Oxalaia

Oxalaia
Alexander Vieira's reconstruction of Oxalaia quilombensis
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
clade:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	†Spinosauridae
Subfamily:	†Spinosaurinae
Genus:	†Oxalaia Kellner et al., 2011
Referred species
†Oxalaia quilombensis (Kellner et al., 2011) (type)

Oxalaia is a genus of large spinosaurid theropod dinosaur, which lived in late Cretaceous Brazil during the Cenomanian age. The type and only species of Oxalaia is O. quilombensis. The animal noted to resemble one of its closest relatives Spinosaurus, but studies have shown that it has more than enough physical differentiation in morphology to be considered its own genus.

Discovery and Naming

The theropod's name; Oxalaia; is a reference to the African deity Oxala.

The only known Oxalaia fossil

All known Fossils of Oxalaia recovered in 2004 from the Laje do Coringa locality of the Alcantara Formation, from the São Luís Basin; part of the Itapecuru Group. Besides these bone fragments, numerous instances of spinosaurid teeth had earlier been reported from the site.

The genus was named by Alexander Wilhelm Armin Kellner, Sergio A.K. Azevedeo, Elaine B. Machado, Luciana B. Carvalho and Deise D.R. Henriques in 2011 and the type species is Oxalaia quilombensis.

The specific name quilombensis refers to the Quilombo settlements, such as on Cajual Island, which was founded by escaped slaves.

Oxalaia reconsturction. Credit: Petite Paleoartist | Sauriazoicillus

Description

Estimates suggest that it was 12.1 to 14.5 meters (39 to 46 ft) in length and 5.5 to 7 tonnes (5.5 to 7.7 short tons) in weight. It is the largest theropod known from Brazil and the eighth officially named species of theropod from Brazil. In 2018; several known fossils, albeit not all, are destroyed by fire that happened on the National History Museum of Brazil.

Classification

Oxalaia reconstruction. Credit: theultimatenaturelover

Oxalaia live reconstruction. Credit: Cisiopurple

Oxalaia quilombensis. Credit: leonardismos

Oxalaia has been formally placed in the family Spinosauridae and the subfamily Spinosaurinae thanks to its unique jaw and teeth morphology.

It was once speculated that Oxalaia might potentially be a synonym of Spinosaurus aeygyptecus but is currently considered very unlikely due to higher geographic distance. However in 2020, a publication has contributed to possibility that the Oxalaia being a synonym to Spinosaurus; albeit more research on the topic is necessary before the final conclusion.

In 2021, Lacerda, Grillo and Romano noted that the anteromedial processes of the holotype maxillae; named: MN 6117-V, contact medially, a condition that is clearly not observed in MSNM V4047 : which has been referred to as a specimen of Spinosaurus, and thus adding a new possible diagnostic feature of Oxalaia. They also suggested that the premaxilla of Oxalaia is wider in the posterior portion than that of MSNM V4047, and that the lateral morphology of its rostrum was distinguished from other spinosaurines based on their morphometric analysis.

Oxalaia quilombensis. Credit: victor sales

Further analysis and studies; such as one conducted in 2023, by Isasmendi and colleagues. The studies did considered Oxalaia as a truly valid taxon based on the examination of its referred maxilla; from the specimen MN 6119-V; which suggests that the position of its external naris would have been more anteriorly located, a condition similar to that of Irritator and baryonychines, differing from Spinosaurus aegyptiacus.

Paleoecology

Oxalaia's dietary preference was presumably similar to other known spinosaurid and spinosaurine species, such as Irritator; a generalist with a broader diet; a carnivore. It will eat any source of viable meat; although it likely had a preference for animals in and around water. Ironically the conducted studies did find similarities between Oxalaia's skull structure and Irritator's skull structure.

In the Media

• It’s possible that the fictional spinosaurid referred to as an Empirosaur in Terra Nova might be an adult Oxalaia, though there is debate it could be its own species.