''Maxakalisaurus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

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 ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

, found in the

Adamantina Formation The Adamantina Formation is a geological Formation (geology), formation in the Bauru Basin of western São Paulo (state), São Paulo state in southeastern Brazil. Its strata date back to the Late Cretaceous epoch of the Cretaceous, Cretaceous Per ...

of Brazil, in the state of

Minas Gerais Minas Gerais () is one of the 27 federative units of Brazil, being the fourth largest state by area and the second largest in number of inhabitants with a population of 20,539,989 according to the 2022 Brazilian census, 2022 census. Located in ...

in 1998. The genus name is derived from the tribe of the

Maxakali The Maxakali are an ethnic group of indigenous people in Brazil. Geography and ethnology The Maxakali live in the districts of Santa Helena de Minas, Bertópolis, Ladainha, Minas Gerais, Ladainha and Teófilo Otoni in the federal state Minas ...

; Topa is one of their divinities.

Discovery and naming

Over the course of four field seasons, from 1998 to 2002, the

National Museum of Brazil National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, ...

excavated a partial skeleton of a titanosaur along the Campina Verde - Prata road, 45 km to the west of Prata, Minas Gerais. In 2006, a team led by Alexander W. A. Kellner described the remains as a new genus and species of sauropod, ''Maxakalisaurus topai''. The genus name honors the

, an ethnic group indigenous to the region, and the species name refers to the Maxakali deity Topa.

Fossil record

Fossils of ''Maxakalisaurus topai'' are known from the

. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

, MN 5013-V, was housed at the National Museum of Brazil. It included a fragmentary right

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

with teeth, twelve

cervical vertebrae In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In saurop ...

and some cervical ribs, seven dorsal vertebrae and some dorsal ribs, a neural spine and centrum from the

sacrum The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, ...

, six

caudal vertebrae Caudal vertebrae are the vertebrae of the tail in many vertebrates. In birds, the last few caudal vertebrae fuse into the pygostyle, and in apes, including humans, the caudal vertebrae are fused into the coccyx. In many reptiles, some of the caud ...

, some

haemal arches A haemal arch, also known as a chevron, is a bony arch on the ventral side of a tail vertebra of a vertebrate. The canal formed by the space between the arch and the vertebral body is the haemal canal. A spinous ventral process emerging from the ha ...

, pieces of the

scapulae The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

, both sternal plates, part of the left

ischium The ischium (; : is ...

, both humeri, two

metacarpals In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular skeleton, appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones (wrist, wris ...

, part of the

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

, an

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 (extinct amph ...

, and some unidentified pieces. Two other sternal plates and part of a third scapula were also found at the site, and are considered to belong to a second individual. Some of the elements from the type locality pertained to an adult individual and others pertained to a subadult individual. A partial dentary and some teeth were subsequently recovered from the type locality and are also considered to belong to ''M. topai''. Some elements of the holotype were lost in the National Museum of Brazil fire on 2 September 2018, but several elements survived the fire and were recovered.

Description

''Maxakalisaurus'' is considered a medium-sized titanosaur. The type specimen of ''Maxakalisaurus'' belonged to an animal about long, with an estimated weight of . It had a long neck and tail, ridged teeth (unusual among sauropods) and lived about 80

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

. Because sauropods seem to have lacked significant competition in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

, they evolved there with greater diversity and more unusual traits than elsewhere in the world. Like many other titanosaurs, ''Maxakalisaurus'' had osteoderms.

Classification

França ''et al.'''s 2016 description of the second specimen also included a phylogenetic analysis, which placed ''Maxakalisaurus'' as a basal member of the Aeolosaurini. Their cladogram is shown below:

References

* Santucci, R. M. & Bertini, R.J. (2006). "A large sauropod titanosaur from Peirópolis, Bauru Group, Brazil." ''N. Jb. Geol. Paläont. Mh.'', 2006: 344-360; Stuttgart.

External links

Brazil's Biggest Dinosaur Unveiled
- LiveScience.com {{Taxonbar, from=Q134814 Lithostrotia Dinosaur genera Maastrichtian dinosaurs Adamantina Formation Fossil taxa described in 2006 Taxa named by Alexander Kellner Dinosaurs of Brazil