[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

First titanosaur embryo from Asia



From: Ben Creisler
bh480@scn.org

First, apologies for glaring typos in my last two DML 
postings that were sent off bit too hastily. In one the 
subject line should have read "Cloverly 
tyrannosauroid..." and in the other PaleoBios was spelled 
without a capital B and a final ?s.? My bad.

Another new paper:

Gerald Grellet-Tinner, Cheul Muu Sim, Dong Hee Kim, 
Patrick Trimby, Alessandra Higa, Seung Lak An, Hwa Suk 
Oh, TaeJoo Kim and Nikolay Kardjilov (2011)
Description of the first lithostrotian titanosaur embryo 
in ovo with Neutron characterization and implications for 
lithostrotian Aptian migration and dispersion. 
Gondwana Research (advance online publication)
doi:10.1016/j.gr.2011.02.007  


Abstract
Although titanosaurs represent one of the most diverse 
radiations of non-avian dinosaurs during the Cretaceous, 
our knowledge of their early developmental stages was 
restricted to the Auca Mahuevo (Argentina) embryos in 
ovo. Here, we present the first complete lithostrotia 
titanosaur embryo in ovo. The relatively small spherical 
87.07 to 91.1 mm egg was discovered at the Lower 
Cretaceous locality Algui Ulaan Tsav in Mongolia, and is, 
to date, the smallest positively identified titanosaur 
egg. Through taphonomic processes, the egg was 
transformed into a calcite geode at the bottom of which 
the embryonic bones settled down and are now partially 
exposed on the lower egg surface. Neutron tomography 
characterization reveals a fully developed embryo 
fossilized within a thin (7.6 mm ~ 8.6 mm) calcite layer. 
EBSD, a SEM-based diffraction technique, which measures 
the complete crystallographic orientation of the crystal 
lattice from a submicron area on the sample surface, is 
used for the first time on an extinct dinosaur eggshell. 
Observations of the egg and its embryo combined with 
eggshell microcharacterizations suggest that this new 
embryo was a lithostrotia titanosaur with an intermediate 
robusticity index that shares a mosaic of skeletal 
characters with Diamantinasaurus matildae from Queensland 
(Australia) and the nemegtosaurid Rapetosaurus krausei 
(Madagascar) more than with any other titanosaurs. The 
Early Cretaceous age of Algui Ulaan Tsav implies that 
this specimen greatly predates the previously described 
lithostrotian titanosaurs from the Late Cretaceous 
sediments of Mongolia. In addition, the recognized amount 
of similar eggs that have been recovered during the last 
70 years at Algui Ulaan Tsav suggests that a well-
established population of lithostrotian titanosaurs used 
this site as a nesting site. The combined observations 
provide an important addition to Mongolian fossil 
richness and alter our understanding of the 
paleodispersion of this sauropod group. It now appears 
that lithostrotian sauropods would have reached Mongolia 
during the Aptian-Albian, thus suggesting the existence 
of a passage before the complete separation of the 
Laurasian and Gondwanan continents. Possibly, the 
lithostrotian north and eastward migration could have 
occurred between North Africa, Spain, and the rest of 
Europe prior to its fragmentation in large islands during 
the Cretaceous, thus justifying the presence of 
lithostrotians in the Cretaceous Romanian Hateg Island.

Research Highlights:
First and oldest articulated lithostrothian sauropod 
embryo in a ~ 91 mm egg from Asia;
NT and EBSD characterizations and imaging of the Aptian-
Albian embryo and eggshell; 
Northeastward lithostrothian migration from Africa 
through Europe during the Aptian

Keywords: Lithostrotia; egg; embryo; Mongolia; Neutron 
tomography; EBSD; lithostrotian paleodispersion


http://www.sciencedirect.com/science?
_ob=ArticleURL&_udi=B7XNB-52890RC-
1&_user=10&_coverDate=02%2F26%
2F2011&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_so
rt=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVe
rsion=0&_userid=10&md5=0bb3e1acfcb8bd02c7c0239d94e4fd0e&se
archtype=a