''Ibirania'' (meaning " Ibirá wanderer" or "tree wanderer") is a genus of dwarf

saltasaurine Saltasauridae (named after the Salta region of Argentina where they were first found) is a family of armored herbivorous sauropods from the Upper Cretaceous. They are known from fossils found in South America, Africa, Asia, North America, and Eur ...

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 from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

(

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 m ...

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. Campa ...

)

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 * Serb Autonomous Regions (''Srpska autonomna oblast'', SAO), during the breakup of Y ...

(

Bauru Basin The Bauru Group is a geological group of the Bauru Sub-basin, Paraná Basin in Minas Gerais, São Paulo, General Salgado, Itapecuru-Mirim, Mato Grosso, Brazil whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils t ...

) of

Southeast Brazil The Southeast Region of Brazil ( ) is composed of the states of Espírito Santo, Minas Gerais, Rio de Janeiro and São Paulo. It is the richest region of the country, responsible for approximately 53% of the Brazilian GDP (2022) , as São Paulo, ...

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

Magyarosaurus ''Magyarosaurus'' (" Hungarian 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 less than long and weighing less than ...

''.

Discovery and naming

The ''Ibirania''

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 ...

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 * Serb Autonomous Regions (''Srpska autonomna oblast'', SAO), during the breakup of ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

, 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 of intermediate size between the cervical and lumbar ve ...

, partial

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 ...

, a fragmentary

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

and

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

, a partial

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

, and a nearly complete

metatarsal The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...

. Additional material, including partial cervical, 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 Ibirá, the municipality where the specimens were discovered (also a Portuguese derivative of the Tupi word "ybyrá", meaning "tree", in reference to ''Ibirania''s hypothesized browsing behavior), with "ania", a modified form of the

Greek Greek may refer to: 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 of all kno ...

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 languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

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, cosmochemistry, ast ...

, 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 (: trabeculae, from Latin for 'small beam') is a small, often microscopic, biological tissue, tissue element in the form of a small Beam (structure), beam, strut or rod that supports or anchors a framework of parts within a body or ...

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 nec ...

, 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 language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below displays the results of the

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

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 disease. 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 the context of modern medical treatme ...

called acute

osteomyelitis Osteomyelitis (OM) is the infectious inflammation of bone marrow. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The feet, spine, and hips are the most commonly involved bones in adults. The cause is ...

. Aureliano ''et al''. (2021) sampled histological thin sections of the lesion and described the step-by-step development of

periosteal The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. (At the joints of long bones the bone's outer surface is lined with "articular cartilage ...

remodeling caused by the infection. They also used

CT scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (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 or ...

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 is a Latin phrase meaning 'in place' or 'on site', derived from ' ('in') and ' ( ablative of ''situs'', ). The term typically refers to the examination or occurrence of a process within its original context, without relocation. The term is use ...

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'' (meaning 'Europe lizard') is a basal macronarian sauropod, a form of quadrupedal herbivorous dinosaur. It lived during the Late Jurassic (middle Kimmeridgian, from about 154 to 151 million years ago) of northern Germany, and has ...

'' 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 foun ...

theropod '' Thanos simonattoi'' and a larger, unnamed probable

megaraptora Megaraptora is a clade of carnivorous theropod dinosaurs. Its derived members, the Megaraptoridae are noted for their large hand claws and powerfully-built forelimbs, which are usually reduced in size in other large theropods. Although undoubt ...

n, as well as an indeterminate

notosuchia Notosuchia is a clade of primarily Gondwanan mesoeucrocodylian Crocodylomorpha, crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogeny, phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group ...

References

{{Taxonbar, from1=Q113996051 Saltasauridae Dinosaur genera Santonian dinosaurs Fossil taxa described in 2022 Dinosaurs of Brazil