Lognkosauria is a

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, ...

of giant long-necked

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their bo ...

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 within the

Titanosauria Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

. It includes some of the largest and heaviest dinosaurs known.

Description

Lognkosaurians can be distinguished from other titanosaurs by the wide and unusually thick cervical rib loops on their neck vertebrae, their extremely robust neck neural spines, the relatively narrow neural canal, and their huge vaulted

neural arch 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 characteristic i ...

es. They also had very wide dorsal vertebrae with wing-like side processes, and extremely wide rib cages. Their dorsal side processes are also fairly in-line with the level of the neural canal, instead of being attached further up the neural arch as in

lithostrotians 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 ...

. Skull material from ''

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 ...

'', the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

to Lognkosauria, indicates that lognkosaurians at least began with the big-nosed, rounded head shape of earlier titanosaurs and more basal

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 ...

ns.

Classification

Lognkosauria was defined as the

encompassing the

most recent common ancestor In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The ...

of ''

Futalognkosaurus dukei ''Futalognkosaurus'' ( ; meaning "giant chief lizard") is a genus of titanosaurian dinosaur. The herbivorous ''Futalognkosaurus'' lived approximately 87 million years ago in the Portezuelo Formation, in what is now Argentina, of the Coniacian st ...

'' and ''

Mendozasaurus neguyelap ''Mendozasaurus'' is a genus of titanosaurian sauropod dinosaur. It was a member of Titanosauria, which were massive sauropods that were common on the southern landmasses during the Cretaceous. It is represented by several partial skeletons from ...

'' and all its descendants. ''

'' may be related to this group. Lognkosauria has been found to include other giant sauropods, such as ''

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 ...

'', ''

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 animals o ...

'', ''

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 announce ...

'', ''

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 ...

'', ''

Drusilasaura ''Drusilasaura'' is an extinct genus of possible lognkosaurian titanosaur sauropod dinosaur which lived during the late Cretaceous (Cenomanian-Turonian stage) of Santa Cruz Province of southern Patagonia, Argentina. ''Drusilasaura'' is known fr ...

'' and '' Traukutitan''.

References

{{Portal bar, Dinosaurs, Paleontology, Cretaceous Lithostrotians