AmericanChemicalSociety.com

Introduction: The motivation of this project is to bring to light vertebrate life in Afro-Arabia during the end-Cretaceous. The rationale for this focus is that the paleobiogeographic relationships between Africa and neighboring landmasses during the Cretaceous remain a major question, in part because of the uneven distribution of fossiliferous sediments on southern landmasses. Southern South America is the only region of Gondwana with good representation of terrestrial vertebrates from both Lower and Upper Cretaceous sediments. Those of India, Antarctica, and Madagascar are only known from uppermost Cretaceous sediments, whereas those of Africa and Australia are only adequately known from Cenomanian and older horizons. This sampling discrepancy and conflicting paleogeographic reconstructions have led to competing scenarios to explain paleobiogeographic relationships between southern landmasses. Whilst Africa has relatively few latest Cretaceous vertebrate localities, the Arabian Peninsula has extensive Cretaceous exposures that have seen relatively little concerted collecting. Africa and Arabia maintained a broad geographic connection until rifting of the African and Arabian Plates and opening of the Red Sea ~34 mya and the relatively recent collision between the Arabian Peninsula and Eurasia ~10 mya. Jordan forms the northwestern part of the Arabian Peninsula, which was ringed by seas that received erosional products from the continent throughout the Phanerozoic. Latest Cretaceous deposits are abundant in central and southern Jordan and represent a coastal environment that preserves both terrestrial and aquatic animals.

Field Work: PRF-supported field research in Cretaceous deposits in Jordan (Feb–Mar 2008) brought to light several exciting fossils that provide much-needed data. As I reported last year, fossil materials were collected from approximately 75 localities of varying richness were placed in a stratigraphic context. Detailed lithological sections were measured at 4 of the richest and most geographically separated localities will provide the stratigraphic context for interpreting the discoveries. The highlights of the discoveries are:

—two large marine turtles (both new genera)

—the partial skull and skeleton of the most complete pterosaur (flying reptile) from Africa (a new genus or species)

—the first diagnostic dinosaur from the Arabian Peninsula (a new genus), which represents and evolutionarily dwarfed taxon – a 'small giant' or dwarf sauropod

—the first Cretaceous mangrove palms of the Nipa family (possibly a new genus)

The emerging picture is that the Jordanian localities are all part of a coastal or near-coastal environment that sample elements of the terrestrial and marine communities, as well as marginal forms. The dinosaur, which is unique for its small adult size, likely fed on mangrove palms, which are abundant and well preserved. The pterosaur is quite large and may have habituated coastal environments.

Fossil Preparation: This past year was spent preparing fossil remains collected in Jordan. I hired two university graduates (Manz, Stinson) using an alternate funding source to clean fossils in our preparation laboratory. All fossil materials are cleaned except for the fossil turtles, which are only partly prepared. These will be prepared in the upcoming year.

Future Prospects for Additional Exploration: Despite the success we had in Jordan, I is my opinion that there are not enough outcrops remaining to justify a full-length season there. For that reason, late last year and early this year I took advantage of opportunities to visit contemporaneous deposits in Saudi Arabia. I hosted Saudi paleontologists in 2008 whilst I was in the field in Jordan, and they invited me and team member Iyad Zalmout to visit in 2008 and 2009. Zalmout was offered part time employment by the Saudi Geological Survey, and is now working there several months a year and completing a postdoctoral fellowship here at University of Michigan. Exploration of contemporaneous exposures in northern Saudi Arabia produced a poor sampling of vertebrate remains. However, exploration of redbeds that were mapped as Eocene (but actually Oligocene in age) produced extraordinary fossils, including a new fossil primate that is near the split between monkeys and apes. This exciting fossil will be described shortly in a paper to be submitted to Nature. I plan to explore Cretaceous rocks in southern Saudi Arabia and possibly Yemen, where new dinosaur trackways have recently been found. Plans for these trips are in the initial stages.

Results/Implications: Very little is known of terrestrial vertebrates (such as dinosaurs) from the latest Cretaceous of Afro-Arabia. The new dwarf sauropod is important because it offers an opportunity to reconstruct the phylogenetic links that may evidence a recent paleobiogeographic history between Afro-Arabia and neighboring landmasses. Our next task will be to finalize the manuscript on the dwarf titanosaur and to conduct histological analysis to document, as far as is possible, the adult status of this individual. We will attempt to put the Jordanian dinosaur into a phylogenetic context and to investigate potential evolutionary and paleoecological links between the Jordanian dwarf sauropod and a contemporaneous sauropods that lived on the northern margin of the Tethys in present day Spain, Romania, and Egypt. We will also need to complete the description and phylogenetic interpretation of the large pterosaur, seems to be quite similar to the giant pterosaur Quetzalcoatlus, from the Maastrichtian of North America.