Titanosaurids(Titanosauridae)

Titanosauridae is a group of macronarian sauropods comprised of more than 50 described species and achieved great evolutionary success during Cretaceous times.The titanosaurs were the last great group of sauropods, which existed from about 136 to 66 million years ago, before the Cretaceous–Paleogene extinction event, and were the dominant herbivores of their time.The fossil evidence suggests they replaced the other sauropods, like the diplodocids and the brachiosaurids, which died out between the late Jurassic and the mid-Cretaceous Periods,Titanosaurs were widespread. Such success is highlighted by the wide geographic range of their fossil record, as this clade was present on virtually all continents and contained a very diverse number of species formally described in South America, North America, Africa,Europe, Asia and Australia.

In December 2011, Argentine scientists announced titanosaur fossils had been found on Antarctica—meaning that titanosaur fossils have been found on all continents. Four well-preserved skeletons of a titanosaur species were found in Italy, a discovery first reported on 2 May 2006.They are especially numerous in the southern continents (then part of the supercontinent of Gondwana). Australia had titanosaurs around 96 million years ago: fossils have been discovered in Queensland of a creature around 25 metres (82 ft) long.Remains have also been discovered in New Zealand.One of the largest ever titanosaur footprints was discovered in the Gobi desert in 2016.One of the oldest remains of this group was found from the Valley of the Dinosaurs, Paraнba state of Brazil, representing a 136-million-year-old subadult individual.

1. Saltasaurus 2. Paralititan 3. Titanosaurus 4. Argentinosaurus 5. Alamosaurus
Titanosauridae is one of the largest families of dinosaurs. Because Titanosaurus is based on poor materials, it has been suggested that the name be changed to Saltasauridae. Titanosaurids are mostly known from the Cretaceous of Gondwana, especially South America, but they were also representative of  India, Madagascar, and even Europe. While some were as huge in size as their name indicates, many were of moderate proportions, and there were also dwarf forms that seem to have been island-dwellers. Many titanosaurids are rather poorly known, and it is not unlikely that - as is usually the case - a lot of the taxa based on fragmentary material will turn out to be invalid. It used to be thought that the Titanosauridae were cousins to the diplodocids. More recent studies reveal that titanosaurid skulls were not diplodocid-like (as restored by von Huene, an early but influential worker in this field) nor extremely flat (as has also been suggested), but were instead similiar to Camarasaurus and Brachiosaurus, although not as high (see illustration of Rapetosaurus).

The way in which the teeth mesh together is different from that of other sauropod groups, especially diplodocoids. The head is surprisingly small, even by sauropod standards (say around 30 cm for a 14.5 meter long animal).
A vast nesting colony of titanosaurids has been discovered in Argentina recently, with some fossilised embryos showing skin impressions, and another such possible colony was uncovered in Spain. The embryo skin impressions indicate (according to the placement of these scales) that these titanosaurs would not have sported the keratinous dorsal spikes found associated with a diplodocid specimen. Neither were the juveniles feathered.
The existence of nesting grounds indicates that these were social animals, perhaps congregating and nesting in large heards. Possibly the safety of numbers protected them from the carnivorous abelisaurs that were well placed to be their main predator.Titanosauriformes has a conspicuous fossil record in Cretaceous continental deposits. More apical titanosauriforms (Titanosauria) seem to be even more common in fossil record as rebbachisaurids had become extinct by the early Late Cretaceous, and consequently, they were the only sauropods that faced the Cretaceous–Paleogene extinction event.


Argentinosaurus

The first fossils identified as Argentinosaurus were found in 1987 by a rancher in Argentina, who mistook the leg for a giant piece of petrified wood. A gigantic vertebra was also found, it was almost as tall as a man.
The type species of Argentinosaurus, A. huinculensis, was described and published in 1993 by the Argentine palaeontologists Josй F. Bonaparte and Rodolfo Coria. Its more specific time-frame within the Cretaceous is the late Cenomanian faunal stage, ~97 to 94 million years ago.The fossil discovery site is in the Huincul Formation of the Rнo Limay Subgroup in Neuquйn Province, Argentina.
Not much of Argentinosaurus has been recovered. The holotype included only a series of vertebrae (six from the back, five partial vertebrae from the hip region), ribs of the right side of the hip region, a part of a rib from the flank, and the right fibula (lower leg bone). One of these vertebra was 1.59 meters tall, and the fibula was about 1.55 meters (58 inches). In addition to these bones, an incomplete femur (upper leg bone, specimen number MLP-DP 46-VIII-21-3) is assigned to Argentinosaurus; this incomplete femur shaft has a minimum circumference of about 1.18 meters.The proportions of these bones and comparisons with other sauropod relatives allow paleontologists to estimate the size of the animal.
An early reconstruction by Gregory S. Paul estimated Argentinosaurus at between 30–35 metres (98–115 ft) in length and with a weight of up to 80–100 tonnes (88–110 short tons).The length of the skeletal restoration mounted in Museo Carmen Funes is 39.7 metres (130 ft) long and 7.3 metres (24 ft) high. This is the longest reconstruction in a museum and contains the original material, including a mostly complete fibula.Other estimates have compared the fragmentary material to relatively complete titanosaurs to help estimate the size of Argentinosaurus.
In 2013, in a study published in Plos One on October 30, 2013 by Dr. Bill Sellers, Dr. Rodolfo Coria, Lee Margetts et al, Argentinosaurus was digitally reconstructed to test its locomotion for the first time. Before this study, the most common way of estimating speed was through studying bone histology and ichnology. Commonly, studies about sauropod bone histology and speed focus on the postcranial skeleton which holds many unique features, such as an enlarged process on the ulna, a wide lobe on the ilia, an inward-slanting top third of the femur, and an extremely ovoid femur shaft. Those features are useful when attempting to explain trackway patterns of graviportal animals. When studying ichnology to calculate sauropod speed, there are a few problems, such as only providing estimates for certain gaits because of preservation bias, and being subject to many more accuracy problems.
To estimate the gait and speed of Argentinosaurus, the study performed a musculoskeletal analysis. The only previous musculoskeletal analyses were conducted on hominids, terror birds, and other dinosaurs. Before they could conduct the analysis, the team had to create a digital skeleton of the animal in question, show where there would be muscle layering, locate the muscles and joints, and finally find the muscle properties before finding the gait and speed. The results of the biomechanical study revealed that Argentinosaurus was mechanically competent at a top speed of 2 m/s (5 mph) given the great weight of the animal and the strain that its joints were capable of bearing. The results further revealed that much larger terrestrial vertebrates might be possible, but would require significant body remodeling and possibly behavioral change to prevent joint collapse.
Argentinosaurus was, like all sauropods, a herbivore. It probably used its long neck to reach into conifers, or sweep the ground in search of ferns and bushes. Once swallowed, the food would have needed to travel all the way down the neck before entering the stomach. Inside the stomach, the vegetation would have been ground or broken down by smooth stones known as gastroliths
Argentinosaurus adults were some of the largest animals ever, but their hatchlings were not. One article found that Argentinosaurus hatchlings would have had to grow 25,000 times their original size before reaching adult size. Argentinosaurus probably traveled in herds of a few dozen animals, including juveniles. Young animals were vulnerable to attacks from predators. It is thought that only a handful of juveniles would be lucky enough to make it into adulthood. Sauropods related to Argentinosaurus have had fossilized eggs preserved. These eggs indicate that every year, hundreds of adults would gather just to nest. Wide, flat floodplains have been identified as the preferred nesting sites. The eggs were around 22 centimetres (8.7 in) in diameter, and each adult probably laid large numbers of eggs each season. Once hatched, it took about 15 years for the tiny hatchlings to reach adulthood, and gigantic size.


Futalognkosaurus
Its fossils were found in the Neuquйn province of Argentina in 2000, and were scientifically described in 2007. The genus name is derived from the local indigenous language Mapudungun and is pronounced foo-ta-long-koh-sohr-us: "futa" means "giant" and "lognko" means "chief".It is based on three fossil specimens, yielding an estimated 70% of the skeleton in total. The fossil team described the find as "the most complete giant dinosaur known so far".
The type species, Futalognkosaurus dukei, is estimated to be 26 metres (85 ft) in length, rivaling Argentinosaurus. Its long neck contained 14 vertebrae, and was over a meter deep in places, due to its extremely tall neural spines which had a distinctive "shark-fin" shape. The hips were also extremely large and bulky, reaching a width of nearly 3 metres (9.8 ft).The alternate early spelling "Futalongkosaurus" may be found in some press reports and on websites.
In their phylogenetic analysis, Calvo and colleagues found Futalognkosaurus to be a member of the Titanosauridae (or Lithostrotia, depending on the definitions being used), and most closely related to Mendozasaurus. They defined a new clade for the group containing both Futalognkosaurus and Mendozasaurus, their common ancestor, and all descendants, which they named the Lognkosauria.The authors found Malawisaurus to be the sister group of this new clade. Another, much later member of Lognkosauria is the colossal Puertasaurus, which may be the biggest dinosaur so far known. Besides Futalognkosaurus, other fauna was discovered in the Futalognko site, including two further undescribed sauropod taxa, specimens of Megaraptor, Unenlagia and some pleurodiran turtles.

Puertasaurus with estimated lengths of 30–35 metres (98–115 ft) and weights of 60–100 metric tons (66–110 short tons).
 
Puertasaurus is a genus of titanosaurid sauropod that appeared during the Late Cretaceous. It lived in what is now Patagonia. The type species, Puertasaurus reuili, is named in honor of Pablo Puerta and Santiago Reuil, who discovered the specimen in January 2001. Puertasaurus is based on a partial spinal column: a neck vertebra, a dorsal (back) vertebra, and two tail vertebrae.
Of the four neck, back and tail vertebrae discovered, together forming the holotype MPM 10002, the most impressive is the back vertebra measuring 1.06 meters (3.48 ft) tall and 1.68 meters (5.51 ft) wide. This is the broadest sauropod vertebra known, and two-thirds of its width is made up of the huge wing-like diapophyses (side processes which supported the ribs), which are heavily buttresed and merge with both the centrum and the neural spine, forming a wide spade-like shape (in most sauropods, like Argentinosaurus, they are far less large, lack buttresses, and form a simple cross-bar shape). The huge size of the diapophyses indicated a very wide rib cage, which would have been anywhere from 5 to 8 meters wide, which would make it not just one of the largest dinosaurs, but also possibly the widest and heaviest. The neck was also unusual; based on the single known neck vertebra, Puertasaurus had a very long, squat neck with wide cervical ribs and thick but short neural spines (unlike its relative Futalognkosaurus, whose neck was also very long, but was much deeper, with tall "shark fin" neural spines). This gave the neck a huge vertical range of motion and flexibility, and it may have been able to "bend over backwards" so that Puertasaurus could reach higher branches behind its head, without having to move its whole body - as a trade-off, the neck"s sideways flexibility was more limited, though the extreme width of the neck may indicate a wide head as well, the jaws of which could take in more food per bite to make up for the lack of lateral flexibility. This strange, highly specialized squat-neck designis seen nowhere else in the Dinosauria.
Fernando Novas, one of the paleontologists who described Puertasaurus reuili, estimated that the new species was approximately 35 to 40 meters (115 to 131 ft) long and weighed between 80 and 100 metric tons (88 to 110 short tons).If correct, this would place it as one of the biggest dinosaurs (and the biggest titanosaur) ever to walk the earth, though rivaled in size by the more primitive Argentinosaurus. It would also extend the period of time in which such very large sauropods lived; this species roamed what is now Patagonia towards the end of the Cretaceous period, about 70 million years ago, in the early Maastrichtian.
Puertasaurus belonged to the clade Titanosauria.Based on the shape of its known vertebrae, it is most closely related to the lognkosaurians,a transitional group within Titanosauria which includes the gigantic Futalognkosaurus and the somewhat smaller Mendozasaurus, known for their hefty necks and wide rib cages, as well as similar wing-like diapophyses. If it is a lognkosaurian, Puertasaurus would be not only the largest but also the last known member of the group. Lognkosaurians were common in the Turonian and Coniacian epochs, but Puertasaurus lived in the Maastrichtian, the very last stage of the Late Cretaceous, when the much smaller Saltasaurids were the most common titanosaur group.


Argyrosaurus

Argyrosaurus is a genus of herbivorous titanosaurid dinosaur that lived about 90 million years ago, during the Late Cretaceous Period of what is now Argentina. This animal is estimated to be 55-65 tons. It is poorly known from a forelimb and some other material. Its size estimes range from 35 to 40 m long.
The type species, Argyrosaurus superbus, was formally described by Richard Lydekker in 1893.The genus name means "silver lizard" from Greek argyros, "silver", and sauros, "lizard", because it was discovered in Argentina, which literally means "silver land". The specific epithet means "proud" in Latin.
The holotype specimen of Argyrosaurus superbus is a huge left forelimb, MLP 77-V-29-1. Although numerous other remains have been referred, the holotype remains the only material which unambiguously pertains to the genus.


Antarctosaurus giganteus

Antarctosaurus (meaning "southern lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, A. wichmannianus, was described by prolific German paleontologist Friedrich von Huene in 1929, who also described a second species in 1929. Three additional species of Antarctosaurus have been named since then. Later studies indicate that none of these pertain to Antarctosaurus.
Antarctosaurus was very large, even for a sauropod. Scientists still have much to learn about Antarctosaurus, as a complete skeleton remains elusive.
Von Huene named a second species of Antarctosaurus in 1929, which he called A. giganteus because of its enormous size. It includes a left and right femur, a partial left and right pubis, the distal end of a damaged tibia, numerous rib and distal caudal vertebrae fragments, and six large and unidentifiable bones.Very few remains are known of this species and it is regarded as a nomen dubium by some.The most famous of these bones are two gigantic femora, which are among the largest of any known sauropod. They measure about 2.35 meters in length. Extrapolating from the size of these bones has led to a mass estimate of approximately 69 metric tonnes (152,000 pounds) in one study, slightly smaller than Argentinosaurus, which at nearly 73 metric tonnes (160,000 pounds) is among the heaviest known land animals of all time.
The bones mentioned above were recovered in Neuquйn Province of Argentina, from the Plottier Formation, which dates to the late Coniacian stage of the Late Cretaceous.

Notocolossus

Notocolossus is a genus of herbivorous lithostrotian titanosaur sauropod dinosaur from late Cretaceous strata of Mendoza Province, Argentina.
In 2016, the type species Notocolossus gonzalezparejasi was named and described by Bernardo J. Gonzбlez Riga, Matthew Carl Lamanna, , Leonardo Daniel Ortiz David, Jorge Orlando Calvo and Juan P. Coria.
The evidence suggests that Notocolossus was among the largest titanosaurs, and therefore one of the heaviest land animals, yet discovered. Although the incompleteness of the skeleton of the new sauropod has prevented scientists from making precise estimates of its size, its humerus, or upper arm bone, is 1.76 m (5 ft 9 in) in length, which is longer than that of any other titanosaur for which this bone is known, including other giants such as Dreadnoughtus, Futalognkosaurus, and Paralititan. If, as is likely, the body proportions of Notocolossus were comparable to those of better preserved titanosaurs, the new dinosaur may have weighed in the range of 44.9–75.9 tonnes (44.2–74.7 long tons; 49.5–83.7 short tons), most likely 60.4 tonnes (59.4 long tons; 66.6 short tons)
In 2016, several distinguishing traits of Notocolossus were determined. Nine of these were autapomorphies, unique derived qualities. At the anterior back vertebra, the depression between the front edge of the side process and the lower edge of the side process is divided by two accessory ridges, one of which runs vertically while the other crosses the first horizontally. On the front side of the neural spines of the front tail vertebrae, run vertical ridges fusing at their lower ends, above the level of the front joint processes, creating a V-shaped structure. The upper inner corner of the humerus is strongly expanded, extending far beyond the inner side of the shaft. The humerus has in general a strongly expanded upper edge, 2.9 wider than the shaft diameter. On the humerus shaft, below the scar for the musculus coracobrachialis, runs a diagonal ridge, from the upper and outer side to the inner and lower side. The first metatarsal has an upper width exceeding its length. The third metatarsal is relatively short with 1.2 times the length of the first metatarsal. The upper toe phalanges are 50% wider at their tops than their respective metatarsals are long. The toe claws are reduced, rough and truncated.