Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of
sauropod dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thriving at the time of the
extinction event
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
at the end of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
. This group includes some of the largest land animals known to have ever existed, such as ''
Patagotitan
''Patagotitan'' is a genus of titanosaurian sauropod dinosaur from the Cerro Barcino Formation in Chubut Province, Patagonia, Argentina. The genus contains a single species known from multiple individuals: ''Patagotitan mayorum'', first announc ...
''—estimated at long with a weight of
—and the comparably-sized ''
Argentinosaurus
''Argentinosaurus'' is a genus of giant sauropod dinosaur that lived during the Late Cretaceous period in what is now Argentina. Although it is only known from fragmentary remains, ''Argentinosaurus'' is one of the largest known land animal ...
'' and ''
Puertasaurus
''Puertasaurus'' is a genus of sauropod dinosaur that lived in South America during the Late Cretaceous Period. It is known from a single specimen recovered from sedimentary rocks of the Cerro Fortaleza Formation in southwestern Patagonia, Ar ...
'' from the
same region.
The group's name alludes to the
mythological Titans
In Greek mythology, the Titans ( grc, οἱ Τῑτᾶνες, ''hoi Tītânes'', , ''ho Tītân'') were the pre-Olympian gods. According to the ''Theogony'' of Hesiod, they were the twelve children of the primordial parents Uranus (Sky) and Gai ...
of ancient
Greek mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical co ...
, via the type
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
(now considered a ''
nomen dubium)'' ''
Titanosaurus
''Titanosaurus'' (; ) is a dubious genus of sauropod dinosaurs, first described by Richard Lydekker in 1877.R. Lydekker. (1877). Notices of new and other Vertebrata from Indian Tertiary and Secondary rocks. ''Records of the Geological Survey of I ...
''. Together with the
brachiosaurids and relatives, titanosaurs make up the larger sauropod
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
Titanosauriformes
Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...
. Titanosaurs have long been a poorly-known group, and the relationships between titanosaur species are still not well-understood.
Description
Titanosauria have the largest range of body size of any sauropod clade, and includes both the largest known sauropods and some of the smallest.
One of the largest titanosaurs, ''
Patagotitan
''Patagotitan'' is a genus of titanosaurian sauropod dinosaur from the Cerro Barcino Formation in Chubut Province, Patagonia, Argentina. The genus contains a single species known from multiple individuals: ''Patagotitan mayorum'', first announc ...
'', had a body mass estimated to be , whereas one of the smallest, ''
Magyarosaurus
''Magyarosaurus'' (" Magyar lizard") is a genus of dwarf sauropod dinosaur from late Cretaceous Period (early to late Maastrichtian) in Romania. It is one of the smallest-known adult sauropods, measuring only in length and in body mass. The t ...
'', had a body mass of approximately .
Even relatively closely related titanosaurs could have very different body sizes, as the small rinconsaurs were closely related to the gigantic lognkosaurs.[ Fossils from perhaps the largest dinosaur ever found were discovered in 2021 in the Neuquén Province of northwest Patagonia, Argentina. It is believed that they are from a titanosaur. Some of smallest titanosaurs, such as '']Magyarosaurus
''Magyarosaurus'' (" Magyar lizard") is a genus of dwarf sauropod dinosaur from late Cretaceous Period (early to late Maastrichtian) in Romania. It is one of the smallest-known adult sauropods, measuring only in length and in body mass. The t ...
'', inhabited Europe, which was largely made up of islands during the Cretaceous, and were likely island dwarfs. Another taxon of tiny titanosaurs, '' Ibirania'', lived a non-insular context in Upper Creaceous Brazil, and is an example of nanism resultant from other ecological pressures.
Head and neck
The heads of titanosaurs are poorly known. However, several different cranial morphologies are apparent. In some species, such as ''Sarmientosaurus
''Sarmientosaurus'' is a genus of titanosaurian sauropod dinosaur belonging to the Titanosauria. It lived in what is now South America, specifically Argentina, during the Upper Cretaceous Period about 95 million years ago. The type species is ...
'', the head resembled that of brachiosaurids. In others, such as ''Rapetosaurus
''Rapetosaurus'' ( ) is a genus of titanosaurian sauropod dinosaur that lived in Madagascar from 70 to 66 million years ago, at the end of the Cretaceous Period. Only one species, ''Rapetosaurus krausei'', has been identified.
Like other sauropo ...
'' and ''Nemegtosaurus
''Nemegtosaurus'' (meaning 'Reptile from the Nemegt') was a sauropod dinosaur from the Late Cretaceous Period of what is now Mongolia. It was named after the Nemegt Basin in the Gobi Desert, where the remains — a single skull — were found. ...
'', the head resembled that of diplodocids
Diplodocids, or members of the family Diplodocidae ("double beams"), are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including ''Diplodocus'' and '' Supersaurus'', some of which may ha ...
. In some titanosaurs, the skull was especially diplodocid-like due to square-shaped jaws; the titanosaur ''Antarctosaurus
''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, ''Antarctosaurus wichmannianus'', and a second species, ''Antarctosau ...
'' is especially similar to the rebbachisaurid ''Nigersaurus
''Nigersaurus'' is a genus of rebbachisaurid sauropod dinosaur that lived during the middle Cretaceous period, about 115 to 105 million years ago. It was discovered in the Elrhaz Formation in an area called Gadoufaoua, in Niger. Fossils of th ...
''. Titanosaurs had small heads, even when compared with other sauropods. The head was also wide, similar to the heads of '' Camarasaurus'' and ''Brachiosaurus
''Brachiosaurus'' () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 154to 150million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in th ...
,'' though somewhat more elongated. Titanosaurian nostrils were large ("macronaria
Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...
n") and all had crests formed by the nasal bones. Their teeth were either somewhat spatulate (spoon-like) or like pegs or pencils, but were always very small.
Titanosaur necks were of average length for sauropods, and their tail
The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...
s were whip-like though not as long as in the diplodocids. While the pelvis was slimmer than some sauropods, the pectoral (chest) area was much wider, giving them a uniquely "wide-legged" stance. As a result, the fossilized trackways of titanosaurs are distinctly broader than other sauropods. Their forelimbs were also stocky, and often longer than their hind limbs. Unlike other sauropods, some titanosaurs had no digits, walking only on horseshoe-shaped "stumps" made up of the columnar metacarpal bones.[Apesteguía, S. (2005). "Evolution of the titanosaur metacarpus". Pp. 321–345 in Tidwell, V. and Carpenter, K. (eds.) ''Thunder-Lizards: The Sauropodomorph Dinosaurs''. Indianapolis: Indiana University Press.] Their vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...
e (back bones) were solid (not hollowed-out), which may be a reversal to more basal saurischia
Saurischia ( , meaning "reptile-hipped" from the Greek ' () meaning 'lizard' and ' () meaning 'hip joint') is one of the two basic divisions of dinosaurs (the other being Ornithischia), classified by their hip structure. Saurischia and Ornithis ...
n characteristics. Their spinal column was relatively flexible, likely making them more agile than other sauropods and more able to rear onto their hind legs. One of the most characteristic features shared by most titanosaurs were their procoelous caudal vertebrae, with ball-and-socket articulations between the vertebral centra.
Torso and limbs
The dorsal vertebrae
In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...
of titanosaurs show multiple derived features among sauropods. Similarly to the Rebbachisauridae, titanosaurs lost the , a set of surfaces between vertebrae that prevent additional rotation of the bones. ''Andesaurus
''Andesaurus'' ( ; "Andes lizard") is a genus of basal titanosaurian sauropod dinosaur which existed during the middle of the Cretaceous Period in South America. Like most sauropods, belonging to one of the largest animals ever to walk the Ea ...
'', one of the most basal titanosaurs, shows a normal hyposphene. The same area is reduced in ''Argentinosaurus
''Argentinosaurus'' is a genus of giant sauropod dinosaur that lived during the Late Cretaceous period in what is now Argentina. Although it is only known from fragmentary remains, ''Argentinosaurus'' is one of the largest known land animal ...
'' to only two ridges, and is fully absent in taxa like ''Opisthocoelicaudia
''Opisthocoelicaudia'' is a genus of sauropod dinosaur of the Late Cretaceous Period discovered in the Gobi Desert of Mongolia. The type species is ''Opisthocoelicaudia skarzynskii''. A well-preserved skeleton lacking only the head and neck wa ...
'' and ''Saltasaurus
''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...
''. Both ''Argentinosaurus'' and ''Epachthosaurus
''Epachthosaurus'' (meaning "heavy lizard") was a genus of titanosaurian sauropod dinosaur from the Late Cretaceous. It was a basal lithostrotian titanosaur. Its fossils have been found in Central and Northern Patagonia in South America.
Discov ...
'' bear similar intermediate "hyposphenal ridges", which suggests they represent a more primitive form of dorsal vertebrae.
Sauropod hands already are highly derived from other dinosaurs, being reduced into columnar metacarpal
In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...
s and blocky phalanges with fewer claws. However, titanosaurs evolved the manus even further, completely losing the phalanges and heavily modifying the metacarpals. '' Argyrosaurus'' is the only titanosaur known to possess carpal
The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the ...
s. Other taxa like ''Epachthosaurus'' show a reduction of phalanges to one or two bones. ''Opisthoeoclicaudia'' shows even more reduction of the hand than other titanosaurs, with both carpals and phalanges completely absent. However, ''Diamantinasaurus
''Diamantinasaurus'' is a genus of titanosaurian sauropod from Australia that lived during the early Late Cretaceous, about 94 million years ago. The type species of the genus is ''D. matildae'', first described and named in 2009 in paleontology, ...
'', while lacking carpals, preserves a manual formula of , including a thumb claw and phalanges on all other digits. This, coupled with the preservation of a single phalanx on digit IV of ''Epachthosaurus'' and potentially ''Opisthocoelicaudia'' (further study is necessary), show that preservation biases may be responsible for the lack of hand phalanges in these taxa. This suggests that ''Alamosaurus'', ''Neuquensaurus
''Neuquensaurus'' (meaning "Neuquén lizard") is a genus of saltasaurid sauropod dinosaur that lived in the Late Cretaceous, about 80 million years ago in Argentina and Uruguay in South America. Its fossils were recovered from outcrops of the Ana ...
'', ''Saltasaurus'' and ''Rapetosaurus -'' all known from imperfect or disarticulated remains previously associated with a lack of phalanges - may have had phalanges but lost them after death.
Titanosaurs have a poor fossil record of their pedes (feet), only being complete in five definitive titanosaurs. Among these, ''Notocolossus
''Notocolossus'' is a genus of titanosaurian sauropod dinosaur from late Cretaceous strata of Mendoza Province, Argentina.
Discovery and naming
A fossil of a large sauropod was discovered by the Argentine paleontologist Dr. Bernardo Javier ...
'' is the largest, and also has the most specialized pes: like all titanosaurs, its pes is composed of short, thick metatarsal
The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the me ...
s of approximately the same lengths; however, metatarsals I and V are notably more robust than in other taxa.
Integument
From skin impressions found with fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s, it has been determined that the skin of many titanosaurs was armored
Armour (British English) or armor (American English; see spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, especially direct contact weapons or projectiles during combat, or f ...
with a small mosaic of small, bead-like scales
Scale or scales may refer to:
Mathematics
* Scale (descriptive set theory), an object defined on a set of points
* Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original
* Scale factor, a number w ...
surrounding larger scales. While most titanosaurs were very large animals, many were fairly average in size compared to other giant dinosaurs. Some island-dwelling dwarf titanosaurs, such as ''Magyarosaurus
''Magyarosaurus'' (" Magyar lizard") is a genus of dwarf sauropod dinosaur from late Cretaceous Period (early to late Maastrichtian) in Romania. It is one of the smallest-known adult sauropods, measuring only in length and in body mass. The t ...
'', were probably the result of allopatric speciation
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
and insular dwarfism
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size when their population's range is limited to a small environment, primarily islands. This natural process is disti ...
.
Some titanosaurs had osteoderm
Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinc ...
s. Osteoderms were first confirmed in the genus ''Saltasaurus
''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...
'' but are now known to have been present in a variety of titanosaurs within the clade Lithostrotia. The exact arrangement of osteoderms on the body of a titanosaur is not known, but some paleontologists consider it likely that the osteoderms were arranged in two parallel rows on the animal's back, an arrangement similar to the plates of stegosaurs. Several other arrangements have been proposed, such as a single row along the midline, and it is possible that different species had different arrangements. The osteoderms were certainly far more sparse than those of ankylosaurs, and did not completely cover the back in scutes. Because of their sparse arrangement, it was unlikely that they served a significant role in defense. However, they may have played an important role in nutrient storage for titanosaurs living in highly seasonal climates and for female titanosaurs laying eggs. Osteoderms were present on both large and small species, so they were not solely used by smaller species as protection against predators. New evidence published in 2021 suggests there were indeed some defensive purposes in titanosaur osteoderms; simulated bite marks from both baurusuchid crocodiles and abelisaurids on titanosaurid osteoderms suggest they could be useful for protecting the animals in addition to functioning in mineral storage.
Classification
Titanosaurs are classified as sauropod dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s. This highly diverse group forms the dominant clade of Cretaceous sauropods. Within Sauropoda, titanosaurs were once classified as close relatives of Diplodocidae
Diplodocids, or members of the family Diplodocidae ("double beams"), are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including ''Diplodocus'' and ''Supersaurus'', some of which may have ...
due to their shared characteristic of narrow teeth, but this is now known to be the result of convergent evolution. Titanosaurs are now known to be most closely related to euhelopodids and brachiosaurids; together they form a clade named Titanosauriformes.
For much of the 20th century, most known species of titanosaurs were classified in the family Titanosauridae, which is no longer in widespread use.[ Titanosauria was first proposed in 1993 as a taxon to encompass titanosaurids and their close relatives.][ It has been phylogenetically defined as the clade composed of the most recent common ancestor of '']Saltasaurus
''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...
'' and ''Andesaurus
''Andesaurus'' ( ; "Andes lizard") is a genus of basal titanosaurian sauropod dinosaur which existed during the middle of the Cretaceous Period in South America. Like most sauropods, belonging to one of the largest animals ever to walk the Ea ...
'' and all of its descendants. The relationships of species within Titanosauria remain largely unresolved, and it is considered one of the most poorly-understood areas of dinosaur classification. One of the few areas of agreement is that the majority of titanosaurs except ''Andesaurus'' and some other basal species form a clade called Lithostrotia
Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch ''et al.'' in 2004 as the most recent common ancestor of '' Malawisaurus'' and '' Saltasaurus'' ...
, which some researchers consider equivalent to the deprecated Titanosauridae. Lithostrotians include titanosaurs such as ''Alamosaurus'', ''Isisaurus'', ''Malawisaurus'', ''Rapetosaurus'', and ''Saltasaurus''.
Early history
''Titanosaurus indicus
''Titanosaurus'' (; ) is a dubious genus of sauropod dinosaurs, first described by Richard Lydekker in 1877.R. Lydekker. (1877). Notices of new and other Vertebrata from Indian Tertiary and Secondary rocks. ''Records of the Geological Survey of ...
'' was first named by British paleontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
Richard Lydekker
Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history.
Biography
Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker, ...
in 1877, as a new taxon of dinosaur based on two caudals and a femur collected on different occasions at the same location in India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. While it was later given a position as a sauropod within Cetiosauridae
Cetiosauridae is a family of sauropod dinosaurs which was first proposed by Richard Lydekker in 1888. While traditionally a wastebasket taxon containing various unrelated species, some recent studies have found that it may represent a natural c ...
by Lydekker in 1888, he named the new sauropod family Titanosauridae
Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch ''et al.'' in 2004 as the most recent common ancestor of ''Malawisaurus'' and ''Saltasaurus'' an ...
for the genus in 1893, which included only ''Titanosaurus'' and '' Argyrosaurus'', united by caudals, presacrals, a lack of pleurocoels and open chevrons. Following this, Austro-Hungarian paleontologist Franz Nopcsa Franz may refer to:
People
* Franz (given name)
* Franz (surname)
Places
* Franz (crater), a lunar crater
* Franz, Ontario, a railway junction and unorganized town in Canada
* Franz Lake, in the state of Washington, United States – see ...
reviewed reptile genera in 1928, and provided a short classification of Sauropoda, where he placed the Titanosaurinae (a reranking of Lydekker's Titanosauridae) in Morosauridae
Camarasauridae is a family of sauropod dinosaurs. Among sauropods, camarasaurids are small to medium-sized, with relatively short necks. They are visually identifiable by a short skull with large nares, and broad, spatulate teeth filling a thic ...
, and included the genera ''Titanosaurus'', ''Hypselosaurus
''Hypselosaurus'' (meaning 'highest lizard', from Greek meaning 'high' or 'lofty' and meaning 'lizard') is a dubious genus of titanosaurian sauropod that lived in southern France during the Late Cretaceous, approximately 70 million years ago in ...
'' and '' Macrurosaurus'' because they all had strongly procoelous caudals. German paleontologist Friedrich von Huene provided a significant revision of Titanosauridae the following year in 1929, where he reviewed the dinosaurs of Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
, and named multiple new genera. Huene included multiple species of ''Titanosaurus'' from India, England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
, France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, Romania
Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...
, Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
and Argentina, ''Hypselosaurus'' and '' Aepisaurus'' from France, ''Macrurosaurus'' from England, '' Alamosaurus'' from United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, and ''Argyrosaurus'', ''Antarctosaurus
''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, ''Antarctosaurus wichmannianus'', and a second species, ''Antarctosau ...
'', and '' Laplatasaurus'' from Argentina. The material between them represented almost all regions of the skeleton, which showed they were derived sauropods Huene interpreted as closest to '' Pleurocoelus'' of the various non-titanosaurid genera.
For his 1986 thesis, Argentinian paleontologist Jaime Powell described and classified many new genera of South American titanosaurs. Using the family Titanosauridae to include them all, he grouped the genera into Titanosaurinae, Saltasaurinae
Saltasaurinae is a subfamily of titanosaurian sauropods known from the late Cretaceous period of South America, India and Madagascar.
Description
Saltasaurines are relatively small sauropods with the general body shape of a small head, long ne ...
, Antarctosaurinae, Argyrosaurinae and Titanosauridae indet. Titanosaurinae included ''Titanosaurus'' and the new genus ''Aeolosaurus
''Aeolosaurus'' (; "Aeolus' lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck and tail. ''Aeolos ...
'', united by multiple features of the caudal vertebrae; the new clade Saltasaurinae was created to include ''Saltasaurus
''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...
'' and the new genus ''Neuquensaurus
''Neuquensaurus'' (meaning "Neuquén lizard") is a genus of saltasaurid sauropod dinosaur that lived in the Late Cretaceous, about 80 million years ago in Argentina and Uruguay in South America. Its fossils were recovered from outcrops of the Ana ...
'', united by very distinct dorsals, caudals, and ilia; the new clade Antarctosaurinae was created to include ''Antarctosaurus'', distinguished by large size, a different form of braincase, more elongate girdle bones, and more robust limb bones; and Argyrosaurinae was created for ''Argyrosaurus'', bearing a more robust forelimb and hand and more primitive dorsals. The new genus ''Epachthosaurus
''Epachthosaurus'' (meaning "heavy lizard") was a genus of titanosaurian sauropod dinosaur from the Late Cretaceous. It was a basal lithostrotian titanosaur. Its fossils have been found in Central and Northern Patagonia in South America.
Discov ...
'' was named for a more basal titanosaurid classified as Titanosauridae indet. along with unnamed specimens, '' Clasmodosaurus'' and ''Campylodoniscus
''Campylodoniscus'' is a genus of titanosaur sauropod dinosaur from the Late Cretaceous Period of what is now Argentina.
The type species was first named and described by Friedrich von Huene in 1929 as ''Campylodon ameghinoi'', the genus name ...
''.
John Stanton McIntosh
John is a common English name and surname:
* John (given name)
* John (surname)
John may also refer to:
New Testament
Works
* Gospel of John, a title often shortened to John
* First Epistle of John, often shortened to 1 John
* Second ...
provided a synopsis of sauropod relationships in 1990, using Titanosauridae as the group to contain all taxa like previous authors. ''Opisthocoelicaudia'' was placed in Opisthocoelicaudiinae within Camarasauridae
Camarasauridae is a family of sauropod dinosaurs. Among sauropods, camarasaurids are small to medium-sized, with relatively short necks. They are visually identifiable by a short skull with large nares, and broad, spatulate teeth filling a thick ...
, following its original description and not later works, and ''Nemegtosaurus
''Nemegtosaurus'' (meaning 'Reptile from the Nemegt') was a sauropod dinosaur from the Late Cretaceous Period of what is now Mongolia. It was named after the Nemegt Basin in the Gobi Desert, where the remains — a single skull — were found. ...
'' and '' Quaesitosaurus'' were placed within Dicraeosaurinae. Titanosauridae included many previously named genera, plus taxa like ''Tornieria
''Tornieria'' ("for Tornier") is a genus of diplodocid sauropod dinosaur from the Late Jurassic in Lindi Region of Tanzania. It has a convoluted taxonomic history.
Discovery and naming
In 1907, German paleontologist Eberhard Fraas who wa ...
'' and ''Janenschia
''Janenschia'' (named after Werner Janensch) is a large herbivorous sauropod dinosaur from the Late Jurassic Tendaguru Formation of Lindi Region, Tanzania around 155 million years ago.
Discovery and naming
''Janenschia'' has had a convolut ...
''. ''Saltasaurus'' included the species previously known as ''Titanosaurus australis'' and ''T. robustus'', which were named ''Neuquensaurus'' by Powell in 1986. McIntosh provided a large diagnosis of the family: "dorsals with irregularly shaped pleurocoels and spines directed strongly backward; transverse processes directed dorsally as well as laterally, very robust in shoulder region; a second dorsosacral, its rib fused to ilium; caudals strongly procoelous with a prominent ball on distal end of centrum throughout tail; caudal arches on front half of centrum; sternal plates large; preacetabular process of ilium swept outward to become almost horizontal", but stressed that the relationships of titanosaurids to other sauropod groups couldn't be determined due to a lack of cranial material.
A brief review of putative titanosaurids from Europe was authored by Jean Le Loeuff
Jean may refer to:
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* Jean ...
in 1993, and covered the supposed genera known so far. The Barremian
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is precede ...
(middle Early Cretaceous) species ''Titanosaurus valdensis'', named decades previous by Huene, was kept as the oldest of the titanosaurid and given the new genus name ''Iuticosaurus
''Iuticosaurus'' (meaning " Jute lizard") is a genus of titanosaur sauropod dinosaur from the Early Cretaceous of the Isle of Wight. Two species have been named: ''I. valdensis'' and ''I. lydekkeri''. ''I. valdensis'' was found in the Wessex For ...
''. The French taxon ''Aepisaurus'' was removed from the family and placed in undetermined Sauropoda. ''Macrurosaurus'' was considered a chimaera of titanosaurid and non-titanosaurid material because of the presence of both procoelous and caudals. Huene's species ''Titanosaurus lydekkeri'' was left as a nomen dubium, but left within Titanosauridae. Maastrichtian
The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...
fossils from France and Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, i ...
were removed from ''Hypselosaurus'' and ''Titanosaurus'', with ''Hypselosaurus'' being declared dubious like ''T. lydekkeri''. The variety of Romanian fossils named as ''Magyarosaurus'' by Huene were also moved into the same species again, ''M. dacus'' as originally named by Nopcsa.
Titanosauria named
José Bonaparte and Rodolfo Coria in 1993 concluded that a new clade of derived sauropods was necessary because ''Argentinosaurus
''Argentinosaurus'' is a genus of giant sauropod dinosaur that lived during the Late Cretaceous period in what is now Argentina. Although it is only known from fragmentary remains, ''Argentinosaurus'' is one of the largest known land animal ...
'', ''Andesaurus'' and ''Epachthosaurus'' were distinct from Titanosauridae as they possessed , but were still very closely related to the titanosaurids. The taxa that possessed the articulations were united within the new family Andesauridae, and the two families were grouped together within the new clade Titanosauria. The titanosaurs were diagnosed by possessing small centered within an anteroposteriorly elongate depression and the presence of two well defined depressions on the posterior face of the neural arch. The entire group was compared favourably with cetiosaurids like ''Patagosaurus
''Patagosaurus'' (meaning "Patagonia lizard") is an extinct genus of eusauropod dinosaur from the Middle-Late Toarcian of Patagonia, Argentina. It was first found in deposits of the Cañadón Asfalto Formation, which date to around 179 to 177&n ...
'' and ''Volkheimeria
''Volkheimeria'' is an extinct genus of sauropod dinosaurs that lived in what is now Argentina during the Early Jurassic, 178–179 million years ago. Its type and only species is ''Volkheimeria chubutensis''.
Discovery and naming
The only kn ...
''.
Overlooking the naming of Titanosauria, Paul Upchurch
Paul may refer to:
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Christianity
* Paul the Apostle (AD c.5–c.64/65), also known as Saul of Tarsus or Saint Paul, early Chri ...
in 1995 named the clade Titanosauroidea, to include ''Opisthocoelicaudia
''Opisthocoelicaudia'' is a genus of sauropod dinosaur of the Late Cretaceous Period discovered in the Gobi Desert of Mongolia. The type species is ''Opisthocoelicaudia skarzynskii''. A well-preserved skeleton lacking only the head and neck wa ...
'' and the more derived Titanosauridae (''Malawisaurus
''Malawisaurus'' (meaning "Malawi lizard") is an extinct genus of titanosaurian sauropod dinosaur. It is known from the Dinosaur Beds of northern Malawi, which probably date to the Aptian stage of the Early Cretaceous. The type species is ''M. di ...
'', '' Alamosaurus'' and ''Saltasaurus
''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...
''). United by: caudals with anteriorly-shifted neural spines, extremely robust forearm bones, a prominent concavity on the ulna
The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...
for articulation with the humerus, a laterally flared and flattened ilium, and a less robust pubis; Upchurch considered the clade sister taxon to Diplodocoidea
Diplodocoidea is a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like '' Supersaurus'', ''Diplodocus'', ''Apatosaurus'', and '' Amphicoelias''. Most had very long necks and lo ...
, because of their shared dental anatomy, although he noted that peg-like teeth might have been independently evolved. This was followed up by Upchurch's 1998 study on sauropod phylogenetics, which additionally recovered ''Phuwiangosaurus
''Phuwiangosaurus'' (meaning "Phu Wiang lizard") is a genus of titanosaur dinosaur from the Early Cretaceous (Valanginian-Hauterivian) Sao Khua Formation of Thailand. The type species, ''P. sirindhornae'', was described by Martin, Buffetaut, and ...
'' and ''Andesaurus'' within Titanosauroidea and resolved ''Opisthocoelicaudia'' as the sister of ''Saltasaurus'' instead of the most basal titanosauroid. This result places Titanosauroidea in a group with '' Camarasaurus'' and ''Brachiosaurus
''Brachiosaurus'' () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 154to 150million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in th ...
'', although Nemegtosauridae (''Nemegtosaurus
''Nemegtosaurus'' (meaning 'Reptile from the Nemegt') was a sauropod dinosaur from the Late Cretaceous Period of what is now Mongolia. It was named after the Nemegt Basin in the Gobi Desert, where the remains — a single skull — were found. ...
'' and '' Quaesitosaurus'') was still classified as the basalmost family of diplodocoids. Upchurch chose to use Titanosauroidea as a replacement name for Titanosauria due to the recommended use of Linnean taxonomy
Linnaean taxonomy can mean either of two related concepts:
# The particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his ''Systema Naturae'' (1735) and subsequent works. In the taxonomy of Linnaeus t ...
and ranks.
In 1997, Leonardo Salgado ''et al.'' published a phylogenetic study on Titanosauriformes
Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...
, including relationships within Titanosauria. They provided a definition for the clade of "including the most recent common ancestor of ''Andesaurus delgadoi'' and Titanosauridae and all of its descendants". Titanosauria resolved including the same two subclades as Bonaparte & Coria (1993), where Andesauridae was monotypic, only including the name genus, and Titanosauridae was all other titanosaurs. Titanosauria was additionally rediagnosed, with eye-shaped pleurocoels, forked infradiapophyseal , centro-parapophyseal laminae, procoelous anterior caudals, and a significantly longer pubis than ischium. Titanosauridae was less strongly defined because of the polytomy between ''Malawisaurus'' and ''Epachthosaurus'', so some diagnostic features couldn't be resolved. Saltasaurinae was defined as the most recent ancestor of ''Neuquensaurus'', ''Saltasaurus'' and its descendants, and diagnosed by short cervical , vertically compressed anterior caudals, and a posteriorly shifted anterior caudal neural spine.
Contributing additional work to the systematics of titanosaurs, Spanish paleontologist José Sanz ''et al.'' published an additional study in 1999, utilizing both the names Titanosauria and Titanosauroidea in displaying their results. Similar to Upchurch (1995), Sanz ''et al.'' recovered ''Opisthocoelicaudia'' as a titanosauroid outside Titanosauria, while Titanosauria was redefined to include only the taxa classified by their study. Eutitanosauria
Eutitanosauria is a clade of titanosaurs, encompassing the more derived members of the group and characterized by the absence of the hyposphene-hypantrum articulation and possibly the presence of osteoderms. The group was first named by Sanz and ...
was proposed as a name for the titanosaurs more derived than ''Epachthosaurus'', and noted the presence of osteoderms
Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amphi ...
as a probable synapomorphy
In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ...
of this clade. ''Aeolosaurus'', ''Alamosaurus'', ''Ampelosaurus
''Ampelosaurus'' ( ; meaning "vine lizard") is a titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now France. Its type species is ''A. atacis'', named by Le Loeuff in 1995. A possible unnamed species has given ''Ampel ...
'' and ''Magyarosaurus
''Magyarosaurus'' (" Magyar lizard") is a genus of dwarf sauropod dinosaur from late Cretaceous Period (early to late Maastrichtian) in Romania. It is one of the smallest-known adult sauropods, measuring only in length and in body mass. The t ...
'' were looked at using their character list, but were considered too incomplete to add to the final study.
Argentinian paleontologist Jaime Powell published his 1986 thesis in 2003, with revisions to bring his old work up to date, including the addition of more phylogenetics and the recognition of Titanosauria as a clade name. Using the datamatrix of Sanz ''et al.'' (1999) and modifying it to include additional taxa and some character changes, Powell found that titanosaurs formed mostly a single gradual radiation beginning with ''Epachthosaurus'' as the most basal titanosaur, and ''Ampelosaurus
''Ampelosaurus'' ( ; meaning "vine lizard") is a titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now France. Its type species is ''A. atacis'', named by Le Loeuff in 1995. A possible unnamed species has given ''Ampel ...
'' and ''Isisaurus
''Isisaurus'' (named after the Indian Statistical Institute) is a genus of titanosaurian dinosaur from the Late Cretaceous Lameta Formation of India. The genus contains a single species, ''Isisaurus colberti''.
Discovery and Naming
The type spe ...
'' as the most derived. Titanosauroidea (following Upchurch 1995), was distinguished by pre- and post-spinal laminae in anterior caudals, a laterally flared ilium, a lateral expansion of the upper femur, and strongly opisthocoelous posterior dorsals. Less inclusive, Titanosauria was diagnosed by horizontally facing dorsal , prominent procoelous anterior caudals, and a ridge on the sternal plates. Within Titanosauria, Eutitanosauria was characterized by the absence of a hyposphene-hypantrum, no femoral fourth trochanter, and osteoderms. A small clade of ''Alamosaurus'', ''Lirainosaurus
''Lirainosaurus'' (meaning "slender lizard"; from the Basque ''lirain'', meaning "slender", and the Greek ''sauros'', meaning "lizard")is a genus of titanosaur sauropod which lived in what is now Spain. The type species, ''Lirainosaurus astibiae ...
'' and the "Peirópolis titanosaur" ('' Trigonosaurus'') was resolved, and diagnosed by only a rotation of the tibia so the proximal end is perpendicular to the distal end. More derived clades, while resolved, were only weakly supported, or characterized by reversions of diagnostic traits of larger groups (below and left).
Powell (2003)
Curry-Rogers & Forster (2001)
''Rapetosaurus
''Rapetosaurus'' ( ) is a genus of titanosaurian sauropod dinosaur that lived in Madagascar from 70 to 66 million years ago, at the end of the Cretaceous Period. Only one species, ''Rapetosaurus krausei'', has been identified.
Like other sauropo ...
'' was described in 2001 by Kristina Curry-Rogers and Catherine Forster
Catherine Ann Forster is an American paleontologist, taxonomist and expert in ornithopod evolution and ''Triceratops
''Triceratops'' ( ; ) is a genus of herbivorous chasmosaurine ceratopsid dinosaur that first appeared during the late ...
, who additionally provided a new phylogenetic analysis of Titanosauriformes
Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...
(above and right). Titanosauria was strongly supported, distinguished by up to 20 characters depending on unknown traits in basal taxa. Similarly, Saltasaurinae was characterised by up to 16 traits, and the clade of ''Rapetosaurus'' and related taxa possessed four unique features. ''Nemegtosaurus'' and ''Quaesitosaurus'' were resolved within Titanosauria for the first time, after being placed in Diplodocoidea by multiple other analyses, because ''Rapetosaurus'' provided the first significant titanosaur cranial material with associated postcrania. All three genera were resolved in a clade together, although Curry-Rogers & Forster noted that it was possible the group was only resolved because no other titanosaurs had comparable cranial material. ''Opisthocoelicaudia'' was also nested deeply in Saltasaurinae, though a further investigation of titanosaur interrelationships was proposed.
American paleontologist Jeff Wilson presented another revision of overall sauropod phylogeny in 2002, resolving strong support for most groups, and a similar result to Upchurch (1998) although with ''Euhelopus
''Euhelopus'' is a genus of sauropod dinosaur that lived between 145 and 133 million years ago during the Berriasian and Valanginian stages of the Early Cretaceous in what is now Shandong Province in China. It was a large quadrupedal herbivore. U ...
'' closest to titanosaurs instead of outside Neosauropoda
Neosauropoda is a clade within Dinosauria, coined in 1986 by Argentine paleontologist José Bonaparte and currently described as ''Saltasaurus loricatus'', ''Diplodocus longus'', and all animals directly descended from their most recent common ...
. More internal clades were resolved for Titanosauria, with ''Nemegtosaurus'' and ''Rapetosaurus'' united within Nemegtosauridae, and Saltasauridae including two subfamilies, Opisthocoelicaudiinae and Saltasaurinae. Saltasauridae was defined as a node-stem triplet, where everything descended from the common ancestor of ''Opisthocoelicaudia'' and ''Saltasaurus'' was within Saltasauridae, and the subfamilies Saltasaurinae and Opisthocoelicaudiinae were for every taxon on one branch of the saltasaurid tree or the other.
Wilson and Paul Upchurch followed this study up in 2003 with a significant revision of the type genus ''Titanosaurus'', and revisited all the material that had been assigned to the genus while reviewing titanosaur inter-relationships. Because they found ''Titanosaurus'' to be a dubious name, they proposed that Linnaean-named groups Titanosauridae and Titanosauroidea should be considered invalid as well. Wilson & Upchurch (2003) supported the definition of Salgado ''et al.'' (1997) for Titanosauria, since it was oldest and most similar to the original content of the group when named by Bonaparte & Coria (1993). Lithostrotia
Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch ''et al.'' in 2004 as the most recent common ancestor of '' Malawisaurus'' and '' Saltasaurus'' ...
(Upchurch ''et al.'' 2004) was defined to be ''Malawisaurus
''Malawisaurus'' (meaning "Malawi lizard") is an extinct genus of titanosaurian sauropod dinosaur. It is known from the Dinosaur Beds of northern Malawi, which probably date to the Aptian stage of the Early Cretaceous. The type species is ''M. di ...
'' and all more derived titanosaurs, and the clade Eutitanosauria
Eutitanosauria is a clade of titanosaurs, encompassing the more derived members of the group and characterized by the absence of the hyposphene-hypantrum articulation and possibly the presence of osteoderms. The group was first named by Sanz and ...
(Sanz ''et al.'' 1999) was considered a possible synonym of Saltasauridae. Wilson & Upchurch (2003) presented a reduced cladogram of Titanosauria, including only the most commonly-analyzed taxa from previous studies, resulting in a tree similar to that of Wilson (2002) but with ''Rapetosaurus'' and ''Nemegtosaurus'' excluded and ''Epachthosaurus'' included. ''Alamosaurus'' and ''Opisthocoelicaudia'' were united within Opisthocoelicaudiinae, ''Neuquensaurus'' and ''Saltasaurus'' formed Saltasaurinae, and ''Isisaurus'' placed as the next most derived titanosaurid.
At the same time as Wilson & Upchurch redescribing the species of ''Titanosaurus'', Saldago (2003) looked over the potential invalidity of the family Titanosauridae and redefined the internal clades of Titanosauria. Titanosauria was defined as more inclusive than Titanosauroidea, contrasting with earlier used by Upchurch (1995) and Sanz ''et al.'' (1999), as all taxa in Somphospondyli
Somphospondyli is an extinct clade of titanosauriform sauropods that lived from the Late Jurassic until the end of the Late Cretaceous, comprising all titanosauriforms more closely related to Titanosauria proper than Brachiosauridae. The remains ...
closer to ''Saltasaurus'' than ''Euhelopus
''Euhelopus'' is a genus of sauropod dinosaur that lived between 145 and 133 million years ago during the Berriasian and Valanginian stages of the Early Cretaceous in what is now Shandong Province in China. It was a large quadrupedal herbivore. U ...
''. In order to create additional stability, Saldago also defined Andesauroidea for only ''Andesaurus'', as every titanosaur closer to that genus than ''Saltasaurus'', and also it's opposite Titanosauroidea as every titanosaur closer to ''Saltasaurus'' than ''Andesaurus''. Next most inclusive, Salgado revitalised Titanosauridae to include everything descended from the ancestor of ''Epachthosaurus'' and ''Saltasaurus'', and to replace the node-stem triplet of Saltasauridae, defined the clades Epachthosaurinae and Eutitanosauria as ''Epachthosaurus''>''Saltasaurus'' and ''Saltasaurus''<''Epachthosaurus'' respectively. Saltasaurinae and Opisthocoelicaudiinae were retained with their original definitions, but Lithostrotia was considered a synonym of Titanosauridae, and Titanosaurinae was considered a paraphyletic clade of unrelated titanosaurids.
Following the clade definitions proposed in previous Salgado studies, Bernardo González-Riga published two papers in 2003 describing new taxa in Titanosauria: '' Mendozasaurus'', and '' Rinconsaurus'' (with Jorge O. Calvo
Jorge Orlando Calvo (27 April 1961 – 10 January 2023) was an Argentine geologist and paleontologist working for "Centro de Investigaciones Paleontológicas Lago Barreales" (National University of Comahue).
Dr. Jorge Orlando Calvo was born in ...
). In both studies, the new taxa formed clades within Titanosauridae, although neither were named, and new diagnostic features were proposed for the family. For ''Mendozasaurus'', the new genus grouped with ''Malawisaurus'' as basal within Titanosauridae, but because of the features of caudal vertebrae in these basal taxa, González-Riga recommended revising the diagnosis of the family, instead of changing the content. The situation of caudals in ''Rinconsaurus'' also suggested procoelous caudals were no longer diagnostic, because in the tail of ''Rinconsaurus'' the vertebrae regularly changed their articular surfaces, being from procoelous caudals interspersed with amphicoelous, opisthocoelous and biconvex vertebrae. ''Rinconsaurus'' was then included in Aeolosaurini, a clade named the following year by Aldirene Franco-Rosas ''et al.'' containing everything closer to ''Aeolosaurus'' and ''Gondwanatitan'' than ''Saltasaurus'' or ''Opisthocoelicaudia''. Only the three genera and various intermediate specimens were included in Aeolosaurini in their 2004 paper, with the tribe being considered to be within Saltasaurinae.
The second edition of ''The Dinosauria
''The Dinosauria'' is an extensive book on dinosaurs, compiled by David B. Weishampel, Peter Dodson, and Halszka Osmólska. It has been published in 2 editions, with the first edition published in 1990, consisting of material from 23 scientists.B ...
'', published in 2004, included newly described titanosaurs and other taxa reidentified as titanosaurs. Written by Upchurch, Paul Barrett
Paul Franklyn "Legs" Barrett (14 December 1940 – 20 January 2019) was a UK agent and manager of 1950s style Rock and Roll artistes, an author and previously a singer, songwriter and film actor. Barrett is the discoverer, mentor and first ma ...
and Peter Dodson
Peter Dodson (born August 20, 1946) is an American paleontologist who has published many papers and written and collaborated on books about dinosaurs. An authority on Ceratopsians, he has also authored several papers and textbooks on hadrosaurs a ...
, a review of Sauropoda included a more expansive Titanosauria for sauropods more derived than brachiosaurids. Titanosauria, defined as everything closer to ''Saltasaurus'' than ''Brachiosaurus
''Brachiosaurus'' () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 154to 150million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in th ...
'', included a very large variety of taxa, and the new clade Lithostrotia
Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch ''et al.'' in 2004 as the most recent common ancestor of '' Malawisaurus'' and '' Saltasaurus'' ...
was named for a large number of more derived taxa, although Nemegtosauridae was placed in Diplodocoidea following earlier publications of Upchurch. Lithostrotia adopted the distinguishing feature of strongly procoelous caudals, previously used for Titanosauria.
New phylogenetic frameworks
In 2005, Curry-Rogers proposed a new phylogenetic analysis that focused on the inter-relationships of Titanosauria and included the most expansive character and taxon list of any study before it. 364 characters were selected from all previous phylogenetic analyses and scored across 29 probable titanosaurs, ranging from the Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987.
In European lithostratigraphy, the name ...
African ''Janenschia'' to the large variety of Late Cretaceous global genera. Proposing her analysis as the basis for a new phylogenetic framework of Titanosauria, Curry-Rogers recommended only using named for clades that were very strongly supported. For the strict consensus, every taxon more derived than ''Brachiosaurus'' was in an unresolved polytomy except for a clade of ''Rapetosaurus'' and ''Nemegtosaurus'', and one of Saltasaurinae. Within the recommended results, she only named Titanosauria, Lithostrotia, Saltasauridae, Saltasaurinae and Opisthocoelicaudiinae, because of the weakness of support (below and left).
Curry-Rogers (2005)
Carballido ''et al.'' (2017)
Another form of composite matrix was created by Calvo, González-Riga and Juan Porfiri in 2007, based upon multiple previous studies between 1997 and 2003. The final analysis included 15 titanosaurs and 65 characters, and the typical titanosaur subclades were resolved, Titanosauridae being used over Lithostrotia following Salgado (2003), and the new clade Rinconsauria for the clade of '' Rinconsaurus'' and '' Muyelensaurus''. The new clade (defined as ''Rinconsaurus'' and ''Muyelensaurus'') was placed as the sister taxon of Aeolosaurini, which together grouped with ''Rapetosaurus'' as sister to Saltasauridae. In the same year, Calvo ''et al.'' published another paper, describing the basal titanosaur '' Futalognkosaurus''. The only difference in the resulting phylogeny, based on the matrix of the Calvo, González-Riga & Porfiri (2007), was the addition of ''Futalognkosaurus'' as the sister taxon to '' Mendozasaurus'' in a clade Calvo ''et al.'' named Lognkosauria
Lognkosauria is a clade of giant long-necked sauropod dinosaurs within the clade Titanosauria. It includes some of the largest and heaviest dinosaurs known.
Description
Lognkosaurians can be distinguished from other titanosaurs by the wide and u ...
, defined by the two genera classified within it. A very similar result was also recovered by González-Riga ''et al.'' in 2009 in a phylogenetic analysis based partially on that of Calvo ''et al.'' (2007), although ''Epachthosaurus'' was nested with ''Rapetosaurus'' outside the clades of aeolosaurines. Further updates and modifications were then made by Palbo Gallina & Apesteguía in 2011, with the additions of ''Ligabuesaurus
''Ligabuesaurus'' is a genus of somphospondylan sauropod dinosaur from the Early Cretaceous that lived in what is now Argentina. The type species, ''Ligabuesaurus leanzai'', was described by Jose Bonaparte, Gonzalez Riga, and Sebastián Apeste ...
'', ''Antarctosaurus'', ''Nemegtosaurus'' and '' Bonitasaura'' and character updates to match, bringing the total to 77 characters and 22 taxa. Significantly contrasting the earlier results, internal relationships of Titanosauria were rearranged. ''Malawisaurus'' nested with ''Andesaurus'' in a clade of the basalmost titanosaurs outside Titanosauroidea, where ''Lirainosaurus'', instead of being the basal member of the saltasaur-branch was instead basalmost titanosauroid. Lognkosauria moved to be within rinconsaurs, while Nemegtosauridae was resolved as the sister of ''Aeolosaurus'' and ''Gondwanatitan'', and the rinconsaur-lognkosaur branch. ''Antarctosaurus'' was unstable, but placed in a polytomy with the lognkosaurs and rinconsaurs before being excluded. Saltasaurinae and its relationship with ''Opisthocoelicaudia'' remained the same.
Nemegtosauridae was additionally revised by Hussam Zaher ''et al.'' (2011) with the description of '' Tapuiasaurus'', which nested closer to ''Rapetosaurus'' than ''Nemegtosaurus'', with all three forming a clade of derived lithostrotians. Using the matrix of Wilson (2002), following the additions of a few cranial characters and ''Diamantinasaurus
''Diamantinasaurus'' is a genus of titanosaurian sauropod from Australia that lived during the early Late Cretaceous, about 94 million years ago. The type species of the genus is ''D. matildae'', first described and named in 2009 in paleontology, ...
'', ''Tangvayosaurus
''Tangvayosaurus'' (meaning "Tang Vay lizard") is a genus of sauropod dinosaur from the Aptian-Albian age Lower Cretaceous Gres superieurs Formation of Savannakhet Province, Laos. It was a basal somphospondylan, about 15 m long, and is ...
'' and ''Phuwiangosaurus
''Phuwiangosaurus'' (meaning "Phu Wiang lizard") is a genus of titanosaur dinosaur from the Early Cretaceous (Valanginian-Hauterivian) Sao Khua Formation of Thailand. The type species, ''P. sirindhornae'', was described by Martin, Buffetaut, and ...
'', remained the same as originally found by Wilson but with ''Diamantinasaurus'' sister to Saltasauridae and the other two genera as basal titanosaurs outside Lithostrotia, since Titanosauria, while undefined, was labelled to include all taxa closer to ''Saltasaurus'' than ''Euhelopus
''Euhelopus'' is a genus of sauropod dinosaur that lived between 145 and 133 million years ago during the Berriasian and Valanginian stages of the Early Cretaceous in what is now Shandong Province in China. It was a large quadrupedal herbivore. U ...
''. Following a revision of the skull of ''Tapuiasaurus'', Wilson ''et al.'' ( 2016) rescored the analysis of Zaher ''et al.'' and recovered similar results for everything but Nemegtosauridae, where the family dissolved into a more basal ''Tapuiasaurus'' outside Lithostrota and ''Nemegtosaurus'' outside Saltasauridae. While non-titanosaur phylogeny remained identical in every single result, the topology within Titanosauria was very labile and prone to change with minor adjustments.
Also following the 2002 analysis of Wilson, José Carballido and colleagues published a redescription of ''Chubutisaurus
''Chubutisaurus'' (meaning " Chubut lizard") is a genus of dinosaur from the Early Cretaceous Period. It lived in South America. It is classified as a sauropod, specifically one of the titanosaurs. The type species, ''Chubutisaurus insignis'', w ...
'' in 2011, and utilized an updated Wilson matrix, expanded to 289 characters across 41 taxa, including 15 titanosaurs. The primary focus of the analysis was on the basal titanosauriform taxa, but Titanosauria was defined, as the most recent common ancestor of ''Andesaurus delgadoi'' and ''Saltasaurus loricatus'', and all its descendants, although the only autapomorphy of the group recovered was the absence of a prominent ventral process on the scapula. This same matrix and basis of characters was further utilized and expanded for analyses on '' Tehuelchesaurus'', '' Comahuesaurus'' and related rebbachisaurs, '' Europasaurus'', and '' Padillasaurus'', before being expanded upon once again in 2017 by Carballido ''et al.'' during the description of ''Patagotitan
''Patagotitan'' is a genus of titanosaurian sauropod dinosaur from the Cerro Barcino Formation in Chubut Province, Patagonia, Argentina. The genus contains a single species known from multiple individuals: ''Patagotitan mayorum'', first announc ...
'' to 405 characters and 87 taxa, including 28 titanosaurs (above and right). The definition of Titanosauria was preserved following Salgado ''et al.'' (1997) as ''Andesaurus'' plus ''Saltasaurus''. Eutitanosauria (closer to ''Saltasaurus'' than ''Epachthosaurus'') was resolved as a very inclusive clade composed of two distinct branches, one leading to the larger-bodied lognkosaurs and the other to the smaller-bodied saltasaurs. On the lognkosaur branch of Eutitanosauria, there is a branch of lognkosaurs and one of Rinconsauria. Following Calvo, González-Riga and Porfiri (2007), Rinconsauria was defined as ''Muyelensaurus'' plus ''Rinconsaurus'', and Lognkosauria was defined as ''Mendozasaurus'' plus ''Futalognkosaurus''. Rinconsauria included taxa typically found within Aeolosaurini as well, so Aeolosaurini was redefined as ''Aeolosaurus rionegrinus'' plus ''Gondwanatitan'' to preserve the original restricted content, otherwise the entire rinconsaur-lognkosaur branch would be classified within Aeolosaurini. Lithostrotia, Saltasauridae and Saltasaurinae had their definitions preserved from earlier studies, and included their typical content.
Philip Mannion and colleagues redescribed ''Lusotitan
''Lusotitan'' is a genus of herbivorous brachiosaurid sauropod dinosaur from the Late Jurassic Period of Portugal.
Discovery and naming
In 1947 Manuel de Matos, a member of the Geological Survey of Portugal, discovered large sauropod fossils i ...
'' in 2013
File:2013 Events Collage V2.png, From left, clockwise: Edward Snowden becomes internationally famous for leaking classified NSA wiretapping information; Typhoon Haiyan kills over 6,000 in the Philippines and Southeast Asia; The Dhaka garment fact ...
, creating a new analysis of 279 characters drawn from significant previous analyses by Upchurch and Wilson supplemented by other studies. 63 sauropods were included, focusing on non-titanosaurian sauropods, although 14 probable titanosaurs were included. Unique to Mannion ''et al.'', continuous characters were distinguished in a run of the matrix, which resolved almost all of Somphospondyli
Somphospondyli is an extinct clade of titanosauriform sauropods that lived from the Late Jurassic until the end of the Late Cretaceous, comprising all titanosauriforms more closely related to Titanosauria proper than Brachiosauridae. The remains ...
within Titanosauria because of ''Andesaurus'' placing very basal in a large group of Andesauroidea. Titanosauroidea was tentatively retained as the opposite clade of titanosaurs, which included all other traditional titanosaurs, although it was noted because of the invalidity of ''Titanosaurus'', Titanosauroidea should be considered an invalid name as well. While the original analysis didn't focus on titanosaurs, it was utilised during the descriptions of ''Savannasaurus
''Savannasaurus'' is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Winton Formation of Queensland, Australia. It contains one species, ''Savannasaurus elliottorum'', named in 2016 by Stephen Poropat and colleagues. The holot ...
'' and ''Diamantinasaurus
''Diamantinasaurus'' is a genus of titanosaurian sauropod from Australia that lived during the early Late Cretaceous, about 94 million years ago. The type species of the genus is ''D. matildae'', first described and named in 2009 in paleontology, ...
'', ''Yongjinglong
''Yongjinglong'' is an extinct genus of titanosauriform sauropod dinosaur known from the Early Cretaceous of Lanzhou-Minhe Basin of Gansu Province, China. It contains a single species, ''Yongjinglong datangi''.
Discovery
''Yongjinglong'' wa ...
'', an osteology of ''Mendozasaurus'', and redescribing ''Tendaguria
''Tendaguria'' ( ; meaning "the Tendaguru one") is a genus of herbivorous sauropod dinosaur from the Late Jurassic of Lindi Region, Tanzania.
Discovery and naming
In 1911, German geologist Wilhelm Bornhardt at Nambango in German East Africa di ...
''. From these updates, an analysis of 548 characters and 124 taxa was published by Mannion ''et al.'' in 2019 for a redescription of ''Jiangshanosaurus
''Jiangshanosaurus'' is a genus of herbivorous titanosauriform sauropod dinosaur that lived in China approximately 92-88 million years ago, during the Turonian- Coniacian stage of the Late Cretaceous.
Discovery and naming
In 1977 and 1978 a ...
'' and ''Dongyangosaurus
''Dongyangosaurus'' is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous. The only species is ''Dongyangosaurus sinensis'', from which only a single fragmentary skeleton is known, coming from the Zhejiang province of eastern Chin ...
'', and additional revisions of ''Ruyangosaurus
''Ruyangosaurus'' (Ruyang County lizard) is a genus of titanosauriform sauropod dinosaur recovered from the Early Cretaceous Haoling Formation of China. The type species is ''R. giganteus'', described in 2009 by Lü Junchang ''et al''.
Descri ...
'' were made. No differentiation between continuous and discrete characters was made like performed by Mannion ''et al.'' (2013), but a large clade of Andesauroidea was still resolved with implied weights. Both redescribed Asian taxa, as well as ''Yongjinglong'', previously considered derived titanosaurs related to Saltasauridae, were removed to outside the clade.
In the description of '' Mansourasaurus'', Sallam ''et al.'' (2017) published a phylogenetic analysis of Titanosauria including the most taxa of any analysis of the clade. In an updated version of the analysis, with the taxon ''Mnyamawamtuka
''Mnyamawamtuka'' (pronounced "Mm-nya-ma-wah-mm-too-ka" ; meaning "beast of the Mtuka river drainage" in Kiswahili) is a genus of lithostrotian titanosaur sauropod dinosaur from the Cretaceous Galula Formation in Tanzania. The type and only sp ...
'' added, Gorscak & O'Connor (2019) got similar results, with slightly different relationships within small clades.
Paleobiology
Diet
Fossilized dung associated with late Cretaceous titanosaurids from India has revealed phytoliths, silicified plant fragments, that offer clues to a broad, unselective plant diet. Besides the plant remains that might have been expected, such as cycad
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...
s and conifers, discoveries published in 2005 revealed an unexpectedly wide range of monocotyledon
Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...
s, including palm
Palm most commonly refers to:
* Palm of the hand, the central region of the front of the hand
* Palm plants, of family Arecaceae
**List of Arecaceae genera
* Several other plants known as "palm"
Palm or Palms may also refer to:
Music
* Palm (ba ...
s and grasses (Poaceae
Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...
), including ancestors of rice
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
and bamboo
Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...
, which has given rise to speculation that herbivorous dinosaurs and grasses co-evolved.
Nesting
A large titanosaurid nest
A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materia ...
ing ground was discovered in Auca Mahuevo, in Patagonia
Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and g ...
, Argentina and another colony has reportedly been discovered in Spain. Several hundred female saltasaurs dug holes with their back feet, laid eggs in clutches averaging around 25 eggs each, and buried the nests under dirt and vegetation. The small egg
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
s, about in diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...
, contained fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
ised embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
s, complete with skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...
impressions. The impressions showed that titanosaurs were covered in a mosaic armour of small bead-like scales. The huge number of individuals gives evidence of herd
A herd is a social group of certain animals of the same species, either wild or domestic. The form of collective animal behavior associated with this is called ''herding''. These animals are known as gregarious animals.
The term ''herd'' is ...
behavior, which, along with their armor, could have helped provide protection against large predators such as '' Abelisaurus''.
Range
The titanosaurs were the last great group of sauropods, which existed from about 136 to 66 million years ago
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds.
Usage
Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...
, before the Cretaceous–Paleogene extinction event
The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the ...
, and were the dominant herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s of their time. The fossil evidence suggests they replaced the other sauropods, like the diplodocids and the brachiosaurid
The Brachiosauridae ("arm lizards", from Greek ''brachion'' (βραχίων) = "arm" and ''sauros'' = "lizard") are a family or clade of herbivorous, quadrupedal sauropod dinosaurs. Brachiosaurids had long necks that enabled them to access the le ...
s, which died out between the late Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
and the mid-Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
Periods.
Titanosaurs were widespread. In December 2011, Argentine scientists announced titanosaur fossils had been found on Antarctica—meaning that titanosaur fossils have been found on all continents. They are especially numerous in the southern continents (then part of the supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leav ...
of Gondwana). Australia had titanosaurs around 96 million years ago: fossils have been discovered in Queensland
)
, nickname = Sunshine State
, image_map = Queensland in Australia.svg
, map_caption = Location of Queensland in Australia
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, established_ ...
of a creature around 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 described by Ghilardi et al. (2016). It was found from the Valley of the Dinosaurs
''Valley of the Dinosaurs'' is an American animated television series produced by the Australian studios of Hanna-Barbera Productions and broadcast on CBS from September 7 to December 21, 1974, and in syndication from 1977 to 1983. The series, ab ...
, Paraíba state of Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
, representing a 136-million-year-old subadult individual.
Paleopathology
'' Ibirania'', a nanoid titanosaur fossil from Brazil suggests that individuals of various genera were susceptible to diseases such as osteomyelitis
Osteomyelitis (OM) is an infection of bone. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The long bones of the arms and legs are most commonly involved in children e.g. the femur and humerus, while the ...
and parasite infestations. The specimen hails from the late cretaceous São José do Rio Preto Formation
SAO or Sao may refer to:
Places
* Sao civilisation, in Middle Africa from 6th century BC to 16th century AD
* Sao, a town in Boussé Department, Burkina Faso
* Saco Transportation Center (station code SAO), a train station in Saco, Maine, U. ...
, Bauru Basin, and was described in the journal ''Cretaceous Research'' by Aureliano et al. (2021). Examination of the titanosaur's bones revealed what appear to be parasitic blood worms similar to the prehistoric ''Paleoleishmania
''Paleoleishmania'' is an extinct genus of kinetoplastids, a monophyletic group of unicellular parasitic flagellate protozoa. At present it is placed in the family Trypanosomatidae. The genus contains two species, ''Paleoleishmania neotropicum' ...
'' but are 10-100 times larger, that seemed to have caused the osteomyelitis. The fossil is the first known instance of an aggressive case of osteomyelitis being caused by blood worms in an extinct animal.
References
External links
{{Portal bar, Dinosaurs, Paleontology, Cretaceous
Kimmeridgian first appearances
Maastrichtian extinctions