| Rinconsaurus | |
|---|---|
 | |
| Life restoration comparing the animal's size with a human | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauria |
| Clade: | †Rinconsauria |
| Genus: | †Rinconsaurus Calvo & González Riga, 2003 |
| Type species | |
| †Rinconsaurus caudamirus Calvo & González Riga, 2003 | |
Rinconsaurus is agenus oftitanosaursauropoddinosaur from the LateCretaceous in what is nowArgentina. Thetype species,Rinconsaurus caudamirus, was described by Calvo and Riga in 2003, and is based on three partial skeletons.
Like all sauropods,Rinconsaurus was a large long-neckedquadrupedal animal, with a long, whip-like tail and four pillar-like legs.Rinconsaurus was an unusually slender sauropod. Although fossil discoveries are incomplete, and no complete necks or heads have been found, fully grownRinconsaurus are estimated to have been 11 meters (36 ft) long and approximately 2.5 meters (8 ft) high at the shoulder.[1] The body mass ofRinconsaurus has been estimated to be between 3.21 and 5.39 tonnes.[2]
Fossils ofRinconsaurus were discovered in 1997 by Gabriel Benítezin strata belonging to theBajo de la Carpa Formation near Rincón de los Sauces, in theNeuquen province of Argentina. The fossils, which consisted of three individuals (two adults and one juvenile), were excavated by Jorge Calvo of the Paleontology Museum of the National University of Comahue.[1]
Thetype, and only known species,Rinconsaurus caudamirus, was described by Calvo and Bernardo J. González Riga of the Paleovertebrate Laboratory in Mendoza, Argentina, in 2003. The authors noted derived traits unique to the genus, including distinctive tail vertebrae with bony processes. The fossil remains includedvertebrae, limb bones,scapula, hip bones (pubis,ilium, andischium) and several ribs. Two teeth are also known. These teeth resemble those of another titanosaurid,Malawisaurus dixeyi.[1] Calvo and González Riga initially interpreted two elements as belonging to the skull ofRinconsaurus, aprefrontal and part of the mandible, but these were subsequently identified as the ilium of thecrocodyliformPehuenchesuchus[3] and part of a rib ofRinconsaurus[4] respectively.
The generic name refers to Rincón de los Sauces, where the fossils were discovered, while the specific name,caudamirus, means "amazing in the tail" inLatin, in reference to the unusual shape of the tail vertebrae, especially a strange sequence of procoelous, amphicoelous, opisthocoelous, biconvex and ultimately again procoelous vertebrae shown by one individual.[1]
Rinconsaurus is atitanosauridsauropod. Within the titanosaurs, Calvo and Riga regard this dinosaur as closely related toAeolosaurus based on several derived traits.[1] In 2007, Casalet al. assignedRinconsaurus,Gondwanatitan, andAeolosaurus to theAeolosauridae, a proposed stem-basedclade of titanosaurs.Rinconsaurus would form a smaller cladeRinconsauria withMuyelensaurus.[5] It remains to be seen, however, if this classification will receive widespread acceptance.
Rinconsaurus, like all sauropods, was anherbivore.Fossilized dung associated with late Cretaceous titanosaurids has revealed phytoliths, silicified plant fragments, that offer clues to a broad, unselective plant diet. Besides the plant remains that might have been expected, such ascycads andconifers, discoveries published in 2005 revealed an unexpectedly wide range ofmonocotyledons, includingpalms and grasses (Poaceae), including ancestors ofrice andbamboo, which has given rise to speculation that herbivorous dinosaurs and grassesco-evolved.[6]
Titanosaurid teeth are usually spatulate (spoon-shaped) or shaped like pegs. Teeth found in association withRinconsaurus have been described as "pencil-chisel-like teeth" and had sharply inclined wear facets.[1] Without the ability to grind food,Rinconsaurus, like other sauropods, would have stripped foliage.
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