''Ibirania'' (meaning "

Ibirá Ibirá is a municipality in the state of São Paulo, Brazil. The population is 12,518 (2020 est.) in an area of 190 km². Ibirá is known as a tourist resort, due to the thermal waters. Neighboring municipalities * Potirendaba *Cedral *Uchoa *Cata ...

wanderer" or "tree wanderer") is a genus of dwarf saltasaurine

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 th ...

dinosaur from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

(

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. The ...

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...

)

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) of south-east

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 ...

. The type species is ''Ibirania parva''. It is one of the smallest sauropods known to date, comparable in size to the titanosaur ''

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 ...

''.

Discovery and naming

The ''Ibirania''

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 ...

specimen, LPP-PV-0200–0207, was discovered in layers of the São José do Rio Preto Formation on the Garcia Brothers Farm in Vila Ventura, Ibirá Municipality, northeastern

São Paulo State 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.S ...

, which dates to the late

to early

ages of the late Cretaceous period. The holotype consists of a

dorsal vertebra 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 ...

, partial

caudal vertebrae 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 ...

, a fragmentary

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

and

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 ...

, a partial

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 ...

, and a nearly complete

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 med ...

. Additional material, including partial

cervical In anatomy, cervical is an adjective that has two meanings: # of or pertaining to any neck. # of or pertaining to the female cervix: i.e., the ''neck'' of the uterus. *Commonly used medical phrases involving the neck are **cervical collar **cervic ...

, dorsal, and caudal vertebrae, fragments of a fibula, and a nearly complete fibula, was also referred to ''Ibirania''. In 2022, Navarro ''et al''. described ''Ibirania'' as a new genus and species of saltasaurine titanosaur. The generic name, "''Ibirania''", combines a reference to

, the municipality where the specimens were discovered (also a

Portuguese Portuguese may refer to: * anything of, from, or related to the country and nation of Portugal ** Portuguese cuisine, traditional foods ** Portuguese language, a Romance language *** Portuguese dialects, variants of the Portuguese language ** Portu ...

derivative of the

Tupi Tupi may refer to: * Tupi people of Brazil * Tupi or Tupian languages, spoken in South America ** Tupi language, an extinct Tupian language spoken by the Tupi people * Tupi oil field off the coast of Brazil * Tupi Paulista, a Brazilian municipalit ...

word "ybyrá", meaning "tree", in reference to ''Ibirania''s hypothesized browsing behavior), with "ania", a modified form of the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

word "plania", meaning "wanderer". The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, "''parva''", is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word "parvus", meaning "small", after nanism seen in the taxon. The intended name meaning is "little Ibirá wanderer" or "little tree wanderer".

Description

''Ibirania'' is estimated to be only long, making it one of the smallest sauropods. Using computed

tomography Tomography is imaging by sections or sectioning that uses any kind of penetrating wave. The method is used in radiology, archaeology, biology, atmospheric science, geophysics, oceanography, plasma physics, materials science, astrophysics, quantu ...

, Aureliano ''et al''. (2021) discovered highly pneumatized vertebrae in the ''Ibirania'' holotype. Despite the nanoid status of ''Ibirania'', the extreme pneumatization of its axial skeleton was inherited from its giant titanosaurian relatives. The histological thin sections of the vertebral bone revealed the preservation of pneumosteum throughout the internal

trabecula A trabecula (plural trabeculae, from Latin for "small beam") is a small, often microscopic, tissue element in the form of a small beam, strut or rod that supports or anchors a framework of parts within a body or organ. A trabecula generally has ...

e, definitive evidence of the preterit interaction of a bird-like air sac system in the bone.

Classification

''Ibirania'' was a derived member of the

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 ...

, a clade known for encompassing some of the smallest titanosaurs. ''Ibirania'' was recovered as sister taxa of the clade formed by the Patagonian saltasaurines ''

Bonatitan ''Bonatitan'' is a genus of titanosaurian dinosaur from the Late Cretaceous Allen Formation of Argentina. It was named in 2004. Description The type species is ''Bonatitan reigi'', first described by Martinelli and Forasiepi in 2004. The speci ...

'' and ''

Rocasaurus ''Rocasaurus'' (meaning "General Roca lizard") is a genus of titanosaurian sauropod that lived in South America. ''Rocasaurus'' was discovered in Argentina in 2000, within the Allen Formation which is dated to be middle Campanian to early Maastr ...

''. The

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 d ...

below displays the results of the

phylogenetic analyses In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

performed by Navarro ''et al''. (2022):

Paleopathology

One of the specimens of ''Ibirania'' (LPP-PV-0043, a partial fibula) presented a

pathology Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in ...

called acute

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 ...

. Aureliano ''et al''. (2021) sampled histological thin sections of the lesion and described the step-by-step development of periosteal remodeling caused by the infection. They also used

CT scan A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

slices and a reconstructed 3D model to describe the trauma.

Paleoparasitology

Aureliano ''et al''. (2021) also discovered fossilized parasites associated with the bone lesions in ''Ibirania'' (LPP-PV-0043). It was the first report of parasites preserved

in situ ''In situ'' (; often not italicized in English) is a Latin phrase that translates literally to "on site" or "in position." It can mean "locally", "on site", "on the premises", or "in place" to describe where an event takes place and is used in ...

inside the vascular canals of a dinosaur. The taxonomy of these microfossils are currently under study by the rest of the team.

Paleoenvironment

''Ibirania'' lived in an arid, inland environment, which Navarro ''et al.'' (2022) presume is the reason behind its dwarfism. This is in contrast to other dwarf sauropods such as ''

Europasaurus ''Europasaurus'' is a basal macronarian sauropod, a form of quadrupedal herbivorous dinosaur. It lived during the Late Jurassic (middle Kimmeridgian, about 154 million years ago) of northern Germany, and has been identified as an example of insul ...

'' and ''

'', which attained their small size due to

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 ...

. It coexisted alongside other dinosaurs, such as the

abelisaurid Abelisauridae (meaning "Abel's lizards") is a family (or clade) of ceratosaurian theropod dinosaurs. Abelisaurids thrived during the Cretaceous period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are found ...

theropod ''

Thanos simonattoi ''Thanos'' (named for the Marvel Comics character) is a genus of carnivorous brachyrostran abelisaurid dinosaur that lived in Brazil during the Santonian stage of the late Cretaceous Period. It contains only a single species known as ''T. simo ...

'' and a larger, unnamed probable

megaraptora Megaraptora is a clade of carnivorous Tetanurae, tetanuran theropod dinosaurs with controversial relations to other theropods. Its Derived (phylogenetics), derived members, the Megaraptoridae are noted for their elongated hand claws and proporti ...

n, as well as an indeterminate

notosuchia Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group (see below); if Sebecosu ...

References

{{Sauropodomorpha, T. Saltasaurids Santonian life Late Cretaceous dinosaurs of South America Cretaceous Brazil Fossils of Brazil Fossil taxa described in 2022