Jobaria
Name: Jobaria
(Jobar - after a creature in African mythology).
Phonetic: Jo-ba-re-ah.
Named By: P.C. Sereno., A.L. Beck, D.B.
Dutheil, H.C.E. Larsson, G.H. Lyon, B. Moussa, R.W.
Sadleir, C.A. Sidor, D.J. Varricchio, G.P. Wilson
& J.A. Wilson - 1999.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropodomorpha, Sauropoda.
Species: J. tiguidensis (type).
Diet: Herbivore.
Size: Estimated about 21 meters long.
Known locations: Niger, Abaka -
Tiouraren Formation.
Time period: Initially considered to be of the
Hauterivian to Barremian ages of the early Cretaceous, further study
of the sediments at the Tiouraren formation suggest that they actually
represent the Bathonian to Oxfordian stages of the mid Jurassic.
Fossil representation: Two individual specimens.
It
could be said that Jobaria is a sauropod
that
doesn’t know what it is
due to a mix of different traits. The vertebrae of Jobaria
are very
simple in form which has led to some suggestion that Jobaria
is a
primitive sauropod. Study of other areas however has led to
speculation that Jobaria may actually be a
primitive macronarian
(sauropods that were built tall rather than long, such as
Camarasaurus
and Brachiosaurus).
A study by Paul Sereno regarding
the circumferences of the humerus (upper forelimb bone) and femur
(upper rear limb bone) led to the conclusion that the centre of
gravity for Jobaria was nearer the rear legs,
something that has gone
onto to speculation about Jobaria being able to
rear up its hind legs
so that it could reach higher vegetation.
At
eighteen meters long Jobaria was a big dinosaur,
but one that lived
in the same area as the predator Afrovenator.
This relative of
Megalosaurus
is noted for having proportionately longer arms that may
have helped it to grab on to large prey like Jobaria
as it delivered
bites with its jaws. Juvenile and subadult individuals would have
been particularly at risk from this predator.
Further reading
- Cretaceous sauropods from the Sahara and the uneven rate of skeletal
evolution among dinosaurs. - Science 286:1342-1347. - P. C. Sereno, A.
L. Beck, D. B. Dutheil, H. C. E. Larsson, G. H. Lyon, B. Moussa, R. W.
Sadleir, C. A. Sidor, D. J. Varricchio, G. P. Wilson, and J. A. Wilson.
- 1999.
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