Benguela Area Part 1
Near Benguela, there are extensive outcrops of red beds of silt, mud, and sandstones that are mapped as Albian in age. These red rocks show cross-bedding, bioturbation, and tree trunks that indicate that are terrestrial deposits, and therefore a good candidate for yielding dinosaur bones. Moreover, we collected a few dinosaur bone fragments from equivalent beds in the Namibe region.
But reality is not always as we wish: a lot of walking... we found no vertebrate fossils. The most significant finding were some beautiful gymnosperm tree trunks.
The Upper Cretaceous marine beds were more productive, and we found many invertebrates, shark teeth, and some marine reptiles pieces, but mostly fragments. These finds are good for building the record, but we keep looking for new localities and fossils that can tell much more about evolution of vertebrates in Angola.
On July 16th, Louis Jacobs, Ana Marques, and John Graf flew up to Cabinda. Cabinda is a province to the north separated from the main country by the Republic of Congo.
From July 17th to July 20th, we prospected four beaches which had outcroppings that were of more recent ages. For the last four years, members of Project PaleoAngola have collected samples and measured sections at these localities for the purposes of determining the faunal assemblage of these outcrops and determining the ages of the rocks (something that had not previously been accomplished).
During these four days, we found two new localities that were fossil rich. From these localities, we were able to recover the same types of fossils found at the other localities along with a crocodile genus not described from this area before and an Arsinoitherium tooth.
Arsinoitheres are hippo-like mammals with two large horns forming a V at the end of their snouts that lived during the Late Eocene and Early Oligocene.
Image from http://farm6.static.flickr.com/5257/5404145675_50b1457eea_z.jpg
These new fossils will add to the already rich fossil faunal assemblage found in Cabinda and will help narrow down the age of the rocks that they were discovered in.
On July 21st, we flew back to Luanda. On July 22nd, we flew down to Benguela to rejoin Michael and Octavio for the rest of the field season.
Octávio Mateus and Michael Polcyn drove to the Malange area while Louis Jacobs, John Graf, and Ana Marques went to Cabinda. In Malange (also spelled Malanje) and Lunda Norte provinces are in the north central part of the country and previous reports in Baixa de Cassange have shown a rich fauna of Triassic fossil fishes. These areas haven't been visited by paleontologists since the 1960's so we decided to give it a try.
We arrived to Malange on the evening of the 16th and met with our friend Pedro Vaz Pinto, a biologist that studies the giant sable, the Palanca-Negra-Gigante, the national symbol of Angola. He has been capturing sables to fit them with radio tracking collars and told us that while they were darting a sable from a helicopter that day, a large male lion tried to take the sable. Fortunately the helicopter scared the lion away and the sable was safely collared. This sighting is extremely significant, being the first large predator in the area since the war ended.
Yesterday (the 17th) we drove to Xá-Muteba (Lunda Norte), the closest town to the Triassic fossil localities. The local authorities alerted us about the possible presence of landmines in the area we wanted to visit, so we met the de-mining team who informed us that the area surrounding the fossiliferous sites has not been completely cleared, so we headed back to Malanje to regroup and plan for the next day.
Today (the 18th) we decide to see the continental Cretaceous formations near Kiwapa Mzoji (former Brito Godins). There are good rock exposures along the road cuts as the road expansion works progresses. The rocks are a varved mudstone and sandstone with some ripple-marks.... and no fossils. Although we were not able to find any fossils on this leg of the expedition, we did learn a lot about the area, the people and the rocks. In a few years, we expect the mines will be cleared and we will be able to go tot he Triassic localites. Tomorrow, we head back to the coast and plan to base in the port town of Benguela.
The team met in Luanda on the 12th and after gathering the proper permits, and getting the vehicles and supplies organized, we set out for the localities in the north around the village of Iembe. This locality has thus far yielded 4 holotypes; Angolasaurus bocagei, Tylosaurus iembeensis, Angolachelys mbaxi, and Angolatitan adamastor.
Our goals this year for the Iembe locality were threefold. First, we needed to collect fossil molluscs for stable carbon isotope analysis to build a chemostratigraphy of the area which we will compare with the global record to provided better age control for the fossils we have recovered from the site. Second, we needed to revisit previous dig sites to see if any additional material had weathered out of the outcrops, and third, we wanted to prospect for new localities in the area.
We accomplished all of our goals and were especially excited to find a new productive locality to the north of the outcrops that had yielded our previous finds in the area. We found fragmentary material including a disarticulated turtle carpace, plesiosaur limb material, and a disarticulated mosasaur that appears to be Angolasaurus. We collected the plesiosaur limb and Angolasaurus material. Judging from the associated fish and molluscs, we believe this new locality is about the same horizon as the type locality of Angolasaurus and Angolatitan.
We returned to Luanda on the 15th to begin the next leg of the expedition.
Lack of internet access in the field and available time the last week delayed the blog updates. I am not sure if this entry really counts as a "field blog" update, as I am sitting in a nice comfortable chair in my air conditioned family room at home, but I did want to provide a final update for this years field work.
June 11th through the 14th. The morning of the 11th I wrapped up work on "Big Mo", the large Prognathodon I discovered last year. We had determined that collecting the specimen was just too ambitious for this year given our available time and crew size, so we have decided to rebury the specimen for collection in 2013. In the afternoon I shifted my focus to collecting other specimens found in previous years and some from this season. I checked out the articulated vertebrae that Octavio had found the previous day. We had a student from the Methodist University in Luanda working with us this year, Ana Marques, and together we began to excavate the specimen. It turned out to be the portion of the tail preserved in articulation was the section that bears a dorsal fleshy fluke and ventral bend. There
were also a number of isolated vertebrae from the anterior part of the tail surrounding it, but it appeared that this was the only portion of the animal preserved; However, the next morning we decided to move more of the overburden and witihin five minutes of arriving on site we found what appears to be a relatively complete skull and artculated neck vertebrae and some isolated limb and girdle elements. Over the next two days and with the help of Ana, Ricardo, and Louis we recovered the entire specimen in two large jackets and a number of smaller ones.
Articulated portions of tail of russellosaurian mosasaur.
Skeleton of the new specimen.
Ricardo and Ana excavating tail block.
Ricardo has been largely focused on collecting plesiosaur specimens to augment the collection made in previous years, the material on which his Phd work is based. This year he was able to find additional specimens that allow us to definitively link a number of partial skeletons to specific taxa, giving us a better composite view of their anatomy and thus providing better data to determine their relationships.
Ricardo excavating plesiosaur specimens.
Octavio has spent most of his time prospecting for dinosaurs in the terrestrial sediments near Bentiaba, finding a large number of bone fragments, some identifiable as sauropod limb elements. He also found yet another partial skull of the turtle Euclastes
Octavio and Ana excavating a partial Euclastes skull.
Partial Euclastes skull
On the 15th I drove Louis, Ricardo, Tyrone, and Ana to Lubango. Tyrone and Ana are finished with their field work for this year. Louis and Ricardo will meet another member of our crew, Scott Myers, in Luanda on the 17th. Those three will then travel to the northern province of Cabinda to collect fossil and isotope samples and collect data to work out the stratigraphy and paleotemperature of these fossil bearing sediments. During the trip to Cabinda the crew collected numerous fish teeth, a complete skull of a turtle, a crocodile humerous, and a single vertebra of a small snake. A major focus of the Cabinda leg was to sample and examine the rocks and fossils of Cabinda that are relevant to human evolution and to the climatic and environmental history of Africa and the Tropics. One of the most important topics in African paleontology is human evolution, documented mainly in East Africa. There has been no Tropical lowland West African record of fossil primates until our discovery of a single tooth in Cabinda. The importance of this find cannot be over estimated because it opens a new chapter that cannot be found elsewhere. Additioanally, they sampled the rocks for magnetic and chemical analysis that will be used to understand climatic changes in the African Tropics associated with such global events as the onset of Antarctic glaciation, which provide an environmental context for human evolution. Because the age of the rocks is imprecisely known, our work will have a major impact on this facet of science.
Cabinda localities. Jungle covers just about everything except the cliffs along the shore. These beach localities are the focus on our work here.
Ricardo and Scott on the largely vertical outcrops.
Louis and Scott collecting samples.
Turtle skull collected this year at Landana
Johanna Salminen (University of Helsinki, Finland) joined the team in Lubango on the 15th, returning with me to Bentiaba. She is a specialist in paleomagnetism. Throughout its history, the magentic polarity of the Earth has changed occassionally, and in some cases, as rocks are formed , they record that polarity. The dates of these polarity changes are now well known and the reversals can be used to correlate rocks over long distances. She collected rock samples from the Cretaceous sediments of Bentiaba and the K-Pg boundary section at Namibe to assist us with more precise dating of the rocks. Her colleague David Evans (Yale University) joined her in Lubango on the 27th to sample some of the oldest rocks in Angola to understand how the continent of Africa was formed. Certain kinds of rock found within granite in Namibe and Huíla can show through their magnetic properties how the continent of Africa was originally assembled. This is a fundamental scientific investigation and a direct outgrowth of discussions centered on our original work.
Johanna Salminen (University of Helsinki, Finland) with coring equipment.
Johanna sampling for paleomag at the K-Pg boundary in Namibe province.
Mike, Johanna, and Octavio at K-Pg boundary locality.
I spent the last few days at Bentiaba collecting the large Prognathodon specimen I found this year. Octavio collected a portion of a pterosaur wing. Although most of the specimen was left covered, it is the most complete found so far, consisting of at least three bones in articulation. He also began to uncover one of the turtle specimens I found this year. When I found it, only a few peripheral plates were showing, weathering out of the hill. As Octavio began to uncover the specimen,
the costal ribs were found in place and it became apparent that we had a semi-articulated (and given previous experience here), a relatively complete skeleton. However, this was the last day in the field and we were running out of time, so this fossil was also reburied for excavation next year.
Pterosaur wing block. Top left is the defined block prior to plastering, top right is a detail of the bone that was weathering on the surace, and the bottom image is teh block just prior to removal.
Octavio digging an articulated turtle. This one will need to wait till next year due to time constraints.
During the last week in Angola, Octavio and I began managing the crating and shipping of the collection. Joined by student Claudio Raposo (Agostinho Neto University, Angola), we also took one day to go to the Turonian locality of Iembe to collect the remains of a ninety million-year–old specimen of the turtle
previously named by Projecto PaleoAngola Angolachelys mbaxi. This specimen was discovered by Johan Lindgren who joined us during our 2009 field season, and is the best preserved and most complete specimen found thus far. Louis, Octavio and I had collected the skull block and part of the postcrania in 2011, but the large block collected by Octavio and I this year contains much of the postcrania. On our return drive from Iembe, we stopped to prospect sediments north of Barra do Dande and discovered another locality. It is interesting because it appears to contain a Campanian fauna and we found a couple of teeth of a rare durophageous mosasaur Globidens, that appears to be a different taxon from those reported elsewhere. The rest of the crew joined us in Luanda mid-week to finish the shipping prepartation that includes the collections made in 2011 and 2012 field seasons.
Removing the final block of the 2009 Angolachelys specimen.
Octavio and I talking to the students about fossils at the school in Iembe, the type locality of Angolatitan, Angolasaurus, and Angolachelys.
Repacking crates in Luanda.
Crates being prepared for shipment.
The crew left Luanda on the 30th of June.
The field team for the 2012 Projecto PaleoAngola Field Expedition included the following participants:
Louis L. Jacobs (Southern Methodist University, USA)
Octávio Mateus (FCT, UNL, Portugal)
Michael J. Polcyn (Southern Methodist University, USA)
Scott Myers (Southern Methodist University, USA)
Ricardo Araújo (Southern Methodist University, USA)
Ana Soraya Marques (Angola Methodist University, Angola)
Claudio Raposo (Agostinho Neto University, Angola)
Tyrone Rooney (Michigan State University, USA)
Johanna Salminen (University of Helsinki, Finland)
David Evans (Yale University, USA)
Funding for the field season was provided by Vida Foundation, Esso Angola through the Liga Nacional dos Amigos de 4 de Abril, the Institute for the Study of Earth and Man at Southern Methodist University, The Saurus Institute, and Yale University.
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