''Notocolossus'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial no ...
of
titanosaur
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 ...
ian
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 ...
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 ...
from late
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 ...
strata of
Mendoza Province
Mendoza, officially Province of Mendoza, is a province of Argentina, in the western central part of the country in the Cuyo region. It borders San Juan to the north, La Pampa and Neuquén to the south, San Luis to the east, and the republic ...
,
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 ...
.
Discovery and naming
A fossil of a large
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 ...
was discovered by the Argentine paleontologist Dr.
Bernardo Javier González Riga in
Mendoza province
Mendoza, officially Province of Mendoza, is a province of Argentina, in the western central part of the country in the Cuyo region. It borders San Juan to the north, La Pampa and Neuquén to the south, San Luis to the east, and the republic ...
In 2016, the
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...
''Notocolossus gonzalezparejasi'' was named and described by
Bernardo Javier González Riga,
Matthew Carl Lamanna,
Leonardo Daniel Ortiz David,
Jorge Orlando Calvo and Juan P. Coria. The generic name combines the Greek words νότος, ''notos'', "south wind", and κολοσσός, ''kolossos'', "giant statue", in reference to the provenance from the
Southern Hemisphere and the gigantic size of the animal. The
specific name honours
Jorge González Parejas, for having studied the dinosaur fossils of Mendoza province for two decades.
The
holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
, UNCUYO-LD 301, was found in a layer of the
Plottier Formation dating from the
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded ...
-
Santonian, about eighty-six million years old. It consists of a partial skeleton lacking the skull. It contains an anterior back vertebra, an anterior tail vertebra, a right humerus and the upper part of a left pubic bone. Although the bones have not been discovered in articulation, they were considered to represent a single individual because they were found in close association on a surface of eight by eight metres. A second partial skeleton lacking the skull was referred to ''Notocolossus'': specimen UNCUYO-LD 302 representing a smaller individual. It contains a series of five anterior tail vertebrae and a complete right foot connected to an astragalus. It was recovered on a distance of 403 metres to the holotype from a surface of five by five metres.
Description
The evidence suggests that ''Notocolossus'' was among the largest
titanosaur
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 ...
s, 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 in length, which is longer than that of any other titanosaur for which this bone is known, including other giants such as ''
Dreadnoughtus
''Dreadnoughtus'' is a genus of titanosaurian sauropod dinosaur containing a single species, ''Dreadnoughtus schrani''. ''D. schrani'' is known from two partial skeletons discovered in Upper Cretaceous (Campanian to Maastrichtian; approximately ...
'', ''
Futalognkosaurus'', and ''
Paralititan''.They also estimated the total femur length at ,by using an allometric equation. 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 , most likely .
In 2019
Gregory S. Paul
Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod di ...
estimated the mass of ''Notocolossus'' in the 45-55 tonne (49.6-60.6 short tons) range with the possibility that it might have been larger than that or approaching the mass of ''
Argentinosaurus,'' which was estimated at 65-75 tonnes (71.6-82.7 short tons). This claim though, is considered unlikely . In 2020 Molina-Perez and Larramendi estimated its length at and its weight at 40 tonnes (44 short tons).
In 2016, several distinguishing traits of ''Notocolossus'' were determined. Nine of these were
autapomorphies
In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to ...
, 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.
The foot or
pes of ''Notocolossus'', a skeleton part that is not often preserved in sauropods, shows a unique build. It contains a compact, homogeneous
metatarsus
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 ...
, thought to be adapted for bearing extraordinary weight. It also presents truncated
ungual
An ungual (from Latin ''unguis'', i.e. ''nail'') is a highly modified distal toe bone which ends in a hoof, claw, or nail. Elephants and ungulates have ungual phalanges, as did the sauropod
Sauropoda (), whose members are known as sauropods (; ...
s, characteristics otherwise unknown in the Sauropoda. This parallels the vertical position of the metacarpals and the finger reduction in the hand of other titanosaurs.
Phylogeny
''Notocolossus'' belongs to the
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, ...
Titanosauria, a very diverse group of sauropods.
In 2016, a
cladistic
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived c ...
analysis recovered ''Notocolossus'' as a basal member of
Lithostrotia and a
sister species
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 a ...
of ''
Dreadnoughtus
''Dreadnoughtus'' is a genus of titanosaurian sauropod dinosaur containing a single species, ''Dreadnoughtus schrani''. ''D. schrani'' is known from two partial skeletons discovered in Upper Cretaceous (Campanian to Maastrichtian; approximately ...
''.
A 2017 study by Carballido and colleagues recovered it as the sister taxon of
Lognkosauria and found it to be outside of Lithostrotia.
In 2018, González Riga and colleagues found it to belong to
Lognkosauria, in a
polytomy
An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...
with ''
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 annou ...
'' and ''
Puertasaurus''. This analysis also found Longkosauria to belong to
Lithostrotia.
The following
cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...
shows the position of ''Notocolossus'' in
Lognkosauria according to Gonzalez Riga and colleagues, 2018.
Paleoecology
''Notocolossus'' was discovered in the
Plottier Formation of the
Neuquén Group.
This formation is about thick and composed of light red
claystone
Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too s ...
s and thin bands of pink
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
. The Plottier Formation can be differentiated from the overlying
Portezuelo Formation by the former's higher content of
argillite
:''"Argillite" may also refer to Argillite, Kentucky.''
Argillite () is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillaceous rocks are basically lithified muds and oozes. They contain variable amoun ...
.
Tetrapod
Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct ther ...
s of the Plottier formation are poorly known. They are represented by
mammals
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), f ...
, a large
coelurosaur, and several titanosaurs.
These titanosaurs, in addition to ''Notocolossus'', include ''
Petrobrasaurus'', ''"
Antarctosaurus"'' and two additional specimens, one of which appears to be an
aeolosaurine. Additionally ''
Muyelensaurus'' is sometimes stated to come from this formation, although it may actually be from the aforementioned
Portezuelo Formation instead.
See also
*
2016 in paleontology
Flora Plants
Fungi
Cnidarians
Research
* '' Yunnanoascus haikouensis'', previously thought to be a member of Ctenophora, is reinterpreted as a crown-group medusozoan by Han ''et al.'' (2016).
* A study on the fossil corals from the Late Tr ...
References
{{Taxonbar, from1=Q23768183, from2=Q22226944
Lithostrotians
Coniacian life
Santonian life
Late Cretaceous dinosaurs of South America
Fossils of Argentina
Cretaceous Argentina
Neuquén Basin
Fossil taxa described in 2016
†
Taxa named by Matt Lamanna
Taxa named by Rodolfo Coria
Taxa named by Jorge O. Calvo