Name:
Bajadasaurus
(Bajada lizard).
Phonetic: Ba-ha-da-sor-us.
Named By: P. A. Gallina, S. Apestegu�a,
J. I. Canale & A. Haluza - 2019.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropoda, Dicraeosauridae.
Species: B. pronuspinax
(type).
Diet: Herbivore.
Size: Uncertain due to lack of fossil remains.
Known locations: Argentina - Bajada Colorada
Formation.
Time period: Berriasian to Valanginian of the
Cretaceous.
Fossil representation: Partial skull, jaws,
teeth and cervical vertebrae.
A
passing glance at the dinosaur Bajadasaurus would
likely bring
immediate comparisons to another very popular sauropod
dinosaur known
as Amargasaurus.
Amargasaurus made headlines when it was named
because of the large spines that rose out and back from the neck, at
the time making it unique amongst sauropod dinosaurs. The discovery
of Bajadasaurus however now shows us that Amargasaurus
was not the only
sauropod dinosaur to have these enlarged spines. However, whereas
the spines of Amargasaurus face backwards, those
of Bajadasaurus
pointed forwards. Since the early restorations of both of these
dinosaurs showing the spines exposed, new studies now suggest that the
spines were not exposed, but instead supported fleshy growths.
Bajadasaurus
was a dicraeosaurid sauropod dinosaur. Thought to be derived from the
earlier diplodocid sauropods dicraeosaurids had reasonably stocky
bodies. Thin tails and fairly short necks, at least when compared
to other type of sauropod dinosaurs. Dicraeosaurid sauropods are most
likely to have been low browsers, feeding upon the lowest growing
plants. Inner ear reconstruction of many of these genera (when
fossil study permits) confirms that the resting head angle posture of
these sauropods was with the mouth pointing down, not forwards. For
most of these genera this had led to speculation that vision was
somewhat limited, but the available skull structure of Bajadasaurus
has revealed something different. The bones above the eye sockets are
angled in such a way that the eyes could have faced forwards even when
the head was angled low to the ground. This was an almost unique
discovery, with the first time it was identified was in the related
dicraeosaurid sauropod dinosaur Lingwulong
which
was named roughly a
year before Bajadasaurus. There is even
suggestion that eyes that
angled to the crown of Bajadasaurus may have even
allowed for a limited
scope of stereoscopic vision, something that would be very rare not
just for sauropod dinosaurs but for herbivores in general.
Further reading
- A new long-spined dinosaur from Patagonia sheds light on sauropod
defense system. - Scientific Reports 9:1392:1-10. - P. A.
Gallina, S. Apestegu�a, J. I. Canale & A.
Haluza - 2019.
- Osteohistology of the hyperelongate hemispinous processes of
Amargasaurus cazaui (Dinosauria: Sauropoda): Implications for soft
tissue reconstruction and functional significance. - Journal of
Anatomy. 240 (6): 1005–1019. - Ignacio A. Cerda, Fernando E. Novas,
Jos� Luis Carballido & Leonardo Salgado - 2022.