| Yamanasaurus | |
|---|---|
 | |
| Artistic depiction ofYamanasaurus | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauria |
| Family: | †Saltasauridae |
| Subfamily: | †Saltasaurinae |
| Genus: | †Yamanasaurus Apesteguíaet al.,2019 |
| Type species | |
| †Yamanasaurus lojaensis Apesteguíaet al., 2019 | |
Yamanasaurus (meaning "Yamana lizard") is an extinct genus ofsaltasaurinetitanosauriandinosaur from theRío Playas Formation ofEcuador, which dates to theCampanian-Maastrichtian of the lateCretaceous period (approximately 75-70 million years ago). Thetype and only species isYamanasaurus lojaensis, representing the first non-avian dinosaur described from Ecuador.[1] Theholotype, consisting of fragments of a humerus, ulna, tibia, two sacral vertebrae and a single caudal, was discovered in 2017.
The genusYamanasaurus refers to the locality of Yamana, where the bones were found, which is located in southern Ecuador, about fifty kilometers from thePeruvian border.
Thespecific name,lojaensis, composed ofloja and theLatin suffix-ensis, meaning "which lives in, which inhabits", was given in reference to the town ofLoja, where the discovery was presented and where part of its study was carried out.[1]
As a saltasaurine sauropod,Yamanasaurus is distinguished by a stocky, quadrupedal body, an elongated neck and tail, and a small head, although its neck and overall size are smaller than the average sauropod, as it is estimated to have been around 6 m (20 ft) long.[2][3] Like other saltasaurines, it also likely had a protective armour made ofosteoderms.[3]
The morphology, size, and age of the specimen suggest thatYamanasaurus is closely related toNeuquensaurus, which was discovered inArgentina. It probably fed on low vegetation.
Yamanasaurus is further characterised by its anterior to mid-tail vertebrae having a dorsoventrally compressedcondyle, with the posterior end raised above the midline, without a longitudinal ventral ridge. The internal structure is spongy and lacks internal cavities. The last centrum of thesacral vertebra is as long as it is high, with a small shallowovoid cavity on the lateral side. Theradius is robust with a flatteneddiaphysis and a marked constriction just below theepiphysis, which has a concave, heptagonal proximal surface.[1]
The discovery was made in 2017 by Francisco Celi, an octogenarian resident of Yamana, who, after finding a vertebra of the animal informed university professor Galo Guamán and his geology students, who were on a field trip in the area.
On the subject of its dating, Galo Guamán, who ended up in charge of the study, explains: “The age of the fossils was determined by geological correlation, thanks to rock samples that correspond to the Maastrichtian period, the last period of the Cretaceous, before the impact of theasteroid that caused the extinction of the dinosaurs.”[3]
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