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Re: Brazilian scientists claim oldest dino findings
On 12/15/06, Jamie Stearns <firstname.lastname@example.org> wrote:
Well, this is an interesting find. 228 mya... Is that really older than
Saturnalia and Eoraptor?
The claim of the scientists is that other same age archosaurs -
probably including _Eoraptor_ - do not have the pelvic girdle
constitution that those specimen seems to have.
"I would say that it is *the* dinosaur", jokes Sergio Furtado
Cabreira, paleontologist of Ulbra (Lutheran University of Brazil) at
Cachoeira do Sul (RS). Cabreira, with the geologist Valter Lisboa, had
identified the beast remais in December 2004, in Agudo city (central
Rio Grande Sul).
The paleontologist says that he is "very confident" about their
conclusions: the creature, that was not named yet, would be the only
"true" dinosaur at its epoch. Other species with same age found in Rio
Grande do Sul and Argetina would had been evolutionary dead-ends -
they would have being very close to the dinosaurian lineage, but their
transition to bipedal predators would not have being very efficient.
The key to Cabreira and his collaborator, Valter Lisboa,
argumentarion, is the structure of bone close to the pelvic region
(the creature "hip"). There, the creature had between four or five
vertebrae called sacrals fused into a single strutucture, with
relatively long a ilium (the upper part of hip bone). It had allowed,
according to the paleontologist, the creature to have there a much
more strong and organized musculature. "So, it would have more
stability to be biped", says Cabreira.
To Cabreira, others reptiles at that epoch that became able to walk
with hind legs "achieved bipedalism by a not so favourable way", and,
so would have disappeared, while the new fossil species
characteristics was inherited by all other dinosaurs that came after
then. "Certainly, it have got a very significant evolutionary
advantage", he says.
The creature is fairly complete: the researchers had found most parts
of the cranium, jaws with teeth, vertebrae from every parts of the
trunk and tail, fore and hind limbs and fingers (but no claws). The
curious thing, says Cabreira, "is that it has a guampinha [little
horn] in the nasal bone", as some posterior dinosaurs known from
Argentina. Teeth, serrated and curved backwards, have a primitive
shape compared with others carnivorous dinosaurs - not a surprise for
a so old creature.
The bone are hollow, remembering the bird bones, what certainly made
the creature a featherweight: with 1.5 m from muzzle tip till the end
of tail, it must not have weighted more thant 12 kg. "We render it as
a fast, competitive, cursorial [runner] carnivore", says the
paleontologist. According to him, it was by that image that the
computer graphic staff technician, Joni Marcos Silve, restored the
creature with collor pattern remembering a guepard, the fatest of