Austroposeidon

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Austroposeidon
Temporal range: Campanian-Maastrichtian
~83.6–66.0 Ma
Austroposeidon.PNG
Twelfth neck vertebra
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Clade: Titanosauria
Clade: Lithostrotia
Genus: Austroposeidon
Bandeira et al., 2016
Species:
A. magnificus
Binomial name
Austroposeidon magnificus
Bandeira et al., 2016

Austroposeidon is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous Presidente Prudente Formation of Brazil. It contains one species, Austroposeidon magnificus.[1]

Description[edit]

First dorsal vertebra

Austroposeidon was a large sauropod, with the only known specimen, an adult, having a length of about 25 metres (82 ft) - in fact, it is the largest dinosaur discovered in Brazil to date.[1]

Several traits show that Austroposeidon was a member of the titanosaurs; the hyposphene-hypantrum articulations are missing from the vertebrae, the cervical and dorsal vertebrae do not have forked neural spines, and the internal texture of the bone is camellate (punctuated by many small air chambers). The describers determined that Austroposeidon was a new genus based on a number of autapomorphies (or traits unique to the known fossils) in the vertebrae: the thirteenth cervical vertebra has columnar centropostzygapophyseal laminae, and its rear centrodiapophyseal lamina splits into two prongs; the first dorsal vertebra has front and back centrodiapophyseal laminae that curve downwards and outwards, and its diapophysis stretches down to the top margin of the centrum; and the frontmost part of the spinoprezygapophyseal laminae forks in the dorsal vertebrae positioned towards the back of the torso. Additionally, Austroposeidon possesses a unique combination of other vertebral traits, not seen elsewhere among titanosaurs.[1]

A CT scan showed that the internal bone texture of the vertebrae possessed concentric, alternating rings of camellate tissue and dense tissue; the describers interpreted these as rings of growth within the bone.[1]

Discovery and naming[edit]

Austroposeidon is known from a single specimen, MCT 1628-R, which consists portions of the cervical (neck), dorsal, and sacral vertebrae (including a cervical rib and one complete dorsal vertebra). The specimen was discovered in the Campanian-Maastrichtian Presidente Prudente Formation of the Bauru Group by palaeontologist Llewellyn Ivor Price in 1953, but the remains were not described until 2016. The animal was likely preserved by a crevasse splay on a floodplain, judging by the fine sandstone that the specimen was found in. Unfortunately, the site where the specimen was recovered has now been lost to urban development.[1]

The genus name combines austro ("southern", as in South America, from Latin Auster, the southern wind) and poseidon, a reference to the Greek god of earthquakes of the same name. The specific name is the Latin word magnificus ("great, elevated, noble"), referring to the large size of the specimen.[1]

Classification[edit]

Cervical rib
Thirteenth neck vertebra

A phylogenetic analysis in 2016 recovered Austroposeidon as the sister taxon of the Lognkosauria.[1] The consensus of the two most parsimonious phylogenetic trees recovered is shown below.


 Lithostrotia 

Rukwatitan

Malawisaurus

Puertasaurus

Austroposeidon

 Lognkosauria 

Mendozasaurus

Futalognkosaurus

Quetecsaurus

Isisaurus

Epachthosaurus

Pellegrinisaurus

Trigonosaurus

Tapuiasaurus

Maxakalisaurus

Lirainosaurus

Ampelosaurus

Bonitasaura

Dreadnoughtus

 Opisthocoelicaudiinae 

Alamosaurus

Opisthocoelicaudia

 Saltasaurinae 

Neuquensaurus

Rocasaurus

Saltasaurus

Brasilotitan

Uberabatitan

Rapetosaurus

"Aeolosaurus" maximus

 Rincosauria 

Rinconsaurus

Muyelensaurus

 Aeolosaurini 

Overosaurus

Aeolosaurus rionegrinus

Aeolosaurus colhuehuapensis

Gondwanatitan

See also[edit]

References[edit]

  1. ^ a b c d e f g Bandeira, K.L.N.; Medeiros Simbras, F.; Batista Machado, E.; de Almeida Campos, D.; Oliveira, G.R.; Kellner, A.W.A. (2016). "A New Giant Titanosauria (Dinosauria: Sauropoda) from the Late Cretaceous Bauru Group, Brazil". PLoS ONE. 11 (10): e0163373. doi:10.1371/journal.pone.0163373. PMC 5051738. PMID 27706250.