Nullotitan glaciaris was a large titanosaur from the Chorrillo Formation of Santa Cruz, Argentina. Fernando Novas and colleagues named it in 2019. Its skeleton is incomplete, but vertebrae and major limb bones preserve a diagnostic combination rather than a generic image of any giant sauropod.
Quick facts
| Scientific name | Nullotitan glaciaris Novas et al., 2019 |
|---|---|
| Group | Sauropoda, Titanosauria, Lithostrotia |
| Age | Late Cretaceous, Campanian–Maastrichtian |
| Range | Chorrillo Formation, Santa Cruz, Argentina |
| Holotype | MACN-PV 18644 and MPM 21542 |
| Material | Vertebrae, ribs, scapula and major fore- and hind-limb elements |
| Size | Very large, but exact length and mass uncertain |
| Diet | Herbivorous |
| Skull | Unknown |
| Armour | No osteoderms demonstrated |
What can the material show?
A vertebra found in 1981 became interpretable after later excavations recovered associated bones.
Short broad caudals bear deep enclosed pits, partitions, ridges and a ventral groove.
Massive limb bones prove great size without providing a complete body length.
Skull, teeth, specific plants and skin armour remain unknown.
A discovery with a long history
One probable cervical vertebra was found in 1981 during fieldwork led by José Bonaparte. Researchers first compared it with Antarctosaurus and later with aeolosaurine titanosaurs, but an isolated vertebra was not enough to identify a distinct animal confidently. Renewed excavation near Estancia La Anita recovered additional elements from the same area and made a joint description possible.
The holotype combines catalogues MACN-PV 18644 and MPM 21542. It contains the probable cervical vertebra, rib fragments, several caudal vertebrae, part of the left scapula, a right femur, an almost complete right tibia, a fibula and an astragalus. MPM 21545, a separate humerus associated with pieces of ribs and vertebrae, was referred to the genus more cautiously because it lay about 100 metres from the main concentration.
The genus honours geologist Francisco Nullo, who found the original type material. The species name glaciaris refers to Perito Moreno Glacier, visible from the region where the fossils were excavated.
Diagnostic tail vertebrae
The anterior caudals are extremely short, about twice as wide as they are long. Some bear deep enclosed depressions and pits divided by internal partitions on their side surfaces. At the same time, the authors found no developed internal pneumatic chambers within the tail bones.
Longitudinal ridges and a central groove cross the underside of the vertebrae. The fibula has a marked S-shaped curve, while the lower end of the tibia is wide from side to side and compressed from front to back. The diagnosis rests on this combination of details, not simply on the impressive dimensions of individual bones.
Relationships and limits of the genus
Nullotitan was placed within Lithostrotia, the broad and diverse titanosaur group that includes many genera known from incomplete skeletons. Its precise position can move between phylogenetic analyses as character sets and comparisons change.
The early comparison of an isolated vertebra with Antarctosaurus does not make the two genera synonyms. The larger associated sample assigned to Nullotitan provides a different anatomical combination. Conversely, the distant specimen MPM 21545 is less securely associated than the bones from the type concentration and should not be treated as equally certain evidence.
How large was Nullotitan?
The describing authors called it a giant titanosaur, and the massive limb bones support a very large animal. A complete vertebral column is absent, however, so popular values for total length and body mass depend on scaling from other titanosaurs rather than a direct skeletal measurement.
The secure reconstruction is a heavy, four-legged herbivorous sauropod. No skull or teeth are known, preventing a direct account of snout shape, food processing, preferred plants or feeding height. Osteoderms have not been demonstrated for this genus either.
The Chorrillo environment
The Chorrillo Formation dates to the Late Cretaceous, within the Campanian–Maastrichtian interval. Its sediments accumulated in river channels and on floodplains close to the southern end of South America.
Other dinosaurs from the formation document the surrounding fauna, but occurrence in the same formation does not prove that particular individuals met. The cover reconstruction supplies a general titanosaur outline and a southern Patagonian landscape. Its colour, soft tissues, neck pose and social behaviour remain artistic choices rather than preserved evidence.
Evidence, inference and reconstruction
| Level | Evidence |
|---|---|
| Direct | Diagnostic vertebrae, ribs, scapula and massive limb bones |
| Supported | Giant lithostrotian and terrestrial herbivore |
| Uncertain | Exact position, adult length, mass and referred specimen MPM 21545 |
| Unknown | Head, teeth, plants eaten, osteoderms, colour and social behaviour |
Frequently asked questions
When did Nullotitan live?
During the Late Cretaceous Campanian–Maastrichtian interval.
Why is it called Nullotitan?
The genus honours geologist Francisco Nullo; glaciaris refers to Perito Moreno Glacier.
Is its skull known?
No. The material consists of vertebrae, ribs, part of a shoulder blade and limb bones.
Can its length be stated precisely?
No. Massive bones show a giant titanosaur, but exact length and mass depend on models.