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Dinosaur Genera List corrections #159

I'm forwarding this email in its entirety to the dinosaur list as requested 
by sender  Gunter Van Acker. We add name #904 to the Dinosaur Genera List:

Aucasaurus Chiappe & Dingus, 2001 [nomen nudum]

The nomen nudum part will be removed when the formal description appears, 
presumably later this year.

Also added to Mesozoic Meanderings #3 under South American dinosaurs is this 
genus and species listing:

Aucasaurus Chiappe & Dingus, 2001 [nomen nudum]
    A. garridoi Chiappe & Dingus, 2001 (Type)

By convention in MM #3, even a nomen nudum genus can have a "type" species, 
for example when the species name is also published and is the only species 
in the genus.
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While I'm not (yet) a subscriber of the Dinosaur Mailing List (but I do read
the archives), I couldn't resist reporting an important new species : the
Auca Mahuevo carnotaurine has finally received a name (new genus and
You'll find this information very useful when updating your dinosaur genera
Could you forward this message to the Dinosaur Mailing List ? Thanks.

Aucasaurus garridoi

etymology : (Alberto) Garrido (discoverer)'s Auca (Mahuevo) lizard
describers : Chiappe & Coria, 2001

Source : "Walking On Eggs : The Astonishing Discovery of Thousands of
Dinosaur Eggs in the Badlands of Patagonia", by Chiappe & Dingus (ISBN
0743212118), 224 pages, new publication by Scribner Publishers, price
approx. US$ 20.00

The book mentioned above is an incredible source of information on the
famous Auca Mahuevo site, which yielded embryos and thousands of eggs
belonging to titanosaurs. The book includes complete reports and discussions
of the original discovery, but also includes information on more recent
expeditions during 1999 and 2000. The book includes black/white artwork of
the new species and other Argentinian dinosaurs (Carnotaurus,
Giganotosaurus, Saltasaurus ...). My advice is : get a copy as soon as
possible, it's one of the best dinosaur books published this year.

Additional information on the specimen :

Locality : Auca Mahuevo site, Néuquen Province, Argentina
Age : upper Rio Colorado Formation, early Campanian, 83 - 79 MYA
The specimen was discovered during 1999 and is 70% the size of the
Carnotaurus sastrei holotype specimen, it is described as the most complete
abelisaur skeleton ever collected. The arms are proportionately larger than
those of Carnotaurus, the skull is longer and lower and has bumps instead of
the horns seen in Carnotaurus. The specimen preserves impressions of soft
tissue around the pelvic region.
The specimen had been buried at the bottom of a shallow lake; because part
of its skull was broken apart, the describers suggest it may have been
involved in a fight and killed when another dinosaur bit or struck its head,
the exact cause of death remains uncertain.
In the book, Chiappe states that a more complete scientific paper has been
submitted (probably Journal of Vertebrate Paleontology).

New discoveries made during the most recent expedition (2000) :

Fragmentary bones of a colossal predator (including pubic boot), similar in
shape and size to Giganotosaurus. These remains suggest that
carcharodontosaurines may have survived to roam Auca Mahuevo's river plains,
extending the fossil record of carchardontosaurines by at least another 15
million years (from approx. 95 to 80 MYA).

2 partial titanosaur skeletons, found in the same rock layer as the eggs of
egg layer 4 (middle Rio Colorado Formation). These skeletons were found less
than 3m away from nests. They may represent the first skeletal remains from
the animals that actually produced the eggs at Auca Mahuevo. 1 specimen
shows evidence of being scavenged (shed theropod teeth found associated with
specimen). Both specimens are fragmentary; 1 consists of only a foot and a
portion of the tail, the second specimen is also incomplete (scavenged

A third more complete titanosaur specimen was found in the same rock layer
as the eggs of egg layer 3, but a few miles to the north. The specimen
includes several caudal vertebrae, ribs, a few bones from hindlimb and
pelvis and several other skeletal elements. This specimen hasn't been dug up
yet, but has been protected for future collection. The bones have features
that are clearly not saltasaurine, this could mean that the embryos did not
develop armor (bony scutes, only known for saltasaurines) when fully grown.

The first known well-preserved sauropod nests, each containing more than 25
eggs, laid in a depression surrounded by a tall sandy rim. A total of 4 such
nests were found, but they were too big and too fragile to be collected;
molds have been made of the 2 best-preserved nests.

Additional embryos have been collected.

Layers with large numbers of sauropod tracks were discovered.

Kind regards,
Gunter Van Acker

E-mail : Gunter.VanAcker@Electrabel.com

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