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Re: Bonitasaura



As you've correctly suspected, Bonitasaura have two
unfused dorsal neural arches. However, all the
remaining are well fused as well as all the remaining
bones. This way, although perhaps not fully mature, it
was not a kid. About titanosaur sizes you should be
aware because several latest Cretaceous titanosaurs
were dwarf (see previous discussions at the DML and
the works thata I presented in 2002 in Brazil (I'm
attaching the abstract but the dwarf sauropods are
discussed in the main text). Those are:

Boletim do 6º Simpósio sobre o Cretáceo do Brasil / 2º
Simposio sobre el Cretácico de América del Sur. São
Pedro, Brasil (2002): 135-141. 

SUCCESSIONAL STRUCTURE IN CONTINENTAL TETRAPOD FAUNAS
FROM ARGENTINA ALONG THE CRETACEOUS
ESTRUCTURA SUCESIONAL EN LAS FAUNAS DE TETRÁPODOS
CONTINENTALES DE ARGENTINA DURANTE EL CRETÁCICO

Sebastián Apesteguía

Three main evolutive stages can be recognised in the
faunas of Cretaceous continental tetrapods, specially
dinosaurs, that lived in Argentina. The first
(Neocomian to Early Aptian) involves relics of
widespread global Jurassic faunas. The second (Late
Aptian to Early Campanian) or Gondwanan (Early
Gondwanan + South American + Greatergondwanan),
includes faunas relatively isolated, evolving
separately and with the rise of several endemisms at
family level. The third and last stage involves the
stablishment of several land connections around
different Gondwanan and Laurasian territories,
producing thus several mixed faunas all around the
world. Five faunistic dominance patterns are
recognised as follows: ?Basal Neosauropod-Basal
Tetanuran-Stegosaur Global Dinosaur Domain?
(Neocomian-Early Aptian); ?Carcharodontosaurid-Basal
Titanosauriform-Diplodocimorph Early Gondwanan
Dinosaur Domain? (Late Aptian-Mid Cenomanian);
?Coelurosaur-Titanosaurid-Basal Euiguanodontian South
American Endemic Dinosaur Domain? (Late
Cenomanian-Coniacian); ?Abelisauroid-Saltasaurine
Greatergondwanan Endemic Dinosaur Domain?
(Santonian-Early Campanian) and ?Allochthonous
Ornithischian Dinosaur Domain? (Late
Campanian-Maastrichtian). Some events like the
extinction (or loss of dominance) of basal
titanosauriforms, diplodocimorph and
carcharodontosaurids seem to be linked with the
diversification of titanosaurids and large
coelurosaurs. Rising of saltasaurine sauropods seems
to fit with exctinction of large coelurosaurs
(although remained in Salta) and diversification of
abelisauroids. Arriving of allochthonous
ornithischians disrupted mainly coastal environment
ecology. Crocodiles, turtles and mammals were in
concordance with dinosaur domains. Frogs are not
properly known yet. Birds were not considered because
of its vagility but a continuously increasing
diversity is enviewed.  
 
Boletim do 6º Simpósio sobre o Cretáceo do Brasil / 2º
Simposio sobre el Cretácico de América del Sur. São
Pedro, Brasil(2002): 143-147. 

GREATER GONDWANA AND THE KAWAS SEA COASTAL TETRAPOD
FAUNA (Campanian-Maastrichtian)
GRAN GONDWANA Y LA FAUNA DE TETRÁPODOS DE LAS COSTAS
DEL MAR DE KAWAS (Campaniano-Maastrichtiano)

SEBASTIÁN APESTEGUÍA

American Cretaceous paleogeography was related to
Laurasia and Gondwana behavior and the opening of the
South Atlantic. However, the existence of Greater
Gondwana, would have allow between 110-70 m.y. ago, a
coastal continuity among South America ? Antarctic
peninsula ? continental Antarctica
-Kerguelen-India-Madagascar. Extant coastal marine
faunas are homogeneous. For it, Late Campanian coastal
points should be studied comparatively in South
Gondwanan regions. After Hay et al. consideration of
the closing of aulacogens, Patagonian paleogeography
was slightly modified. This region would have been
close as a fan toward the east, narrowing the south
Atlantic Ocean and reducing the climatic latitudinal
zonation between the 40º and 50º S. The interamerican
Late Campanian connection determined the existence of
two sucessive faunistic associations: The first,
continental and autochthonous, is characterized by
fresh water dipnoan fishes, snakes, sphenodontids,
saltasaurines, abelisaurids, monotremes, dryolestoids,
docodonts and gondwanatheres. The second, mainly
coastal and signed by allochtonous influences, implies
the hadrosaur arrival, more squamates and therian
mammals. The arrival ?timing? of laurasic lineages, in
a careful stratigraphic context, it will allow a
better understanding of the faunistic sucessions along
the coast of the Kawas Sea at the end of the Upper
Cretaceous.

Actually, it is also mentioned in:
Cretaceous Research Volume 25, Issue 1, Pages 1-96
(February 2004).

CRETACEOUS TERRESTRIAL BEDS FROM THE NEUQUÉN BASIN
(ARGENTINA) AND THEIR TETRAPOD ASSEMBLAGES

Héctor A. Leanza, Sebastián Apesteguía, Fernando E.
Novas and Marcelo S. de la Fuente

The Cretaceous terrestrial strata of the Neuquén basin
(northern Patagonia, Argentina) are described together
with their tetrapod records. Six local tetrapod
assemblages are identified: Amargan (Barremian ? Early
Aptian); Lohancuran (Late Aptian ? Albian); Limayan
(Cenomanian ? Early Turonian); Neuquenian (Late
Turonian ? Coniacian); Coloradoan (Santonian ? Early
Campanian) and Allenian [(Late Campanian ? Early
Maastrichtian (=Alamitense=Alamitian SALMA)]. The last
one includes records from northeastern Patagonia.

If you want to know what sauropods were real dwarf
(even smaller than Bonitasaura!) they are
Neuquensaurus, Saltasaurus, Rocasaurus-although
young-, Saltasaurus and probably Magyarosaurus.

Titanosaurs were variegated in size.
 
 --- DRosent288@aol.com escribió: 
> Only 7 meters?  Is it possible that this specimen is
> a juvenile or subadult.  
> I am always 
> suspicious of "adult sauropods" less than 12 meters
> (40 feet) long.
>  

=====
Lic. Sebastian Apesteguia
Seccion Paleontologia de Vertebrados
Museo Argentino de Ciencias Naturales 'B. Rivadavia'
Buenos Aires, ARGENTINA
www.paleoninjapesteguia.com.ar

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