RE: Bicentenaria argentina (Theropoda) paper appears

[Jaime Headden <qi_leong@hotmail.com>]

Let's solve this information gap. Even if the paper in question is "in press," 
it is apparently as much as published, so while I've taken the step to revel in 
some material exposition on the specimens, it may actually BE published by now. 
Leap of faith, here.

Novas, F. E., Ezcurra, M. D., Agnolin, F. L., Pol, D. & Ortíz, R. 2012. New 
Patagonian Cretaceous theropod sheds light about the early radiation of 
Coelurosauria. Revista de Museu Argentino de Ciencas du National 14(1):57-81.

Abstract:

Here we describe a new theropod, *Bicentenaria argentina* nov. gen. et nov. 
sp., from the early Late Cretaceous of Patagonia. It is represented by more 
than a hundred bones belonging to different sized individuals, which were 
buried together in disarticulation after little transportation. The available 
association of skeletal elements suggests a gregarious behaviour for 
*Bicentenaria*, an ethological trait also recorded among other theropod clades. 
Increasing documentation of monospecific assemblages of different groups of 
theropods suggests that a gregarious behaviour may have constituted the 
ancestral condition for Theropoda, at least. *Bicentenaria* characterizes for 
the surangular bone with a high dorsal margin and a prominent lateral shelf, a 
retroarticular process that is low, wide and spoon-shaped, and quadrate bone 
with its lateral condyle larger than the medial one. Phylogenetic analysis 
found the Chinese *Tugulusaurus* and the Patagonian *Bicentenaria* as 
successive sister taxa of all other coelurosaurs, thus revealing the importance 
of the new taxon in the understanding of the early diversification of 
Coelurosauria. In particular, *Bicentenaria* amplifies the array of basal 
coelurosaurs that inhabited Gondwana during the Cretaceous, also including 
compsognathids, *Aniksosaurus* and *Santanaraptor*. Although still restricted 
to a handful of forms, available information indicates that Gondwana was a 
cradle for the evolution of different lineages of basal coelurosaurs, different 
from those documented in Upper Cretaceous beds in the northern landmasses. 
Analysis of body size distribution in averostran theropods results in the 
identification of two main episodes of drastic size reduction in the 
evolutionary history of Coelurosauria: one occurred at the initial radiation of 
the group (as represented by *Bicentenaria*, *Zuolong*, *Tugulusaurus*, 
compsognathids, and *Aniksosaurus*), and a second episode occurred at the early 
diverification of Paraves or avialans. Reduction in body size may have allowe!
d adult c
 to exploit ecological niches not occupied before by larger basal averostrans.


*Bicentenaria argentina* nov. gen. et nov. sp.

Etymology.
>From bicentenary, due to the 200 years of the Revolution of May (25th May 
>1810), which lead to the first Argentinean autonomous government, thus 
>constituting one of the most important chapters in the history of this South 
>American country. Specific epithet honors Argentina, the country where the 
>specimens were recovered.

Holotype.
MPCA 865, caudal half of skull in articulation with the lower jaws (Fig. 2).

Paratypes.
MPCA 866, around 130 bones, including fragments of two articulated premaxillae 
with three pairs of teeth, an incomplete right maxilla with a single tooth, 
fragments of seventeen dorsal vertebrae, fourteen sacral vertebrae, twenty 
caudal vertebrae, fragments of two scapulae, caudodorsal corner of a right 
coracoid, proximal ends of three ulnae, distal end of radius, eight manual 
unguals, fragments of left ilium, proximal fragments of five pubic shafts, five 
incomplete femora, proximal thirds of two left tibiae and distal end of the 
right one, right astragalus, fragments of five metatarsals, fifteen non-ungual 
pedal phalanges, eight pedal unguals, and several isolated rib fragments.

Locality and horizon.
Upper levels of the Candeleros Formation (Cenomanian, early Late Cretaceous; 
Leanza et al., 2004), Río Limay Subgroup, Neuquén Group. The fossiliferous 
locality is placed at the east shore of Ezequiel Ramos Mexía Reservoir, Río 
Negro Province, Northern Patagonia, Argentina (Fig. 1). GPS coordinates of the 
fossil site are 39º 28’ 9.82” S, 68º 54’ 25.01” W. The rocks of the Candeleros 
Formation which yielded the remains of Bicentenaria argentina are made up by 
red medium sized sandstones and mudstones, with abundant dark-brownish 
paleosoils representing a fluvial environment under braided and meandering 
regimes, as well as in aeolian conditions (Leanza et al., 2004; Garrido, 2011).

Diagnosis.
Bicentenaria argentina was a smallsized theropod ca. 3 m long [estimated by 
extrapolating bone measurements from the reconstructed skeletons of 
*Compsognathus* and *Tanycolagreus*; Ostrom, 1978; Carpenter et al., 2005)] and 
ca. 40 kg of body mass [following formula from Seebacher (2001)]. *Bicentenaria 
argentina* is diagnosed on the following autapomorphies: premaxillary teeth 
with mesial denticles only at the base of the crown; quadratojugal with a 
rostral process two times longer than the dorsal process; quadrate with lateral 
condyle much larger than the medial one; surangular with a raised dorsal margin 
trapezoidal-shaped in lateral profile; retroarticular process dorsoventrally 
depressed, transversely wide, and spoon-shaped; humerus with proximal end 
craniocaudally flattened, and distal end bearing a deep fossa on its cranial 
surface; and manual unguals of external digits bearing proximal dorsal lips.

"Collected material of *Bicentenaria argentina*.
The skeletal remains of *Bicentenaria argentina* were collected by Mr. Raul 
Spedale in 1998 during an exceptional fall in the water level of the Ezequiel 
Ramos Mexía Reservoir (Fig. 1). All the bones were collected from a single 
quarry roughly 40 centimeters long, 30 centimeters wide, and 50 centimeters 
thick (R. Spedale, pers. comm.). The recovered bones are well preserved and 
lack signs of aerial exposure or scavenging before burial. Unfortunately, the 
bones suffered several breakages during the excavation process and no 
taphonomic information was collected during the process. Nevertheless, the 
bones were buried almost probably in disarticulation, as revealed by a block of 
sandstone still embedding a partial sacrum and fragments of the corresponding 
right iliac blade, that are chaotically attached with a fragment of left 
maxilla, four caudal vertebrae of different sections of the tail, as well as 
with the proximal end of a cranial dorsal rib. This kind of preservation 
indicates that bones of different individuals were transported and mixed up 
before their final burial. The collected bones include three femora of the left 
side with roughly the same size (approximately 31cm in length), thus indicating 
that the fossil assemblage is made up by, at least, three large different 
specimens. These large femora match with the size observed in several isolated 
dorsal, sacral and caudal vertebrae with a closed neurocentral suture. Thus, 
these large individuals would not be juveniles at the time of their death 
(Brochu, 1996; Irmis, 2007). Besides, the existence of a right distal femur 
with an identical morphology, but considerably smaller than the largest ones, 
indicates the presence of probably younger individuals in the bone assemblage. 
This statement is supported by the presence of a fragmentary maxilla bearing a 
tiny tooth with a crown height of 8 mm, obviously corresponding to a juvenile 
individual. In summary, the bone assemblage seems to be made up by different 
sized juvenile and adult specimens.

We interpret that both the holotype and paratype specimens belong to a single 
species for the following reasons: 1) duplicate hindlimb elements (e.g., femur, 
tibia, metatarsals, and pedal phalanges) possess an identical anatomy; 2) 
available bones exhibit theropod, tetanuran and coelurosaurian synapomorphies 
(these derived features are mentioned in the text below); and 3) there is no 
evidence of any other dinosaur taxon preserved in the quarry. Excepting for the 
fragmentary skull, the disarticulated nature of the assemblage avoids 
recognition of discrete specimens composed for more than a single bone."

I have a _small_ discussion of some of the material up here: 
http://qilong.wordpress.com/2012/08/10/tyrannosaurus-publicity/
(this is definitely a shameless plug).

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


----------------------------------------
> Date: Fri, 10 Aug 2012 13:35:46 -0700
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: Bicentenaria argentina (Theropoda) paper appears
>
> From: Ben Creisler
> bcreisler@gmail.com
>
>
> Based on some blog postings, personal web pages, and Wikipedia entries
> in Spanish and Dutch, the official description of the theropod
> Bicentenaria argentina is out or at least in press. However, it's not
> posted yet on the journal's website so I can't provide an abstract for
> now. It's said to be a basal coelurosaur.
>
> Novas, F.E., Ezcurra, M.D., Agnolín, F.L., Pol, D. and Ortíz, R.
> (2012). New Patagonian Cretaceous theropod sheds light about the early
> radiation of Coelurosauria. Revista del Museo Argentino de Ciencias
> Naturales, nueva serie, 14: 57–81.
>
>
>
> Journal website:
> http://www.macn.secyt.gov.ar/investigacion/publicaciones/revista/indice_volumenes.php