''Caieiria'' (named after the Caieira locality where its fossils were recovered) is a genus 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 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 ...
Serra da Galga Formation
The Serra da Galga Formation is a geological formation in Minas Gerais state of southeastern Brazil. Its strata date back to the Maastrichtian, and are part of the Bauru Group. It was originally considered a member of the Marília Formation.
Di ...
(formerly a unit of the
Marília Formation
The Marília Formation is a geological Formation (geology), formation in Minas Gerais state of southeastern Brazil. Its strata date back to the Maastrichtian, and are part of the Bauru Group.
The fossil-bearing Serra da Galga and Ponte Alta member ...
) 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 ...
. The type and only species is ''Caieiria allocaudata''.
Discovery and naming
From the 1940s to 1960s, the paleontologist
Llewellyn Ivor Price
Llewellyn Ivor Price (October 9, 1905 – June 9, 1980) was one of the first Brazilian paleontologists. His work contributed not only to the development of Brazilian but also to global paleontology. He collected ''Staurikosaurus'' in 1936, th ...
excavated several series of titanosaur fossils in the "Caieira" locality of the Serra da Galga Formation in
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 ...
, Brazil and he discovered the holotype of ''Caieiria'' around 1957. Two of these, "Series B" or MCT 1488-R and "Series C" or MCT 1490-R, have been named the holotypes of two titanosaur genera: ''
Trigonosaurus'' and ''
Baurutitan'' respectively. The describers of ''Trigonosaurus'' also referred a series of ten caudal vertebrae, MCT 1719-R, as the paratype of their new genus.
Further titanosaurs from the BR-262 site of the same locality were reported by Silva Junior and colleagues in 2022, and in light of this new evidence, reconsidered MCT 1488-R to be a specimen of ''Baurutitan'' and thus synonymized ''Trigonosaurus'' with it. They also separated the tail from ''Trigonosaurus'' and named it as the holotype of a new genus and species, ''Caieiria allocaudata''. The generic name "''Caieiria''" honors the Caieira locality while the specific name "''allocaudata''" means "strange tail", referring to its unusual anatomy.
Description
The describing authors indicated two traits in which ''Caieria'' distinguishes itself from ''Baurutitan britoi'', ''Uberabatitan ribeiroi'' and ''
Gondwanatitan faustoi''. The tail vertebrae possess robust side processes that are vertically expanded to almost half the height of their centra. The front tail vertebrae show a deep excavation between the ''lamina postzygapophysealis'' and the ''lamina centrodiapophysealis''.
Classification
Silva Junior ''et al.'' performed a phylogenetic analysis of titanosaurs including both ''Caieiria'' and ''Baurutitan'' with the latter incorporating information from ''Trigonosaurus''. Both taxa were found to be in a clade at the base of
Aeolosaurini
Aeolosaurini is an extinct clade of titanosaurian dinosaurs known from the Cretaceous period of Argentina and Brazil. Rodrigo M. Santucci and Antonio C. de Arruda-Campos (2011) in their cladistic analysis found ''Aeolosaurus'', '' Gondwanatitan'' ...
, which, like many other analyses, is recovered within
Rinconsauria
Rinconsauria is an extinct clade of titanosaurian sauropods known from the late Cretaceous period of Argentina. All members of this clade are fairly small compared to the largest titanosaurs, at less than around long. The membership of Rinconsau ...
. Their cladogram is shown below:
Paleoenvironment
The Serra da Galga Formation's paleofauna were all originally thought to be from the Marília Formation, before its fossil-bearing bed was separated into another formation in 2020.
Other than ''Baurutitan'' and ''Caieiria'', other animals from this formation include the unenlagiine ''
Ypupiara
''Ypupiara'' (meaning "the one who lives in the water") is an extinct genus of unenlagiine theropod from the Late Cretaceous Serra da Galga Formation of Brazil. It was the first member of the Dromaeosauridae to be discovered in South America and ...
'' and the crocodylomorphs ''
Itasuchus'', ''
Peirosaurus
''Peirosaurus'' is an extinct genus of peirosaurid crocodylomorph known from the Late Cretaceous period (late Maastrichtian stage) of Minas Gerais, southern Brazil. It contains a single species, ''Peirosaurus torminni''. It is the type genus of t ...
'', and ''