In the summer of 2002 I co-led an expedition to the Rukwa Rift Basin (RRB) in southwestern Tanzania. Working with colleagues from the US and Tanzania, our team spent 4 weeks searching for fossils in the virtually unexplored Red Sandstone Group deposits. During this time we discovered a number of new Cretaceous localities that preserve an abundant and diverse vertebrate (and invertebrate) assemblage, including fishes, crocodyliforms, turtles, mammals, and both theropod and sauropod dinosaurs. It was also during this trip that we discovered a locality preserving vertebrate fossils of animals much younger than the Cretaceous-age sequences with the aforementioned nonavian dinosaurs. Fossil mammals (e.g., rodents) discovered at this locality closely resemble those recovered from the well-known Fayum Depression (Eocene-Oligocene) in north-central Egypt.

During the summers of 2003, 2004, 2005 and 2006 our team of faculty and students returned to the RRB to (1) expand surveying of Red Sandstone Group strata exposed in different regions of the basin, and (2) continue excavating a number of productive quarries located during the initial field season.  These efforts have resulted the identification of several additional Cretaceous and Paleogene localities and the recovery of hundreds of additional vertebrate, invertebrate, and plant fossils. To date, these expeditions have also provided numerous experiences (e.g., paleontology and geology field methods, laboratory analysis) for a number of students associated with the project. Our team has worked closely with colleagues from the Department of Geology at the University of Dar es Salaam and various Tanzanian government agencies throughout the tenure of the project.

We have just returned from our first National Science Foundation (NSF) funded field season (2007), an effort that significantly expanded the ongoing excavating of two new Cretaceous bone beds discovered during the 2005 expedition. Moreover, we were able to continue geological sampling critical for refining the age and depositional context of the vertebrate-bearing strata. See O'Connor et al. (2006) for an overview of the Cretaceous fauna collected to date, and Roberts et al. (2004) for an overview of the Red Sandstone Group.

The Mahajanga Basin Project, Northwestern Madagascar
     Upper Cretaceous (Campanian - Maastrichtian)

For the past several years I have been involved with a project studying a remarkable Late Cretaceous terrestrial vertebrate assemblage from the Maevarano Formation in Northwestern Madagascar. As part of a multidisciplinary team, my research focuses on the anatomy and systematics of nonavian dinosaurs and birds in addition to a recently initiated large-scale quantitative biogeographic analysis of the entire vertebrate fauna. A review of the fauna recovered to date is provided in the recent Krause et al. (2006) paper . In addition, the detailed anatomy of one of the nonavian dinosaurs recovered from the Maevarano Formation, Majungasaurus crenatissimus, was recently featured in a collection of articles as part of the most recent Society of Vertebrate Paleontology Memoir Series (SVP Memoir 8). Please email me (oconnorp@ohiou.edu) if you would like a copy of the entire memoir.

Our group has also developed a not-for-profit fund for the development of education and health care in Madagascar. If you are interested in additional information, please see: http://www.ankizy.org/

 

Anatomy/Morphology Projects

          (1) Comparative Morphology of Postcranial Skeletal Pneumaticity in Birds - Birds are unique among living amniotes in possessing a pneumatic (or air filled) postcranial skeleton. Air sacs connected with the avian lung are positioned throughout the body, and in some cases, extend finger-like projections (pneumatic diverticula) that penetrate to the interior of bones making up the postcranial skeleton. The amount of such skeletal pneumaticity is different from one bird group to another and my research focuses on the degree to which it varies among different groups of birds. More specifically, I have attempted to quantify 'relative pneumaticity' as a function of body size, clade identity, and a variety of locomotor and behavioral specializations (e.g., diving) exhibited by living birds. An initial study examining anseriform birds (ducks, geese, swans) was published in a recent issue of Journal of Morphology . I am currently conducting a large-scale project with Professor H.-R. Duncker (Institut für Anatomie and Zytobiologie at Justus-Liebig-Universität, in Giessen, Germany) detailing the morphology of pneumatic diverticula (the soft tissue structures responsible for pneumatizing the skeleton) in birds. A preliminary analysis of charadriiform birds is nearing completion, with a broader survey examining all living birds currently underway.

          (2) Evolution of the Respiratory Apparatus and Postcranial Skeletal Pneumaticity in Archosaurs - Based on features preserved in fossil specimens, many extinct archosaur groups (dinosaurs, pterosaurs) are thought to have possessed a pulmonary air-sac system similar to the one in living birds. By characterizing pneumatic features (and the influence of other soft tissue systems on bone) in extant taxa, I have used this dataset to assess the "pneumatic" quality of osteological markers preserved in fossil specimens. This work has allowed me make more accurate reconstructions of different soft tissue systems in extinct taxa, and thereby formulate hypotheses related to the basic structure and possible function of the pulmonary system in groups as diverse as theropod and sauropod dinosaurs and pterosaurs. Results of this work on nonavian theropod dinosaurs have recently been featured in the journal Nature (link to National Science Foundation and Nature press releases) and Natural History Magazine. A detailed analysis of postcranial pneumaticity in archosaurs is was recently published in the Journal of Morphology . Along with my collaborator, Leon Claessens (College of the Holy Cross), we are expanding the analysis of fossil archosaurs to include pterosaurs and other non-dinosaurian archosaurs.

           (3) Scaling Implications and Biomechanical Consequences of Postcranial Skeletal Pneumaticity in Birds - I have recently started collecting data aimed at addressing the biomechanical implications of skeletal pneumatization in birds. This new project will be based at OUμCT, the new μCT facility recently inaugurated (April 2006) at Ohio University. A preliminary study comparing structural features in pneumatic and apneumatic bird vertebrae was recently publishing in the Journal of Anatomy (Fajardo, Hernandez, and O'Connor, 2007) .

http://ravenel.si.edu/paleo/paleoglot/index.cfm