477-2019 , pp. 125-160, doi: 10.1017 / S1477201903001044 .

Individual evidence

  1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ u. a. 2010, ISBN 978-0-691-13720-9 , pp. 204-213, online .
  2. ↑ a b c d e Scott A. Hocknull, Matt A. White, Travis R. Tischler, Alex G. Cook, Naomi D. Calleja, Trish Sloan, David A. Elliott: New mid-Cretaceous (latest Albian) dinosaurs from Winton , Queensland, Australia. In: PLoS ONE . Vol. 4, No. 7, 2009, e6190, doi: 10.1371 / journal.pone.0006190 .
  3. ↑ a b c Hussam Zaher, Diego Pol, Alberto B. Carvalho, Paulo M. Nascimento, Claudio Riccomini, Peter Larson, Rubén Juarez-Valieri, Ricardo Pires-Domingues, Nelson Jorge da Silva Jr., Diógenes de Almeida Campos: A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians. In: PLoS ONE. Vol. 6, No. 2, 2011, e16663, doi: 10.1371 / journal.pone.0016663 .
  4. ↑ Ignacio A. Cerda, Ariana Paulina Carabajal, Leonardo Salgado , Rodolfo A. Coria , Marcelo A. Reguero, Claudia P. Tambussi, Juan J. Moly: The first record of a sauropod dinosaur from Antarctica. In: Natural Sciences . Vol. 99, No. 1, 2011, pp. 83-87, doi: 10.1007 / s00114-011-0869-x .
  5. ↑ a b c d e Jeffrey A. Wilson, Dhananjay M. Mohabey, Shanan E. Peters, Jason J. Head: Predation upon Hatchling Dinosaurs by a New Snake from the Late Cretaceous of India. In: PLOS Biol . Vol. 8, No. 3, 2010, e1000322, doi: 10.1371 / journal.pbio.1000322 .
  6. ↑ a b c d Kristina Curry Rogers: Titanosauria: A Phylogenetic Overview. In: Kristina Curry A. Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. a. 2005, ISBN 0-520-24623-3 , pp. 50-103, doi: 10.1525 / california / 9780520246232.003.0003 .
  7. ↑ a b c d e f g h i j k l m Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria. 2nd edition. University of California Press, Berkeley CA et al. a. 2004, ISBN 0-520-24209-2 , pp. 259-324.
  8. ↑ a b c d e f g h i j k 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 .
  9. ↑ Kristina Curry Rogers, Catherine A. Forster: The Skull of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. In: Journal of Vertebrate Paleontology. Vol. 24, No. 1, 2004, ISSN  0272-4634 , pp. 121-144, doi: 10.1671 / A1109-10 .
  10. ↑ a b c d e f Jeffrey A. Wilson: Redescription of the Mongolian Sauropod Nemegtosaurus mongoliensis Nowinski (Dinosauria: Saurischia) and comments on Late Cretaceous Sauropod diversity. In: Journal of Systematic Palaeontology. Vol. 3, No. 3, 2005, ISSN  1477-2019 , pp. 283-318, doi: 10.1017 / S1477201905001628 .
  11. ↑ a b c Sebastián Apesteguía: Evolution of the Hyposphene-Hypantrum Complex within Sauropoda. In: Virginia Tidwell, Kenneth Carpenter (Eds.): Thunder-lizards. The Sauropodomorph Dinosaurs. Indiana University Press, Bloomington IN et al. a. 2005, ISBN 0-253-34542-1 , pp. 248-267.
  12. ↑ a b c d Leonardo Salgado, Rodolfo A. Coria, Jorge O. Calvo : Evolution of Titanosaurid Sauropods. I: Phylogenetic Analysis Based on the Postcranial Evidence. In: Ameghiniana . Vol. 34, No. 1, 1997, pp. 3–32, digitized version (PDF; 4.42 MB) ( Memento from March 9, 2012 in the Internet Archive )
  13. ↑ a b c d Jeffrey A. Wilson: Overview of Sauropod Phylogeny and Evolution. Kristina Curry Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. a 2005, ISBN 0-520-24623-3 , pp. 15-49, digitized version (PDF; 384.37 KB) .
  14. ^ Mathew J. Wedel: Vertebral pneumaticity, air sacs, and the physiology of sauropod dinosaurs. In: Paleobiology. Vol. 29, No. 2, 2003, ISSN  0094-8373 , pp. 243-255, doi : 10.1666 / 0094-8373 (2003) 029 <0243: VPASAT> 2.0.CO; 2 , digitized version (PDF; 860.30 KB) ( Memento from December 17, 2008 in the Internet Archive ).
  15. ^ A b Jeffrey A. Wilson, Matthew T. Carrano: Titanosaurs and the Origin of "Wide-Gauge" Trackways: A Biomechanical and Systematic Perspective on Sauropod Locomotion. In: Paleobiology. Vol. 25, No. 2, 1999, pp. 252-267.
  16. ^ Matthew T. Carrano: The Evolution of Sauropod Locomotion: morphological diversity of a secondarily quadrupedal radiation. In: Kristina Curry A. Rogers, Jeffrey A. Wilson: The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley, Cal. u. a. 2005, ISBN 0-520-24623-3 , pp. 229-251.
  17. ↑ Sebastián Apesteguía: Evolution of the Titanosaur Metacarpus. In: Virginia Tidwell, Kenneth Carpenter (Eds.): Thunder-lizards. The Sauropodomorph Dinosaurs. Indiana University Press, Bloomington IN et al. a. 2005, ISBN 0-253-34542-1 , pp. 321-346.
  18. ↑ Alejandro Otero: The appendicular skeleton of Neuquensaurus, a Late Cretaceous saltasaurine sauropod from Patagonia, Argentina. In: Acta Palaeontologica Polonica. Vol. 55, No. 3, 2010, ISSN  0567-7920 , pp. 399-426, doi: 10.4202 / app.2009.0099 .
  19. ↑ Bernardo J. González Riga, Jorge Orlando Calvo, Juan Porfiri: An articulated titanosaur from Patagonia (Argentina): New evidence of neosauropod pedal evolution. In: Palaeoworld. Vol. 17, No. 1, 2008, ISSN  1871-174X , pp. 33-40, doi: 10.1016 / j.palwor.2007.08.003 .
  20. ^ A b Kenneth Carpenter: Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus Cope, 1878. In: John R. Foster, Spencer G. Lucas (eds.): Paleontology and geology of the Upper Jurassic Morrison formation (= New Mexico Museum of Natural History & Science. Bulletin. 36, ISSN  1524-4156 ). New Mexico Museum of Natural History & Science, Albuquerque NM 2006, pp. 131-138, online .
  21. ^ A b Gerardo V. Mazzetta, Per Christiansen, Richard A. Fariña: Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs. In: Historical Biology. Vol. 16, No. 2/4, 2004, ISSN  0891-2963 , pp. 71-83, doi: 10.1080 / 08912960410001715132 , digital version (PDF; 574.66 KB) .
  22. ↑ Gary P. Burness, Jared Diamond , Timothy Flannery: Dinosaurs, dragons, and dwarfs: The evolution of maximal body size. In: Proceedings of the National Academy of Sciences of the United States of America . Vol. 98, No. 25, 2001, pp. 14518-14523, doi: 10.1073 / pnas.251548698 .
  23. ↑ Bernardo J. González Riga, Matthew C. Lamanna, Leonardo D. Ortiz David, Jorge O. Calvo, Juan P. Coria (2016): A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot. Scientific Reports 6, Article number: 19165 (2016) doi: 10.1038 / srep19165 (open access)
  24. ^ Karl T. Bates, Peter L. Falkingham, Sophie Macaulay, Charlotte Brassey, Susannah CR Maidment (2015): Downsizing a giant: re-evaluating Dreadnoughtus body mass. Biology Letters 11 (6). doi: 10.1098 / rsbl.2015.0215 (open access)
  25. ↑ a b c d e Jorge O. Calvo, Juan D. Porfiri, Bernardo J. Gonzáles-Riga, Alexander WA Kellner: A new Cretaceous terrestrial ecosystem from Gondwana with the description of a new sauropod dinosaur. In: Anais da Academia Brasileira de Ciências. Vol. 79, No. 3, 2007, ISSN  0001-3765 , pp. 529-541, digital version (PDF; 836.43 KB) .
  26. ↑ a b c P. Martin Sander, Andreas Christian, Marcus Clauss, Regina Fechner, Carole T. Gee, Eva-Maria Griebeler, Hanns-Christian Gunga , Jürgen Hummel, Heinrich Mallison, Steven F. Perry, Holger Preuschoft, Oliver WM Rauhut , Kristian Remes, Thomas Tütken, Oliver Wings, Ulrich Witzel: Biology of the sauropod dinosaurs: the evolution of gigantism. In: Biological Reviews. Vol. 86, No. 1, 2011, ISSN  1464-7931 , pp. 117–155, doi: 10.1111 / j.1469-185X.2010.00137.x , digital version (PDF; 1.25 MB) .
  27. ↑ a b Kenneth J. Lacovara et al .: A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina. (PDF) Nature , September 4, 2014, accessed September 4, 2014 .
  28. ↑ Jeffrey Wilson, Kristi Curry Rogers: Body Size Evolution. In: Evolution & Phylogeny of Titanosauria. Retrieved August 26, 2014 .
  29. ↑ Oliver Wings, Martin Sander: No gastric mill in sauropod dinosaurs: new evidence from analysis of gastrolith mass and function in ostriches . In: The Royal Society . tape 274 , 2006, pp. 635-640 ( PDF ). PDF ( Memento from July 13, 2011 in the Internet Archive )
  30. ↑ a b c Géraldine Garcia, Sauveur Amico, Francois Fournier, Eudes Thouand, Xavier Valentin: A new Titanosaur genus (Dinosauria, Sauropoda) from the Late Cretaceous of southern France and its paleobiogeographic implications. In: Bulletin de la Société Géologique de France. Vol. 181, No. 3, 2010, ISSN  0037-9409 , pp. 269-277.
  31. ^ Paul M. Barrett, Paul Upchurch: Sauropodomorph Diversity through Time: Paleoecological and Macroevolutionary Implications. In: Kristina Curry Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. a. 2005, ISBN 0-520-24623-3 , pp. 125-156.
  32. ^ Vandana Prasad, Caroline Stromberg, Habib Alimohammadian, Ashok Sahni: Dinosaur Coprolites and the Early Evolution of Grasses and Grazers. In: Science . Vol. 310, no. 5751, 2005, pp. 1177-1180, doi: 10.1126 / science.1118806 .
  33. ↑ Jeffrey A. Wilson, Ricardo N. Martinez, Oscar Alcober: Distal tail segment of a titanosaur (Dinosauria: Sauropoda) form the Upper Cretaceous of Mendoza, Argentinia. In: Journal of Vertebrate Paleontology. Vol. 19, No. 3, 1999, pp. 591-594, doi: 10.1080 / 02724634.1999.10011168 .
  34. ↑ a b c d e Bernat Vila, Frankie D. Jackson, Josep Fortuny, Albert G. Sellés, Àngel Galobart: 3-D Modeling of Megaloolithid Clutches: Insights about Nest Construction and Dinosaur Behavior. In: PLoS ONE. Vol. 5, No. 5, 2010, e10362, doi: 10.1371 / journal.pone.0010362 .
  35. ↑ a b c d e f Luis M. Chiappe , Frankie Jackson, Rodolfo A. Coria, Lowell Dingus: Nesting Titanosaurs from Auca Mahuevo and Adjacent Sites: Understanding Sauropod Reproductive Behavior and Embryonic Development. In: Kristina Curry A. Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. a. 2005, ISBN 0-520-24623-3 , pp. 285-302, doi: 10.1525 / california / 9780520246232.003.0011 .
  36. ↑ a b Gerald Grellet-Tinner, Luis M. Chiappe, Rodolfo Coria: Eggs of titanosaurid sauropods from the Upper Cretaceous of Auca Mahuevo (Argentina). In: Canadian Journal of Earth Sciences. Vol. 41, No. 8, 2004, ISSN  0008-4077 , pp. 949-960, doi: 10.1139 / e04-049 .
  37. ↑ Frankie D. Jackson, David J. Varricchio, Robert A. Jackson, Bernat Vila, Luis M. Chiappe: Comparison of water vapor conductance in a titanosaur egg from the Upper Cretaceous of Argentina and a Megaloolithus siruguei egg from Spain. In: Paleobiology. Vol. 34, No. 2, 2008, ISSN  0094-8373 , pp. 229-246, doi : 10.1666 / 0094-8373 (2008) 034 [0229: COWVCI] 2.0.CO; 2 .
  38. ↑ Luis M. Chiappe, James G. Schmitt, Frankie D. Jackson, Alberto Garrido, Lowell Dingus, Gerald Grellet-Tinner: Nest Structure for Sauropods: Sedimentary Criteria for Recognition of Dinosaur Nesting Traces. In: Palaios. Vol. 19, No. 1, 2004, ISSN  0883-1351 , pp. 89-95, doi : 10.1669 / 0883-1351 (2004) 019 <0089: NSFSSC> 2.0.CO; 2 .
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  40. ^ A b Luis M. Chiappe, Leonardo Salgado, Rodolfo A. Coria: Embryonic Skulls of Titanosaur Sauropod Dinosaurs. In: Science. Vol. 293, No. 2444, 2001, pp. 2444-2446, doi: 10.1126 / science.1063723 .
  41. ↑ Ignacio A. Cerda, Jaime E. Powell: Dermal armor histology of Saltasaurus loricatus, an Upper Cretaceous sauropod dinosaur from Northwest Argentina. In: Acta Palaeontologica Polonica. Vol. 55, No. 3, 2010, pp. 389-398, doi: 10.4202 / app.2009.1101 .
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  43. ↑ Leonardo Salgado: Considerations on the bony plates assigned to titanosaurs (Dinosauria, Sauropoda). In: Ameghiniana. Vol. 40, No. 3, 2003, pp. 441-456, abstract .
  44. ↑ Rodolfo A. Coria, Luis M. Chiappe: Embryonic skin from late cretaceous sauropods (Dinosauria) of Auca Mahuevo, Patagonia, Argentinia. In: Journal of Paleontology. Vol. 18, No. 6, 2007, ISSN  0022-3360 , pp. 1528-1532, doi: 10.1666 / 05-150.1 .
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  47. ↑ a b c d e Jeffrey A. Wilson, Paul Upchurch: A Revision of Titanosaurus Lydekker (Dinosauria - Sauropoda), the first dinosaur genus with a 'gondwanan' distribution. In: Journal of Systematic Palaeontology. Vol. 1, No. 3, 2003, pp. 125-160, doi: 10.1017 / S1477201903001044 .
  48. ↑ José F. Bonaparte, Rodolfo A. Coria: Un nuevo y gigantesco saurópodo titanosaurio de la Formación Río Limay (Albiano – Cenomanio) de la Provincia del Neuquén, Argentina. In: Ameghiniana. Vol. 30, No. 3, 1993, pp. 271-282, abstract .
  49. ↑ Jeffrey A. Wilson, Paul C. Sereno : Early Evolution and Higher-level Phylogeny of Sauropod Dinosaurs (= Journal of Vertebrate Paleontology. Vol. 18, Supplement to No. 2 = Society of Vertebrate Paleontology. Memoir. Vol. 5, ISSN  1062-161X ). Society of Vertebrate Paleontology, Chicago IL 1998, doi: 10.1080 / 02724634.1998.10011115 .
  50. ↑ Paul Sereno: Titanosauria. In: Taxon Search. Archived from the original on September 3, 2014 ; Retrieved August 26, 2014 .
  51. ↑ Paul Sereno: Camarasauromorpha. In: Taxon Search. Archived from the original on September 3, 2014 ; Retrieved August 26, 2014 .
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  53. ↑ Rodrigo Miloni Santucci, Reinaldo J. Bertini: A new titanosaur from western São Paolo State, Upper Cretaceous Bauru Group, south-east Brazil. In: Palaeontology. Vol. 49, No. 1, 2006, ISSN  0031-0239 , pp. 59-66, doi: 10.1111 / j.1475-4983.2005.00527.x .
  54. ^ Sebastián Apesteguía: The sauropod diversity of the La Amarga Formation (Barremian), Neuquén (Argentina). In: Gondwana Research. Vol. 12, No. 4, 2007, ISSN  1342-937X , pp. 533-546, doi: 10.1016 / j.gr.2007.04.007 .
  55. ↑ Alexander WA Kellner, David Rubilar-Rogers, Alexander Vargas, Mario Suárez: A new titanosaur sauropod from the Atacama Desert, Chile. In: Anais da Academia Brasileira de Ciências. Vol. 83, No. 1, 2011, pp. 211-219, doi: 10.1590 / S0001-37652011000100011 , digital version (PDF; 1.7 MB) .
  56. ↑ Kamila LN Bandeira, Felipe Medeiros Simbras, Elaine Batista Machado, Diogenes de Almeida Campos, Gustavo R. Oliveira and Alexander WA Kellner. 2016. A New Giant Titanosauria (Dinosauria: Sauropoda) from the Late Cretaceous Bauru Group, Brazil. PLoS ONE. doi: 10.1371 / journal.pone.0163373
  57. ↑ Leonardo Salgado, Rodolfo A. Coria: Barrosasaurus casamiquelai gen. Et sp. nov., a new titanosaur (Dinosauria, Sauropoda) from the Anacleto Formation (Late Cretaceous: early Campanian) of Sierra Barrosa (Neuquén, Argentina). In: Zootaxa . Vol. 2222, 2009, pp. 1–16, abstract (PDF; 16 kB) .
  58. ↑ Alexander Wilhelm Armin Kellner, Diogenes de Almeida Campos, Marcelo NF Trotta: Description of a titanosaurid caudal series from the Bauru Group, Late Cretaceous of Brazil. In: Arquivos do Museu Nacional. Rio de Janeiro. Vol. 63, No. 3, 2005, ISSN  0365-4508 , pp. 529-564, online (PDF; 1.59 MB) ( Memento from July 18, 2014 in the Internet Archive )
  59. ↑ Sebastián Apesteguía: Bonitasaura salgadoi gen. Et sp. nov .: a beaked sauropod from the Late Cretaceous of Patagonia. In: Natural Sciences. Vol. 91, No. 10, 2004, pp. 493-497, doi: 10.1007 / s00114-004-0560-6 .
  60. ↑ Augustín G. Martinelli, Analía M. Forasiepi: Late Cretaceous vertebrates from Bajo de Santa Rosa (Allen Formation), Río Negro province, Argentina, with the description of a new sauropod dinosaur (Titanosauridae). In: Revista del Museo Argentino de Ciencias Naturales. NS Vol. 6, No. 2, 2004, ISSN  1514-5158 , pp. 257–305, Abstract (PDF; 75.55 KB) ( Memento from March 4, 2016 in the Internet Archive )
  61. ↑ Hailu You, Qiang Ji, Matthew C. Lamanna, Jinglu Li, Yinxian Li: A titanosaurian sauropod dinosaur with opsithocoelous caudal vertebrae from the early Late Cretaceous of Liaoning province. In: Acta Geologica Sinica. English edition. Vol. 78, No. 4, 2004, ISSN  1000-9515 , pp. 907-911, doi: 10.1111 / j.1755-6724.2004.tb00212.x .
  62. ↑ Elaine B. Machado, Leonardo dos S. Avilla, William R. Nava, Diogenes de A. Campos, Alexander WA Kellner: A new titanosaur sauropod from the Late Cretaceous of Brazil. In: Zootaxa. Vol. 3701, No. 3, 2013, pp. 301–321, abstract (PDF; 15.5 KB) .
  63. ^ César Navarrete, Gabriel Casal, Rubén Martínez: Drusilasaura deseadensis gen. Et sp. nov., un nuevo titanosaurio (Dinosauria – Sauropoda), de la Formacíon Bajo Barreal, Cretácico Superior del norte de Santa Cruz, Argentina. In: Revista Brasileira de Paleontologia. Vol. 14, No. 1, 2011, ISSN  1519-7530 , pp. 1–14, digital version (PDF; 4.31 MB) .
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This article was added to the list of excellent articles on November 12, 2010 in this version .