This year (2021), has been another bumper year for dinosaur discoveries with over forty new species of dinosaur described, including several from the British Isles such as Pendraig (P. milnerae) from Wales and four new dinosaurs described from fossil finds on the Isle of Wight (Brighstoneus, Ceratosuchops, Riparovenator and Vectiraptor).

New genera are erected based on new fossil discoveries. In addition, a new dinosaur genus or species can be established based on a revision of existing and previously studied fossil material. A new genus of Late Cretaceous, Brazilian titanosaur was announced this year, based on fragmentary remains that had previously been assigned to a titanosaur that roamed Argentina. Time for Arrudatitan maximus to step out of the shadows.

Arrudatitan maximus fossils
The fragmentary fossil bones previously assigned to the Argentinian titanosaur Aeolosaurus maximus and now defined as a new Brazilian titanosaur taxon Arrudatitan maximus. Picture credit: Silva Junior et al.

Aeolosaurus maximus

The Aeolosaurus genus was erected by the Argentinian palaeontologist Jaime Powell in 1987 when the first species was named (A. rionegrinus). It was a widespread genus known from numerous individuals collected from Upper Cretaceous deposits, most notably the Angostura Colorada Formation in Río Negro Province, but dinosaur fossils collected from the Bajo Barreal, Los Alamitos and Allen Formations of Argentina have also been assigned to this genus.

The Brazilian fossil remains that led to the erection of the species Aeolosaurus maximus in 2011, have always been regarded as somewhat of an outlier when compared to Aeolosaurus fossil remains discovered in Argentina. A. maximus was described based on vertebrae, ribs, a left ischium, a fragmentary scapula and elements from the limbs including a left femur discovered in 1997 eroding out of an outcrop of the Adamantina Formation in the state of São Paulo state south-eastern Brazil.

Researchers who included Julian Silva Junior (Universidade de São Paulo), reassessed the fossil material following a cladistic analysis in 2019 that challenged the taxonomic placement. Writing in “Historical Biology”, the scientists have confirmed the assertion expressed previously that the Brazilian fossil material represents a distinct genus and the fossils ascribed to Aeolosaurus maximus have been reassigned to the new dinosaur species Arrudatitan maximus.

Arrudatitan maximus scale drawing.
Although the size of A. maximus remains uncertain, based on the femur length of 1.55 metres, palaeontologists estimate that this titanosaur may have reached a length of around 15 metres.

Commenting on the revision, lead author of the scientific paper, doctoral student Julian Silva Junior stated:

“When analysing the caudal vertebrae, we found that they were different to those assigned to Aeolosaurus and these characteristics served to establish a diagnosis to propose a new genus.”

2021 – A Good Year for Titanosaur Discoveries

Several new titanosaur genera have been erected this year including Menucocelsior (M. arriagadai) and Ninjatitan (N. zapatai), which is the oldest titanosaur known to science.

Everything Dinosaur’s list of new titanosaurs named in 2021

  • Arackar licanantay a titanosaur from the Upper Cretaceous Hornitos Formation of Chile.
  • Arrudatitan maximus from the Upper Cretaceous Adamantina Formation of south-eastern Brazil.
  • Australotitan cooperensis a titanosaur from the Winton Formation of Queensland, Australia.
  • Garrigatitan meridionalis from the Upper Cretaceous Argiles Rutilantes Formation of south-eastern France.
  • Hamititan xinjiangensis from the Lower Cretaceous Shengjinkou Formation of north-western China which was coeval with the euhelopodid sauropod Silutitan (S. sinensis) which was also scientifically described in 2021.
  • Menucocelsior arriagadai from the Upper Cretaceous Allen Formation of Argentina.
  • Ninjatitan zapatai the earliest titanosaur known to date described from fossils found in the Lower Cretaceous Bajada Colorada Formation of Argentina.

To read blog posts about some of these newly described titanosaurs:

A new species of titanosaur from the Atacama Desert of northern Chile (Arackar licanantay): A New Titanosaur from Chile – Arackar licanantay.

Australian dinosaur “Cooper” named: “Cooper” – Australotitan cooperensis.

Our article on Hamititan xinjiangensis and Silutitan sinensis: Two New Sauropods from North-western China.

To read the Everything Dinosaur blog post about the earliest titanosaur known to science: Ninjatitan zapatai the Earliest Titanosaur.

The scientific paper: “Reassessment of Aeolosaurus maximus, a titanosaur dinosaur from the Late Cretaceous of Southeastern Brazil” by Julian C. G. Silva Junior, Agustín G. Martinelli, Fabiano V. Iori, Thiago S. Marinho, E. Martín Hechenleitner and Max C. Langer published in Historical Biology.

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