Pronunciation: moo-YEH-len-SOR-us
Meaning: Muyelen (Colorado river) lizard
Author/s: Calvo et al. (2007)
Synonyms: None known
First Discovery: Neuquén, Argentina
Acta Ordinal: #644
Muyelensaurus pecheni
South America is renowned for its titanosaurs, with around thirty species being named as of 2014. But despite their diversity, most of them have a couple of things in common: (1) they're robust and (2) their remains are fragmentary. Muyelensaurus bucks the latter trend by being represented by a decent chunk of skeleton rather than the odd thigh bone or vertebra. It bucks the former trend too because, despite being a member of Titanosauria—the group of wide-load sauropods named for the giant, primordial Greek deities known as Titans—it's a bit on the skinny side. And it's not the only one.
Muyelensaurus was discovered at "Loma del Lindero" around 10km west of Rincón de los Sauces, where another titanosaur of equally slender proportions (Rinconsaurus) was discovered. Being found in fairly close proximity and of similar build, the suspicious-minded may be thinking that these two critters are one and the same. However, they differ in six features of their vertebrae, including the slant of the neural spines on their back verts. They were assigned to the same raised-for-the-occasion family (Rinconsauria) by Calvo et al. in 2007, and were the only members at that point. But most palaeontologists haven't been keen to embrace it as a stable, well-supported group, mainly because it isn't: more than 20 titanosaurs have been recovered as rinconsaurs in various analyses since then, Muyelensaurus is often not one of them, and the group itself has a habit of jumping all over the titanosaurian family tree.
Some experts think Muyelensaurus and Rinconsaurus, along with Gondwanatitan, may be members of the Aeolosaurus-anchored Aeolosaurini, which is itself recovered within Rinconsauria... 50% of the time.
Muyelensaurus was discovered at "Loma del Lindero" around 10km west of Rincón de los Sauces, where another titanosaur of equally slender proportions (Rinconsaurus) was discovered. Being found in fairly close proximity and of similar build, the suspicious-minded may be thinking that these two critters are one and the same. However, they differ in six features of their vertebrae, including the slant of the neural spines on their back verts. They were assigned to the same raised-for-the-occasion family (Rinconsauria) by Calvo et al. in 2007, and were the only members at that point. But most palaeontologists haven't been keen to embrace it as a stable, well-supported group, mainly because it isn't: more than 20 titanosaurs have been recovered as rinconsaurs in various analyses since then, Muyelensaurus is often not one of them, and the group itself has a habit of jumping all over the titanosaurian family tree.
Some experts think Muyelensaurus and Rinconsaurus, along with Gondwanatitan, may be members of the Aeolosaurus-anchored Aeolosaurini, which is itself recovered within Rinconsauria... 50% of the time.
Etymology
Muyelensaurus is derived from "Muyelen" (one of the names of the Colorado River in the Mapuche indigenous language), and the Greek "sauros" (lizard). The species epithet, pecheni, honours Dr. Ana María Pechén, main head of the National University of Comahue (2002-2006), who supported the study of dinosaur fossils in Neuquén Province, Patagonia.
Discovery
The remains of Muyelensaurus pecheni were discovered at the Loma del Lindero site of the Portezuelo Formation,
Río Neuquén Subgroup, Neuquén Group, 10km West of Rincón de los Sauces City, Neuquén Province, Patagonia, Argentina, by Marcelino Palomo in 1997.
The holotype (MRS-PV 207) is a braincase, but a shed-load of other remains were found at the same site and represent a total of four adults and one juvenile.
