Name:
Saltasaurus
(Salta lizard).
Phonetic: Salt-ah-sore-us.
Named By: Bonaparte & Powell - 1980.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropodomorpha, Sauropoda, Titanosauria,
Saltasauridae.
Species: S. loricatus (type).
Diet: Herbivore.
Size: 12 meters long.
Known locations: Argentina, Salta Province -
Lecho Formation.
Time period: Campanian/Maastrichtian of the
Cretaceous.
Fossil representation: Material of at least two
individuals, eggs and internal embryos are also known.
The
discovery of Saltasaurus was a revelation in that
at least some
titanosaurid sauropods
actually had armour plates on their backs.
These plates are actually called osteoderms and are bony growths that
were within the skin, and in Saltasaurus these
were ten to twelve
centimetres across and seemed to form low conical spikes. These
osteoderms had actually been found before the discovery of the main
Saltasaurus remains and were thought to have been
the remains of an
armoured ankylosaurid dinosaur. Some Other sauropods have since been
found to also possess similar armoured growths, included the related
titanosaurid Laplatasaurus.
The
presence of Saltasaurus in South America was also
proof that while the
sauropods in Northern latitudes declined and disappeared with the
emergence of new herbivores like the hadrosaurs
and ceratopsians,
those that were isolated on the southern Island continents such as
South America did not have to face this new competition and so
continued to thrive until the very end of the Cretaceous when the
dinosaurs became extinct. Other sauropods such as Malawisaurus,
Wintonotitan
and the colossal Argentinosaurus
also indicate a
Cretaceous survival for the sauropods in Southern continents.
A
Saltasaurus nesting site has been identified at Auca
Mahuevo in the
Patagonia region of Argentina. Nests containing an average of
twenty-five eleven to twelve centimetre eggs have been found in a site
that is thought to have been used by hundreds of female Saltasaurus.
The fossilised embryos inside these eggs have revealed that the bony
armour along their backs were present even when the young Saltasaurus
was inside the egg. There large number and close proximity of the
nests to one another has also been taken to indicate herding behaviour
in Saltasaurus, perhaps as an additional defence
against predators
like Abelisaurus
and Carnotaurus.
Further reading
- A continental assemblage of tetrapods from the Upper Cretaceous beds
of El Brete, northwestern Argentina
(Sauropoda-Coelurosauria-Carnosauria-Aves) - Mémoires de la Société
Géologique de France, Nouvelle Série 139:19-28 - J. F. Bonaparte
& J. E. Powell - 1980.
- Osteología de Saltasaurus loricatus (Sauropoda
Titanosauridae) del
Cretácico Superior del noroeste Argentino. - J. E. Powell - 1992.
- Dermal Armor Histology of Saltasaurus loricatus,
an Upper Cretaceous
Sauropod Dinosaur from Northwest Argentina. - Acta Palaeontologica
Polonica, 55(3): 389-398. - Ignacio A. Cerda & Jaime E. Powell
- 2010.