Ampelosaurus (/ˌæmpɪloʊˈsɔːrəs/ AM-pi-loh-SOR-əs; meaning "vine lizard") is a titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now France.

In 2005, over 500 bones have been assigned to Ampelosaurus and additional material has been found since, including a partially articulated skeleton with skull, which makes it one of the best known dinosaurs in France.

However, with a size of about 14 m (46 ft) in length for the largest known individual, Ampelosaurus was not an insular dwarf unlike some other Ibero-Armorican titanosaurs like Lirainosaurus and Atsinganosaurus, or the genus Magyarosaurus from the Hateg island.

It was recovered in the lower levels of the Marnes Rouges Inférieures Formation, which belong to the early Maastrichtian epoch of the Late Cretaceous Period, ~ 70 million years ago.

[1] Historically, the dinosaurs of the Upper Aude Valley were first reported by Paul Gervais in 1877 from two vertebrae discovered in the commune of Fa.

The first discoveries of dinosaur bones at Campagne-sur-Aude date back to the beginning of the twentieth century, but they remained isolated and were quickly forgotten.

Clottes and Raynaud mainly discovered caudal vertebrae and limb bones during simple surface collecting carried out at several sites around the villages of Campagne-sur-Aude and Espéraza.

In 1989, the first systematic excavations carried out by professional paleontologists began on the main site, located at the Bellevue farm.

This new dinosaur was named Ampelosaurus atacis by the French paleontologist Jean Le Loeuff in a preliminary description published in 1995.

[6][2] In 2007, the remains of a larger specimen were discovered, including a sternal plate, a scapula, a 1.20 m femur, a pubis, a caudal vertebra and a chevron.

[2] However, in 2012, a morphometric study of titanosaur femurs from France and Spain suggested the presence of three morphotypes at Bellevue, one of which was tentatively assigned to the genus Lirainosaurus.

[8] In 2021, Díez Díaz and colleagues also agree on the existence at this site of a second titanosaur but find it more similar to the genus Garrigatitan from the Upper Campanian of Provence.

Díez Díaz et al. thus underline the need to revise all the titanosaur bones found at Bellevue to clarify their taxonomy.

[10] The presence of Ampelosaurus has also been reported in other parts of southern France, as well as in Spain, but their identification has so far been shown to be erroneous (or has not been demonstrated in the case of the Labarre sandstone formation).

[12][13] In the same way, in 1999 Eric Buffetaut and colleagues attributed to Ampelosaurus atacis teeth and postcranial bones discovered in the Grès à Reptiles formation at Cruzy (located in the area called Chaînon de Saint-Chinian) in Hérault department.

[14] A later study showed that Cruzy's titanosaur teeth are different from those of Ampelosaurus, and belong to a new taxon whose description is in progress.

[15] In 2009, Fernando Barroso-Barcenilla and colleagues reported in the Spanish site of Lo Hueco, in Cuenca province, the discovery of spatulate teeth with the same morphology as those of Ampelosaurus.

This attribution to the genus Lohuecotitan is based on the fact that the other braincase morphotype was found to be associated with a titanosaur skeleton distinct from Lohuecotitan,[21] and because none of the very abundant titanosaur postcranial remains of Lo Hueco (represented by more than twenty partially articulated skeletons) belong to Ampelosaurus.

[4][6][2] All the material has been assigned to A. atacis, the observed differences in the proportions of limb bones being at the time interpreted by Le Loeuff as related to individual variation.

[2] This set of characters was identified by Le Loeuff in his description of Ampelosaurus to distinguish it from all other genera: teeth that weakly spatulate; a laterally widening distal extremity of neural spines on the dorsal vertebrae; neural arch of the dorsal vertebrae inclining strongly towards the rear; the lack of a distal expansion on the scapular blade; the presence of a light, ventral crest on top of the scapula; the presence of plate, bulb, and spine shaped osteoderms;[1] and, in 2005, Le Loeuff added that the constriction of the neural spine on the dorsal and cervical vertebrae was also probably a characteristic of Ampelosaurus.

[2] Characteristics of the tail vertebrae and the presence of osteoderms indicate that Ampelosaurus belongs to Lithostrotia, a group of derived titanosaurians which also includes Alamosaurus and Saltasaurus.

[1] More recently, Ampelosaurus has been put in a clade with other French and Spanish titanosaurs from the late Campanian to Maastrichtian, which was named Lirainosaurinae by Díez Díaz et al. in 2018.

[26] EFS, a system found on the surface of bones, is thought to show a growth plateau which indicates that maximum body size and skeletal maturity is reached in an individual.

The outer edge of the bones, were EFS would have been found, was well-preserved, and still lacked any fossilized proof of them being present for Ampelosaurus.

Ampelosaurus was also reported in other localities in France and Spain (notably Massecaps and Lo Hueco) but these specimens were found to belong to different titanosaurs.

Ampelosaurus roamed the vast plains of the Ibero-Armorican Island, an emergent landmass made up of much of the present day France and Iberian Peninsula.

[35] The sediments of the Marnes Rouges Inférieures Formation consist of mudstones, sandstones, conglomerates, and siltstones, of fluvial and alluvial origin.

[34] Fauna associated with Ampelosaurus atacis included another yet unnamed titanosaur,[10] the ornithopod Rhabdodon priscus (represented by teeth, jaws, and postcranial bones),[2][36] an indeterminate nodosaurid ankylosaur (known only by dermal scutes),[2] an indeterminate Dromaeosauridae ( represented by teeth),[2] the giant ground bird Gargantuavis philoinos,[37] an undetermined pterosaur,[38][39] the turtles Foxemys mechinorum (known by an incomplete skull and shell elements)[40] and a new yet unnamed compsemydid (one skull and an isolated costal plate),[41] an undescribed allodaposuchid eusuchian (represented by many elements including a complete skull showing similarities with Musturzabalsuchus and Allodaposuchus subjuniperus),[42] and fisches (a lepisosteid and the coelacanth Axelrodichthys megadromos).

Concerning the titanosaurs the pre-turnover assemblage included small-sized species such as Atsinganosaurus and Garrigatitan (latest-middle Campanian to early-late Campanian in age) from southeastern France (Bouches-du-Rhône department) and Lirainosaurus (latest Campanian in age, 72 to 73.5 Ma) from north-central Spain (Burgos province, Treviño enclave), and moderate-sized forms such as Lohuecotitan (late Campanian-early Maastrichtian) from central Spain (Cuenca province) and Ampelosaurus (early Maastrichtian 71.5 Ma) from southwestern France (Aude department).

The post-turnover assemblage is dominated by larger forms such as Abditosaurus (mid-early Maastrichtian, 70.5 Ma) from northeastern Spain (Lleida province).