| Agustinia | |
|---|---|
 | |
| Speculativelife restoration | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Superfamily: | †Diplodocoidea |
| Family: | †Rebbachisauridae |
| Genus: | †Agustinia Bonaparte,1999 |
| Species: | †A. ligabuei |
| Binomial name | |
| †Agustinia ligabuei Bonaparte, 1999 | |
Agustinia (/ɑːɡəˈstɪniə/) is agenus ofsauropoddinosaur from theEarly Cretaceous ofSouth America. The genus contains a single species,A. ligabuei, known from a single specimen that was recovered from theLohan Cura Formation ofNeuquén Province inArgentina. It lived about 116–108 million years ago, in theAptian–Albian stages of the Early Cretaceous Period.
Theholotype and only known specimen ofAgustinia, MCF-PVPH-110, was discovered in 1997 by an expedition from theMuseo Argentino de Ciencias Naturales inBuenos Aires, a few kilometers west of the city ofPicún Leufú in the south of theNeuquén province. The rocks of the site belong stratigraphically to the upper section of the Lohan-Cura Formation . This excursion was part of a program run by the museum in 1996 and 1997 to discover new vertebrate fossils in the Lohan-Cura Formation.[1]
Thegeneric nameAgustinia honors then-student Agustin Martinelli, who discovered the skeleton and was part of the excavation team of the Museo Argentino de Ciencias Naturales. It was first mentioned in anabstract written by Argentine paleontologistJose Bonaparte,[1] and published in a full paper in 1999.[2] Thespecific name,ligabuei, honors Dr. Giancarlo Ligabue, a philanthropist who provided financial support to the expedition which recovered the remains.
Only fragmentary remains ofAgustinia are known. These include fragments ofvertebrae from the back, hips, and tail regions of thespinal column. Parts of the lower hind limb were also recovered, consisting of afibula,tibia, and fivemetatarsals. Afemur (thigh bone) was found at the site, but was too fragmented to collect.[2][3]
Agustinia was known for its distinctive supposed armor plates, calledosteoderms, initially interpreted as a series of wide, vertical spikes and plates down the center of its back, somewhat like the unrelatedStegosaurus.[2] However, subsequent research has challenged the interpretation of these elements as osteoderms.[4] Further study of the poorly preserved fossil material showed that these "plates" were in fact more likely to be fragments of ribs and hip bones.[5] This reassessment was reaffirmed subsequently byhistology of the purported osteoderms, which do not match the internal structure of other titanosaurian osteoderms. The fragmentary hip bone was tentatively identified as part of theilium.[6]
Afibula (lower leg bone) has been recovered that is about 895 millimetres (35.2 in) long. When compared to the same bone in related dinosaurs, this indicates thatAgustinia may have been about 15 metres (49 ft) long. The lower half of thetibia was thin when viewed from the front (anteroposterior), indicating that the tibia was thinner than that of titanosaurs such asAntarctosaurus orSaltasaurus. Thepedal elements are comparable to those of the titanosaurs.[1]
The remains are fragmentary and do not have many distinctive characteristics which can be used to separate it from other sauropods. Because of this, some authors have consideredAgustinia anomen dubium for being based on inadequate remains to compare with related dinosaurs.[5] However, Bellardini et al. (2022) considered it to be valid on the basis of unique morphological characteristics observed in the vertebrae.[7]
Because of its supposedly unusual armor,Agustinia was originally assigned to its own family,Agustiniidae.[2] This family name has not come into wide acceptance.Agustinia is difficult to classify because of its fragmentary nature, and because it exhibits features of bothdiplodocoid[1] andtitanosaurian sauropods.[3] What few distinctive features do exist in the holotype specimen prompted Kristina Curry Rogers to classifyAgustinia as alithostrotian titanosaur in 2005, but Mannion et al. (2013) classified it as a member of the morebasal cladeSomphospondyli.[8][5] In contrast, D'emic et al (2009) concluded that no diagnostic features were present that would allow a classification within the Diplodocoidea or Titanosauria, and therefore classifiedAgustinia asNeosauropodaincertae sedis.[4]
A 2022 publication by Flavio Bellardini et al. found sufficient evidence to classifyAgustinia as arebbachisaurid within the Diplodocoidea, morederived thanAmazonsaurus. Thecladogram below displays the results of theirphylogenetic analyses:[7]
In their 2024 description ofCampananeyen, Lerzo et al. also found support for a rebbachisaurid position ofAgustinia, although their analysis favored affinities closer to the Nigersaurinae within Khebbashia.[9]
Agustinia is known from the Early CretaceousLohan Cura Formation of Neuquén Province, Argentina. Other dinosaurs, including fellow rebbachisauridComahuesaurus and somphospondylanLigabuesaurus have also been named from the formation. Remains of turtles, including two species ofProchelidella, are also known.[10][11]
